Add "-" type to optargs and teach tail.c to use it. Tighten up help text, use xzallo...

diff --git a/lib/args.c b/lib/args.c
index 8b209d9..918119c 100644 (file)
--- a/lib/args.c
+++ b/lib/args.c
@@ -18,6 +18,7 @@
 //       <LOW     - die if less than LOW
 //       >HIGH    - die if greater than HIGH
 //       =DEFAULT - value if not specified
+//     - plus a signed long argument defaulting to negative
 //     . plus a double precision floating point argument (with CFG_TOYBOX_FLOAT)
 //       Chop this out with USE_TOYBOX_FLOAT() around option string
 //       Same <LOW>HIGH=DEFAULT as #
@@ -148,8 +149,9 @@ static int gotflag(struct getoptflagstate *gof)
                        while (*list) list=&((*list)->next);
                        *list = xzalloc(sizeof(struct arg_list));
                        (*list)->arg = arg;
-               } else if (type == '#') {
+               } else if (type == '#' || type == '-') {
                        long l = atolx(arg);
+                       if (type == '-' && !ispunct(*arg)) l*=-1;
                        if (l < opt->val[0].l)
                                error_exit("-%c < %ld", opt->c, opt->val[0].l);
                        if (l > opt->val[1].l)

diff --git a/toys/tail.c b/toys/tail.c
index 5ae295b..b992cd1 100644 (file)
--- a/toys/tail.c
+++ b/toys/tail.c
@@ -6,38 +6,28 @@
  *
  * See http://www.opengroup.org/onlinepubs/009695399/utilities/tail.html
 
-USE_TAIL(NEWTOY(tail, "c:fn:", TOYFLAG_BIN))
+USE_TAIL(NEWTOY(tail, "c-|fn-|", TOYFLAG_BIN))
 
 config TAIL
        bool "tail"
        default n
        help
-         usage: tail [-n number] [-c number] [-f] [file...]
+         usage: tail [-n|c number] [-f] [file...]
 
          Copy last lines from files to stdout. If no files listed, copy from
          stdin. Filename "-" is a synonym for stdin.
 
-         -n    Line offset to start copying from. The number may be signed.
-               When negative, the line offset is counted from the end of the 
-               file. When positive, the offset is counted from the beginning.
-               When the sign is omitted, the offset is counted from the end of
-               the file. Defaults to -10.
-
-         -c    Byte offset to start copying from. As above, may be a positive
-               or negative signed number.
-
-         -f    Continue reading input after reaching the last line of input.
-               This option is ignored if the input file is not a regular file
-               or the given file is a FIFO.
+         -n    output the last X lines (default 10), +X counts from start.
+         -c    output the last X bytes, +X counts from start
+         -f    follow file, waiting for more data to be appended
 */
 
 #include "toys.h"
 
 DEFINE_GLOBALS(
-       char *lines_str;
-       char *bytes_str;
        long lines;
        long bytes;
+
        int file_no;
 )
 
@@ -128,8 +118,7 @@ static void print_last_lines(int fd, long lines)
 
        for (;;) {
                // read from input and append to buffer list
-               cur = xmalloc(sizeof(struct line_list));
-               memset(cur, 0, sizeof(struct line_list));
+               cur = xzalloc(sizeof(struct line_list));
 
                cur->data = xmalloc(size);
                cur->len = readall(fd, cur->data, size);
@@ -170,32 +159,19 @@ static void do_tail(int fd, char *name)
 
        if (toys.optc > 1) {
                // print an extra newline for all but the first file
-               if (TT.file_no++) xprintf("\n");
+               if (TT.file_no++) xputc('\n');
                xprintf("==> %s <==\n", name);
-               xflush();
        }
 
        if (lines > 0 || bytes > 0) print_after_offset(fd, bytes, lines);
        else if (bytes < 0) print_last_bytes(fd, bytes * -1);
-       else if (lines < 0) print_last_lines(fd, lines * -1);
-}
-
-long atolx_default_negative(char *str)
-{
-       long val = atolx(str);
-       return str[0] != '+' && str[0] != '-' ? val * -1 : val;
+       else print_last_lines(fd, lines * -1);
 }
 
 void tail_main(void)
 {
-       // if option -c or -n has no sign then we make it negative
-       if (toys.optflags & FLAG_c)
-               TT.bytes = atolx_default_negative(TT.bytes_str);
-
-       if (toys.optflags & FLAG_n)
-               TT.lines = atolx_default_negative(TT.lines_str);
-       else
-               TT.lines = -10;
+       // if nothing specified, default -n to -10
+       if (!(toys.optflags&(FLAG_n|FLAG_c))) TT.lines = -10;
 
        loopfiles(toys.optargs, do_tail);
 }