gpg: Fix possible dead code elimination.

* g10/encrypt.c: Change condition for detecting a real file.
--

Detected by Stack 3.0:

  bug: anti-dce
  model: |
    %tobool155 = icmp ne i32 %call154, 0, !dbg !1298
    -->  true
    ************************************************************
    land.lhs.true156:
    %96 = icmp eq i8* %filename, null
    call void @opt.bugon(i1 %96), !dbg !1298, !bug !1250
    %97 = load i8* %filename, align 1, !dbg !1298
    %conv157 = sext i8 %97 to i32, !dbg !1298
    %tobool158 = icmp ne i32 %conv157, 0, !dbg !1298
    br i1 %tobool158, label %land.lhs.true159, label %if.else177,\
          !dbg !1298
  stack:
    - /home/wk/s/gnupg/g10/encrypt.c:639:0
  ncore: 1
  core:
    - /home/wk/s/gnupg/g10/encrypt.c:639:0
      - null pointer dereference

1 files changed, 7 insertions, 3 deletions

diff --git a/g10/encrypt.c b/g10/encrypt.c
index 8d2b325f9..7b5028d31 100644
--- a/g10/encrypt.c
+++ b/g10/encrypt.c
@@ -453,6 +453,9 @@ write_symkey_enc (STRING2KEY *symkey_s2k, DEK *symkey_dek, DEK *dek,
  * supplied).  Either FILENAME or FILEFD must be given, but not both.
  * The caller may provide a checked list of public keys in
  * PROVIDED_PKS; if not the function builds a list of keys on its own.
+ *
+ * Note that FILEFD is currently only used by cmd_encrypt in the the
+ * not yet finished server.c.
  */
 int
 encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
@@ -476,7 +479,7 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
   int do_compress;
 
   if (filefd != -1 && filename)
-    return gpg_error (GPG_ERR_INV_ARG);
+    return gpg_error (GPG_ERR_INV_ARG);  /* Both given.  */
 
   do_compress = !!opt.compress_algo;
 
@@ -635,8 +638,9 @@ encrypt_crypt (ctrl_t ctrl, int filefd, const char *filename,
   if (!opt.no_literal)
     pt = setup_plaintext_name (filename, inp);
 
-  if (filefd != -1
-      && !iobuf_is_pipe_filename (filename) && *filename && !opt.textmode )
+  /* Get the size of the file if possible, i.e., if it is a real file.  */
+  if (filename && *filename
+      && !iobuf_is_pipe_filename (filename) && !opt.textmode )
     {
       off_t tmpsize;
       int overflow;