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https://github.com/git/git
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![Junio C Hamano](/assets/img/avatar_default.png)
Given an object name, use open_istream() to get a git_istream handle that you can read_istream() from as if you are using read(2) to read the contents of the object, and close it with close_istream() when you are done. Currently, we do not do anything fancy--it just calls read_sha1_file() and keeps the contents in memory as a whole, and carve it out as you request with read_istream(). Signed-off-by: Junio C Hamano <gitster@pobox.com>
194 lines
4 KiB
C
194 lines
4 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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enum input_source {
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stream_error = -1,
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incore = 0,
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loose = 1,
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pack_non_delta = 2
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};
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typedef int (*open_istream_fn)(struct git_istream *,
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struct object_info *,
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const unsigned char *,
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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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struct stream_vtbl {
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close_istream_fn close;
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read_istream_fn read;
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};
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#define open_method_decl(name) \
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int open_istream_ ##name \
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(struct git_istream *st, struct object_info *oi, \
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const unsigned char *sha1, \
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enum object_type *type)
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#define close_method_decl(name) \
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int close_istream_ ##name \
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(struct git_istream *st)
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#define read_method_decl(name) \
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ssize_t read_istream_ ##name \
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(struct git_istream *st, char *buf, size_t sz)
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/* forward declaration */
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static open_method_decl(incore);
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static open_method_decl(loose);
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static open_method_decl(pack_non_delta);
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static open_istream_fn open_istream_tbl[] = {
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open_istream_incore,
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open_istream_loose,
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open_istream_pack_non_delta,
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};
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struct git_istream {
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const struct stream_vtbl *vtbl;
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unsigned long size; /* inflated size of full object */
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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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int fd; /* open for reading */
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/* NEEDSWORK: what else? */
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} loose;
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struct {
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int fd; /* open for reading */
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/* NEEDSWORK: what else? */
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} in_pack;
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} u;
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};
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int close_istream(struct git_istream *st)
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{
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return st->vtbl->close(st);
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}
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ssize_t read_istream(struct git_istream *st, char *buf, size_t sz)
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{
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return st->vtbl->read(st, buf, sz);
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}
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static enum input_source istream_source(const unsigned char *sha1,
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enum object_type *type,
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struct object_info *oi)
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{
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unsigned long size;
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int status;
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oi->sizep = &size;
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status = sha1_object_info_extended(sha1, oi);
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if (status < 0)
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return stream_error;
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*type = status;
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switch (oi->whence) {
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case OI_LOOSE:
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return loose;
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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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return pack_non_delta;
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/* fallthru */
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default:
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return incore;
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}
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}
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struct git_istream *open_istream(const unsigned char *sha1,
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enum object_type *type,
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unsigned long *size)
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{
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struct git_istream *st;
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struct object_info oi;
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const unsigned char *real = lookup_replace_object(sha1);
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enum input_source src = istream_source(real, type, &oi);
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if (src < 0)
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return NULL;
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st = xmalloc(sizeof(*st));
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if (open_istream_tbl[src](st, &oi, real, type)) {
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if (open_istream_incore(st, &oi, 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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*size = st->size;
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return st;
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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 open_method_decl(loose)
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{
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return -1; /* for now */
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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 open_method_decl(pack_non_delta)
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{
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return -1; /* for now */
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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 close_method_decl(incore)
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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 read_method_decl(incore)
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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 struct stream_vtbl incore_vtbl = {
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close_istream_incore,
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read_istream_incore,
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};
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static open_method_decl(incore)
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{
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st->u.incore.buf = read_sha1_file_extended(sha1, type, &st->size, 0);
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st->u.incore.read_ptr = 0;
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st->vtbl = &incore_vtbl;
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return st->u.incore.buf ? 0 : -1;
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}
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