[PATCH] Introduce diff-tree-helper.

This patch introduces a new program, diff-tree-helper.  It reads
output from diff-cache and diff-tree, and produces a patch file.
The diff format customization can be done the same way the
show-diff uses; the same external diff interface introduced by
the previous patch to drive diff from show-diff is used so this
is not surprising.

It is used like the following examples:

   $ diff-cache --cached -z <tree> | diff-tree-helper -z -R paths...
   $ diff-tree -r -z <tree1> <tree2> | diff-tree-helper -z paths...

 - As usual, the use of the -z flag is recommended in the script
   to pass NUL-terminated filenames through the pipe between
   commands.

 - The -R flag is used to generate reverse diff.  It does not
   matter for diff-tree case, but it is sometimes useful to get
   a patch in the desired direction out of diff-cache.

 - The paths parameters are used to restrict the paths that
   appears in the output.  Again this is useful to use with
   diff-cache, which, unlike diff-tree, does not take such paths
   restriction parameters.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index e108b98e63..2d2913b6b9 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,8 @@ SCRIPTS=git-merge-one-file-script git-prune-script git-pull-script git-tag-scrip
 PROG=   update-cache show-diff init-db write-tree read-tree commit-tree \
 	cat-file fsck-cache checkout-cache diff-tree rev-tree show-files \
 	check-files ls-tree merge-base merge-cache unpack-file git-export \
-	diff-cache convert-cache http-pull rpush rpull rev-list git-mktag
+	diff-cache convert-cache http-pull rpush rpull rev-list git-mktag \
+	diff-tree-helper
 
 all: $(PROG)
 
@@ -28,6 +29,9 @@ LIB_OBJS=read-cache.o sha1_file.o usage.o object.o commit.o tree.o blob.o
 LIB_FILE=libgit.a
 LIB_H=cache.h object.h
 
+LIB_H += strbuf.h
+LIB_OBJS += strbuf.o
+
 LIB_H += diff.h
 LIB_OBJS += diff.o