shared.c: avoid SEGFAULT when checking for binary buffers

Before calling buffer_is_binary() we need to verify that the buffer
is valid.

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/shared.c b/shared.c
index dbb84d8..cce0af4 100644
--- a/shared.c
+++ b/shared.c
@@ -250,50 +250,50 @@ int filediff_cb(void *priv, mmbuffer_t *mb, int nbuf)
         if (diffbuf) {
                 ((linediff_fn)priv)(diffbuf, buflen);
                 free(diffbuf);
                 diffbuf = NULL;
                 buflen = 0;
         }
         return 0;
 }
 
 int cgit_diff_files(const unsigned char *old_sha1,
                     const unsigned char *new_sha1, unsigned long *old_size,
                     unsigned long *new_size, int *binary, linediff_fn fn)
 {
         mmfile_t file1, file2;
         xpparam_t diff_params;
         xdemitconf_t emit_params;
         xdemitcb_t emit_cb;
 
         if (!load_mmfile(&file1, old_sha1) || !load_mmfile(&file2, new_sha1))
                 return 1;
 
         *old_size = file1.size;
         *new_size = file2.size;
 
-        if (buffer_is_binary(file1.ptr, file1.size) ||
-            buffer_is_binary(file2.ptr, file2.size)) {
+        if ((file1.ptr && buffer_is_binary(file1.ptr, file1.size)) ||
+            (file2.ptr && buffer_is_binary(file2.ptr, file2.size))) {
                 *binary = 1;
                 return 0;
         }
 
         memset(&diff_params, 0, sizeof(diff_params));
         memset(&emit_params, 0, sizeof(emit_params));
         memset(&emit_cb, 0, sizeof(emit_cb));
         diff_params.flags = XDF_NEED_MINIMAL;
         emit_params.ctxlen = 3;
         emit_params.flags = XDL_EMIT_FUNCNAMES;
         emit_cb.outf = filediff_cb;
         emit_cb.priv = fn;
         xdl_diff(&file1, &file2, &diff_params, &emit_params, &emit_cb);
         return 0;
 }
 
 void cgit_diff_tree(const unsigned char *old_sha1,
                     const unsigned char *new_sha1,
                     filepair_fn fn, const char *prefix)
 {
         struct diff_options opt;
         int ret;
         int prefixlen;