Re: [PATCH 1/2] date: recognize bogus FreeBSD gmtime output
From: Jeff King <hidden>
Date: 2016-06-15 23:00:37
Subsystem:
kernel build + files below scripts/ (unless maintained elsewhere), the rest · Maintainers:
Nathan Chancellor, Nicolas Schier, Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-06-15 · [PATCH 1/2] date: recognize bogus FreeBSD gmtime output · Jeff King <hidden>
- 2016-06-15 · Re: [PATCH 1/2] date: recognize bogus FreeBSD gmtime output · René Scharfe <hidden>
On Tue, Apr 01, 2014 at 11:17:14PM +0200, René Scharfe wrote:
quoted
So are you saying we should set EOVERFLOW ourselves, or does FreeBSD set EOVERFLOW for us in this case and we do not have to worry?If we correct the return value then we should correct errno as well. gmtime() on FreeBSD 10 leaves errno untouched when it encounters an overflow. While testing this again I just noticed that FreeBSD doesn't strictly return a pointer to a cleared struct tm. It simply leaves its static buffer untouched. We should probably clear it (memset in git_gmtime_r).
Thanks, that all makes sense (we do not ever care about gmtime's errno in our code, but it does not hurt to be thorough to avoid surprising any new callers). Here's a replacement for patch 1. -- >8 -- Subject: date: recognize bogus FreeBSD gmtime output Most gmtime implementations return a NULL value when they encounter an error (and this behavior is specified by ANSI C and POSIX). FreeBSD's implementation, however, will simply leave the "struct tm" untouched. Let's also recognize this and convert it to a NULL (with this patch, t4212 should pass on FreeBSD). Reported-by: René Scharfe <redacted> Signed-off-by: Jeff King <redacted> --- Makefile | 8 ++++++++ compat/gmtime.c | 29 +++++++++++++++++++++++++++++ config.mak.uname | 1 + git-compat-util.h | 7 +++++++ 4 files changed, 45 insertions(+) create mode 100644 compat/gmtime.c
diff --git a/Makefile b/Makefile
index 3646391..2f3758c 100644
--- a/Makefile
+++ b/Makefile@@ -338,6 +338,9 @@ all:: # Define TEST_GIT_INDEX_VERSION to 2, 3 or 4 to run the test suite # with a different indexfile format version. If it isn't set the index # file format used is index-v[23]. +# +# Define GMTIME_UNRELIABLE_ERRORS if your gmtime() function does not +# return NULL when it receives a bogus time_t. GIT-VERSION-FILE: FORCE @$(SHELL_PATH) ./GIT-VERSION-GEN
@@ -1489,6 +1492,11 @@ ifneq (,$(XDL_FAST_HASH)) BASIC_CFLAGS += -DXDL_FAST_HASH endif +ifdef GMTIME_UNRELIABLE_ERRORS + COMPAT_OBJS += compat/gmtime.o + BASIC_CFLAGS += -DGMTIME_UNRELIABLE_ERRORS +endif + ifeq ($(TCLTK_PATH),) NO_TCLTK = NoThanks endif
diff --git a/compat/gmtime.c b/compat/gmtime.c
new file mode 100644
index 0000000..e8362dd
--- /dev/null
+++ b/compat/gmtime.c@@ -0,0 +1,29 @@ +#include "../git-compat-util.h" +#undef gmtime +#undef gmtime_r + +struct tm *git_gmtime(const time_t *timep) +{ + static struct tm result; + return git_gmtime_r(timep, &result); +} + +struct tm *git_gmtime_r(const time_t *timep, struct tm *result) +{ + struct tm *ret; + + memset(result, 0, sizeof(*result)); + ret = gmtime_r(timep, result); + + /* + * Rather than NULL, FreeBSD gmtime simply leaves the "struct tm" + * untouched when it encounters overflow. Since "mday" cannot otherwise + * be zero, we can test this very quickly. + */ + if (ret && !ret->tm_mday) { + ret = NULL; + errno = EOVERFLOW; + } + + return ret; +}
diff --git a/config.mak.uname b/config.mak.uname
index 6069a44..0e22ac0 100644
--- a/config.mak.uname
+++ b/config.mak.uname@@ -187,6 +187,7 @@ ifeq ($(uname_S),FreeBSD) endif PYTHON_PATH = /usr/local/bin/python HAVE_PATHS_H = YesPlease + GMTIME_UNRELIABLE_ERRORS = UnfortunatelyYes endif ifeq ($(uname_S),OpenBSD) NO_STRCASESTR = YesPlease
diff --git a/git-compat-util.h b/git-compat-util.h
index 892032b..5191866 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h@@ -716,4 +716,11 @@ void warn_on_inaccessible(const char *path); /* Get the passwd entry for the UID of the current process. */ struct passwd *xgetpwuid_self(void); +#ifdef GMTIME_UNRELIABLE_ERRORS +struct tm *git_gmtime(const time_t *); +struct tm *git_gmtime_r(const time_t *, struct tm *); +#define gmtime git_gmtime +#define gmtime_r git_gmtime_r +#endif + #endif
--
1.9.1.656.ge8a0637