xargs: code shrink -15 bytes
authorDenys Vlasenko <vda.linux@googlemail.com>
Sun, 13 Jun 2010 01:43:43 +0000 (03:43 +0200)
committerDenys Vlasenko <vda.linux@googlemail.com>
Sun, 13 Jun 2010 01:43:43 +0000 (03:43 +0200)
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
findutils/xargs.c
testsuite/xargs.tests

index 9133b8f..25a7853 100644 (file)
@@ -122,53 +122,49 @@ typedef struct xlist_t {
        char xstr[1];
 } xlist_t;
 
-static smallint eof_stdin_detected;
-
-#define ISBLANK(c) ((c) == ' ' || (c) == '\t')
-#define ISSPACE(c) (ISBLANK(c) || (c) == '\n' || (c) == '\r' \
-                   || (c) == '\f' || (c) == '\v')
+/* In POSIX/C locale isspace is only these chars: "\t\n\v\f\r" and space.
+ * "\t\n\v\f\r" happen to have ASCII codes 9,10,11,12,13.
+ */
+#define ISSPACE(a) ({ unsigned char xargs__isspace = (a) - 9; xargs__isspace == (' ' - 9) || xargs__isspace <= (13 - 9); })
 
 #if ENABLE_FEATURE_XARGS_SUPPORT_QUOTES
-static xlist_t *process_stdin(xlist_t *list_arg,
+static xlist_tprocess_stdin(xlist_t *list_arg,
        const char *eof_str, size_t mc, char *buf)
 {
 #define NORM      0
 #define QUOTE     1
 #define BACKSLASH 2
 #define SPACE     4
-
-       char *s = NULL;         /* start word */
-       char *p = NULL;         /* pointer to end word */
+       char *s = NULL;         /* start of the word */
+       char *p = NULL;         /* pointer to end of the word */
        char q = '\0';          /* quote char */
        char state = NORM;
        char eof_str_detected = 0;
-       size_t line_l = 0;      /* size loaded args line */
-       int c;                  /* current char */
+       size_t line_l = 0;      /* size of loaded args */
        xlist_t *cur;
        xlist_t *prev;
 
        prev = cur = list_arg;
-       while (1) {
-               if (!cur) break;
+       while (cur) {
                prev = cur;
                line_l += cur->length;
                cur = cur->link;
        }
 
-       while (!eof_stdin_detected) {
-               c = getchar();
+       while (1) {
+               int c = getchar();
                if (c == EOF) {
-                       eof_stdin_detected = 1;
                        if (s)
                                goto unexpected_eof;
                        break;
                }
-               if (eof_str_detected)
+               if (eof_str_detected) /* skip till EOF */
                        continue;
                if (state == BACKSLASH) {
                        state = NORM;
                        goto set;
-               } else if (state == QUOTE) {
+               }
+               if (state == QUOTE) {
                        if (c != q)
                                goto set;
                        q = '\0';
@@ -202,7 +198,7 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                bb_error_msg_and_die("unmatched %s quote",
                                        q == '\'' ? "single" : "double");
                        }
-                       /* word loaded */
+                       /* A full word is loaded */
                        if (eof_str) {
                                eof_str_detected = (strcmp(s, eof_str) == 0);
                        }
@@ -220,10 +216,8 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                }
                                prev = cur;
                                line_l += length;
-                               if (line_l > mc) {
-                                       /* stop memory usage :-) */
+                               if (line_l > mc) /* limit stop memory usage */
                                        break;
-                               }
                        }
                        s = NULL;
                        state = NORM;
@@ -233,33 +227,32 @@ static xlist_t *process_stdin(xlist_t *list_arg,
 }
 #else
 /* The variant does not support single quotes, double quotes or backslash */
-static xlist_t *process_stdin(xlist_t *list_arg,
+static xlist_tprocess_stdin(xlist_t *list_arg,
                const char *eof_str, size_t mc, char *buf)
 {
-
-       int c;                  /* current char */
        char eof_str_detected = 0;
-       char *s = NULL;         /* start word */
-       char *p = NULL;         /* pointer to end word */
-       size_t line_l = 0;      /* size loaded args line */
+       char *s = NULL;         /* start of the word */
+       char *p = NULL;         /* pointer to end of the word */
+       size_t line_l = 0;      /* size of loaded args */
        xlist_t *cur;
        xlist_t *prev;
 
        prev = cur = list_arg;
-       while (1) {
-               if (!cur) break;
+       while (cur) {
                prev = cur;
                line_l += cur->length;
                cur = cur->link;
        }
 
