Bump to version 1.22.1
[platform/upstream/busybox.git] / editors / sed.c
index ac3d8d4..e18e48a 100644 (file)
  * Copyright (C) 1999,2000,2001 by Lineo, inc. and Mark Whitley
  * Copyright (C) 1999,2000,2001 by Mark Whitley <markw@codepoet.org>
  * Copyright (C) 2002  Matt Kraai
- * Copyright (C) 2003 by Glenn McGrath <bug1@iinet.net.au>
+ * Copyright (C) 2003 by Glenn McGrath
  * Copyright (C) 2003,2004 by Rob Landley <rob@landley.net>
  *
  * MAINTAINER: Rob Landley <rob@landley.net>
  *
- * Licensed under GPL version 2, see file LICENSE in this tarball for details.
+ * Licensed under GPLv2, see file LICENSE in this source tree.
  */
 
 /* Code overview.
+ *
+ * Files are laid out to avoid unnecessary function declarations.  So for
+ * example, every function add_cmd calls occurs before add_cmd in this file.
+ *
+ * add_cmd() is called on each line of sed command text (from a file or from
+ * the command line).  It calls get_address() and parse_cmd_args().  The
+ * resulting sed_cmd_t structures are appended to a linked list
+ * (G.sed_cmd_head/G.sed_cmd_tail).
+ *
+ * process_files() does actual sedding, reading data lines from each input FILE*
+ * (which could be stdin) and applying the sed command list (sed_cmd_head) to
+ * each of the resulting lines.
+ *
+ * sed_main() is where external code calls into this, with a command line.
+ */
 
-  Files are laid out to avoid unnecessary function declarations.  So for
-  example, every function add_cmd calls occurs before add_cmd in this file.
-
-  add_cmd() is called on each line of sed command text (from a file or from
-  the command line).  It calls get_address() and parse_cmd_args().  The
-  resulting sed_cmd_t structures are appended to a linked list
-  (bbg.sed_cmd_head/bbg.sed_cmd_tail).
-
-  add_input_file() adds a FILE * to the list of input files.  We need to
-  know all input sources ahead of time to find the last line for the $ match.
+/* Supported features and commands in this version of sed:
+ *
+ * - comments ('#')
+ * - address matching: num|/matchstr/[,num|/matchstr/|$]command
+ * - commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
+ * - edit commands: (a)ppend, (i)nsert, (c)hange
+ * - file commands: (r)ead
+ * - backreferences in substitution expressions (\0, \1, \2...\9)
+ * - grouped commands: {cmd1;cmd2}
+ * - transliteration (y/source-chars/dest-chars/)
+ * - pattern space hold space storing / swapping (g, h, x)
+ * - labels / branching (: label, b, t, T)
+ *
+ * (Note: Specifying an address (range) to match is *optional*; commands
+ * default to the whole pattern space if no specific address match was
+ * requested.)
+ *
+ * Todo:
+ * - Create a wrapper around regex to make libc's regex conform with sed
+ *
+ * Reference
+ * http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
+ * http://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
+ */
 
-  process_files() does actual sedding, reading data lines from each input FILE *
-  (which could be stdin) and applying the sed command list (sed_cmd_head) to
-  each of the resulting lines.
+//config:config SED
+//config:      bool "sed"
+//config:      default y
+//config:      help
+//config:        sed is used to perform text transformations on a file
+//config:        or input from a pipeline.
+
+//kbuild:lib-$(CONFIG_SED) += sed.o
+
+//applet:IF_SED(APPLET(sed, BB_DIR_BIN, BB_SUID_DROP))
+
+//usage:#define sed_trivial_usage
+//usage:       "[-inrE] [-f FILE]... [-e CMD]... [FILE]...\n"
+//usage:       "or: sed [-inrE] CMD [FILE]..."
+//usage:#define sed_full_usage "\n\n"
+//usage:       "       -e CMD  Add CMD to sed commands to be executed"
+//usage:     "\n       -f FILE Add FILE contents to sed commands to be executed"
+//usage:     "\n       -i[SFX] Edit files in-place (otherwise sends to stdout)"
+//usage:     "\n               Optionally back files up, appending SFX"
+//usage:     "\n       -n      Suppress automatic printing of pattern space"
+//usage:     "\n       -r,-E   Use extended regex syntax"
+//usage:     "\n"
+//usage:     "\nIf no -e or -f, the first non-option argument is the sed command string."
+//usage:     "\nRemaining arguments are input files (stdin if none)."
+//usage:
+//usage:#define sed_example_usage
+//usage:       "$ echo \"foo\" | sed -e 's/f[a-zA-Z]o/bar/g'\n"
+//usage:       "bar\n"
+
+#include "libbb.h"
+#include "xregex.h"
 
-  sed_main() is where external code calls into this, with a command line.
-*/
+#if 0
+# define dbg(...) bb_error_msg(__VA_ARGS__)
+#else
+# define dbg(...) ((void)0)
+#endif
 
 
-/*
-       Supported features and commands in this version of sed:
-
-        - comments ('#')
-        - address matching: num|/matchstr/[,num|/matchstr/|$]command
-        - commands: (p)rint, (d)elete, (s)ubstitue (with g & I flags)
-        - edit commands: (a)ppend, (i)nsert, (c)hange
-        - file commands: (r)ead
-        - backreferences in substitution expressions (\0, \1, \2...\9)
-        - grouped commands: {cmd1;cmd2}
-        - transliteration (y/source-chars/dest-chars/)
-        - pattern space hold space storing / swapping (g, h, x)
-        - labels / branching (: label, b, t, T)
-
-        (Note: Specifying an address (range) to match is *optional*; commands
-        default to the whole pattern space if no specific address match was
-        requested.)
-
-       Todo:
-        - Create a wrapper around regex to make libc's regex conform with sed
-
-       Reference http://www.opengroup.org/onlinepubs/007904975/utilities/sed.html
-*/
-
-#include "busybox.h"
-#include "xregex.h"
+enum {
+       OPT_in_place = 1 << 0,
+};
 
 /* Each sed command turns into one of these structures. */
 typedef struct sed_cmd_s {
        /* Ordered by alignment requirements: currently 36 bytes on x86 */
+       struct sed_cmd_s *next; /* Next command (linked list, NULL terminated) */
 
        /* address storage */
        regex_t *beg_match;     /* sed -e '/match/cmd' */
        regex_t *end_match;     /* sed -e '/match/,/end_match/cmd' */
        regex_t *sub_match;     /* For 's/sub_match/string/' */
        int beg_line;           /* 'sed 1p'   0 == apply commands to all lines */
+       int beg_line_orig;      /* copy of the above, needed for -i */
        int end_line;           /* 'sed 1,3p' 0 == one line only. -1 = last line ($) */
 
-       FILE *file;             /* File (sw) command writes to, -1 for none. */
+       FILE *sw_file;          /* File (sw) command writes to, -1 for none. */
        char *string;           /* Data string for (saicytb) commands. */
 
-       unsigned short which_match;     /* (s) Which match to replace (0 for all) */
+       unsigned which_match;   /* (s) Which match to replace (0 for all) */
 
        /* Bitfields (gcc won't group them if we don't) */
-       unsigned int invert:1;          /* the '!' after the address */
-       unsigned int in_match:1;        /* Next line also included in match? */
-       unsigned int sub_p:1;           /* (s) print option */
+       unsigned invert:1;      /* the '!' after the address */
+       unsigned in_match:1;    /* Next line also included in match? */
+       unsigned sub_p:1;       /* (s) print option */
 
-       int last_char;                  /* Last line written by (sw) had no '\n' */
+       char sw_last_char;      /* Last line written by (sw) had no '\n' */
 
        /* GENERAL FIELDS */
        char cmd;               /* The command char: abcdDgGhHilnNpPqrstwxy:={} */
-       struct sed_cmd_s *next; /* Next command (linked list, NULL terminated) */
 } sed_cmd_t;
 
-static const char *const semicolon_whitespace = "; \n\r\t\v";
+static const char semicolon_whitespace[] ALIGN1 = "; \n\r\t\v";
 
-struct sed_globals {
+struct globals {
        /* options */
        int be_quiet, regex_type;
+
        FILE *nonstdout;
        char *outname, *hold_space;
+       smallint exitcode;
 
-       /* List of input files */
-       int input_file_count, current_input_file;
-       FILE **input_file_list;
+       /* list of input files */
+       int current_input_file, last_input_file;
+       char **input_file_list;
+       FILE *current_fp;
 
        regmatch_t regmatch[10];
        regex_t *previous_regex_ptr;
 
        /* linked list of sed commands */
-       sed_cmd_t sed_cmd_head, *sed_cmd_tail;
+       sed_cmd_t *sed_cmd_head, **sed_cmd_tail;
 
-       /* Linked list of append lines */
+       /* linked list of append lines */
        llist_t *append_head;
 
        char *add_cmd_line;
 
        struct pipeline {
-               char *buf;      /* Space to hold string */
-               int idx;        /* Space used */
-               int len;        /* Space allocated */
+               char *buf;  /* Space to hold string */
+               int idx;    /* Space used */
+               int len;    /* Space allocated */
        } pipeline;
-} bbg;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
+struct BUG_G_too_big {
+       char BUG_G_too_big[sizeof(G) <= COMMON_BUFSIZE ? 1 : -1];
+};
+#define INIT_G() do { \
+       G.sed_cmd_tail = &G.sed_cmd_head; \
+} while (0)
 
 
-void sed_free_and_close_stuff(void);
 #if ENABLE_FEATURE_CLEAN_UP
 static void sed_free_and_close_stuff(void)
 {
-       sed_cmd_t *sed_cmd = bbg.sed_cmd_head.next;
+       sed_cmd_t *sed_cmd = G.sed_cmd_head;
 
