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