bulk-checkin.c - jrn/git - Git at Google

 /*
  * Copyright (c) 2011, Google Inc.
  */
 #include "bulk-checkin.h"
 #include "csum-file.h"
 #include "pack.h"

 static int pack_compression_level = Z_DEFAULT_COMPRESSION;

 static struct bulk_checkin_state {
 	unsigned plugged:1;

 	char *pack_tmp_name;
 	struct sha1file *f;
 	off_t offset;
 	struct pack_idx_option pack_idx_opts;

 	struct pack_idx_entry **written;
 	uint32_t alloc_written;
 	uint32_t nr_written;
 } state;

 static void finish_bulk_checkin(struct bulk_checkin_state *state)
 {
 	unsigned char sha1[20];
 	char packname[PATH_MAX];
 	int i;

 	if (!state->f)
 		return;

 	if (state->nr_written == 0) {
 		close(state->f->fd);
 		unlink(state->pack_tmp_name);
 		goto clear_exit;
 	} else if (state->nr_written == 1) {
 		sha1close(state->f, sha1, CSUM_FSYNC);
 	} else {
 		int fd = sha1close(state->f, sha1, 0);
 		fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
 					 state->nr_written, sha1,
 					 state->offset);
 		close(fd);
 	}

 	sprintf(packname, "%s/pack/pack-", get_object_directory());
 	finish_tmp_packfile(packname, state->pack_tmp_name,
 			    state->written, state->nr_written,
 			    &state->pack_idx_opts, sha1);
 	for (i = 0; i < state->nr_written; i++)
 		free(state->written[i]);

 clear_exit:
 	free(state->written);
 	memset(state, 0, sizeof(*state));

 	/* Make objects we just wrote available to ourselves */
 	reprepare_packed_git();
 }

 static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
 {
 	int i;

 	/* The object may already exist in the repository */
 	if (has_sha1_file(sha1))
 		return 1;

 	/* Might want to keep the list sorted */
 	for (i = 0; i < state->nr_written; i++)
 		if (!hashcmp(state->written[i]->sha1, sha1))
 			return 1;

 	/* This is a new object we need to keep */
 	return 0;
 }

 /*
  * Read the contents from fd for size bytes, streaming it to the
  * packfile in state while updating the hash in ctx. Signal a failure
  * by returning a negative value when the resulting pack would exceed
  * the pack size limit and this is not the first object in the pack,
  * so that the caller can discard what we wrote from the current pack
  * by truncating it and opening a new one. The caller will then call
  * us again after rewinding the input fd.
  *
  * The already_hashed_to pointer is kept untouched by the caller to
  * make sure we do not hash the same byte when we are called
  * again. This way, the caller does not have to checkpoint its hash
  * status before calling us just in case we ask it to call us again
  * with a new pack.
  */
 static int stream_to_pack(struct bulk_checkin_state *state,
 			  git_SHA_CTX *ctx, off_t *already_hashed_to,
 			  int fd, size_t size, enum object_type type,
 			  const char *path, unsigned flags)
 {
 	git_zstream s;
 	unsigned char obuf[16384];
 	unsigned hdrlen;
 	int status = Z_OK;
 	int write_object = (flags & HASH_WRITE_OBJECT);
 	off_t offset = 0;

 	memset(&s, 0, sizeof(s));
 	git_deflate_init(&s, pack_compression_level);

 	hdrlen = encode_in_pack_object_header(type, size, obuf);
 	s.next_out = obuf + hdrlen;
 	s.avail_out = sizeof(obuf) - hdrlen;

 	while (status != Z_STREAM_END) {
 		unsigned char ibuf[16384];

 		if (size && !s.avail_in) {
 			ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
 			if (xread(fd, ibuf, rsize) != rsize)
 				die("failed to read %d bytes from '%s'",
 				    (int)rsize, path);
 			offset += rsize;
 			if (*already_hashed_to < offset) {
 				size_t hsize = offset - *already_hashed_to;
 				if (rsize < hsize)
 					hsize = rsize;
 				if (hsize)
 					git_SHA1_Update(ctx, ibuf, hsize);
 				*already_hashed_to = offset;
 			}
 			s.next_in = ibuf;
 			s.avail_in = rsize;
 			size -= rsize;
 		}

 		status = git_deflate(&s, size ? 0 : Z_FINISH);

 		if (!s.avail_out || status == Z_STREAM_END) {
 			if (write_object) {
 				size_t written = s.next_out - obuf;

