/*

 * csum-file.c

 *

 * Copyright (C) 2005 Linus Torvalds

 *

 * Simple file write infrastructure for writing SHA1-summed

 * files. Useful when you write a file that you want to be

 * able to verify hasn't been messed with afterwards.

 */

#include "cache.h"

#include "progress.h"

#include "csum-file.h"

static void flush(struct hashfile *f, const void *buf, unsigned int count)

{

	if (0 <= f->check_fd && count)  {

		unsigned char check_buffer[8192];

		ssize_t ret = read_in_full(f->check_fd, check_buffer, count);

		if (ret < 0)

			die_errno("%s: sha1 file read error", f->name);

		if (ret != count)

			die("%s: sha1 file truncated", f->name);

		if (memcmp(buf, check_buffer, count))

			die("sha1 file '%s' validation error", f->name);

	}

	for (;;) {

		int ret = xwrite(f->fd, buf, count);

		if (ret > 0) {

			f->total += ret;

			display_throughput(f->tp, f->total);

			buf = (char *) buf + ret;

			count -= ret;

			if (count)

				continue;

			return;

		}

		if (!ret)

			die("sha1 file '%s' write error. Out of diskspace", f->name);

		die_errno("sha1 file '%s' write error", f->name);

	}

}

void hashflush(struct hashfile *f)

{

	unsigned offset = f->offset;

	if (offset) {

		the_hash_algo->update_fn(&f->ctx, f->buffer, offset);

		flush(f, f->buffer, offset);

		f->offset = 0;

	}

}

int finalize_hashfile(struct hashfile *f, unsigned char *result, unsigned int flags)

{

	int fd;

	hashflush(f);

	the_hash_algo->final_fn(f->buffer, &f->ctx);

	if (result)

		hashcpy(result, f->buffer);

	if (flags & CSUM_HASH_IN_STREAM)

		flush(f, f->buffer, the_hash_algo->rawsz);

	if (flags & CSUM_FSYNC)

		fsync_or_die(f->fd, f->name);

	if (flags & CSUM_CLOSE) {

		if (close(f->fd))

			die_errno("%s: sha1 file error on close", f->name);

		fd = 0;

	} else

		fd = f->fd;

	if (0 <= f->check_fd) {

		char discard;

		int cnt = read_in_full(f->check_fd, &discard, 1);

		if (cnt < 0)

			die_errno("%s: error when reading the tail of sha1 file",

				  f->name);

		if (cnt)

			die("%s: sha1 file has trailing garbage", f->name);

		if (close(f->check_fd))

			die_errno("%s: sha1 file error on close", f->name);

	}

	free(f);

	return fd;

}

void hashwrite(struct hashfile *f, const void *buf, unsigned int count)

{

	while (count) {

		unsigned offset = f->offset;

		unsigned left = sizeof(f->buffer) - offset;

		unsigned nr = count > left ? left : count;

		const void *data;

		if (f->do_crc)

			f->crc32 = crc32(f->crc32, buf, nr);

		if (nr == sizeof(f->buffer)) {

			/* process full buffer directly without copy */

			data = buf;

		} else {

			memcpy(f->buffer + offset, buf, nr);

			data = f->buffer;

		}

		count -= nr;

		offset += nr;

		buf = (char *) buf + nr;

		left -= nr;

		if (!left) {

			the_hash_algo->update_fn(&f->ctx, data, offset);

			flush(f, data, offset);

			offset = 0;

		}

		f->offset = offset;

	}

}

struct hashfile *hashfd(int fd, const char *name)

{

	return hashfd_throughput(fd, name, NULL);

}

struct hashfile *hashfd_check(const char *name)

{

	int sink, check;

	struct hashfile *f;

	sink = open("/dev/null", O_WRONLY);

	if (sink < 0)

		die_errno("unable to open /dev/null");

	check = open(name, O_RDONLY);

	if (check < 0)

		die_errno("unable to open '%s'", name);

	f = hashfd(sink, name);

	f->check_fd = check;

	return f;

}

struct hashfile *hashfd_throughput(int fd, const char *name, struct progress *tp)

{

	struct hashfile *f = xmalloc(sizeof(*f));

	f->fd = fd;

	f->check_fd = -1;

	f->offset = 0;

	f->total = 0;

	f->tp = tp;

	f->name = name;

	f->do_crc = 0;

	the_hash_algo->init_fn(&f->ctx);

	return f;

}

void hashfile_checkpoint(struct hashfile *f, struct hashfile_checkpoint *checkpoint)

{

	hashflush(f);

	checkpoint->offset = f->total;

	checkpoint->ctx = f->ctx;

}

int hashfile_truncate(struct hashfile *f, struct hashfile_checkpoint *checkpoint)

{

	off_t offset = checkpoint->offset;

	if (ftruncate(f->fd, offset) ||

	    lseek(f->fd, offset, SEEK_SET) != offset)

		return -1;

	f->total = offset;

	f->ctx = checkpoint->ctx;

	f->offset = 0; /* hashflush() was called in checkpoint */

	return 0;

}

void crc32_begin(struct hashfile *f)

{

	f->crc32 = crc32(0, NULL, 0);

	f->do_crc = 1;

}

uint32_t crc32_end(struct hashfile *f)

{

	f->do_crc = 0;

	return f->crc32;

}