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/*
* 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);
}
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