wrapper: avoid undefined behaviour in macOS

0620b39b3b ("compat: add a mkstemps() compatibility function", 2009-05-31)
included a function based on code from libiberty which would result in
undefined behaviour in platforms where timeval's tv_usec is a 32-bit signed
type as shown by:

wrapper.c:505:31: runtime error: left shift of 594546 by 16 places cannot be represented in type '__darwin_suseconds_t' (aka 'int')

interestingly the version of this code from gcc never had this bug and the
code had a cast that would had prevented the issue (at least in 64-bit
platforms) but was misapplied.

change the cast to uint64_t so it also works in 32-bit platforms.

Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/wrapper.c b/wrapper.c
index ea3cf64d4c399ae84c156b850002459a8ffde72c..1e45ab7b92749b653484f522701f5d86521b03c7 100644 (file)
--- a/wrapper.c
+++ b/wrapper.c
@@ -502,7 +502,7 @@ int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
         * Try TMP_MAX different filenames.
         */
        gettimeofday(&tv, NULL);
-       value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
+       value = ((uint64_t)tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
        filename_template = &pattern[len - 6 - suffix_len];
        for (count = 0; count < TMP_MAX; ++count) {
                uint64_t v = value;