[Cc:ing Benjamin Kramer & René Scharfe because they both worked on
the REG_STARTEND code in grep.c that I replace in this iteration of the
patch series]
This patch series addresses a problem where `git diff` is called using
`-G` or `-S --pickaxe-regex` on new-born files that are configured
without user diff drivers, and that hence get mmap()ed into memory.
The problem with that: mmap()ed memory is *not* NUL-terminated, yet the
pickaxe code calls regexec() on it just the same.
This problem has been reported by my colleague Chris Sidi.
We solve this by introducing a helper, regexec_buf(), that takes a
pointer and a length instead of a NUL-terminated string.
This helper then uses REG_STARTEND where available, and falls back to
allocating and constructing a NUL-terminated string. Given the
wide-spread support for REG_STARTEND (Linux has it, MacOSX has it, Git
for Windows has it because it uses compat/regex/ that has it), I think
this is a fair trade-off.
Changes since v3:
- reworded the onelines as per Junio's suggestions.
- removed fallback when REG_STARTEND is not supported, in favor of
requiring NO_REGEX.
- removed the regmatch() function from grep.c, in favor of using
regexec_buf().
Johannes Schindelin (3):
regex: -G<pattern> feeds a non NUL-terminated string to regexec() and
fails
regex: add regexec_buf() that can work on a non NUL-terminated string
regex: use regexec_buf()
Makefile | 3 ++-
diff.c | 3 ++-
diffcore-pickaxe.c | 18 ++++++++----------
git-compat-util.h | 13 +++++++++++++
grep.c | 14 ++------------
t/t4061-diff-pickaxe.sh | 22 ++++++++++++++++++++++
xdiff-interface.c | 13 ++++---------
7 files changed, 53 insertions(+), 33 deletions(-)
create mode 100755 t/t4061-diff-pickaxe.sh
Published-As: https://github.com/dscho/git/releases/tag/mmap-regexec-v4
Fetch-It-Via: git fetch https://github.com/dscho/git mmap-regexec-v4
Interdiff vs v3:
diff --git a/Makefile b/Makefile
index df4f86b..c6f7f66 100644
--- a/Makefile
+++ b/Makefile
@@ -301,7 +301,8 @@ all::
# crashes due to allocation and free working on different 'heaps'.
# It's defined automatically if USE_NED_ALLOCATOR is set.
#
-# Define NO_REGEX if you have no or inferior regex support in your C library.
+# Define NO_REGEX if your C library lacks regex support with REG_STARTEND
+# feature.
#
# Define HAVE_DEV_TTY if your system can open /dev/tty to interact with the
# user.
diff --git a/git-compat-util.h b/git-compat-util.h
index 627ec5f..8aab0c3 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -977,25 +977,17 @@ void git_qsort(void *base, size_t nmemb, size_t size,
#define qsort git_qsort
#endif
+#ifndef REG_STARTEND
+#error "Git requires REG_STARTEND support. Compile with
NO_REGEX=NeedsStartEnd"
+#endif
+
static inline int regexec_buf(const regex_t *preg, const char *buf, size_t
size,
size_t nmatch, regmatch_t pmatch[], int eflags)
{
-#ifdef REG_STARTEND
assert(nmatch > 0 && pmatch);
pmatch[0].rm_so = 0;
pmatch[0].rm_eo = size;
return regexec(preg, buf, nmatch, pmatch, eflags | REG_STARTEND);
-#else
- char *buf2 = xmalloc(size + 1);
- int ret;
-
- memcpy(buf2, buf, size);
- buf2[size] = '\0';
- ret = regexec(preg, buf2, nmatch, pmatch, eflags);
- free(buf2);
-
- return ret;
-#endif
}
#ifndef DIR_HAS_BSD_GROUP_SEMANTICS
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;
}
--
2.10.0.windows.1.10.g803177d
base-commit: f6727b0509ec3417a5183ba6e658143275a734f5
