Re: git-apply fails on creating a new file, with both -p and --directory specified

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 25, 2009, 10:56 UTC
Message-ID: <7vws1e3ma1.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20091123194523.GZ15966@cl.cam.ac.uk>

"Steven J. Murdoch" <git+Steven.Murdoch@cl.cam.ac.uk> writes:

> This appears to be because I was both using -p to strip some path
> components, and --directory to add different ones in. Only creating
> new files was affected.

A very nicely done report.

In addition to your test case, I suspect that a patch that only changes mode would have acted funny with -p<n> option.

-- >8 -- [PATCH] builtin-apply.c: pay attention to -p<n> when determining the name

The patch structure has def_name component that is used to validate the sanity of a "diff --git" patch by checking pathnames that appear on the patch header lines for consistency. The git_header_name() function is used to compute this out of "diff --git a/... b/..." line, but the code always stripped one level of prefix (i.e. "a/" and "b/"), without paying attention to -p<n> option. Code in find_name() function that parses other lines in the patch header (e.g. "--- a/..." and "+++ b/..." lines) however did strip the correct number of leading paths prefixes, and the sanity check between these computed values failed.

Teach git_header_name() to honor -p<n> option like find_name() function does.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 builtin-apply.c |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/builtin-apply.c b/builtin-apply.c
index f667368..36e2f9d 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -823,12 +823,13 @@ static int gitdiff_unrecognized(const char *line, struct patch *patch)
 
 static const char *stop_at_slash(const char *line, int llen)
 {
+	int nslash = p_value;
 	int i;
 
 	for (i = 0; i < llen; i++) {
 		int ch = line[i];
-		if (ch == '/')
-			return line + i;
+		if (ch == '/' && --nslash <= 0)
+			return &line[i];
 	}
 	return NULL;
 }