Add a "check-files" command, which is useful for scripting

patches.

In particular, it verifies that all the listed files are up-to-date
in the cache (or don't exist and are ready to be added).

Makefile

@@ -2,7 +2,8 @@ CFLAGS=-g -O3 -Wall
 CC=gcc
 
 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
+	cat-file fsck-cache checkout-cache diff-tree rev-tree show-files \
+	check-files
 
 all: $(PROG)
 
@@ -46,6 +47,9 @@ rev-tree: rev-tree.o read-cache.o
 show-files: show-files.o read-cache.o
 	$(CC) $(CFLAGS) -o show-files show-files.o read-cache.o $(LIBS)
 
+check-files: check-files.o read-cache.o
+	$(CC) $(CFLAGS) -o check-files check-files.o read-cache.o $(LIBS)
+
 read-cache.o: cache.h
 show-diff.o: cache.h
 

check-files.c

@@ -0,0 +1,47 @@
+/*
+ * check-files.c
+ *
+ * Check that a set of files are up-to-date in the filesystem or
+ * do not exist. Used to verify a patch target before doing a patch.
+ *
+ * Copyright (C) 2005 Linus Torvalds
+ */
+#include "cache.h"
+
+static void check_file(const char *path)
+{
+	int fd = open(path, O_RDONLY);
+	struct cache_entry *ce;
+	struct stat st;
+	int pos, changed;
+
+	/* Nonexistent is fine */
+	if (fd < 0) {
+		if (errno != ENOENT)
+			usage("%s: %s", path, strerror(errno));
+		return;
+	}
+
+	/* Exists but is not in the cache is not fine */
+	pos = cache_name_pos(path, strlen(path));
+	if (pos < 0)
+		usage("preparing to update existing file '%s' not in cache", path);
+	ce = active_cache[pos];
+
+	if (fstat(fd, &st) < 0)
+		usage("fstat(%s): %s", path, strerror(errno));
+
+	changed = cache_match_stat(ce, &st);
+	if (changed)
+		usage("preparing to update file '%s' not uptodate in cache", path);
+}
+
+int main(int argc, char **argv)
+{
+	int i;
+
+	read_cache();
+	for (i = 1; i < argc ; i++)
+		check_file(argv[i]);
+	return 0;
+}