int cmd_change(int argc, const char *argv[]);

#ifndef CHANGE_H
#define CHANGE_H
/**
 * Required headers
 *  * stdint.h
 */
#define CHANGE_VERSION 6
/**
 * A table of contents for a change, indicating where each section is, to allow
 * seeking inside a change file.
 */
struct offsets {
	uint64_t version;
	uint64_t hashed_len;	/* length of hashed contents */
	uint64_t unhashed_off;
	uint64_t unhashed_len;	/* length of unhashed contents */
	uint64_t contents_off;
	uint64_t contents_len;	/* length of contents (uncompressed) */
	uint64_t total;		/* contents_off + length(compressed contents) */
};
/* sizeof(struct offsets) */
#define OFFSETS_SIZE 56
/**
 * The possible errors that can arise when working with change files.
 */
enum change_err {
	VERMISMATCH = -1
};
/**
 * Decode the 'struct offsets' from the given fd
 *
 * Return 0 if decoding completed successfully, a negative number indicates an
 * error.
 */
int decode_offsets(int fd, struct offsets *);
#endif

#include <stdint.h>
#include <unistd.h>	/* read() */
#include <fcntl.h>	/* open() */
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include "change.h"
/** Read a uint64_t from byte buffer as little endian */
#define legetu64(buf) (((uint64_t)buf[7]) << 56 | (uint64_t)buf[6] << 48 | (uint64_t)buf[5] << 40 | (uint64_t)buf[4] << 32 | (uint64_t)buf[3] << 24 | (uint64_t)buf[2] << 16 | (uint64_t)buf[1] << 8 | (uint64_t)buf[0]);
int
decode_offsets(int fd, struct offsets *off)
{
	/*  */
	ssize_t r;
	uint8_t buf[OFFSETS_SIZE];
	uint8_t *bufp;
	if ((r = read(fd, buf, OFFSETS_SIZE)) < OFFSETS_SIZE) {
		int err;
		if (r >= 0) {
			printf("error: not enough was read: %ld\n", r);
			err = -2;
		} else {
			printf("error: not enough was read: %ld\n", r);
			err = -1;
		}
		return err;
	}
	bufp = (uint8_t *)buf;
	off->version = legetu64(bufp);
	bufp += 8;
	off->hashed_len = legetu64(bufp)
	bufp += 8;
	off->unhashed_off = legetu64(bufp)
	bufp += 8;
	off->unhashed_len = legetu64(bufp)
	bufp += 8;
	off->contents_off = legetu64(bufp)
	bufp += 8;
	off->contents_len = legetu64(bufp)
	bufp += 8;
	off->total = legetu64(bufp)
	return 0;
}
int
change()
{
	int fd;
	int err;
	struct offsets off;
	/* FIXME: A very fixed example */
	fd = open(
		".pijul/changes/AH/IXA5ZESN6QJXV2LKRSC4H5ZRFMJFHFPY2RQRARTH3XJLLCMCGQC.change",
		O_RDONLY
	);
	if (fd == -1) {
		printf("error: %s\n", strerror(errno));
		return -1;
	}
	err = decode_offsets(fd, &off);
	if (err != 0) {
		printf("error: failed to decode offsets\n");
		goto out;
	}
	printf("version           : %lu\n", off.version);
	printf("hashed_len        : %lu\n", off.hashed_len);
	printf("unhashed_off      : %lu\n", off.unhashed_off);
	printf("unhashed_len      : %lu\n", off.unhashed_len);
	printf("contents_off      : %lu\n", off.contents_off);
	printf("contents_len      : %lu\n", off.contents_len);
	printf("total             : %lu\n", off.total);
out:
	close(fd);
	return err;
}
int cmd_change(int argc, const char **argv)
{
	/* FIXME: Add argument handling */
	return change();
}

	" change Show information about a particular change\n"

/* List of builtin commands, by name and the function to invoke */

	{ "change", cmd_change },

OBJS += change.o