[v5,3/3] posix: regexec(): fix REG_STARTEND, pmatch->rm_so != 0 w/^ anchor
Commit Message
re_search_internal () starts with
/* If initial states with non-begbuf contexts have no elements,
the regex must be anchored. If preg->newline_anchor is set,
we'll never use init_state_nl, so do not check it. */
if (dfa->init_state->nodes.nelem == 0
&& dfa->init_state_word->nodes.nelem == 0
&& (dfa->init_state_nl->nodes.nelem == 0
|| !preg->newline_anchor))
{
if (start != 0 && last_start != 0)
return REG_NOMATCH;
start = last_start = 0;
}
and heretofor start and last_start (for example when "abc", {1, 2},
so matching just the "b") were != 0, and the return was taken for a "^b"
regex, which is erroneous.
Fix this by giving re_search_internal (string+rm_so, start=0),
then fixing up the returned matches in an after-pass.
This brings us to compatibility with the BSD spec and implementations.
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
---
posix/regexec.c | 41 ++++++++++++++++++++++++++++-------------
1 file changed, 28 insertions(+), 13 deletions(-)
@@ -187,38 +187,53 @@ static reg_errcode_t extend_buffers (re_match_context_t *mctx, int min_len);
string; if REG_NOTEOL is set, then $ does not match at the end.
Return 0 if a match is found, REG_NOMATCH if not, REG_BADPAT if
- EFLAGS is invalid. */
+ EFLAGS is invalid.
+
+ If REG_STARTEND, the bounds are
+ [STRING + PMATCH->rm_so, STRING + PMATCH->rm_eo)
+ instead of the usual
+ [STRING, STRING + strlen(STRING)),
+ but returned matches are still referenced to STRING,
+ and matching is unaffected (i.e. "abc", {1, 2} matches regex "^b$").
+ re_search_internal () has a built-in assumption of
+ (start != 0) <=> (^ doesn't match), so give it a truncated view
+ and fix up the matches afterward. */
int
regexec (const regex_t *__restrict preg, const char *__restrict string,
size_t nmatch, regmatch_t pmatch[_REGEX_NELTS (nmatch)], int eflags)
{
reg_errcode_t err;
- Idx start, length;
+ Idx startoff = 0, length;
re_dfa_t *dfa = preg->buffer;
+ size_t i = 0;
if (eflags & ~(REG_NOTBOL | REG_NOTEOL | REG_STARTEND))
return REG_BADPAT;
if (eflags & REG_STARTEND)
{
- start = pmatch[0].rm_so;
- length = pmatch[0].rm_eo;
+ startoff = pmatch[0].rm_so;
+ string += startoff;
+ length = pmatch[0].rm_eo - startoff;
}
else
- {
- start = 0;
- length = strlen (string);
- }
+ length = strlen (string);
lock_lock (dfa->lock);
if (preg->no_sub)
- err = re_search_internal (preg, string, length, start, length,
- length, 0, NULL, eflags);
- else
- err = re_search_internal (preg, string, length, start, length,
- length, nmatch, pmatch, eflags);
+ nmatch = 0;
+ err = re_search_internal (preg, string, length, 0, length,
+ length, nmatch, pmatch, eflags);
lock_unlock (dfa->lock);
+
+ if (err == REG_NOERROR && startoff)
+ for (i = 0; i < nmatch; ++i)
+ if (pmatch[i].rm_so != -1)
+ {
+ pmatch[i].rm_so += startoff;
+ pmatch[i].rm_eo += startoff;
+ }
return err != REG_NOERROR;
}