-       llist_free(bbg.append_head, free);
+       llist_free(G.append_head, free);
 
        while (sed_cmd) {
                sed_cmd_t *sed_cmd_next = sed_cmd->next;
 
-               if (sed_cmd->file)
-                       xprint_and_close_file(sed_cmd->file);
+               if (sed_cmd->sw_file)
+                       xprint_and_close_file(sed_cmd->sw_file);
 
                if (sed_cmd->beg_match) {
                        regfree(sed_cmd->beg_match);
@@ -151,44 +198,55 @@ static void sed_free_and_close_stuff(void)
                sed_cmd = sed_cmd_next;
        }
 
-       if (bbg.hold_space) free(bbg.hold_space);
+       free(G.hold_space);
 
-       while (bbg.current_input_file < bbg.input_file_count)
-               fclose(bbg.input_file_list[bbg.current_input_file++]);
+       if (G.current_fp)
+               fclose(G.current_fp);
 }
+#else
+void sed_free_and_close_stuff(void);
 #endif
 
 /* If something bad happens during -i operation, delete temp file */
 
 static void cleanup_outname(void)
 {
-       if (bbg.outname) unlink(bbg.outname);
+       if (G.outname) unlink(G.outname);
 }
 
-/* strdup, replacing "\n" with '\n', and "\delimiter" with 'delimiter' */
+/* strcpy, replacing "\from" with 'to'. If to is NUL, replacing "\any" with 'any' */
 
-static void parse_escapes(char *dest, char *string, int len, char from, char to)
+static void parse_escapes(char *dest, const char *string, int len, char from, char to)
 {
        int i = 0;
 
        while (i < len) {
                if (string[i] == '\\') {
                        if (!to || string[i+1] == from) {
-                               *(dest++) = to ? to : string[i+1];
+                               *dest++ = to ? to : string[i+1];
                                i += 2;
                                continue;
-                       } else *(dest++) = string[i++];
+                       }
+                       *dest++ = string[i++];
                }
-               *(dest++) = string[i++];
+               /* TODO: is it safe wrt a string with trailing '\\' ? */
+               *dest++ = string[i++];
        }
-       *dest = 0;
+       *dest = '\0';
 }
 
-static char *copy_parsing_escapes(char *string, int len)
+static char *copy_parsing_escapes(const char *string, int len)
 {
+       const char *s;
        char *dest = xmalloc(len + 1);
 
-       parse_escapes(dest, string, len, 'n', '\n');
+       /* sed recognizes \n */
+       /* GNU sed also recognizes \t and \r */
+       for (s = "\nn\tt\rr"; *s; s += 2) {
+               parse_escapes(dest, string, len, s[1], s[0]);
+               string = dest;
+               len = strlen(dest);
+       }
        return dest;
 }
 
@@ -196,10 +254,10 @@ static char *copy_parsing_escapes(char *string, int len)
 /*
  * index_of_next_unescaped_regexp_delim - walks left to right through a string
  * beginning at a specified index and returns the index of the next regular
- * expression delimiter (typically a forward slash ('/')) not preceded by
+ * expression delimiter (typically a forward slash ('/')) not preceded by
  * a backslash ('\').  A negative delimiter disables square bracket checking.
  */
-static int index_of_next_unescaped_regexp_delim(int delimiter, char *str)
+static int index_of_next_unescaped_regexp_delim(int delimiter, const char *str)
 {
        int bracket = -1;
        int escaped = 0;
@@ -211,11 +269,13 @@ static int index_of_next_unescaped_regexp_delim(int delimiter, char *str)
                delimiter = -delimiter;
        }
 
-       for (; (ch = str[idx]); idx++) {
+       for (; (ch = str[idx]) != '\0'; idx++) {
                if (bracket >= 0) {
-                       if (ch == ']' && !(bracket == idx - 1 || (bracket == idx - 2
-                                       && str[idx - 1] == '^')))
+                       if (ch == ']'
+                        && !(bracket == idx - 1 || (bracket == idx - 2 && str[idx - 1] == '^'))
+                       ) {
                                bracket = -1;
+                       }
                } else if (escaped)
                        escaped = 0;
                else if (ch == '\\')
@@ -233,10 +293,10 @@ static int index_of_next_unescaped_regexp_delim(int delimiter, char *str)
 /*
  *  Returns the index of the third delimiter
  */
-static int parse_regex_delim(char *cmdstr, char **match, char **replace)
+static int parse_regex_delim(const char *cmdstr, char **match, char **replace)
 {
-       char *cmdstr_ptr = cmdstr;
-       char delimiter;
+       const char *cmdstr_ptr = cmdstr;
+       unsigned char delimiter;
        int idx = 0;
 
        /* verify that the 's' or 'y' is followed by something.  That something
@@ -251,7 +311,7 @@ static int parse_regex_delim(char *cmdstr, char **match, char **replace)
 
        /* save the replacement string */
        cmdstr_ptr += idx + 1;
-       idx = index_of_next_unescaped_regexp_delim(-delimiter, cmdstr_ptr);
+       idx = index_of_next_unescaped_regexp_delim(- (int)delimiter, cmdstr_ptr);
        *replace = copy_parsing_escapes(cmdstr_ptr, idx);
 
        return ((cmdstr_ptr - cmdstr) + idx);
@@ -260,12 +320,12 @@ static int parse_regex_delim(char *cmdstr, char **match, char **replace)
 /*
  * returns the index in the string just past where the address ends.
  */
-static int get_address(char *my_str, int *linenum, regex_t ** regex)
+static int get_address(const char *my_str, int *linenum, regex_t ** regex)
 {
-       char *pos = my_str;
+       const char *pos = my_str;
 
        if (isdigit(*my_str)) {
-               *linenum = strtol(my_str, &pos, 10);
+               *linenum = strtol(my_str, (char**)&pos, 10);
                /* endstr shouldnt ever equal NULL */
        } else if (*my_str == '$') {
                *linenum = -1;
@@ -276,11 +336,12 @@ static int get_address(char *my_str, int *linenum, regex_t ** regex)
                char *temp;
 
                delimiter = '/';
-               if (*my_str == '\\') delimiter = *++pos;
+               if (*my_str == '\\')
+                       delimiter = *++pos;
                next = index_of_next_unescaped_regexp_delim(delimiter, ++pos);
                temp = copy_parsing_escapes(pos, next);
-               *regex = xmalloc(sizeof(regex_t));
-               xregcomp(*regex, temp, bbg.regex_type|REG_NEWLINE);
+               *regex = xzalloc(sizeof(regex_t));
+               xregcomp(*regex, temp, G.regex_type);
                free(temp);
                /* Move position to next character after last delimiter */
                pos += (next+1);
@@ -289,34 +350,38 @@ static int get_address(char *my_str, int *linenum, regex_t ** regex)
 }
 
 /* Grab a filename.  Whitespace at start is skipped, then goes to EOL. */
-static int parse_file_cmd(sed_cmd_t *sed_cmd, char *filecmdstr, char **retval)
+static int parse_file_cmd(/*sed_cmd_t *sed_cmd,*/ const char *filecmdstr, char **retval)
 {
        int start = 0, idx, hack = 0;
 
        /* Skip whitespace, then grab filename to end of line */
-       while (isspace(filecmdstr[start])) start++;
+       while (isspace(filecmdstr[start]))
+               start++;
        idx = start;
-       while (filecmdstr[idx] && filecmdstr[idx] != '\n') idx++;
+       while (filecmdstr[idx] && filecmdstr[idx] != '\n')
+               idx++;
 
        /* If lines glued together, put backslash back. */
-       if (filecmdstr[idx] == '\n') hack = 1;
+       if (filecmdstr[idx] == '\n')
+               hack = 1;
        if (idx == start)
                bb_error_msg_and_die("empty filename");
        *retval = xstrndup(filecmdstr+start, idx-start+hack+1);
-       if (hack) (*retval)[idx] = '\\';
+       if (hack)
+               (*retval)[idx] = '\\';
 
        return idx;
 }
 
-static int parse_subst_cmd(sed_cmd_t *sed_cmd, char *substr)
+static int parse_subst_cmd(sed_cmd_t *sed_cmd, const char *substr)
 {
-       int cflags = bbg.regex_type;
+       int cflags = G.regex_type;
        char *match;
-       int idx = 0;
+       int idx;
 
        /*
         * A substitution command should look something like this:
-        *    s/match/replace/ #gIpw
+        *    s/match/replace/ #giIpw
         *    ||     |        |||
         *    mandatory       optional
         */
@@ -335,20 +400,22 @@ static int parse_subst_cmd(sed_cmd_t *sed_cmd, char *substr)
                if (isdigit(substr[idx])) {
                        if (match[0] != '^') {
                                /* Match 0 treated as all, multiple matches we take the last one. */
-                               char *pos = substr + idx;
-                               /* FIXME: error check? */
-                               sed_cmd->which_match = (unsigned short)strtol(substr+idx, &pos, 10);
+                               const char *pos = substr + idx;
+/* FIXME: error check? */
+                               sed_cmd->which_match = (unsigned)strtol(substr+idx, (char**) &pos, 10);
                                idx = pos - substr;
                        }
                        continue;
                }
                /* Skip spaces */
-               if (isspace(substr[idx])) continue;
+               if (isspace(substr[idx]))
+                       continue;
 
                switch (substr[idx]) {
                /* Replace all occurrences */
                case 'g':
-                       if (match[0] != '^') sed_cmd->which_match = 0;
+                       if (match[0] != '^')
+                               sed_cmd->which_match = 0;
                        break;
                /* Print pattern space */
                case 'p':
@@ -358,17 +425,18 @@ static int parse_subst_cmd(sed_cmd_t *sed_cmd, char *substr)
                case 'w':
                {
                        char *temp;
-                       idx += parse_file_cmd(sed_cmd, substr+idx, &temp);
-
+                       idx += parse_file_cmd(/*sed_cmd,*/ substr+idx, &temp);
                        break;
                }
                /* Ignore case (gnu exension) */
+               case 'i':
                case 'I':
                        cflags |= REG_ICASE;
                        break;
                /* Comment */
                case '#':
-                       while (substr[++idx]) /*skip all*/;
+                       // while (substr[++idx]) continue;
+                       idx += strlen(substr + idx); // same
                        /* Fall through */
                /* End of command */
                case ';':
@@ -378,12 +446,14 @@ static int parse_subst_cmd(sed_cmd_t *sed_cmd, char *substr)
                        bb_error_msg_and_die("bad option in substitution expression");
                }
        }
-out:
+ out:
        /* compile the match string into a regex */
        if (*match != '\0') {
                /* If match is empty, we use last regex used at runtime */
-               sed_cmd->sub_match = (regex_t *) xmalloc(sizeof(regex_t));
+               sed_cmd->sub_match = xzalloc(sizeof(regex_t));
+               dbg("xregcomp('%s',%x)", match, cflags);
                xregcomp(sed_cmd->sub_match, match, cflags);
+               dbg("regcomp ok");
        }
        free(match);
 
