Re: [PATCH 0/5] Split-up "unpack_trees()" cleanup series

[Linus Torvalds <torvalds@linux-foundation.org>]

On Thu, 6 Mar 2008, Daniel Barkalow wrote:
>
> On Wed, 5 Mar 2008, Linus Torvalds wrote:
> > 
> > It's a series of five patches:
> >  -  Add 'df_name_compare()' helper function
> >  - Make 'traverse_tree()' use linked structure rather than 'const char *base'
> >  - Add return value to 'traverse_tree()' callback
> >  - Make 'traverse_trees()' traverse conflicting DF entries in parallel
> >  - Move 'unpack_trees()' over to 'traverse_trees()' interface
> 
> This all looks good to me.

There's a really stupid bug in function that compares filenames using 
the the linked list structure which makes it not compare the first path 
component when using "--prefix".

So it can only hit in the case of us having a "prefix" entry that makes 
the name of the "root" info structure non-empty, and I suspect that 
because of all the other horrid crud we do for --prefix=xyzzy handling in 
builtin-read-tree.c you can't actually trigger this bug, but my other 
cleanups (which I'll send out once I've tested them a bit more) will make 
this bug trigger.

This fairly obvious patch fixes it by just making sure that we always end 
up having a ->prev entry if we have a pathname component.

			Linus

---
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Thu Mar 6 15:44:48 2008 -0800

Fix tree-walking compare_entry() in the presense of --prefix

When we make the "root" tree-walk info entry have a pathname in it, we
need to have a ->prev pointer so that compare_entry will actually notice
and traverse into the root.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 tree-walk.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/tree-walk.c b/tree-walk.c
index 842cb6a..02e2aed 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -107,6 +107,7 @@ int tree_entry(struct tree_desc *desc, struct name_entry *entry)
 void setup_traverse_info(struct traverse_info *info, const char *base)
 {
 	int pathlen = strlen(base);
+	static struct traverse_info dummy;
 
 	memset(info, 0, sizeof(*info));
 	if (pathlen && base[pathlen-1] == '/')
@@ -114,6 +115,8 @@ void setup_traverse_info(struct traverse_info *info, const char *base)
 	info->pathlen = pathlen ? pathlen + 1 : 0;
 	info->name.path = base;
 	info->name.sha1 = (void *)(base + pathlen + 1);
+	if (pathlen)
+		info->prev = &dummy;
 }
 
 char *make_traverse_path(char *path, const struct traverse_info *info, const struct name_entry *n)