[PATCH v4 3/3] regex: use regexec_buf()
- From
Johannes Schindelin <johannes.schindelin@gmx.de>
- Date
- Sep 21, 2016, 18:24 UTC
- Message-ID
- <53f3609d99c865d59d7bfd8219a5334339e9e6bc.1474482164.git.johannes.schindelin@gmx.de>
- In-Reply-To
- <cover.1474482164.git.johannes.schindelin@gmx.de>
The new regexec_buf() function operates on buffers with an explicitly specified length, rather than NUL-terminated strings.
We need to use this function whenever the buffer we want to pass to regexec() may have been mmap()ed (and is hence not NUL-terminated).
Note: the original motivation for this patch was to fix a bug where `git diff -G <regex>` would crash. This patch converts more callers, though, some of which explicitly allocated and constructed NUL-terminated strings (or worse: modified read-only buffers to insert NULs).
Some of the buffers actually may be NUL-terminated. As regexec_buf() uses REG_STARTEND where available, but has to fall back to allocating and constructing NUL-terminated strings where REG_STARTEND is not available, this makes the code less efficient in the latter case.
However, given the widespread support for REG_STARTEND, combined with the improved ease of code maintenance, we strike the balance in favor of REG_STARTEND.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> --- diff.c | 3 ++- diffcore-pickaxe.c | 18 ++++++++---------- grep.c | 14 ++------------ t/t4061-diff-pickaxe.sh | 2 +- xdiff-interface.c | 13 ++++--------- 5 files changed, 17 insertions(+), 33 deletions(-)
diff --git a/diff.c b/diff.c index c6da383..fb99235 100644 --- a/diff.c +++ b/diff.c @@ -952,7 +952,8 @@ static int find_word_boundaries(mmfile_t *buffer, regex_t *word_regex, { if (word_regex && *begin < buffer->size) { regmatch_t match[1]; - if (!regexec(word_regex, buffer->ptr + *begin, 1, match, 0)) { + if (!regexec_buf(word_regex, buffer->ptr + *begin, + buffer->size - *begin, 1, match, 0)) { char *p = memchr(buffer->ptr + *begin + match[0].rm_so, '\n', match[0].rm_eo - match[0].rm_so); *end = p ? p - buffer->ptr : match[0].rm_eo + *begin; diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c index 55067ca..9795ca1 100644 --- a/diffcore-pickaxe.c +++ b/diffcore-pickaxe.c @@ -23,7 +23,6 @@ static void diffgrep_consume(void *priv, char *line, unsigned long len) { struct diffgrep_cb *data = priv; regmatch_t regmatch; - int hold; if (line[0] != '+' && line[0] != '-') return; @@ -33,11 +32,8 @@ static void diffgrep_consume(void *priv, char *line, unsigned long len) * caller early. */ return; - /* Yuck -- line ought to be "const char *"! */ - hold = line[len]; - line[len] = '\0'; - data->hit = !regexec(data->regexp, line + 1, 1, ®match, 0); - line[len] = hold; + data->hit = !regexec_buf(data->regexp, line + 1, len - 1, 1, + ®match, 0); } static int diff_grep(mmfile_t *one, mmfile_t *two, @@ -50,9 +46,11 @@ static int diff_grep(mmfile_t *one, mmfile_t *two, xdemitconf_t xecfg; if (!one) - return !regexec(regexp, two->ptr, 1, ®match, 0); + return !regexec_buf(regexp, two->ptr, two->size, + 1, ®match, 0); if (!two) - return !regexec(regexp, one->ptr, 1, ®match, 0); + return !regexec_buf(regexp, one->ptr, one->size, + 1, ®match, 0); /* * We have both sides; need to run textual diff and see if @@ -83,8 +81,8 @@ static unsigned int contains(mmfile_t *mf, regex_t *regexp, kwset_t kws) regmatch_t regmatch; int flags = 0; - assert(data[sz] == '\0'); - while (*data && !regexec(regexp, data, 1, ®match, flags)) { + while (*data && + !regexec_buf(regexp, data, sz, 1, ®match, flags)) { flags |= REG_NOTBOL; data += regmatch.rm_eo; if (*data && regmatch.rm_so == regmatch.rm_eo) diff --git a/grep.c b/grep.c index d7d00b8..1194d35 100644 --- a/grep.c +++ b/grep.c @@ -898,17 +898,6 @@ static int fixmatch(struct grep_pat *p, char *line, char *eol, } } -static int regmatch(const regex_t *preg, char *line, char *eol, - regmatch_t *match, int eflags) -{ -#ifdef REG_STARTEND - match->rm_so = 0; - match->rm_eo = eol - line; - eflags |= REG_STARTEND; -#endif - return regexec(preg, line, 1, match, eflags); -} - static int patmatch(struct grep_pat *p, char *line, char *eol, regmatch_t *match, int eflags) { @@ -919,7 +908,8 @@ static int patmatch(struct grep_pat *p, char *line, char *eol, else if (p->pcre_regexp) hit = !pcrematch(p, line, eol, match, eflags); else - hit = !regmatch(&p->regexp, line, eol, match, eflags); + hit = !regexec_buf(&p->regexp, line, eol - line, 1, match, + eflags); return hit; } diff --git a/t/t4061-diff-pickaxe.sh b/t/t4061-diff-pickaxe.sh index 5929f2e..f0bf50b 100755 --- a/t/t4061-diff-pickaxe.sh +++ b/t/t4061-diff-pickaxe.sh @@ -14,7 +14,7 @@ test_expect_success setup ' test_tick && git commit -m "A 4k file" ' -test_expect_failure '-G matches' ' +test_expect_success '-G matches' ' git diff --name-only -G "^0{4096}$" HEAD^ >out && test 4096-zeroes.txt = "$(cat out)" ' diff --git a/xdiff-interface.c b/xdiff-interface.c index 3bfc69c..060038c 100644 --- a/xdiff-interface.c +++ b/xdiff-interface.c @@ -214,11 +214,10 @@ struct ff_regs { static long ff_regexp(const char *line, long len, char *buffer, long buffer_size, void *priv) { - char *line_buffer; struct ff_regs *regs = priv; regmatch_t pmatch[2]; int i; - int result = -1; + int result; /* Exclude terminating newline (and cr) from matching */ if (len > 0 && line[len-1] == '\n') { @@ -228,18 +227,16 @@ static long ff_regexp(const char *line, long len, len--; } - line_buffer = xstrndup(line, len); /* make NUL terminated */ - for (i = 0; i < regs->nr; i++) { struct ff_reg *reg = regs->array + i; - if (!regexec(®->re, line_buffer, 2, pmatch, 0)) { + if (!regexec_buf(®->re, line, len, 2, pmatch, 0)) { if (reg->negate) - goto fail; + return -1; break; } } if (regs->nr <= i) - goto fail; + return -1; i = pmatch[1].rm_so >= 0 ? 1 : 0; line += pmatch[i].rm_so; result = pmatch[i].rm_eo - pmatch[i].rm_so; @@ -248,8 +245,6 @@ static long ff_regexp(const char *line, long len, while (result > 0 && (isspace(line[result - 1]))) result--; memcpy(buffer, line, result); - fail: - free(line_buffer); return result; }
-- 2.10.0.windows.1.10.g803177d