@@ -393,37 +463,81 @@ out:
 /*
  *  Process the commands arguments
  */
-static char *parse_cmd_args(sed_cmd_t *sed_cmd, char *cmdstr)
+static const char *parse_cmd_args(sed_cmd_t *sed_cmd, const char *cmdstr)
 {
+       static const char cmd_letters[] = "saicrw:btTydDgGhHlnNpPqx={}";
+       enum {
+               IDX_s = 0,
+               IDX_a,
+               IDX_i,
+               IDX_c,
+               IDX_r,
+               IDX_w,
+               IDX_colon,
+               IDX_b,
+               IDX_t,
+               IDX_T,
+               IDX_y,
+               IDX_d,
+               IDX_D,
+               IDX_g,
+               IDX_G,
+               IDX_h,
+               IDX_H,
+               IDX_l,
+               IDX_n,
+               IDX_N,
+               IDX_p,
+               IDX_P,
+               IDX_q,
+               IDX_x,
+               IDX_equal,
+               IDX_lbrace,
+               IDX_rbrace,
+               IDX_nul
+       };
+       struct chk { char chk[sizeof(cmd_letters)-1 == IDX_nul ? 1 : -1]; };
+
+       unsigned idx = strchrnul(cmd_letters, sed_cmd->cmd) - cmd_letters;
+
        /* handle (s)ubstitution command */
-       if (sed_cmd->cmd == 's')
+       if (idx == IDX_s) {
                cmdstr += parse_subst_cmd(sed_cmd, cmdstr);
+       }
        /* handle edit cmds: (a)ppend, (i)nsert, and (c)hange */
-       else if (strchr("aic", sed_cmd->cmd)) {
-               if ((sed_cmd->end_line || sed_cmd->end_match) && sed_cmd->cmd != 'c')
-                       bb_error_msg_and_die
-                               ("only a beginning address can be specified for edit commands");
+       else if (idx <= IDX_c) { /* a,i,c */
+               if (idx < IDX_c) { /* a,i */
+                       if (sed_cmd->end_line || sed_cmd->end_match)
+                               bb_error_msg_and_die("command '%c' uses only one address", sed_cmd->cmd);
+               }
                for (;;) {
                        if (*cmdstr == '\n' || *cmdstr == '\\') {
                                cmdstr++;
                                break;
-                       } else if (isspace(*cmdstr))
-                               cmdstr++;
-                       else
+                       }
+                       if (!isspace(*cmdstr))
                                break;
+                       cmdstr++;
                }
                sed_cmd->string = xstrdup(cmdstr);
-               parse_escapes(sed_cmd->string, sed_cmd->string, strlen(cmdstr), 0, 0);
+               /* "\anychar" -> "anychar" */
+               parse_escapes(sed_cmd->string, sed_cmd->string, strlen(cmdstr), '\0', '\0');
                cmdstr += strlen(cmdstr);
+       }
        /* handle file cmds: (r)ead */
-       } else if (strchr("rw", sed_cmd->cmd)) {
-               if (sed_cmd->end_line || sed_cmd->end_match)
-                       bb_error_msg_and_die("command only uses one address");
-               cmdstr += parse_file_cmd(sed_cmd, cmdstr, &sed_cmd->string);
-               if (sed_cmd->cmd == 'w')
-                       sed_cmd->file = xfopen(sed_cmd->string, "w");
+       else if (idx <= IDX_w) { /* r,w */
+               if (idx < IDX_w) { /* r */
+                       if (sed_cmd->end_line || sed_cmd->end_match)
+                               bb_error_msg_and_die("command '%c' uses only one address", sed_cmd->cmd);
+               }
+               cmdstr += parse_file_cmd(/*sed_cmd,*/ cmdstr, &sed_cmd->string);
+               if (sed_cmd->cmd == 'w') {
+                       sed_cmd->sw_file = xfopen_for_write(sed_cmd->string);
+                       sed_cmd->sw_last_char = '\n';
+               }
+       }
        /* handle branch commands */
-       } else if (strchr(":btT", sed_cmd->cmd)) {
+       else if (idx <= IDX_T) { /* :,b,t,T */
                int length;
 
                cmdstr = skip_whitespace(cmdstr);
@@ -434,7 +548,7 @@ static char *parse_cmd_args(sed_cmd_t *sed_cmd, char *cmdstr)
                }
        }
        /* translation command */
-       else if (sed_cmd->cmd == 'y') {
+       else if (idx == IDX_y) {
                char *match, *replace;
                int i = cmdstr[0];
 
@@ -454,7 +568,7 @@ static char *parse_cmd_args(sed_cmd_t *sed_cmd, char *cmdstr)
        /* if it wasnt a single-letter command that takes no arguments
         * then it must be an invalid command.
         */
-       else if (strchr("dDgGhHlnNpPqx={}", sed_cmd->cmd) == 0) {
+       else if (idx >= IDX_nul) { /* not d,D,g,G,h,H,l,n,N,p,P,q,x,=,{,} */
                bb_error_msg_and_die("unsupported command %c", sed_cmd->cmd);
        }
 
@@ -465,24 +579,26 @@ static char *parse_cmd_args(sed_cmd_t *sed_cmd, char *cmdstr)
 
 /* Parse address+command sets, skipping comment lines. */
 
-static void add_cmd(char *cmdstr)
+static void add_cmd(const char *cmdstr)
 {
        sed_cmd_t *sed_cmd;
-       int temp;
+       unsigned len, n;
 
        /* Append this line to any unfinished line from last time. */
-       if (bbg.add_cmd_line) {
-               cmdstr = xasprintf("%s\n%s", bbg.add_cmd_line, cmdstr);
-               free(bbg.add_cmd_line);
-               bbg.add_cmd_line = cmdstr;
+       if (G.add_cmd_line) {
+               char *tp = xasprintf("%s\n%s", G.add_cmd_line, cmdstr);
+               free(G.add_cmd_line);
+               cmdstr = G.add_cmd_line = tp;
        }
 
-       /* If this line ends with backslash, request next line. */
-       temp = strlen(cmdstr);
-       if (temp && cmdstr[temp-1] == '\\') {
-               if (!bbg.add_cmd_line)
-                       bbg.add_cmd_line = xstrdup(cmdstr);
-               bbg.add_cmd_line[temp-1] = 0;
+       /* If this line ends with unescaped backslash, request next line. */
+       n = len = strlen(cmdstr);
+       while (n && cmdstr[n-1] == '\\')
+               n--;
+       if ((len - n) & 1) { /* if odd number of trailing backslashes */
+               if (!G.add_cmd_line)
+                       G.add_cmd_line = xstrdup(cmdstr);
+               G.add_cmd_line[len-1] = '\0';
                return;
        }
 
@@ -498,7 +614,7 @@ static void add_cmd(char *cmdstr)
                if (*cmdstr == '#') {
                        /* "#n" is the same as using -n on the command line */
                        if (cmdstr[1] == 'n')
-                               bbg.be_quiet++;
+                               G.be_quiet++;
                        cmdstr = strpbrk(cmdstr, "\n\r");
                        if (!cmdstr) break;
                        continue;
@@ -514,6 +630,7 @@ static void add_cmd(char *cmdstr)
 
                /* first part (if present) is an address: either a '$', a number or a /regex/ */
                cmdstr += get_address(cmdstr, &sed_cmd->beg_line, &sed_cmd->beg_match);
+               sed_cmd->beg_line_orig = sed_cmd->beg_line;
 
                /* second part (if present) will begin with a comma */
                if (*cmdstr == ',') {
@@ -541,17 +658,23 @@ static void add_cmd(char *cmdstr)
                /* last part (mandatory) will be a command */
                if (!*cmdstr)
                        bb_error_msg_and_die("missing command");
-               sed_cmd->cmd = *(cmdstr++);
+               sed_cmd->cmd = *cmdstr++;
                cmdstr = parse_cmd_args(sed_cmd, cmdstr);
 
+               /* cmdstr now points past args.
+                * GNU sed requires a separator, if there are more commands,
+                * else it complains "char N: extra characters after command".
+                * Example: "sed 'p;d'". We also allow "sed 'pd'".
+                */
+
                /* Add the command to the command array */
-               bbg.sed_cmd_tail->next = sed_cmd;
-               bbg.sed_cmd_tail = bbg.sed_cmd_tail->next;
+               *G.sed_cmd_tail = sed_cmd;
+               G.sed_cmd_tail = &sed_cmd->next;
        }
 
        /* If we glued multiple lines together, free the memory. */
-       free(bbg.add_cmd_line);
-       bbg.add_cmd_line = NULL;
+       free(G.add_cmd_line);
+       G.add_cmd_line = NULL;
 }
 
