agent: correct length for uri and comment on 64-bit big-endian platforms

* agent/findkey.c (agent_public_key_from_file): pass size_t as int to
gcry_sexp_build_array's %b.

--

This is only a problem on big-endian systems where size_t is not the
same size as an int.  It was causing failures on debian's s390x,
powerpc64, and sparc64 platforms.

There may well be other failures with %b on those platforms in the
codebase, and it probably needs an audit.

Once you have a key in private-keys-v1.d/$KEYGRIP.key with a comment
or a uri of reasonable length associated with it, this fix can be
tested with:

   gpg-agent --server <<<"READKEY $KEYGRIP"

On the failing platforms, the printed comment will be of length 0.

Gnupg-bug-id: 4501
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/agent/findkey.c b/agent/findkey.c
index 755a90be1..20c9dc56a 100644
--- a/agent/findkey.c
+++ b/agent/findkey.c
@@ -1366,6 +1366,7 @@ agent_public_key_from_file (ctrl_t ctrl,
   gcry_sexp_t uri_sexp, comment_sexp;
   const char *uri, *comment;
   size_t uri_length, comment_length;
+  int uri_intlen, comment_intlen;
   char *format, *p;
   void *args[2+7+2+2+1]; /* Size is 2 + max. # of elements + 2 for uri + 2
                             for comment + end-of-list.  */
@@ -1447,14 +1448,16 @@ agent_public_key_from_file (ctrl_t ctrl,
     {
       p = stpcpy (p, "(uri %b)");
       assert (argidx+1 < DIM (args));
-      args[argidx++] = (void *)&uri_length;
+      uri_intlen = (int)uri_length;
+      args[argidx++] = (void *)&uri_intlen;
       args[argidx++] = (void *)&uri;
     }
   if (comment)
     {
       p = stpcpy (p, "(comment %b)");
       assert (argidx+1 < DIM (args));
-      args[argidx++] = (void *)&comment_length;
+      comment_intlen = (int)comment_length;
+      args[argidx++] = (void *)&comment_intlen;
       args[argidx++] = (void*)&comment;
     }
   *p++ = ')';