[patch libiberty]: Fix PR 53285 on 4.7 branch

[Kai Tietz]

Hi,

this patch backports a fix from trunk
ChangeLog

2013-01-30  Kai Tietz  <kti...@redhat.com>
        2012-07-31  Mike Frysinger  <vap...@gentoo.org>

        Merged from trunk.
        PR other/53285
        * md5.c (md5_finish_ctx): Declare swap_bytes.  Assign SWAP() output
        to swap_bytes, and then call memcpy to move it to ctx->buffer.

Tested for x86_64-unknown-linux-gnu, i686-w64-mingw32, and
i686-pc-cygwin.  Ok for apply?

Regards,
Kai

Index: md5.c
===================================================================
--- md5.c       (Revision 194858)
+++ md5.c       (Arbeitskopie)
@@ -103,6 +103,7 @@ md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
 {
   /* Take yet unprocessed bytes into account.  */
   md5_uint32 bytes = ctx->buflen;
+  md5_uint32 swap_bytes;
   size_t pad;

   /* Now count remaining bytes.  */
@@ -113,10 +114,13 @@ md5_finish_ctx (struct md5_ctx *ctx, void *resbuf)
   pad = bytes >= 56 ? 64 + 56 - bytes : 56 - bytes;
   memcpy (&ctx->buffer[bytes], fillbuf, pad);

-  /* Put the 64-bit file length in *bits* at the end of the buffer.  */
-  *(md5_uint32 *) &ctx->buffer[bytes + pad] = SWAP (ctx->total[0] << 3);
-  *(md5_uint32 *) &ctx->buffer[bytes + pad + 4] = SWAP ((ctx->total[1] << 3) |
-                                                       (ctx->total[0] >> 29));
+  /* Put the 64-bit file length in *bits* at the end of the buffer.
+     Use memcpy to avoid aliasing problems.  On most systems, this
+     will be optimized away to the same code.  */
+  swap_bytes = SWAP (ctx->total[0] << 3);
+  memcpy (&ctx->buffer[bytes + pad], &swap_bytes, sizeof (swap_bytes));
+  swap_bytes = SWAP ((ctx->total[1] << 3) | (ctx->total[0] >> 29));
+  memcpy (&ctx->buffer[bytes + pad + 4], &swap_bytes, sizeof (swap_bytes));

   /* Process last bytes.  */
   md5_process_block (ctx->buffer, bytes + pad + 8, ctx);