Re: [PATCH v2] diff -c -p: do not die on submodules

Alex Riesen [off-list ref] writes:

2009/4/29 Junio C Hamano [off-list ref]:

quoted

+
+       if (S_ISGITLINK(mode)) {
+               blob = xmalloc(100);
+               *size = snprintf(blob, 100,
+                                "Subproject commit %s\n", sha1_to_hex(sha1));

snprintf returns a signed value. It also has a bad record of returning
negative values for obscure reasons (on obscure platforms, admittedly).

The arena is sufficiently large that there is no way any broken snprintf
can return negative here.

This is a copy from Linus's diff_populate_gitlink(), that dates back to
0478675 (Expose subprojects as special files to "git diff" machinery,
2007-04-15), and you have never seen any breakage, which should tell you
something.

As I mentioned in the original patch, the codepath that reads one side of
diff (either from a blob or from a work tree entity) in show_patch_diff()
and grab_blob() in combine-diff.c should do the same thing as what
diff_populate_filespec() in diff.c does, and these three functions need
some refactoring to share more code.  The patch however is about fixing
the existing breakage without invasive refactoring.