 				/* would we bust the size limit? */
 				if (state->nr_written &&
 				    pack_size_limit_cfg &&
 				    pack_size_limit_cfg < state->offset + written) {
 					git_deflate_abort(&s);
 					return -1;
 				}

 				sha1write(state->f, obuf, written);
 				state->offset += written;
 			}
 			s.next_out = obuf;
 			s.avail_out = sizeof(obuf);
 		}

 		switch (status) {
 		case Z_OK:
 		case Z_BUF_ERROR:
 		case Z_STREAM_END:
 			continue;
 		default:
 			die("unexpected deflate failure: %d", status);
 		}
 	}
 	git_deflate_end(&s);
 	return 0;
 }

 /* Lazily create backing packfile for the state */
 static void prepare_to_stream(struct bulk_checkin_state *state,
 			      unsigned flags)
 {
 	if (!(flags & HASH_WRITE_OBJECT) || state->f)
 		return;

 	state->f = create_tmp_packfile(&state->pack_tmp_name);
 	reset_pack_idx_option(&state->pack_idx_opts);

 	/* Pretend we are going to write only one object */
 	state->offset = write_pack_header(state->f, 1);
 	if (!state->offset)
 		die_errno("unable to write pack header");
 }

 static int deflate_to_pack(struct bulk_checkin_state *state,
 			   unsigned char result_sha1[],
 			   int fd, size_t size,
 			   enum object_type type, const char *path,
 			   unsigned flags)
 {
 	off_t seekback, already_hashed_to;
 	git_SHA_CTX ctx;
 	unsigned char obuf[16384];
 	unsigned header_len;
 	struct sha1file_checkpoint checkpoint;
 	struct pack_idx_entry *idx = NULL;

 	seekback = lseek(fd, 0, SEEK_CUR);
 	if (seekback == (off_t) -1)
 		return error("cannot find the current offset");

 	header_len = sprintf((char *)obuf, "%s %" PRIuMAX,
 			     typename(type), (uintmax_t)size) + 1;
 	git_SHA1_Init(&ctx);
 	git_SHA1_Update(&ctx, obuf, header_len);

 	/* Note: idx is non-NULL when we are writing */
 	if ((flags & HASH_WRITE_OBJECT) != 0)
 		idx = xcalloc(1, sizeof(*idx));

 	already_hashed_to = 0;

 	while (1) {
 		prepare_to_stream(state, flags);
 		if (idx) {
 			sha1file_checkpoint(state->f, &checkpoint);
 			idx->offset = state->offset;
 			crc32_begin(state->f);
 		}
 		if (!stream_to_pack(state, &ctx, &already_hashed_to,
 				    fd, size, type, path, flags))
 			break;
 		/*
 		 * Writing this object to the current pack will make
 		 * it too big; we need to truncate it, start a new
 		 * pack, and write into it.
 		 */
 		if (!idx)
 			die("BUG: should not happen");
 		sha1file_truncate(state->f, &checkpoint);
 		state->offset = checkpoint.offset;
 		finish_bulk_checkin(state);
 		if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
 			return error("cannot seek back");
 	}
 	git_SHA1_Final(result_sha1, &ctx);
 	if (!idx)
 		return 0;

 	idx->crc32 = crc32_end(state->f);
 	if (already_written(state, result_sha1)) {
 		sha1file_truncate(state->f, &checkpoint);
 		state->offset = checkpoint.offset;
 		free(idx);
 	} else {
 		hashcpy(idx->sha1, result_sha1);
 		ALLOC_GROW(state->written,
 			   state->nr_written + 1,
 			   state->alloc_written);
 		state->written[state->nr_written++] = idx;
 	}
 	return 0;
 }

 int index_bulk_checkin(unsigned char *sha1,
 		       int fd, size_t size, enum object_type type,
 		       const char *path, unsigned flags)
 {
 	int status = deflate_to_pack(&state, sha1, fd, size, type,
 				     path, flags);
 	if (!state.plugged)
 		finish_bulk_checkin(&state);
 	return status;
 }

