agent: Simplify a function.

* agent/findkey.c (agent_public_key_from_file): Use a membuf instead
of handcounting space.

Signed-off-by: Werner Koch <wk@gnupg.org>

1 files changed, 23 insertions, 32 deletions

diff --git a/agent/findkey.c b/agent/findkey.c
index dd39472a9..28ff61781 100644
--- a/agent/findkey.c
+++ b/agent/findkey.c
@@ -1196,7 +1196,8 @@ agent_public_key_from_file (ctrl_t ctrl,
   const char *uri, *comment;
   size_t uri_length, comment_length;
   int uri_intlen, comment_intlen;
-  char *format, *p;
+  membuf_t format_mb;
+  char *format;
   void *args[2+7+2+2+1]; /* Size is 2 + max. # of elements + 2 for uri + 2
                             for comment + end-of-list.  */
   int argidx;
@@ -1238,44 +1239,23 @@ agent_public_key_from_file (ctrl_t ctrl,
   s_skey = NULL;
 
 
-  /* FIXME: The following thing is pretty ugly code; we should
-     investigate how to make it cleaner.  Probably code to handle
-     canonical S-expressions in a memory buffer is better suited for
-     such a task.  After all that is what we do in protect.c.  Need
-     to find common patterns and write a straightformward API to use
-     them.  */
   log_assert (sizeof (size_t) <= sizeof (void*));
 
-  format = xtrymalloc (15+4+7*npkey+10+15+1+1);
-  if (!format)
-    {
-      err = gpg_error_from_syserror ();
-      for (i=0; array[i]; i++)
-        gcry_mpi_release (array[i]);
-      gcry_sexp_release (curve);
-      gcry_sexp_release (flags);
-      gcry_sexp_release (uri_sexp);
-      gcry_sexp_release (comment_sexp);
-      return err;
-    }
-
+  init_membuf (&format_mb, 256);
   argidx = 0;
-  p = stpcpy (stpcpy (format, "(public-key("), algoname);
-  p = stpcpy (p, "%S%S");       /* curve name and flags.  */
+  put_membuf_printf (&format_mb, "(public-key(%s%%S%%S", algoname);
   args[argidx++] = &curve;
   args[argidx++] = &flags;
   for (idx=0, s=elems; idx < npkey; idx++)
     {
-      *p++ = '(';
-      *p++ = *s++;
-      p = stpcpy (p, " %m)");
+      put_membuf_printf (&format_mb, "(%c %%m)", *s++);
       log_assert (argidx < DIM (args));
       args[argidx++] = &array[idx];
     }
-  *p++ = ')';
+  put_membuf_str (&format_mb, ")");
   if (uri)
     {
-      p = stpcpy (p, "(uri %b)");
+      put_membuf_str (&format_mb, "(uri %b)");
       log_assert (argidx+1 < DIM (args));
       uri_intlen = (int)uri_length;
       args[argidx++] = (void *)&uri_intlen;
@@ -1283,17 +1263,29 @@ agent_public_key_from_file (ctrl_t ctrl,
     }
   if (comment)
     {
-      p = stpcpy (p, "(comment %b)");
+      put_membuf_str (&format_mb, "(comment %b)");
       log_assert (argidx+1 < DIM (args));
       comment_intlen = (int)comment_length;
       args[argidx++] = (void *)&comment_intlen;
-      args[argidx++] = (void*)&comment;
+      args[argidx++] = (void *)&comment;
     }
-  *p++ = ')';
-  *p = 0;
+  put_membuf (&format_mb, ")", 2);
   log_assert (argidx < DIM (args));
   args[argidx] = NULL;
 
+  format = get_membuf (&format_mb, NULL);
+  if (!format)
+    {
+      err = gpg_error_from_syserror ();
+      for (i=0; array[i]; i++)
+        gcry_mpi_release (array[i]);
+      gcry_sexp_release (curve);
+      gcry_sexp_release (flags);
+      gcry_sexp_release (uri_sexp);
+      gcry_sexp_release (comment_sexp);
+      return err;
+    }
+
   err = gcry_sexp_build_array (&list, NULL, format, args);
   xfree (format);
   for (i=0; array[i]; i++)
@@ -1309,7 +1301,6 @@ agent_public_key_from_file (ctrl_t ctrl,
 }
 
 
-
 /* Check whether the secret key identified by GRIP is available.
    Returns 0 is the key is available.  */
 int