[PATCH v2] binutils: objcopy/strip: fix preserving dates in ar archives

[Gleb Fotengauer-Malinovskiy]

After commit 985e0264516 copy_archive function began to pass invalid values to
the utimensat(2) function when it tries to preserve timestamps in ar archives:

$ gcc -c -xc /dev/null -o t.o
$ ar rcsU t.a t.o
$ strace --failed-only -e /time strip -p t.a
utimensat(AT_FDCWD, "steICERy/t.o", [{tv_sec=140428413401793, tv_nsec=48} /* 4451969-04-09T19:36:33.000000048+0000 */, {tv_sec=1632773474, tv_nsec=94919810130032}], 0) = -1 EINVAL (Invalid argument)
strip: steICERy/t.o: cannot set time: Invalid argument
+++ exited with 0 +++
$ strace --failed-only -e /time objcopy -p t.a t1.a
utimensat(AT_FDCWD, "stk5ToKP/t.o", [{tv_sec=640, tv_nsec=48} /* 1970-01-01T00:10:40.000000048+0000 */, {tv_sec=0, tv_nsec=223338299408}], 0) = -1 EINVAL (Invalid argument)
objcopy: stk5ToKP/t.o: cannot set time: Invalid argument
+++ exited with 0 +++

This happens because the bfd_stat_arch_elt implementation for ar
archives fills only the st_mtim.tv_sec part of the st_mtim timespec
structure, but leaves the st_mtim.tv_nsec part and the whole st_atim timespec
untouched leaving them uninitialized.
This behavior did not lead to any problems before because only
the st_atim.tv_sec were passed to the utime(2) function uninitialized,
but it was applied to temporary file, whose access time doesn't affect
archive contents later.

Fixes: 985e0264516 ("PR27725, better objcopy -p times")

	PR binutils/28391
	* binutils/objcopy.c (copy_archive): Clear buf using memset.
---
 binutils/objcopy.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index a6c2e0dcc26..0a3a9fb062e 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -3600,6 +3600,7 @@ copy_archive (bfd *ibfd, bfd *obfd, const char *output_target,
 
       if (preserve_dates)
 	{
+	  memset (&buf, 0, sizeof(buf));
 	  stat_status = bfd_stat_arch_elt (this_element, &buf);
 
 	  if (stat_status != 0)

-- 
glebfm