Improve robustness and help lint.

* cipher/rsa.c (rsa_encrypt): Check for !DATA.
* cipher/md.c (search_oid): Check early for !OID.
(md_copy): Use gpg_err_code_from_syserror.  Replace chains of if(!err)
tests.
* cipher/cipher.c (search_oid): Check early for !OID.
* src/misc.c (do_printhex): Allow for BUFFER==NULL even with LENGTH>0.
* mpi/mpicoder.c (onecompl): Allow for A==NULL to help static
analyzers.
--

The change for md_copy is to help static analyzers which have no idea
that gpg_err_code_from_syserror will never return 0.  A gcc attribute
returns_nonzero would be a nice to have.

Some changes are due to the fact the macros like mpi_is_immutable
gracefully handle a NULL arg but a static analyzer the considers that
the function allows for a NULL arg.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/mpi/mpicoder.c b/mpi/mpicoder.c
index e3155766..4c63a147 100644
--- a/mpi/mpicoder.c
+++ b/mpi/mpicoder.c
@@ -403,14 +403,16 @@ onecompl (gcry_mpi_t a)
   mpi_ptr_t ap;
   mpi_size_t n;
   unsigned int i;
-  unsigned int nbits = mpi_get_nbits (a);
+  unsigned int nbits;
 
-  if (mpi_is_immutable (a))
+  if (!a || mpi_is_immutable (a))
     {
       mpi_immutable_failed ();
       return;
     }
 
+  nbits = mpi_get_nbits (a);
+
   mpi_normalize (a);
   ap = a->d;
   n = a->nlimbs;