git/streaming.c
Ævar Arnfjörð Bjarmason d4e2d15a8b streaming.c: move {open,close,read} from vtable to "struct git_istream"
Move the definition of the structure around the open/close/read
functions introduced in 46bf043807 (streaming: a new API to read from
the object store, 2011-05-11) to instead populate "close" and "read"
members in the "struct git_istream".

This gets us rid of an extra pointer deference, and I think makes more
sense. The "close" and "read" functions are the primary interface to
the stream itself.

Let's also populate a "open" callback in the same struct. That's now
used by open_istream() after istream_source() decides what "open"
function should be used. This isn't needed to get rid of the
"stream_vtbl" variables, but makes sense for consistency.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-05-06 12:56:10 +09:00

532 lines
12 KiB
C

/*
* Copyright (c) 2011, Google Inc.
*/
#include "cache.h"
#include "streaming.h"
#include "repository.h"
#include "object-store.h"
#include "replace-object.h"
#include "packfile.h"
typedef int (*open_istream_fn)(struct git_istream *,
struct repository *,
const struct object_id *,
enum object_type *);
typedef int (*close_istream_fn)(struct git_istream *);
typedef ssize_t (*read_istream_fn)(struct git_istream *, char *, size_t);
#define FILTER_BUFFER (1024*16)
struct filtered_istream {
struct git_istream *upstream;
struct stream_filter *filter;
char ibuf[FILTER_BUFFER];
char obuf[FILTER_BUFFER];
int i_end, i_ptr;
int o_end, o_ptr;
int input_finished;
};
struct git_istream {
open_istream_fn open;
close_istream_fn close;
read_istream_fn read;
unsigned long size; /* inflated size of full object */
git_zstream z;
enum { z_unused, z_used, z_done, z_error } z_state;
union {
struct {
char *buf; /* from read_object() */
unsigned long read_ptr;
} incore;
struct {
void *mapped;
unsigned long mapsize;
char hdr[32];
int hdr_avail;
int hdr_used;
} loose;
struct {
struct packed_git *pack;
off_t pos;
} in_pack;
struct filtered_istream filtered;
} u;
};
/*****************************************************************
*
* Common helpers
*
*****************************************************************/
static void close_deflated_stream(struct git_istream *st)
{
if (st->z_state == z_used)
git_inflate_end(&st->z);
}
/*****************************************************************
*
* Filtered stream
*
*****************************************************************/
static int close_istream_filtered(struct git_istream *st)
{
free_stream_filter(st->u.filtered.filter);
return close_istream(st->u.filtered.upstream);
}
static ssize_t read_istream_filtered(struct git_istream *st, char *buf,
size_t sz)
{
struct filtered_istream *fs = &(st->u.filtered);
size_t filled = 0;
while (sz) {
/* do we already have filtered output? */
if (fs->o_ptr < fs->o_end) {
size_t to_move = fs->o_end - fs->o_ptr;
if (sz < to_move)
to_move = sz;
memcpy(buf + filled, fs->obuf + fs->o_ptr, to_move);
fs->o_ptr += to_move;
sz -= to_move;
filled += to_move;
continue;
}
fs->o_end = fs->o_ptr = 0;
/* do we have anything to feed the filter with? */
if (fs->i_ptr < fs->i_end) {
size_t to_feed = fs->i_end - fs->i_ptr;
size_t to_receive = FILTER_BUFFER;
if (stream_filter(fs->filter,
fs->ibuf + fs->i_ptr, &to_feed,
fs->obuf, &to_receive))
return -1;
fs->i_ptr = fs->i_end - to_feed;
fs->o_end = FILTER_BUFFER - to_receive;
continue;
}
/* tell the filter to drain upon no more input */
if (fs->input_finished) {
size_t to_receive = FILTER_BUFFER;
if (stream_filter(fs->filter,
NULL, NULL,
fs->obuf, &to_receive))
return -1;
fs->o_end = FILTER_BUFFER - to_receive;
if (!fs->o_end)
break;
continue;
}
fs->i_end = fs->i_ptr = 0;
/* refill the input from the upstream */
if (!fs->input_finished) {
fs->i_end = read_istream(fs->upstream, fs->ibuf, FILTER_BUFFER);
if (fs->i_end < 0)
