[PATCH] ls-tree for listing trees

ls-tree tool provides just a way to export the binary tree objects
to a usable text format. This is bound to be useful in variety
of scripts, although none of those I have currently uses it.
But e.g. the simple script I've sent to HPA for purging the object
database uses it.

Signed-off-by: Petr Baudis <pasky@ucw.cz>

Makefile

@@ -1,9 +1,9 @@
 CFLAGS=-g -O3 -Wall
 CC=gcc
 
-PROG=	update-cache show-diff init-db write-tree read-tree commit-tree \
+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
+	check-files ls-tree
 
 all: $(PROG)
 
@@ -50,6 +50,9 @@ show-files: show-files.o read-cache.o
 check-files: check-files.o read-cache.o
 	$(CC) $(CFLAGS) -o check-files check-files.o read-cache.o $(LIBS)
 
+ls-tree: ls-tree.o read-cache.o
+	$(CC) $(CFLAGS) -o ls-tree ls-tree.o read-cache.o $(LIBS)
+
 read-cache.o: cache.h
 show-diff.o: cache.h
 

ls-tree.c

@@ -0,0 +1,53 @@
+/*
+ * GIT - The information manager from hell
+ *
+ * Copyright (C) Linus Torvalds, 2005
+ */
+#include "cache.h"
+
+static int list(unsigned char *sha1)
+{
+	void *buffer;
+	unsigned long size;
+	char type[20];
+
+	buffer = read_sha1_file(sha1, type, &size);
+	if (!buffer)
+		usage("unable to read sha1 file");
+	if (strcmp(type, "tree"))
+		usage("expected a 'tree' node");
+	while (size) {
+		int len = strlen(buffer)+1;
+		unsigned char *sha1 = buffer + len;
+		char *path = strchr(buffer, ' ')+1;
+		unsigned int mode;
+		unsigned char *type;
+
+		if (size < len + 20 || sscanf(buffer, "%o", &mode) != 1)
+			usage("corrupt 'tree' file");
+		buffer = sha1 + 20;
+		size -= len + 20;
+		/* XXX: We do some ugly mode heuristics here.
+		 * It seems not worth it to read each file just to get this
+		 * and the file size. -- pasky@ucw.cz */
+		type = S_ISDIR(mode) ? "tree" : "blob";
+		printf("%03o\t%s\t%s\t%s\n", mode, type, sha1_to_hex(sha1), path);
+	}
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	unsigned char sha1[20];
+
+	if (argc != 2)
+		usage("ls-tree <key>");
+	if (get_sha1_hex(argv[1], sha1) < 0)
+		usage("ls-tree <key>");
+	sha1_file_directory = getenv(DB_ENVIRONMENT);
+	if (!sha1_file_directory)
+		sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
+	if (list(sha1) < 0)
+		usage("list failed");
+	return 0;
+}