 /* Append to a string, reallocating memory as necessary. */
@@ -560,117 +683,165 @@ static void add_cmd(char *cmdstr)
 
 static void pipe_putc(char c)
 {
-       if (bbg.pipeline.idx == bbg.pipeline.len) {
-               bbg.pipeline.buf = xrealloc(bbg.pipeline.buf,
-                               bbg.pipeline.len + PIPE_GROW);
-               bbg.pipeline.len += PIPE_GROW;
+       if (G.pipeline.idx == G.pipeline.len) {
+               G.pipeline.buf = xrealloc(G.pipeline.buf,
+                               G.pipeline.len + PIPE_GROW);
+               G.pipeline.len += PIPE_GROW;
        }
-       bbg.pipeline.buf[bbg.pipeline.idx++] = c;
+       G.pipeline.buf[G.pipeline.idx++] = c;
 }
 
 static void do_subst_w_backrefs(char *line, char *replace)
 {
-       int i,j;
+       int i, j;
 
        /* go through the replacement string */
        for (i = 0; replace[i]; i++) {
-               /* if we find a backreference (\1, \2, etc.) print the backref'ed * text */
-               if (replace[i] == '\\' && replace[i+1] >= '0' && replace[i+1] <= '9') {
-                       int backref = replace[++i]-'0';
-
-                       /* print out the text held in bbg.regmatch[backref] */
-                       if (bbg.regmatch[backref].rm_so != -1) {
-                               j = bbg.regmatch[backref].rm_so;
-                               while (j < bbg.regmatch[backref].rm_eo)
-                                       pipe_putc(line[j++]);
+               /* if we find a backreference (\1, \2, etc.) print the backref'ed text */
+               if (replace[i] == '\\') {
+                       unsigned backref = replace[++i] - '0';
+                       if (backref <= 9) {
+                               /* print out the text held in G.regmatch[backref] */
+                               if (G.regmatch[backref].rm_so != -1) {
+                                       j = G.regmatch[backref].rm_so;
+                                       while (j < G.regmatch[backref].rm_eo)
+                                               pipe_putc(line[j++]);
+                               }
+                               continue;
                        }
+                       /* I _think_ it is impossible to get '\' to be
+                        * the last char in replace string. Thus we dont check
+                        * for replace[i] == NUL. (counterexample anyone?) */
+                       /* if we find a backslash escaped character, print the character */
+                       pipe_putc(replace[i]);
+                       continue;
                }
-
-               /* if we find a backslash escaped character, print the character */
-               else if (replace[i] == '\\') pipe_putc(replace[++i]);
-
                /* if we find an unescaped '&' print out the whole matched text. */
-               else if (replace[i] == '&') {
-                       j = bbg.regmatch[0].rm_so;
-                       while (j < bbg.regmatch[0].rm_eo)
+               if (replace[i] == '&') {
+                       j = G.regmatch[0].rm_so;
+                       while (j < G.regmatch[0].rm_eo)
                                pipe_putc(line[j++]);
+                       continue;
                }
                /* Otherwise just output the character. */
-               else pipe_putc(replace[i]);
+               pipe_putc(replace[i]);
        }
 }
 
-static int do_subst_command(sed_cmd_t *sed_cmd, char **line)
+static int do_subst_command(sed_cmd_t *sed_cmd, char **line_p)
 {
-       char *oldline = *line;
-       int altered = 0;
-       int match_count = 0;
+       char *line = *line_p;
+       unsigned match_count = 0;
+       bool altered = 0;
+       bool prev_match_empty = 1;
+       bool tried_at_eol = 0;
        regex_t *current_regex;
 
+       current_regex = sed_cmd->sub_match;
        /* Handle empty regex. */
-       if (sed_cmd->sub_match == NULL) {
-               current_regex = bbg.previous_regex_ptr;
+       if (!current_regex) {
+               current_regex = G.previous_regex_ptr;
                if (!current_regex)
                        bb_error_msg_and_die("no previous regexp");
-       } else
-               bbg.previous_regex_ptr = current_regex = sed_cmd->sub_match;
+       }
+       G.previous_regex_ptr = current_regex;
 
        /* Find the first match */
-       if (REG_NOMATCH == regexec(current_regex, oldline, 10, bbg.regmatch, 0))
+       dbg("matching '%s'", line);
+       if (REG_NOMATCH == regexec(current_regex, line, 10, G.regmatch, 0)) {
+               dbg("no match");
                return 0;
+       }
+       dbg("match");
 
        /* Initialize temporary output buffer. */
-       bbg.pipeline.buf = xmalloc(PIPE_GROW);
-       bbg.pipeline.len = PIPE_GROW;
-       bbg.pipeline.idx = 0;
+       G.pipeline.buf = xmalloc(PIPE_GROW);
+       G.pipeline.len = PIPE_GROW;
+       G.pipeline.idx = 0;
 
        /* Now loop through, substituting for matches */
        do {
+               int start = G.regmatch[0].rm_so;
+               int end = G.regmatch[0].rm_eo;
                int i;
 
-               /* Work around bug in glibc regexec, demonstrated by:
-                  echo " a.b" | busybox sed 's [^ .]* x g'
-                  The match_count check is so not to break
-                  echo "hi" | busybox sed 's/^/!/g' */
-               if (!bbg.regmatch[0].rm_so && !bbg.regmatch[0].rm_eo && match_count) {
-                       pipe_putc(*oldline++);
-                       continue;
-               }
-
                match_count++;
 
                /* If we aren't interested in this match, output old line to
-                  end of match and continue */
-               if (sed_cmd->which_match && sed_cmd->which_match != match_count) {
-                       for (i = 0; i < bbg.regmatch[0].rm_eo; i++)
-                               pipe_putc(*oldline++);
-                       continue;
+                * end of match and continue */
+               if (sed_cmd->which_match
+                && (sed_cmd->which_match != match_count)
+               ) {
+                       for (i = 0; i < end; i++)
+                               pipe_putc(*line++);
+                       /* Null match? Print one more char */
+                       if (start == end && *line)
+                               pipe_putc(*line++);
+                       goto next;
                }
 
-               /* print everything before the match */
-               for (i = 0; i < bbg.regmatch[0].rm_so; i++)
-                       pipe_putc(oldline[i]);
+               /* Print everything before the match */
+               for (i = 0; i < start; i++)
+                       pipe_putc(line[i]);
 
-               /* then print the substitution string */
-               do_subst_w_backrefs(oldline, sed_cmd->string);
+               /* Then print the substitution string,
+                * unless we just matched empty string after non-empty one.
+                * Example: string "cccd", pattern "c*", repl "R":
+                * result is "RdR", not "RRdR": first match "ccc",
+                * second is "" before "d", third is "" after "d".
+                * Second match is NOT replaced!
+                */
+               if (prev_match_empty || start != 0 || start != end) {
+                       //dbg("%d %d %d", prev_match_empty, start, end);
+                       dbg("inserting replacement at %d in '%s'", start, line);
+                       do_subst_w_backrefs(line, sed_cmd->string);
+                       /* Flag that something has changed */
+                       altered = 1;
+               } else {
+                       dbg("NOT inserting replacement at %d in '%s'", start, line);
+               }
+
+               /* If matched string is empty (f.e. "c*" pattern),
+                * copy verbatim one char after it before attempting more matches
+                */
+               prev_match_empty = (start == end);
+               if (prev_match_empty) {
+                       if (!line[end]) {
+                               tried_at_eol = 1;
+                       } else {
+                               pipe_putc(line[end]);
+                               end++;
+                       }
+               }
 
-               /* advance past the match */
-               oldline += bbg.regmatch[0].rm_eo;
-               /* flag that something has changed */
-               altered++;
+               /* Advance past the match */
+               dbg("line += %d", end);
+               line += end;
 
                /* if we're not doing this globally, get out now */
-               if (sed_cmd->which_match) break;
-       } while (*oldline && (regexec(current_regex, oldline, 10, bbg.regmatch, 0) != REG_NOMATCH));
+               if (sed_cmd->which_match != 0)
+                       break;
+ next:
+               /* Exit if we are at EOL and already tried matching at it */
+               if (*line == '\0') {
+                       if (tried_at_eol)
+                               break;
+                       tried_at_eol = 1;
+               }
 
-       /* Copy rest of string into output pipeline */
+//maybe (end ? REG_NOTBOL : 0) instead of unconditional REG_NOTBOL?
+       } while (regexec(current_regex, line, 10, G.regmatch, REG_NOTBOL) != REG_NOMATCH);
 
-       while (*oldline)
-               pipe_putc(*oldline++);
-       pipe_putc(0);
+       /* Copy rest of string into output pipeline */
+       while (1) {
+               char c = *line++;
+               pipe_putc(c);
+               if (c == '\0')
+                       break;
+       }
 
-       free(*line);
-       *line = bbg.pipeline.buf;
+       free(*line_p);
+       *line_p = G.pipeline.buf;
        return altered;
 }
 
@@ -679,7 +850,7 @@ static sed_cmd_t *branch_to(char *label)
 {
        sed_cmd_t *sed_cmd;
 
-       for (sed_cmd = bbg.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next) {
+       for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
                if (sed_cmd->cmd == ':' && sed_cmd->string && !strcmp(sed_cmd->string, label)) {
                        return sed_cmd;
                }
@@ -689,593 +860,703 @@ static sed_cmd_t *branch_to(char *label)
 
 static void append(char *s)
 {
-       llist_add_to_end(&bbg.append_head, xstrdup(s));
+       llist_add_to_end(&G.append_head, s);
 }
 