return -1;
if (fs->i_end)
continue;
}
fs->input_finished = 1;
}
return filled;
}
static struct git_istream *attach_stream_filter(struct git_istream *st,
struct stream_filter *filter)
{
struct git_istream *ifs = xmalloc(sizeof(*ifs));
struct filtered_istream *fs = &(ifs->u.filtered);
ifs->close = close_istream_filtered;
ifs->read = read_istream_filtered;
fs->upstream = st;
fs->filter = filter;
fs->i_end = fs->i_ptr = 0;
fs->o_end = fs->o_ptr = 0;
fs->input_finished = 0;
ifs->size = -1; /* unknown */
return ifs;
}
/*****************************************************************
*
* Loose object stream
*
*****************************************************************/
static ssize_t read_istream_loose(struct git_istream *st, char *buf, size_t sz)
{
size_t total_read = 0;
switch (st->z_state) {
case z_done:
return 0;
case z_error:
return -1;
default:
break;
}
if (st->u.loose.hdr_used < st->u.loose.hdr_avail) {
size_t to_copy = st->u.loose.hdr_avail - st->u.loose.hdr_used;
if (sz < to_copy)
to_copy = sz;
memcpy(buf, st->u.loose.hdr + st->u.loose.hdr_used, to_copy);
st->u.loose.hdr_used += to_copy;
total_read += to_copy;
}
while (total_read < sz) {
int status;
st->z.next_out = (unsigned char *)buf + total_read;
st->z.avail_out = sz - total_read;
status = git_inflate(&st->z, Z_FINISH);
total_read = st->z.next_out - (unsigned char *)buf;
if (status == Z_STREAM_END) {
git_inflate_end(&st->z);
st->z_state = z_done;
break;
}
if (status != Z_OK && (status != Z_BUF_ERROR || total_read < sz)) {
git_inflate_end(&st->z);
st->z_state = z_error;
return -1;
}
}
return total_read;
}
static int close_istream_loose(struct git_istream *st)
{
close_deflated_stream(st);
munmap(st->u.loose.mapped, st->u.loose.mapsize);
return 0;
}
static int open_istream_loose(struct git_istream *st, struct repository *r,
const struct object_id *oid,
enum object_type *type)
{
st->u.loose.mapped = map_loose_object(r, oid, &st->u.loose.mapsize);
if (!st->u.loose.mapped)
return -1;
if ((unpack_loose_header(&st->z,
st->u.loose.mapped,
st->u.loose.mapsize,
st->u.loose.hdr,
sizeof(st->u.loose.hdr)) < 0) ||
(parse_loose_header(st->u.loose.hdr, &st->size) < 0)) {
git_inflate_end(&st->z);
munmap(st->u.loose.mapped, st->u.loose.mapsize);
return -1;
}
st->u.loose.hdr_used = strlen(st->u.loose.hdr) + 1;
st->u.loose.hdr_avail = st->z.total_out;
st->z_state = z_used;
st->close = close_istream_loose;
st->read = read_istream_loose;
return 0;
}
/*****************************************************************
*
* Non-delta packed object stream
*
*****************************************************************/
static ssize_t read_istream_pack_non_delta(struct git_istream *st, char *buf,
size_t sz)
{
size_t total_read = 0;
switch (st->z_state) {
case z_unused:
memset(&st->z, 0, sizeof(st->z));
git_inflate_init(&st->z);
st->z_state = z_used;
break;
case z_done:
return 0;
case z_error:
return -1;
case z_used:
break;
}
while (total_read < sz) {
int status;
struct pack_window *window = NULL;
unsigned char *mapped;
mapped = use_pack(st->u.in_pack.pack, &window,
st->u.in_pack.pos, &st->z.avail_in);
st->z.next_out = (unsigned char *)buf + total_read;
st->z.avail_out = sz - total_read;
st->z.next_in = mapped;
status = git_inflate(&st->z, Z_FINISH);
st->u.in_pack.pos += st->z.next_in - mapped;
total_read = st->z.next_out - (unsigned char *)buf;
unuse_pack(&window);
if (status == Z_STREAM_END) {
git_inflate_end(&st->z);
st->z_state = z_done;
break;
}
/*
* Unlike the loose object case, we do not have to worry here
* about running out of input bytes and spinning infinitely. If
* we get Z_BUF_ERROR due to too few input bytes, then we'll
* replenish them in the next use_pack() call when we loop. If
* we truly hit the end of the pack (i.e., because it's corrupt
* or truncated), then use_pack() catches that and will die().