 void plug_bulk_checkin(void)
 {
 	state.plugged = 1;
 }

 void unplug_bulk_checkin(void)
 {
 	state.plugged = 0;
 	if (state.f)
 		finish_bulk_checkin(&state);
 }
	/*
	* Copyright (c) 2011, Google Inc.
	*/
	#include "bulk-checkin.h"
	#include "csum-file.h"
	#include "pack.h"

	static int pack_compression_level = Z_DEFAULT_COMPRESSION;

	static struct bulk_checkin_state {
	unsigned plugged:1;

	char *pack_tmp_name;
	struct sha1file *f;
	off_t offset;
	struct pack_idx_option pack_idx_opts;

	struct pack_idx_entry **written;
	uint32_t alloc_written;
	uint32_t nr_written;
	} state;

	static void finish_bulk_checkin(struct bulk_checkin_state *state)
	{
	unsigned char sha1[20];
	char packname[PATH_MAX];
	int i;

	if (!state->f)
	return;

	if (state->nr_written == 0) {
	close(state->f->fd);
	unlink(state->pack_tmp_name);
	goto clear_exit;
	} else if (state->nr_written == 1) {
	sha1close(state->f, sha1, CSUM_FSYNC);
	} else {
	int fd = sha1close(state->f, sha1, 0);
	fixup_pack_header_footer(fd, sha1, state->pack_tmp_name,
	state->nr_written, sha1,
	state->offset);
	close(fd);
	}

	sprintf(packname, "%s/pack/pack-", get_object_directory());
	finish_tmp_packfile(packname, state->pack_tmp_name,
	state->written, state->nr_written,
	&state->pack_idx_opts, sha1);
	for (i = 0; i < state->nr_written; i++)
	free(state->written[i]);

	clear_exit:
	free(state->written);
	memset(state, 0, sizeof(*state));

	/* Make objects we just wrote available to ourselves */
	reprepare_packed_git();
	}

	static int already_written(struct bulk_checkin_state *state, unsigned char sha1[])
	{
	int i;

	/* The object may already exist in the repository */
	if (has_sha1_file(sha1))
	return 1;

	/* Might want to keep the list sorted */
	for (i = 0; i < state->nr_written; i++)
	if (!hashcmp(state->written[i]->sha1, sha1))
	return 1;

	/* This is a new object we need to keep */
	return 0;
	}

	/*
	* Read the contents from fd for size bytes, streaming it to the
	* packfile in state while updating the hash in ctx. Signal a failure
	* by returning a negative value when the resulting pack would exceed
	* the pack size limit and this is not the first object in the pack,
	* so that the caller can discard what we wrote from the current pack
	* by truncating it and opening a new one. The caller will then call
	* us again after rewinding the input fd.
	*
	* The already_hashed_to pointer is kept untouched by the caller to
	* make sure we do not hash the same byte when we are called
	* again. This way, the caller does not have to checkpoint its hash
	* status before calling us just in case we ask it to call us again
	* with a new pack.
	*/
	static int stream_to_pack(struct bulk_checkin_state *state,
	git_SHA_CTX ctx, off_t already_hashed_to,
	int fd, size_t size, enum object_type type,
	const char *path, unsigned flags)
	{
	git_zstream s;
	unsigned char obuf[16384];
	unsigned hdrlen;
	int status = Z_OK;
	int write_object = (flags & HASH_WRITE_OBJECT);
	off_t offset = 0;

	memset(&s, 0, sizeof(s));
	git_deflate_init(&s, pack_compression_level);

	hdrlen = encode_in_pack_object_header(type, size, obuf);
	s.next_out = obuf + hdrlen;
	s.avail_out = sizeof(obuf) - hdrlen;

	while (status != Z_STREAM_END) {
	unsigned char ibuf[16384];

	if (size && !s.avail_in) {
	ssize_t rsize = size < sizeof(ibuf) ? size : sizeof(ibuf);
	if (xread(fd, ibuf, rsize) != rsize)
	die("failed to read %d bytes from '%s'",
	(int)rsize, path);
	offset += rsize;
	if (*already_hashed_to < offset) {
	size_t hsize = offset - *already_hashed_to;
	if (rsize < hsize)
	hsize = rsize;
	if (hsize)
	git_SHA1_Update(ctx, ibuf, hsize);
	*already_hashed_to = offset;
	}
	s.next_in = ibuf;
	s.avail_in = rsize;
	size -= rsize;
	}

	status = git_deflate(&s, size ? 0 : Z_FINISH);

	if (!s.avail_out \|\| status == Z_STREAM_END) {
	if (write_object) {
	size_t written = s.next_out - obuf;