-static void flush_append(void)
+/* Output line of text. */
+/* Note:
+ * The tricks with NO_EOL_CHAR and last_puts_char are there to emulate gnu sed.
+ * Without them, we had this:
+ * echo -n thingy >z1
+ * echo -n again >z2
+ * >znull
+ * sed "s/i/z/" z1 z2 znull | hexdump -vC
+ * output:
+ * gnu sed 4.1.5:
+ * 00000000  74 68 7a 6e 67 79 0a 61  67 61 7a 6e              |thzngy.agazn|
+ * bbox:
+ * 00000000  74 68 7a 6e 67 79 61 67  61 7a 6e                 |thzngyagazn|
+ */
+enum {
+       NO_EOL_CHAR = 1,
+       LAST_IS_NUL = 2,
+};
+static void puts_maybe_newline(char *s, FILE *file, char *last_puts_char, char last_gets_char)
 {
-       char *data;
+       char lpc = *last_puts_char;
 
-       /* Output appended lines. */
-       while ((data = (char *)llist_pop(&bbg.append_head))) {
-               fprintf(bbg.nonstdout, "%s\n", data);
-               free(data);
+       /* Need to insert a '\n' between two files because first file's
+        * last line wasn't terminated? */
+       if (lpc != '\n' && lpc != '\0') {
+               fputc('\n', file);
+               lpc = '\n';
        }
+       fputs(s, file);
+
+       /* 'x' - just something which is not '\n', '\0' or NO_EOL_CHAR */
+       if (s[0])
+               lpc = 'x';
+
+       /* had trailing '\0' and it was last char of file? */
+       if (last_gets_char == LAST_IS_NUL) {
+               fputc('\0', file);
+               lpc = 'x'; /* */
+       } else
+       /* had trailing '\n' or '\0'? */
+       if (last_gets_char != NO_EOL_CHAR) {
+               fputc(last_gets_char, file);
+               lpc = last_gets_char;
+       }
+
+       if (ferror(file)) {
+               xfunc_error_retval = 4;  /* It's what gnu sed exits with... */
+               bb_error_msg_and_die(bb_msg_write_error);
+       }
+       *last_puts_char = lpc;
 }
 
-static void add_input_file(FILE *file)
+static void flush_append(char *last_puts_char, char last_gets_char)
 {
-       bbg.input_file_list = xrealloc(bbg.input_file_list,
-                       (bbg.input_file_count + 1) * sizeof(FILE *));
-       bbg.input_file_list[bbg.input_file_count++] = file;
+       char *data;
+
+       /* Output appended lines. */
+       while ((data = (char *)llist_pop(&G.append_head))) {
+               puts_maybe_newline(data, G.nonstdout, last_puts_char, last_gets_char);
+               free(data);
+       }
 }
 
-/* Get next line of input from bbg.input_file_list, flushing append buffer and
+/* Get next line of input from G.input_file_list, flushing append buffer and
  * noting if we ran out of files without a newline on the last line we read.
  */
-static char *get_next_line(int *last_char)
+static char *get_next_line(char *gets_char, char *last_puts_char, char last_gets_char)
 {
        char *temp = NULL;
-       int len, lc;
-
-       lc = 0;
-       flush_append();
-       while (bbg.current_input_file < bbg.input_file_count) {
-               temp = bb_get_chunk_from_file(
-                       bbg.input_file_list[bbg.current_input_file], &len);
+       int len;
+       char gc;
+
+       flush_append(last_puts_char, last_gets_char);
+
+       /* will be returned if last line in the file
+        * doesn't end with either '\n' or '\0' */
+       gc = NO_EOL_CHAR;
+       for (; G.current_input_file <= G.last_input_file; G.current_input_file++) {
+               FILE *fp = G.current_fp;
+               if (!fp) {
+                       const char *path = G.input_file_list[G.current_input_file];
+                       fp = stdin;
+                       if (path != bb_msg_standard_input) {
+                               fp = fopen_or_warn(path, "r");
+                               if (!fp) {
+                                       G.exitcode = EXIT_FAILURE;
+                                       continue;
+                               }
+                       }
+                       G.current_fp = fp;
+               }
+               /* Read line up to a newline or NUL byte, inclusive,
+                * return malloc'ed char[]. length of the chunk read
+                * is stored in len. NULL if EOF/error */
+               temp = bb_get_chunk_from_file(fp, &len);
                if (temp) {
                        /* len > 0 here, it's ok to do temp[len-1] */
                        char c = temp[len-1];
                        if (c == '\n' || c == '\0') {
                                temp[len-1] = '\0';
-                               lc |= (unsigned char)c;
-                               break;
+                               gc = c;
+                               if (c == '\0') {
+                                       int ch = fgetc(fp);
+                                       if (ch != EOF)
+                                               ungetc(ch, fp);
+                                       else
+                                               gc = LAST_IS_NUL;
+                               }
                        }
-                       /* will be returned if last line in the file
-                        * doesn't end with either '\n' or '\0' */
-                       lc |= 0x100;
+                       /* else we put NO_EOL_CHAR into *gets_char */
                        break;
+
+               /* NB: I had the idea of peeking next file(s) and returning
+                * NO_EOL_CHAR only if it is the *last* non-empty
+                * input file. But there is a case where this won't work:
+                * file1: "a woo\nb woo"
+                * file2: "c no\nd no"
+                * sed -ne 's/woo/bang/p' input1 input2 => "a bang\nb bang"
+                * (note: *no* newline after "b bang"!) */
                }
                /* Close this file and advance to next one */
-               fclose(bbg.input_file_list[bbg.current_input_file++]);
-               /* "this is the first line from new input file" */
-               lc |= 0x200;
+               fclose_if_not_stdin(fp);
+               G.current_fp = NULL;
        }
-       *last_char = lc;
+       *gets_char = gc;
        return temp;
 }
 
-/* Output line of text. */
-/* Note:
- * The tricks with 0x200 and last_puts_char are there to emulate gnu sed.
- * Without them, we had this:
- * echo -n thingy >z1
- * echo -n again >z2
- * >znull
- * sed "s/i/z/" z1 z2 znull | hexdump -vC output:
- * gnu sed 4.1.5:
- * 00000000  74 68 7a 6e 67 79 0a 61  67 61 7a 6e              |thzngy.agazn|
- * bbox:
- * 00000000  74 68 7a 6e 67 79 61 67  61 7a 6e                 |thzngyagazn|
- */
+#define sed_puts(s, n) (puts_maybe_newline(s, G.nonstdout, &last_puts_char, n))
 
-static int puts_maybe_newline(char *s, FILE *file, int prev_last_char, int last_char)
+static int beg_match(sed_cmd_t *sed_cmd, const char *pattern_space)
 {
-       static char last_puts_char;
-
-       /* Is this a first line from new file
-        * and old file didn't end with '\n'? */
-       if ((last_char & 0x200) && last_puts_char != '\n') {
-               fputc('\n', file);
-               last_puts_char = '\n';
-       }
-       fputs(s, file);
-       /* 'x': we don't care what is it, but we know it isn't '\n' */
-       if (s[0]) last_puts_char = 'x';
-       if (!(last_char & 0x100)) { /* had trailing '\n' or '\0'? */
-               last_char &= 0xff;
-               fputc(last_char, file);
-               last_puts_char = last_char;
-       }
-
-       if (ferror(file)) {
-               xfunc_error_retval = 4;  /* It's what gnu sed exits with... */
-               bb_error_msg_and_die(bb_msg_write_error);
-       }
-
-       return last_char;
+       int retval = sed_cmd->beg_match && !regexec(sed_cmd->beg_match, pattern_space, 0, NULL, 0);
+       if (retval)
+               G.previous_regex_ptr = sed_cmd->beg_match;
+       return retval;
 }
 
-#define sed_puts(s, n) \
-       (prev_last_char = puts_maybe_newline(s, bbg.nonstdout, prev_last_char, n))
-
 /* Process all the lines in all the files */
 
 static void process_files(void)
 {
        char *pattern_space, *next_line;
-       int linenum = 0, prev_last_char = 0;
-       int last_char, next_last_char = 0;
+       int linenum = 0;
+       char last_puts_char = '\n';
+       char last_gets_char, next_gets_char;
        sed_cmd_t *sed_cmd;
        int substituted;
 
        /* Prime the pump */
-       next_line = get_next_line(&next_last_char);
+       next_line = get_next_line(&next_gets_char, &last_puts_char, '\n' /*last_gets_char*/);
 
-       /* go through every line in each file */
-again:
+       /* Go through every line in each file */
+ again:
        substituted = 0;
 
        /* Advance to next line.  Stop if out of lines. */
        pattern_space = next_line;
-       if (!pattern_space) return;
-       last_char = next_last_char;
+       if (!pattern_space)
+               return;
+       last_gets_char = next_gets_char;
 
        /* Read one line in advance so we can act on the last line,
         * the '$' address */
-       next_line = get_next_line(&next_last_char);
+       next_line = get_next_line(&next_gets_char, &last_puts_char, last_gets_char);
        linenum++;
-restart:
-       /* for every line, go through all the commands */
-       for (sed_cmd = bbg.sed_cmd_head.next; sed_cmd; sed_cmd = sed_cmd->next) {
+
+       /* For every line, go through all the commands */
+ restart:
+       for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
                int old_matched, matched;
 
                old_matched = sed_cmd->in_match;
 