-       while (!eof_stdin_detected) {
-               c = getchar();
+       while (1) {
+               int c = getchar();
                if (c == EOF) {
-                       eof_stdin_detected = 1;
+                       if (s == NULL)
+                               break;
                }
-               if (eof_str_detected)
+               if (eof_str_detected) { /* skip till EOF */
                        continue;
+               }
                if (c == EOF || ISSPACE(c)) {
                        if (s == NULL)
                                continue;
@@ -271,7 +264,7 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                        bb_error_msg_and_die("argument line too long");
                *p++ = (c == EOF ? '\0' : c);
                if (c == EOF) { /* word's delimiter or EOF detected */
-                       /* word loaded */
+                       /* A full word is loaded */
                        if (eof_str) {
                                eof_str_detected = (strcmp(s, eof_str) == 0);
                        }
@@ -289,12 +282,10 @@ static xlist_t *process_stdin(xlist_t *list_arg,
                                }
                                prev = cur;
                                line_l += length;
-                               if (line_l > mc) {
-                                       /* stop memory usage :-) */
+                               if (line_l > mc) /* limit stop memory usage */
                                        break;
-                               }
-                               s = NULL;
                        }
+                       s = NULL;
                }
        }
        return list_arg;
@@ -325,28 +316,25 @@ static int xargs_ask_confirmation(void)
 #endif /* FEATURE_XARGS_SUPPORT_CONFIRMATION */
 
 #if ENABLE_FEATURE_XARGS_SUPPORT_ZERO_TERM
-static xlist_t *process0_stdin(xlist_t *list_arg,
+static xlist_tprocess0_stdin(xlist_t *list_arg,
                const char *eof_str UNUSED_PARAM, size_t mc, char *buf)
 {
-       int c;                  /* current char */
-       char *s = NULL;         /* start word */
-       char *p = NULL;         /* pointer to end word */
-       size_t line_l = 0;      /* size loaded args line */
+       char *s = NULL;         /* start of the word */
+       char *p = NULL;         /* pointer to end of the word */
+       size_t line_l = 0;      /* size of loaded args */
        xlist_t *cur;
        xlist_t *prev;
 
        prev = cur = list_arg;
-       while (1) {
-               if (!cur) break;
+       while (cur) {
                prev = cur;
                line_l += cur->length;
                cur = cur->link;
        }
 
-       while (!eof_stdin_detected) {
-               c = getchar();
+       while (1) {
+               int c = getchar();
                if (c == EOF) {
-                       eof_stdin_detected = 1;
                        if (s == NULL)
                                break;
                        c = '\0';
@@ -357,7 +345,7 @@ static xlist_t *process0_stdin(xlist_t *list_arg,
                        bb_error_msg_and_die("argument line too long");
                *p++ = c;
                if (c == '\0') {   /* word's delimiter or EOF detected */
-                       /* word loaded */
+                       /* A full word is loaded */
                        size_t length = (p - buf);
                        /* Dont xzalloc - it can be quite big */
                        cur = xmalloc(offsetof(xlist_t, xstr) + length);
@@ -371,10 +359,8 @@ static xlist_t *process0_stdin(xlist_t *list_arg,
                        }
                        prev = cur;
                        line_l += length;
-                       if (line_l > mc) {
-                               /* stop memory usage :-) */
+                       if (line_l > mc) /* limit stop memory usage */
                                break;
-                       }
                        s = NULL;
                }
        }
@@ -412,12 +398,11 @@ enum {
 int xargs_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 int xargs_main(int argc, char **argv)
 {
-       char **args;
-       int i, n;
        xlist_t *list = NULL;
-       xlist_t *cur;
        int child_error = 0;
-       char *max_args, *max_chars;
+       char *max_args;
+       char *max_chars;
+       char *buf;
        int n_max_arg;
        const char *eof_str = NULL;
        unsigned opt;
@@ -441,15 +426,12 @@ int xargs_main(int argc, char **argv)
 
        argv += optind;
        argc -= optind;
-       if (!argc) {
+       if (!argv[0]) {
                /* default behavior is to echo all the filenames */
-               *argv = (char*)"echo";
+               *--argv = (char*)"echo";
                argc++;
        }
 
