[PATCH] Diff-tree-helper take two.

This reworks the diff-tree-helper and show-diff to further make external
diff command interface simpler.

These commands now honor GIT_EXTERNAL_DIFF environment variable which
can point at an arbitrary program that takes 7 parameters:

  name file1 file1-sha1 file1-mode file2 file2-sha1 file2-mode

The parameters for an external diff command are as follows:

  name        this invocation of the command is to emit diff
	      for the named cache/tree entry.

  file1       pathname that holds the contents of the first
	      file.  This can be a file inside the working
	      tree, or a temporary file created from the blob
	      object, or /dev/null.  The command should not
	      attempt to unlink it -- the temporary is
	      unlinked by the caller.

  file1-sha1  sha1 hash if file1 is a blob object, or "."
	      otherwise.

  file1-mode  mode bits for file1, or "." for a deleted file.

If GIT_EXTERNAL_DIFF environment variable is not set, the
default is to invoke diff with the set of parameters old
show-diff used to use.  This built-in implementation honors the
GIT_DIFF_CMD and GIT_DIFF_OPTS environment variables as before.

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

1 files changed, 3 insertions, 14 deletions

diff --git a/show-diff.c b/show-diff.c
index 3e798be303..967c523990 100644
--- a/show-diff.c
+++ b/show-diff.c
@@ -53,14 +53,11 @@ int main(int argc, char **argv)
 		perror("read_cache");
 		exit(1);
 	}
-	prepare_diff_cmd();
+
 	for (i = 0; i < entries; i++) {
 		struct stat st;
 		struct cache_entry *ce = active_cache[i];
 		int changed;
-		unsigned long size;
-		char type[20];
-		void *old;
 
 		if (1 < argc &&
 		    ! matches_pathspec(ce, argv+1, argc-1))
@@ -87,8 +84,7 @@ int main(int argc, char **argv)
 			else {
 				printf("%s: %s\n", ce->name, strerror(errno));
 				if (errno == ENOENT)
-					show_diff_empty(ce->sha1, ce->name,
-							reverse);
+					show_diff_empty(ce, reverse);
 			}
 			continue;
 		}
@@ -104,14 +100,7 @@ int main(int argc, char **argv)
 		if (silent)
 			continue;
 
-		old = read_sha1_file(ce->sha1, type, &size);
-		if (! old)
-			error("unable to read blob object for %s (%s)",
-			      ce->name, sha1_to_hex(ce->sha1));
-		else
-			show_differences(ce->name, ce->name, old, size,
-					 reverse);
-		free(old);
+		show_differences(ce, reverse);
 	}
 	return 0;
 }