	/* would we bust the size limit? */
	if (state->nr_written &&
	pack_size_limit_cfg &&
	pack_size_limit_cfg < state->offset + written) {
	git_deflate_abort(&s);
	return -1;
	}

	sha1write(state->f, obuf, written);
	state->offset += written;
	}
	s.next_out = obuf;
	s.avail_out = sizeof(obuf);
	}

	switch (status) {
	case Z_OK:
	case Z_BUF_ERROR:
	case Z_STREAM_END:
	continue;
	default:
	die("unexpected deflate failure: %d", status);
	}
	}
	git_deflate_end(&s);
	return 0;
	}

	/* Lazily create backing packfile for the state */
	static void prepare_to_stream(struct bulk_checkin_state *state,
	unsigned flags)
	{
	if (!(flags & HASH_WRITE_OBJECT) \|\| state->f)
	return;

	state->f = create_tmp_packfile(&state->pack_tmp_name);
	reset_pack_idx_option(&state->pack_idx_opts);

	/* Pretend we are going to write only one object */
	state->offset = write_pack_header(state->f, 1);
	if (!state->offset)
	die_errno("unable to write pack header");
	}

	static int deflate_to_pack(struct bulk_checkin_state *state,
	unsigned char result_sha1[],
	int fd, size_t size,
	enum object_type type, const char *path,
	unsigned flags)
	{
	off_t seekback, already_hashed_to;
	git_SHA_CTX ctx;
	unsigned char obuf[16384];
	unsigned header_len;
	struct sha1file_checkpoint checkpoint;
	struct pack_idx_entry *idx = NULL;

	seekback = lseek(fd, 0, SEEK_CUR);
	if (seekback == (off_t) -1)
	return error("cannot find the current offset");

	header_len = sprintf((char *)obuf, "%s %" PRIuMAX,
	typename(type), (uintmax_t)size) + 1;
	git_SHA1_Init(&ctx);
	git_SHA1_Update(&ctx, obuf, header_len);

	/* Note: idx is non-NULL when we are writing */
	if ((flags & HASH_WRITE_OBJECT) != 0)
	idx = xcalloc(1, sizeof(*idx));

	already_hashed_to = 0;

	while (1) {
	prepare_to_stream(state, flags);
	if (idx) {
	sha1file_checkpoint(state->f, &checkpoint);
	idx->offset = state->offset;
	crc32_begin(state->f);
	}
	if (!stream_to_pack(state, &ctx, &already_hashed_to,
	fd, size, type, path, flags))
	break;
	/*
	* Writing this object to the current pack will make
	* it too big; we need to truncate it, start a new
	* pack, and write into it.
	*/
	if (!idx)
	die("BUG: should not happen");
	sha1file_truncate(state->f, &checkpoint);
	state->offset = checkpoint.offset;
	finish_bulk_checkin(state);
	if (lseek(fd, seekback, SEEK_SET) == (off_t) -1)
	return error("cannot seek back");
	}
	git_SHA1_Final(result_sha1, &ctx);
	if (!idx)
	return 0;

	idx->crc32 = crc32_end(state->f);
	if (already_written(state, result_sha1)) {
	sha1file_truncate(state->f, &checkpoint);
	state->offset = checkpoint.offset;
	free(idx);
	} else {
	hashcpy(idx->sha1, result_sha1);
	ALLOC_GROW(state->written,
	state->nr_written + 1,
	state->alloc_written);
	state->written[state->nr_written++] = idx;
	}
	return 0;
	}

	int index_bulk_checkin(unsigned char *sha1,
	int fd, size_t size, enum object_type type,
	const char *path, unsigned flags)
	{
	int status = deflate_to_pack(&state, sha1, fd, size, type,
	path, flags);
	if (!state.plugged)
	finish_bulk_checkin(&state);
	return status;
	}

	void plug_bulk_checkin(void)
	{
	state.plugged = 1;
	}

	void unplug_bulk_checkin(void)
	{
	state.plugged = 0;
	if (state.f)
	finish_bulk_checkin(&state);
	}