                /* Determine if this command matches this line: */
 
+               dbg("match1:%d", sed_cmd->in_match);
+               dbg("match2:%d", (!sed_cmd->beg_line && !sed_cmd->end_line
+                               && !sed_cmd->beg_match && !sed_cmd->end_match));
+               dbg("match3:%d", (sed_cmd->beg_line > 0
+                       && (sed_cmd->end_line || sed_cmd->end_match
+                           ? (sed_cmd->beg_line <= linenum)
+                           : (sed_cmd->beg_line == linenum)
+                           )
+                       ));
+               dbg("match4:%d", (beg_match(sed_cmd, pattern_space)));
+               dbg("match5:%d", (sed_cmd->beg_line == -1 && next_line == NULL));
+
                /* Are we continuing a previous multi-line match? */
                sed_cmd->in_match = sed_cmd->in_match
                        /* Or is no range necessary? */
                        || (!sed_cmd->beg_line && !sed_cmd->end_line
                                && !sed_cmd->beg_match && !sed_cmd->end_match)
                        /* Or did we match the start of a numerical range? */
-                       || (sed_cmd->beg_line > 0 && (sed_cmd->beg_line == linenum))
+                       || (sed_cmd->beg_line > 0
+                           && (sed_cmd->end_line || sed_cmd->end_match
+                                 /* note: even if end is numeric and is < linenum too,
+                                  * GNU sed matches! We match too, therefore we don't
+                                  * check here that linenum <= end.
+                                  * Example:
+                                  * printf '1\n2\n3\n4\n' | sed -n '1{N;N;d};1p;2,3p;3p;4p'
+                                  * first three input lines are deleted;
+                                  * 4th line is matched and printed
+                                  * by "2,3" (!) and by "4" ranges
+                                  */
+                               ? (sed_cmd->beg_line <= linenum)    /* N,end */
+                               : (sed_cmd->beg_line == linenum)    /* N */
+                               )
+                           )
                        /* Or does this line match our begin address regex? */
-                       || (sed_cmd->beg_match &&
-                           !regexec(sed_cmd->beg_match, pattern_space, 0, NULL, 0))
+                       || (beg_match(sed_cmd, pattern_space))
                        /* Or did we match last line of input? */
                        || (sed_cmd->beg_line == -1 && next_line == NULL);
 
                /* Snapshot the value */
-
                matched = sed_cmd->in_match;
 
+               dbg("cmd:'%c' matched:%d beg_line:%d end_line:%d linenum:%d",
+                       sed_cmd->cmd, matched, sed_cmd->beg_line, sed_cmd->end_line, linenum);
+
                /* Is this line the end of the current match? */
 
                if (matched) {
+                       /* once matched, "n,xxx" range is dead, disabling it */
+                       if (sed_cmd->beg_line > 0) {
+                               sed_cmd->beg_line = -2;
+                       }
                        sed_cmd->in_match = !(
                                /* has the ending line come, or is this a single address command? */
-                               (sed_cmd->end_line ?
-                                       sed_cmd->end_line == -1 ?
-                                               !next_line
+                               (sed_cmd->end_line
+                                       ? sed_cmd->end_line == -1
+                                               !next_line
                                                : (sed_cmd->end_line <= linenum)
                                        : !sed_cmd->end_match
                                )
                                /* or does this line matches our last address regex */
                                || (sed_cmd->end_match && old_matched
                                     && (regexec(sed_cmd->end_match,
-                                                pattern_space, 0, NULL, 0) == 0))
+                                               pattern_space, 0, NULL, 0) == 0)
+                               )
                        );
                }
 
-               /* Skip blocks of commands we didn't match. */
+               /* Skip blocks of commands we didn't match */
                if (sed_cmd->cmd == '{') {
-                       if (sed_cmd->invert ? matched : !matched)
-                               while (sed_cmd && sed_cmd->cmd != '}')
+                       if (sed_cmd->invert ? matched : !matched) {
+                               unsigned nest_cnt = 0;
+                               while (1) {
+                                       if (sed_cmd->cmd == '{')
+                                               nest_cnt++;
+                                       if (sed_cmd->cmd == '}') {
+                                               nest_cnt--;
+                                               if (nest_cnt == 0)
+                                                       break;
+                                       }
                                        sed_cmd = sed_cmd->next;
-                       if (!sed_cmd) bb_error_msg_and_die("unterminated {");
+                                       if (!sed_cmd)
+                                               bb_error_msg_and_die("unterminated {");
+                               }
+                       }
                        continue;
                }
 
                /* Okay, so did this line match? */
-               if (sed_cmd->invert ? !matched : matched) {
-                       /* Update last used regex in case a blank substitute BRE is found */
-                       if (sed_cmd->beg_match) {
-                               bbg.previous_regex_ptr = sed_cmd->beg_match;
-                       }
+               if (sed_cmd->invert ? matched : !matched)
+                       continue; /* no */
 
-                       /* actual sedding */
-                       switch (sed_cmd->cmd) {
+               /* Update last used regex in case a blank substitute BRE is found */
+               if (sed_cmd->beg_match) {
+                       G.previous_regex_ptr = sed_cmd->beg_match;
+               }
 
-                       /* Print line number */
-                       case '=':
-                               fprintf(bbg.nonstdout, "%d\n", linenum);
-                               break;
+               /* actual sedding */
+               dbg("pattern_space:'%s' next_line:'%s' cmd:%c",
+                               pattern_space, next_line, sed_cmd->cmd);
+               switch (sed_cmd->cmd) {
 
-                       /* Write the current pattern space up to the first newline */
-                       case 'P':
-                       {
-                               char *tmp = strchr(pattern_space, '\n');
+               /* Print line number */
+               case '=':
+                       fprintf(G.nonstdout, "%d\n", linenum);
+                       break;
 
-                               if (tmp) {
-                                       *tmp = '\0';
-                                       sed_puts(pattern_space, 1);
-                                       *tmp = '\n';
-                                       break;
-                               }
-                               /* Fall Through */
+               /* Write the current pattern space up to the first newline */
+               case 'P':
+               {
+                       char *tmp = strchr(pattern_space, '\n');
+                       if (tmp) {
+                               *tmp = '\0';
+                               /* TODO: explain why '\n' below */
+                               sed_puts(pattern_space, '\n');
+                               *tmp = '\n';
+                               break;
                        }
+                       /* Fall Through */
+               }
 
-                       /* Write the current pattern space to output */
-                       case 'p':
-                               sed_puts(pattern_space, last_char);
-                               break;
-                       /* Delete up through first newline */
-                       case 'D':
-                       {
-                               char *tmp = strchr(pattern_space, '\n');
-
-                               if (tmp) {
-                                       tmp = xstrdup(tmp+1);
-                                       free(pattern_space);
-                                       pattern_space = tmp;
-                                       goto restart;
-                               }
+               /* Write the current pattern space to output */
+               case 'p':
+                       /* NB: we print this _before_ the last line
+                        * (of current file) is printed. Even if
+                        * that line is nonterminated, we print
+                        * '\n' here (gnu sed does the same) */
+                       sed_puts(pattern_space, '\n');
+                       break;
+               /* Delete up through first newline */
+               case 'D':
+               {
+                       char *tmp = strchr(pattern_space, '\n');
+                       if (tmp) {
+                               overlapping_strcpy(pattern_space, tmp + 1);
+                               goto restart;
                        }
-                       /* discard this line. */
-                       case 'd':
-                               goto discard_line;
-
-                       /* Substitute with regex */
-                       case 's':
-                               if (!do_subst_command(sed_cmd, &pattern_space))
-                                       break;
-                               substituted |= 1;
-
-                               /* handle p option */
-                               if (sed_cmd->sub_p)
-                                       sed_puts(pattern_space, last_char);
-                               /* handle w option */
-                               if (sed_cmd->file)
-                                       sed_cmd->last_char = puts_maybe_newline(
-                                               pattern_space, sed_cmd->file,
-                                               sed_cmd->last_char, last_char);
-                               break;
+               }
+               /* discard this line. */
+               case 'd':
+                       goto discard_line;
 
-                       /* Append line to linked list to be printed later */
-                       case 'a':
-                               append(sed_cmd->string);
+               /* Substitute with regex */
+               case 's':
+                       if (!do_subst_command(sed_cmd, &pattern_space))
                                break;
+                       dbg("do_subst_command succeeded:'%s'", pattern_space);
+                       substituted |= 1;
+
+                       /* handle p option */
+                       if (sed_cmd->sub_p)
+                               sed_puts(pattern_space, last_gets_char);
+                       /* handle w option */
+                       if (sed_cmd->sw_file)
+                               puts_maybe_newline(
+                                       pattern_space, sed_cmd->sw_file,
+                                       &sed_cmd->sw_last_char, last_gets_char);
+                       break;
 
-                       /* Insert text before this line */
-                       case 'i':
-                               sed_puts(sed_cmd->string, 1);
-                               break;
+               /* Append line to linked list to be printed later */
+               case 'a':
+                       append(xstrdup(sed_cmd->string));
+                       break;
 
-                       /* Cut and paste text (replace) */
-                       case 'c':
-                               /* Only triggers on last line of a matching range. */
-                               if (!sed_cmd->in_match)
-                                       sed_puts(sed_cmd->string, 0);
-                               goto discard_line;
-
-                       /* Read file, append contents to output */
-                       case 'r':
-                       {
-                               FILE *rfile;
-
-                               rfile = fopen(sed_cmd->string, "r");
-                               if (rfile) {
-                                       char *line;
-
-                                       while ((line = xmalloc_getline(rfile))
-                                                       != NULL)
-                                               append(line);
-                                       xprint_and_close_file(rfile);
-                               }
+               /* Insert text before this line */
+               case 'i':
+                       sed_puts(sed_cmd->string, '\n');
+                       break;
 
-                               break;
+               /* Cut and paste text (replace) */
+               case 'c':
+                       /* Only triggers on last line of a matching range. */
+                       if (!sed_cmd->in_match)
+                               sed_puts(sed_cmd->string, '\n');
+                       goto discard_line;
+
+               /* Read file, append contents to output */
+               case 'r':
+               {
+                       FILE *rfile;
+                       rfile = fopen_for_read(sed_cmd->string);
+                       if (rfile) {
+                               char *line;
+                               while ((line = xmalloc_fgetline(rfile))
+                                               != NULL)
+                                       append(line);
+                               fclose(rfile);
                        }
 
