This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
[PATCH 3/3] Use urandom in gcc.c too
- From: Andi Kleen <andi at firstfloor dot org>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Andi Kleen <ak at linux dot intel dot com>
- Date: Wed, 28 Sep 2011 14:49:23 +0200
- Subject: [PATCH 3/3] Use urandom in gcc.c too
- References: <1317214163-26010-1-git-send-email-andi@firstfloor.org>
From: Andi Kleen <ak@linux.intel.com>
gcc also takes generates a random number in some special circumstances,
so teach it about /dev/urandom too.
gcc/:
2011-09-27 Andi Kleen <ak@linux.intel.com>
* gcc.c (get_local_tick). Rename to get_random_number. Read from /dev/urandom.
Add getpid call.
(compare_debug_dump_opt_spec_function): Drop getpid call.
---
gcc/gcc.c | 22 ++++++++++++++++------
1 files changed, 16 insertions(+), 6 deletions(-)
diff --git a/gcc/gcc.c b/gcc/gcc.c
index ddec8db..3bfdf77 100644
--- a/gcc/gcc.c
+++ b/gcc/gcc.c
@@ -8062,12 +8062,22 @@ print_asm_header_spec_function (int arg ATTRIBUTE_UNUSED,
return NULL;
}
-/* Compute a timestamp to initialize flag_random_seed. */
+/* Get a random number for -frandom-seed */
-static unsigned
-get_local_tick (void)
+static unsigned HOST_WIDE_INT
+get_random_number (void)
{
- unsigned ret = 0;
+ unsigned HOST_WIDE_INT ret = 0;
+ int fd;
+
+ fd = open ("/dev/urandom", O_RDONLY);
+ if (fd >= 0)
+ {
+ read (fd, &ret, sizeof (HOST_WIDE_INT));
+ close (fd);
+ if (ret)
+ return ret;
+ }
/* Get some more or less random data. */
#ifdef HAVE_GETTIMEOFDAY
@@ -8086,7 +8096,7 @@ get_local_tick (void)
}
#endif
- return ret;
+ return ret ^ getpid();
}
/* %:compare-debug-dump-opt spec function. Save the last argument,
@@ -8145,7 +8155,7 @@ compare_debug_dump_opt_spec_function (int arg,
if (!which)
{
- unsigned HOST_WIDE_INT value = get_local_tick () ^ getpid ();
+ unsigned HOST_WIDE_INT value = get_random_number ();
sprintf (random_seed, HOST_WIDE_INT_PRINT_HEX, value);
}
--
1.7.5.4