*/
if (status != Z_OK && status != Z_BUF_ERROR) {
git_inflate_end(&st->z);
st->z_state = z_error;
return -1;
}
}
return total_read;
}
static int close_istream_pack_non_delta(struct git_istream *st)
{
close_deflated_stream(st);
return 0;
}
static int open_istream_pack_non_delta(struct git_istream *st,
struct repository *r,
const struct object_id *oid,
enum object_type *type)
{
struct pack_window *window;
enum object_type in_pack_type;
window = NULL;
in_pack_type = unpack_object_header(st->u.in_pack.pack,
&window,
&st->u.in_pack.pos,
&st->size);
unuse_pack(&window);
switch (in_pack_type) {
default:
return -1; /* we do not do deltas for now */
case OBJ_COMMIT:
case OBJ_TREE:
case OBJ_BLOB:
case OBJ_TAG:
break;
}
st->z_state = z_unused;
st->close = close_istream_pack_non_delta;
st->read = read_istream_pack_non_delta;
return 0;
}
/*****************************************************************
*
* In-core stream
*
*****************************************************************/
static int close_istream_incore(struct git_istream *st)
{
free(st->u.incore.buf);
return 0;
}
static ssize_t read_istream_incore(struct git_istream *st, char *buf, size_t sz)
{
size_t read_size = sz;
size_t remainder = st->size - st->u.incore.read_ptr;
if (remainder <= read_size)
read_size = remainder;
if (read_size) {
memcpy(buf, st->u.incore.buf + st->u.incore.read_ptr, read_size);
st->u.incore.read_ptr += read_size;
}
return read_size;
}
static int open_istream_incore(struct git_istream *st, struct repository *r,
const struct object_id *oid, enum object_type *type)
{
st->u.incore.buf = read_object_file_extended(r, oid, type, &st->size, 0);
st->u.incore.read_ptr = 0;
st->close = close_istream_incore;
st->read = read_istream_incore;
return st->u.incore.buf ? 0 : -1;
}
/*****************************************************************************
* static helpers variables and functions for users of streaming interface
*****************************************************************************/
static int istream_source(struct git_istream *st,
struct repository *r,
const struct object_id *oid,
enum object_type *type)
{
unsigned long size;
int status;
struct object_info oi = OBJECT_INFO_INIT;
oi.typep = type;
oi.sizep = &size;
status = oid_object_info_extended(r, oid, &oi, 0);
if (status < 0)
return status;
switch (oi.whence) {
case OI_LOOSE:
st->open = open_istream_loose;
return 0;
case OI_PACKED:
if (!oi.u.packed.is_delta && big_file_threshold < size) {
st->u.in_pack.pack = oi.u.packed.pack;
st->u.in_pack.pos = oi.u.packed.offset;
st->open = open_istream_pack_non_delta;
return 0;
}
/* fallthru */
default:
st->open = open_istream_incore;
return 0;
}
}
/****************************************************************
* Users of streaming interface
****************************************************************/
int close_istream(struct git_istream *st)
{
int r = st->close(st);
free(st);
return r;
}
ssize_t read_istream(struct git_istream *st, void *buf, size_t sz)
{
return st->read(st, buf, sz);
}
struct git_istream *open_istream(struct repository *r,
const struct object_id *oid,
enum object_type *type,
unsigned long *size,
struct stream_filter *filter)
{
struct git_istream *st = xmalloc(sizeof(*st));
const struct object_id *real = lookup_replace_object(r, oid);
int ret = istream_source(st, r, real, type);
if (ret) {
free(st);
return NULL;
}
if (st->open(st, r, real, type)) {
if (open_istream_incore(st, r, real, type)) {
free(st);
return NULL;
}
}
if (filter) {
/* Add "&& !is_null_stream_filter(filter)" for performance */
struct git_istream *nst = attach_stream_filter(st, filter);
if (!nst) {
close_istream(st);
return NULL;
}
st = nst;
}
*size = st->size;
return st;
}
int stream_blob_to_fd(int fd, const struct object_id *oid, struct stream_filter *filter,
int can_seek)
{
struct git_istream *st;
enum object_type type;
unsigned long sz;
ssize_t kept = 0;
int result = -1;
st = open_istream(the_repository, oid, &type, &sz, filter);
if (!st) {
if (filter)
free_stream_filter(filter);
return result;
}
if (type != OBJ_BLOB)
goto close_and_exit;
for (;;) {
char buf[1024 * 16];
ssize_t wrote, holeto;
ssize_t readlen = read_istream(st, buf, sizeof(buf));
if (readlen < 0)
goto close_and_exit;
if (!readlen)
break;
if (can_seek && sizeof(buf) == readlen) {
for (holeto = 0; holeto < readlen; holeto++)
if (buf[holeto])
break;
if (readlen == holeto) {
kept += holeto;
continue;
}
}
if (kept && lseek(fd, kept, SEEK_CUR) == (off_t) -1)
goto close_and_exit;
else
kept = 0;
wrote = write_in_full(fd, buf, readlen);
if (wrote < 0)
goto close_and_exit;
}
if (kept && (lseek(fd, kept - 1, SEEK_CUR) == (off_t) -1 ||
xwrite(fd, "", 1) != 1))
goto close_and_exit;
result = 0;
close_and_exit:
close_istream(st);
return result;
}