-       n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
-       if (n_max_chars < 4*1024); /* paranoia */
-               n_max_chars = LONG_MAX;
        /* The Open Group Base Specifications Issue 6:
         * "The xargs utility shall limit the command line length such that
         * when the command line is invoked, the combined argument
@@ -457,27 +439,32 @@ int xargs_main(int argc, char **argv)
         * in the System Interfaces volume of IEEE Std 1003.1-2001)
         * shall not exceed {ARG_MAX}-2048 bytes".
         */
+       n_max_chars = ARG_MAX; /* might be calling sysconf(_SC_ARG_MAX) */
+       if (n_max_chars < 4*1024); /* paranoia */
+               n_max_chars = 4*1024;
        n_max_chars -= 2048;
        /* Sanity check for systems with huge ARG_MAX defines (e.g., Suns which
-        * have it at 1 meg).  Things will work fine with a large ARG_MAX but it
-        * will probably hurt the system more than it needs to; an array of this
-        * size is allocated.
+        * have it at 1 meg).  Things will work fine with a large ARG_MAX
+        * but it will probably hurt the system more than it needs to;
+        * an array of this size is allocated.
         */
        if (n_max_chars > 20 * 1024)
                n_max_chars = 20 * 1024;
 
        if (opt & OPT_UPTO_SIZE) {
+               int i;
                size_t n_chars = 0;
                n_max_chars = xatoul_range(max_chars, 1, n_max_chars);
-               for (i = 0; i < argc; i++) {
-                       n_chars += strlen(*argv) + 1;
+               for (i = 0; argv[i]; i++) {
+                       n_chars += strlen(argv[i]) + 1;
                }
-               if (n_max_chars <= n_chars) {
+               n_max_chars -= n_chars;
+               if ((ssize_t)n_max_chars <= 0) {
                        bb_error_msg_and_die("can't fit single argument within argument list size limit");
                }
-               n_max_chars -= n_chars;
        }
-       max_chars = xmalloc(n_max_chars);
+
+       buf = xmalloc(n_max_chars);
 
        if (opt & OPT_UPTO_NUMBER) {
                n_max_arg = xatoul_range(max_args, 1, INT_MAX);
@@ -485,10 +472,14 @@ int xargs_main(int argc, char **argv)
                n_max_arg = n_max_chars;
        }
 
-       while ((list = read_args(list, eof_str, n_max_chars, max_chars)) != NULL ||
-               !(opt & OPT_NO_EMPTY))
-       {
+       while ((list = read_args(list, eof_str, n_max_chars, buf)) != NULL
+        ||    !(opt & OPT_NO_EMPTY)
+       ) {
+               char **args;
+               xlist_t *cur;
+               int i, n;
                size_t n_chars = 0;
+
                opt |= OPT_NO_EMPTY;
                n = 0;
 #if ENABLE_FEATURE_XARGS_SUPPORT_TERMOPT
@@ -510,15 +501,14 @@ int xargs_main(int argc, char **argv)
                                break;
                        }
                }
-#endif /* FEATURE_XARGS_SUPPORT_TERMOPT */
+#endif
 
-               /* allocate pointers for execvp:
-                  argc*arg, n*arg from stdin, NULL */
-               args = xzalloc((n + argc + 1) * sizeof(char *));
+               /* allocate pointers for execvp */
+               args = xzalloc(sizeof(args[0]) * (argc + n + 1));
 
                /* store the command to be executed
-                  (taken from the command line) */
-               for (i = 0; i < argc; i++)
+                * (taken from the command line) */
+               for (i = 0; argv[i]; i++)
                        args[i] = argv[i];
                /* (taken from stdin) */
                for (cur = list; n; cur = cur->link) {
@@ -535,6 +525,7 @@ int xargs_main(int argc, char **argv)
                        if (!(opt & OPT_INTERACTIVE))
                                bb_putchar_stderr('\n');
                }
+
                if (!(opt & OPT_INTERACTIVE) || xargs_ask_confirmation()) {
                        child_error = xargs_exec(args);
                }
@@ -546,12 +537,15 @@ int xargs_main(int argc, char **argv)
                        free(cur);
                }
                free(args);
+
                if (child_error > 0 && child_error != 123) {
                        break;
                }
        } /* while */
+
        if (ENABLE_FEATURE_CLEAN_UP)
-               free(max_chars);
+               free(buf);
+
        return child_error;
 }
 
index 17f4e7a..c733630 100755 (executable)
@@ -26,4 +26,9 @@ testing "xargs does not stop on underscore ('new' GNU behavior)" \
        "a _ b\n" \
        "" "a\n_\nb\n"
 
+testing "xargs -s7 can take one-char input" \
+       "xargs -s7" \
+       "a\n" \
+       "" "a\n"
+
 exit $FAILCOUNT