/*
 * rename files in a git repository, keeping the guid.
 * 
 * Copyright Simon Fowler <simon@dreamcraft.com.au>, 2005.
 */
#include <unistd.h>
#include <sys/stat.h>
#include <errno.h>
#include "cache.h"

static int remove_lock = 0;

static void remove_lock_file(void)
{
	if (remove_lock)
		unlink(".git/index.lock");
}

int main(int argc, char *argv[])
{
	struct stat stats;
	struct cache_entry *ce, *new;
	int newfd, entries, pos, pos2;

	if (argc != 3)
		usage("rename-file <old> <new>");
	if (stat(argv[1], &stats)) {
		perror("rename-file: ");
		exit(1);
	}
	if (!stat(argv[2], &stats))
		die("rename-file: destination file already exists");
	
	newfd = open(".git/index.lock", O_RDWR | O_CREAT | O_EXCL, 0600);
	if (newfd < 0)
		die("unable to create new cachefile");

	atexit(remove_lock_file);
	remove_lock = 1;

	entries = read_cache();
	if (entries < 0)
		die("cache corrupted");

	pos = cache_name_pos(argv[1], strlen(argv[1]));
	pos2 = cache_name_pos(argv[2], strlen(argv[2]));
		
	if (pos < 0) 
		die("original file not in cache");
	if (pos2 >= 0)
		die("destination file already in cache");
	ce = active_cache[pos];
	new = malloc(sizeof(struct cache_entry) + strlen(argv[2]) + 1);
	memcpy(new, ce, sizeof(struct cache_entry));
	new->namelen = strlen(argv[2]);
	memcpy(new->name, argv[2], new->namelen);
	
	if (rename(argv[1], argv[2])) {
		perror("rename-file: ");
		exit(1);
	}

	remove_file_from_cache(argv[1]);
	add_cache_entry(new, 1);

	if (write_cache(newfd, active_cache, active_nr) ||
	    rename(".git/index.lock", ".git/index"))
		die("Unable to write new cachefile");
      
	remove_lock = 0;
	return 0;
}