-                       /* Write pattern space to file. */
-                       case 'w':
-                               sed_cmd->last_char = puts_maybe_newline(
-                                       pattern_space, sed_cmd->file,
-                                       sed_cmd->last_char, last_char);
-                               break;
+                       break;
+               }
 
-                       /* Read next line from input */
-                       case 'n':
-                               if (!bbg.be_quiet)
-                                       sed_puts(pattern_space, last_char);
-                               if (next_line) {
-                                       free(pattern_space);
-                                       pattern_space = next_line;
-                                       last_char = next_last_char;
-                                       next_line = get_next_line(&next_last_char);
-                                       linenum++;
-                                       break;
-                               }
-                               /* fall through */
-
-                       /* Quit.  End of script, end of input. */
-                       case 'q':
-                               /* Exit the outer while loop */
-                               free(next_line);
-                               next_line = NULL;
-                               goto discard_commands;
-
-                       /* Append the next line to the current line */
-                       case 'N':
-                       {
-                               int len;
-                               /* If no next line, jump to end of script and exit. */
-                               if (next_line == NULL) {
-                                       /* Jump to end of script and exit */
-                                       free(next_line);
-                                       next_line = NULL;
-                                       goto discard_line;
-                               /* append next_line, read new next_line. */
-                               }
-                               len = strlen(pattern_space);
-                               pattern_space = realloc(pattern_space, len + strlen(next_line) + 2);
-                               pattern_space[len] = '\n';
-                               strcpy(pattern_space + len+1, next_line);
-                               last_char = next_last_char;
-                               next_line = get_next_line(&next_last_char);
+               /* Write pattern space to file. */
+               case 'w':
+                       puts_maybe_newline(
+                               pattern_space, sed_cmd->sw_file,
+                               &sed_cmd->sw_last_char, last_gets_char);
+                       break;
+
+               /* Read next line from input */
+               case 'n':
+                       if (!G.be_quiet)
+                               sed_puts(pattern_space, last_gets_char);
+                       if (next_line) {
+                               free(pattern_space);
+                               pattern_space = next_line;
+                               last_gets_char = next_gets_char;
+                               next_line = get_next_line(&next_gets_char, &last_puts_char, last_gets_char);
+                               substituted = 0;
                                linenum++;
                                break;
                        }
+                       /* fall through */
 
-                       /* Test/branch if substitution occurred */
-                       case 't':
-                               if (!substituted) break;
-                               substituted = 0;
-                               /* Fall through */
-                       /* Test/branch if substitution didn't occur */
-                       case 'T':
-                               if (substituted) break;
-                               /* Fall through */
-                       /* Branch to label */
-                       case 'b':
-                               if (!sed_cmd->string) goto discard_commands;
-                               else sed_cmd = branch_to(sed_cmd->string);
-                               break;
-                       /* Transliterate characters */
-                       case 'y':
-                       {
-                               int i, j;
-
-                               for (i = 0; pattern_space[i]; i++) {
-                                       for (j = 0; sed_cmd->string[j]; j += 2) {
-                                               if (pattern_space[i] == sed_cmd->string[j]) {
-                                                       pattern_space[i] = sed_cmd->string[j + 1];
-                                                       break;
-                                               }
-                                       }
-                               }
+               /* Quit.  End of script, end of input. */
+               case 'q':
+                       /* Exit the outer while loop */
+                       free(next_line);
+                       next_line = NULL;
+                       goto discard_commands;
 
-                               break;
+               /* Append the next line to the current line */
+               case 'N':
+               {
+                       int len;
+                       /* If no next line, jump to end of script and exit. */
+                       /* http://www.gnu.org/software/sed/manual/sed.html:
+                        * "Most versions of sed exit without printing anything
+                        * when the N command is issued on the last line of
+                        * a file. GNU sed prints pattern space before exiting
+                        * unless of course the -n command switch has been
+                        * specified. This choice is by design."
+                        */
+                       if (next_line == NULL) {
+                               //goto discard_line;
+                               goto discard_commands; /* GNU behavior */
                        }
-                       case 'g':       /* Replace pattern space with hold space */
-                               free(pattern_space);
-                               pattern_space = xstrdup(bbg.hold_space ? bbg.hold_space : "");
-                               break;
-                       case 'G':       /* Append newline and hold space to pattern space */
-                       {
-                               int pattern_space_size = 2;
-                               int hold_space_size = 0;
-
-                               if (pattern_space)
-                                       pattern_space_size += strlen(pattern_space);
-                               if (bbg.hold_space)
-                                       hold_space_size = strlen(bbg.hold_space);
-                               pattern_space = xrealloc(pattern_space,
-                                               pattern_space_size + hold_space_size);
-                               if (pattern_space_size == 2)
-                                       pattern_space[0] = 0;
-                               strcat(pattern_space, "\n");
-                               if (bbg.hold_space)
-                                       strcat(pattern_space, bbg.hold_space);
-                               last_char = '\n';
+                       /* Append next_line, read new next_line. */
+                       len = strlen(pattern_space);
+                       pattern_space = xrealloc(pattern_space, len + strlen(next_line) + 2);
+                       pattern_space[len] = '\n';
+                       strcpy(pattern_space + len+1, next_line);
+                       last_gets_char = next_gets_char;
+                       next_line = get_next_line(&next_gets_char, &last_puts_char, last_gets_char);
+                       linenum++;
+                       break;
+               }
 
-                               break;
+               /* Test/branch if substitution occurred */
+               case 't':
+                       if (!substituted) break;
+                       substituted = 0;
+                       /* Fall through */
+               /* Test/branch if substitution didn't occur */
+               case 'T':
+                       if (substituted) break;
+                       /* Fall through */
+               /* Branch to label */
+               case 'b':
+                       if (!sed_cmd->string) goto discard_commands;
+                       else sed_cmd = branch_to(sed_cmd->string);
+                       break;
+               /* Transliterate characters */
+               case 'y':
+               {
+                       int i, j;
+                       for (i = 0; pattern_space[i]; i++) {
+                               for (j = 0; sed_cmd->string[j]; j += 2) {
+                                       if (pattern_space[i] == sed_cmd->string[j]) {
+                                               pattern_space[i] = sed_cmd->string[j + 1];
+                                               break;
+                                       }
+                               }
                        }
-                       case 'h':       /* Replace hold space with pattern space */
-                               free(bbg.hold_space);
-                               bbg.hold_space = xstrdup(pattern_space);
-                               break;
-                       case 'H':       /* Append newline and pattern space to hold space */
-                       {
-                               int hold_space_size = 2;
-                               int pattern_space_size = 0;
-
-                               if (bbg.hold_space)
-                                       hold_space_size += strlen(bbg.hold_space);
-                               if (pattern_space)
-                                       pattern_space_size = strlen(pattern_space);
-                               bbg.hold_space = xrealloc(bbg.hold_space,
-                                               hold_space_size + pattern_space_size);
-
-                               if (hold_space_size == 2)
-                                       *bbg.hold_space = 0;
-                               strcat(bbg.hold_space, "\n");
-                               if (pattern_space)
-                                       strcat(bbg.hold_space, pattern_space);
 
-                               break;
-                       }
-                       case 'x': /* Exchange hold and pattern space */
-                       {
-                               char *tmp = pattern_space;
-                               pattern_space = bbg.hold_space ? : xzalloc(1);
-                               last_char = '\n';
-                               bbg.hold_space = tmp;
-                               break;
-                       }
-                       }
+                       break;
                }
-       }
+               case 'g':       /* Replace pattern space with hold space */
+                       free(pattern_space);
+                       pattern_space = xstrdup(G.hold_space ? G.hold_space : "");
+                       break;
+               case 'G':       /* Append newline and hold space to pattern space */
+               {
+                       int pattern_space_size = 2;
+                       int hold_space_size = 0;
+
+                       if (pattern_space)
+                               pattern_space_size += strlen(pattern_space);
+                       if (G.hold_space)
+                               hold_space_size = strlen(G.hold_space);
+                       pattern_space = xrealloc(pattern_space,
+                                       pattern_space_size + hold_space_size);
+                       if (pattern_space_size == 2)
+                               pattern_space[0] = 0;
+                       strcat(pattern_space, "\n");
+                       if (G.hold_space)
+                               strcat(pattern_space, G.hold_space);
+                       last_gets_char = '\n';
+
+                       break;
+               }
+               case 'h':       /* Replace hold space with pattern space */
+                       free(G.hold_space);
+                       G.hold_space = xstrdup(pattern_space);
+                       break;
+               case 'H':       /* Append newline and pattern space to hold space */
+               {
+                       int hold_space_size = 2;
+                       int pattern_space_size = 0;
+
+                       if (G.hold_space)
+                               hold_space_size += strlen(G.hold_space);
+                       if (pattern_space)
+                               pattern_space_size = strlen(pattern_space);
+                       G.hold_space = xrealloc(G.hold_space,
+                                       hold_space_size + pattern_space_size);
+
+                       if (hold_space_size == 2)
+                               *G.hold_space = 0;
+                       strcat(G.hold_space, "\n");
+                       if (pattern_space)
+                               strcat(G.hold_space, pattern_space);
+
+                       break;
+               }
+               case 'x': /* Exchange hold and pattern space */
+               {
+                       char *tmp = pattern_space;
+                       pattern_space = G.hold_space ? G.hold_space : xzalloc(1);
+                       last_gets_char = '\n';
+                       G.hold_space = tmp;
+                       break;
+               }
+               } /* switch */
+       } /* for each cmd */
 
        /*
-        * exit point from sedding...
+        * Exit point from sedding...
         */
-discard_commands:
+ discard_commands:
        /* we will print the line unless we were told to be quiet ('-n')
           or if the line was suppressed (ala 'd'elete) */
-       if (!bbg.be_quiet) sed_puts(pattern_space, last_char);
+       if (!G.be_quiet)
+               sed_puts(pattern_space, last_gets_char);
 
