odd patch issue

[John Keeping]

On Mon, Mar 14, 2016 at 03:44:31PM -0600, Kevin Fenzi wrote:
> On Mon, 14 Mar 2016 21:20:37 +0000
> John Keeping <john at keeping.me.uk> wrote:
> 
> > On Mon, Mar 14, 2016 at 01:46:29PM -0600, Kevin Fenzi wrote:
> > > We are seeing an odd behavior with diffs/patches here. I think it's
> > > a bug, but perhaps we are doing something wrong. ;) 
> > > 
> > > If you look at: 
> > > 
> > > https://fedorapeople.org/cgit/adelton/public_git/CGI-sessions.git/diff/app.cgi?id=additional-attributes
> > > 
> > > you can see just the diff for that one file. 
> > > However, if you try and get a patch for just that one file: 
> > > 
> > > https://fedorapeople.org/cgit/adelton/public_git/CGI-sessions.git/patch/app.cgi?id=additional-attributes
> > > 
> > > You get also any other files affected in that patch. (ie, not just
> > > app.cgi). Is this expected? or a bug?  
> > 
> > I think this is expected.  It doesn't really make sense for "patch" to
> > use a path since it includes the header and commit message, so it
> > doesn't take a path argument.  (Hopefully you created that URL
> > manually and didn't follow a link - if we generate such a link that
> > is a bug.)
> 
> The downstream reporter claims that this worked as they want in the
> past. ;( 
> 
> https://fedorahosted.org/fedora-infrastructure/ticket/4811

Indeed it did, so I think we should do this:

-- >8 --
Subject: [PATCH] patch: reapply path limit

This was originally applied added in commit eac1b67 (ui-patch: Apply
path limit to generated patch, 2010-06-10) but the ability to limit
patches to particular paths was lost in commit 455b598 (ui-patch.c: Use
log_tree_commit() to generate diffs, 2013-08-20).

The new output is slightly different from the original because Git's
diff infrastructure doesn't give us a way to insert an annotation
immediately after the "---" separator, so the commit has moved below the
diff stat.

Signed-off-by: John Keeping <john at keeping.me.uk>
---
 ui-patch.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/ui-patch.c b/ui-patch.c
index 4c051e8..e8b5338 100644
--- a/ui-patch.c
+++ b/ui-patch.c
@@ -18,9 +18,13 @@ void cgit_print_patch(const char *new_rev, const char *old_rev,
 	struct commit *commit;
 	unsigned char new_rev_sha1[20], old_rev_sha1[20];
 	char rev_range[2 * 40 + 3];
-	char *rev_argv[] = { NULL, "--reverse", "--format=email", rev_range };
+	const char *rev_argv[] = { NULL, "--reverse", "--format=email", rev_range, "--", prefix };
+	int rev_argc = ARRAY_SIZE(rev_argv);
 	char *patchname;
 
+	if (!prefix)
+		rev_argc--;
+
 	if (!new_rev)
 		new_rev = ctx.qry.head;
 
@@ -79,7 +83,9 @@ void cgit_print_patch(const char *new_rev, const char *old_rev,
 	rev.max_parents = 1;
 	rev.diffopt.output_format |= DIFF_FORMAT_DIFFSTAT |
 			DIFF_FORMAT_PATCH | DIFF_FORMAT_SUMMARY;
-	setup_revisions(ARRAY_SIZE(rev_argv), (const char **)rev_argv, &rev,
+	if (prefix)
+		rev.diffopt.stat_sep = fmt("(limited to '%s')\n\n", prefix);
+	setup_revisions(ARRAY_SIZE(rev_argv), rev_argv, &rev,
 			NULL);
 	prepare_revision_walk(&rev);
 
-- 
2.8.0.rc1.128.gf7e6a6c