#include <assert.h>
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <gdbm.h>

typeof(gdbm_open) *lfs_gdbm_open;
typeof(gdbm_close) *lfs_gdbm_close;
typeof(gdbm_store) *lfs_gdbm_store;
void lfs_init(void)
{
	void *h = dlopen("libgdbm.so.3", RTLD_LAZY|RTLD_LOCAL);
	assert(h != NULL);
	lfs_gdbm_open = dlsym(h, "gdbm_open");
	lfs_gdbm_close = dlsym(h, "gdbm_close");
	lfs_gdbm_store = dlsym(h, "gdbm_store");
}

int main(int argc, char *argv[])
{
	datum key, val;
	struct stat st;
	char *srcf, *dstf;
	GDBM_FILE srcdb, dstdb;
	assert(argc == 2);

	lfs_init();

	srcf = argv[1];
	dstf = malloc(strlen(srcf) + 30);
	sprintf(dstf, "%s.upgrade.tmp", srcf);
	unlink(dstf);

	srcdb = gdbm_open(srcf, 1024, GDBM_NOLOCK | GDBM_READER, 0644, NULL);
	assert(srcdb != NULL);
	stat(srcf, &st);
	dstdb = lfs_gdbm_open(dstf, 1024, GDBM_NOLOCK | GDBM_WRCREAT, st.st_mode, NULL);
	assert(dstdb != NULL);

	key = gdbm_firstkey(srcdb);
	while (key.dptr) {
		val = gdbm_fetch(srcdb, key);
		lfs_gdbm_store(dstdb, key, val, GDBM_INSERT);
		key = gdbm_nextkey(srcdb, key);
	}

	gdbm_close(srcdb);
	lfs_gdbm_close(dstdb);

	chown(dstf, st.st_uid, st.st_gid);

	return 0;
}