        /* Delete and such jump here. */
-discard_line:
-       flush_append();
+ discard_line:
+       flush_append(&last_puts_char, last_gets_char);
        free(pattern_space);
 
        goto again;
 }
 
 /* It is possible to have a command line argument with embedded
-   newlines.  This counts as multiple command lines. */
+ * newlines.  This counts as multiple command lines.
+ * However, newline can be escaped: 's/e/z\<newline>z/'
+ * add_cmd() handles this.
+ */
 
 static void add_cmd_block(char *cmdstr)
 {
-       int go = 1;
-       char *temp = xstrdup(cmdstr), *temp2 = temp;
-
-       while (go) {
-               int len = strcspn(temp2, "\n");
-               if (!temp2[len]) go = 0;
-               else temp2[len] = 0;
-               add_cmd(temp2);
-               temp2 += len+1;
-       }
-       free(temp);
-}
-
-static void add_cmds_link(llist_t *opt_e)
-{
-       if (!opt_e) return;
-       add_cmds_link(opt_e->link);
-       add_cmd_block(opt_e->data);
-       free(opt_e);
-}
+       char *sv, *eol;
 
-static void add_files_link(llist_t *opt_f)
-{
-       char *line;
-       FILE *cmdfile;
-       if (!opt_f) return;
-       add_files_link(opt_f->link);
-       cmdfile = xfopen(opt_f->data, "r");
-       while ((line = xmalloc_getline(cmdfile)) != NULL) {
-               add_cmd(line);
-               free(line);
-       }
-       xprint_and_close_file(cmdfile);
-       free(opt_f);
+       cmdstr = sv = xstrdup(cmdstr);
+       do {
+               eol = strchr(cmdstr, '\n');
+               if (eol)
+                       *eol = '\0';
+               add_cmd(cmdstr);
+               cmdstr = eol + 1;
+       } while (eol);
+       free(sv);
 }
 
-int sed_main(int argc, char **argv)
+int sed_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int sed_main(int argc UNUSED_PARAM, char **argv)
 {
-       enum {
-               OPT_in_place = 1 << 0,
-       };
        unsigned opt;
        llist_t *opt_e, *opt_f;
-       int status = EXIT_SUCCESS;
+       char *opt_i;
+
+#if ENABLE_LONG_OPTS
+       static const char sed_longopts[] ALIGN1 =
+               /* name             has_arg             short */
+               "in-place\0"        Optional_argument   "i"
+               "regexp-extended\0" No_argument         "r"
+               "quiet\0"           No_argument         "n"
+               "silent\0"          No_argument         "n"
+               "expression\0"      Required_argument   "e"
+               "file\0"            Required_argument   "f";
+#endif
 
-       bbg.sed_cmd_tail = &bbg.sed_cmd_head;
+       INIT_G();
 
        /* destroy command strings on exit */
        if (ENABLE_FEATURE_CLEAN_UP) atexit(sed_free_and_close_stuff);
 
        /* Lie to autoconf when it starts asking stupid questions. */
-       if (argc == 2 && !strcmp(argv[1], "--version")) {
+       if (argv[1] && strcmp(argv[1], "--version") == 0) {
                puts("This is not GNU sed version 4.0");
                return 0;
        }
 
        /* do normal option parsing */
        opt_e = opt_f = NULL;
+       opt_i = NULL;
        opt_complementary = "e::f::" /* can occur multiple times */
                            "nn"; /* count -n */
-       opt = getopt32(argc, argv, "irne:f:", &opt_e, &opt_f,
-                           &bbg.be_quiet); /* counter for -n */
-       argc -= optind;
+
+       IF_LONG_OPTS(applet_long_options = sed_longopts);
+
+       /* -i must be first, to match OPT_in_place definition */
+       /* -E is a synonym of -r:
+        * GNU sed 4.2.1 mentions it in neither --help
+        * nor manpage, but does recognize it.
+        */
+       opt = getopt32(argv, "i::rEne:f:", &opt_i, &opt_e, &opt_f,
+                           &G.be_quiet); /* counter for -n */
+       //argc -= optind;
        argv += optind;
        if (opt & OPT_in_place) { // -i
                atexit(cleanup_outname);
        }
-       if (opt & 0x2) bbg.regex_type |= REG_EXTENDED; // -r
-       //if (opt & 0x4) bbg.be_quiet++; // -n
-       if (opt & 0x8) { // -e
-               /* getopt32 reverses order of arguments, handle it */
-               add_cmds_link(opt_e);
+       if (opt & (2|4))
+               G.regex_type |= REG_EXTENDED; // -r or -E
+       //if (opt & 8)
+       //      G.be_quiet++; // -n (implemented with a counter instead)
+       while (opt_e) { // -e
+               add_cmd_block(llist_pop(&opt_e));
        }
-       if (opt & 0x10) { // -f
-               /* getopt32 reverses order of arguments, handle it */
-               add_files_link(opt_f);
+       while (opt_f) { // -f
+               char *line;
+               FILE *cmdfile;
+               cmdfile = xfopen_for_read(llist_pop(&opt_f));
+               while ((line = xmalloc_fgetline(cmdfile)) != NULL) {
+                       add_cmd(line);
+                       free(line);
+               }
+               fclose(cmdfile);
        }
        /* if we didn't get a pattern from -e or -f, use argv[0] */
-       if (!(opt & 0x18)) {
-               if (!argc)
+       if (!(opt & 0x30)) {
+               if (!*argv)
                        bb_show_usage();
                add_cmd_block(*argv++);
-               argc--;
        }
        /* Flush any unfinished commands. */
        add_cmd("");
 
        /* By default, we write to stdout */
-       bbg.nonstdout = stdout;
+       G.nonstdout = stdout;
 
        /* argv[0..(argc-1)] should be names of file to process. If no
         * files were specified or '-' was specified, take input from stdin.
         * Otherwise, we process all the files specified. */
-       if (argv[0] == NULL) {
+       G.input_file_list = argv;
+       if (!argv[0]) {
                if (opt & OPT_in_place)
                        bb_error_msg_and_die(bb_msg_requires_arg, "-i");
-               add_input_file(stdin);
-               process_files();
+               argv[0] = (char*)bb_msg_standard_input;
+               /* G.last_input_file = 0; - already is */
        } else {
-               int i;
-               FILE *file;
+               goto start;
 
-               for (i = 0; i < argc; i++) {
+               for (; *argv; argv++) {
                        struct stat statbuf;
                        int nonstdoutfd;
+                       sed_cmd_t *sed_cmd;
 
-                       if (argv[i][0] == '-' && !argv[i][1]
-                        && !(opt & OPT_in_place)
-                       ) {
-                               add_input_file(stdin);
-                               process_files();
-                               continue;
-                       }
-                       file = fopen_or_warn(argv[i], "r");
-                       if (!file) {
-                               status = EXIT_FAILURE;
-                               continue;
-                       }
+                       G.last_input_file++;
+ start:
                        if (!(opt & OPT_in_place)) {
-                               add_input_file(file);
+                               if (LONE_DASH(*argv)) {
+                                       *argv = (char*)bb_msg_standard_input;
+                                       process_files();
+                               }
                                continue;
                        }
 
-                       bbg.outname = xasprintf("%sXXXXXX", argv[i]);
-                       nonstdoutfd = mkstemp(bbg.outname);
-                       if (-1 == nonstdoutfd)
-                               bb_error_msg_and_die("no temp file");
-                       bbg.nonstdout = fdopen(nonstdoutfd, "w");
+                       /* -i: process each FILE separately: */
 
-                       /* Set permissions of output file */
+                       G.outname = xasprintf("%sXXXXXX", *argv);
+                       nonstdoutfd = xmkstemp(G.outname);
+                       G.nonstdout = xfdopen_for_write(nonstdoutfd);
 
-                       fstat(fileno(file), &statbuf);
+                       /* Set permissions/owner of output file */
+                       stat(*argv, &statbuf);
+                       /* chmod'ing AFTER chown would preserve suid/sgid bits,
+                        * but GNU sed 4.2.1 does not preserve them either */
                        fchmod(nonstdoutfd, statbuf.st_mode);
-                       add_input_file(file);
+                       fchown(nonstdoutfd, statbuf.st_uid, statbuf.st_gid);
+
                        process_files();
-                       fclose(bbg.nonstdout);
-
-                       bbg.nonstdout = stdout;
-                       /* unlink(argv[i]); */
-                       // FIXME: error check / message?
-                       rename(bbg.outname, argv[i]);
-                       free(bbg.outname);
-                       bbg.outname = 0;
+                       fclose(G.nonstdout);
+                       G.nonstdout = stdout;
+
+                       if (opt_i) {
+                               char *backupname = xasprintf("%s%s", *argv, opt_i);
+                               xrename(*argv, backupname);
+                               free(backupname);
+                       }
+                       /* else unlink(*argv); - rename below does this */
+                       xrename(G.outname, *argv); //TODO: rollback backup on error?
+                       free(G.outname);
+                       G.outname = NULL;
+
+                       /* Re-enable disabled range matches */
+                       for (sed_cmd = G.sed_cmd_head; sed_cmd; sed_cmd = sed_cmd->next) {
+                               sed_cmd->beg_line = sed_cmd->beg_line_orig;
+                       }
                }
-               if (bbg.input_file_count > bbg.current_input_file)
-                       process_files();
+               /* Here, to handle "sed 'cmds' nonexistent_file" case we did:
+                * if (G.current_input_file[G.current_input_file] == NULL)
+                *      return G.exitcode;
+                * but it's not needed since process_files() works correctly
+                * in this case too. */
        }
 
-       return status;
+       process_files();
+
+       return G.exitcode;
 }