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Patch from Shaun Jackman:
> This patch modfies expr to use portable POSIX regex rather than BSD > regex. ... > This updated patch implements an anchored regex by checking that the > match starts at offset 0. More to the point, this patch uses the same regex that sed.c is already using (opportunity to suck in less library code), and even building a dynamically linked busybox with just expr the result is a slightly smaller binary (by 94 bytes, I dunno what nm --size-sort has to say about it because I didn't build with debug info, since that changes the binary size a lot by disabling optimization...) Your mileage may vary. Handle with caution. Do not taunt happy fun ball.
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@ -245,10 +245,9 @@ static int arithmetic_common (VALUE *l, VALUE *r, int op)
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static VALUE *docolon (VALUE *sv, VALUE *pv)
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{
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VALUE *v;
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const char *errmsg;
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struct re_pattern_buffer re_buffer;
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struct re_registers re_regs;
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int len;
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regex_t re_buffer;
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const int NMATCH = 2;
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regmatch_t re_regs[NMATCH];
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tostring (sv);
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tostring (pv);
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@ -260,27 +259,22 @@ of a basic regular expression is not portable; it is being ignored",
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pv->u.s);
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}
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len = strlen (pv->u.s);
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memset (&re_buffer, 0, sizeof (re_buffer));
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memset (&re_regs, 0, sizeof (re_regs));
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re_buffer.allocated = 2 * len;
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re_buffer.buffer = (unsigned char *) xmalloc (re_buffer.allocated);
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re_buffer.translate = 0;
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re_syntax_options = RE_SYNTAX_POSIX_BASIC;
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errmsg = re_compile_pattern (pv->u.s, len, &re_buffer);
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if (errmsg) {
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bb_error_msg_and_die("%s", errmsg);
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}
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memset (re_regs, 0, sizeof (*re_regs));
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if( regcomp (&re_buffer, pv->u.s, 0) != 0 )
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bb_error_msg_and_die("Invalid regular expression");
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len = re_match (&re_buffer, sv->u.s, strlen (sv->u.s), 0, &re_regs);
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if (len >= 0) {
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/* expr uses an anchored pattern match, so check that there was a
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* match and that the match starts at offset 0. */
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if (regexec (&re_buffer, sv->u.s, NMATCH, re_regs, 0) != REG_NOMATCH &&
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re_regs[0].rm_so == 0) {
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/* Were \(...\) used? */
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if (re_buffer.re_nsub > 0) { /* was (re_regs.start[1] >= 0) */
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sv->u.s[re_regs.end[1]] = '\0';
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v = str_value (sv->u.s + re_regs.start[1]);
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if (re_buffer.re_nsub > 0) {
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sv->u.s[re_regs[1].rm_eo] = '\0';
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v = str_value (sv->u.s + re_regs[1].rm_so);
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}
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else
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v = int_value (len);
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v = int_value (re_regs[0].rm_eo);
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}
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else {
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/* Match failed -- return the right kind of null. */
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@ -289,7 +283,6 @@ of a basic regular expression is not portable; it is being ignored",
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else
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v = int_value (0);
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}
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free (re_buffer.buffer);
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return v;
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}
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