On Tue, Apr 01, 2014 at 11:17:14PM +0200, René Scharfe wrote:
> >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 <l.s.r@xxxxxx>
Signed-off-by: Jeff King <peff@xxxxxxxx>
---
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
--
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