git/chunk-format.c
Elijah Newren d1cbe1e6d8 hash-ll.h: split out of hash.h to remove dependency on repository.h
hash.h depends upon and includes repository.h, due to the definition and
use of the_hash_algo (defined as the_repository->hash_algo).  However,
most headers trying to include hash.h are only interested in the layout
of the structs like object_id.  Move the parts of hash.h that do not
depend upon repository.h into a new file hash-ll.h (the "low level"
parts of hash.h), and adjust other files to use this new header where
the convenience inline functions aren't needed.

This allows hash.h and object.h to be fairly small, minimal headers.  It
also exposes a lot of hidden dependencies on both path.h (which was
brought in by repository.h) and repository.h (which was previously
implicitly brought in by object.h), so also adjust other files to be
more explicit about what they depend upon.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-04-24 12:47:32 -07:00

200 lines
4.4 KiB
C

#include "git-compat-util.h"
#include "alloc.h"
#include "chunk-format.h"
#include "csum-file.h"
#include "gettext.h"
#include "hash.h"
#include "trace2.h"
/*
* When writing a chunk-based file format, collect the chunks in
* an array of chunk_info structs. The size stores the _expected_
* amount of data that will be written by write_fn.
*/
struct chunk_info {
uint32_t id;
uint64_t size;
chunk_write_fn write_fn;
const void *start;
};
struct chunkfile {
struct hashfile *f;
struct chunk_info *chunks;
size_t chunks_nr;
size_t chunks_alloc;
};
struct chunkfile *init_chunkfile(struct hashfile *f)
{
struct chunkfile *cf = xcalloc(1, sizeof(*cf));
cf->f = f;
return cf;
}
void free_chunkfile(struct chunkfile *cf)
{
if (!cf)
return;
free(cf->chunks);
free(cf);
}
int get_num_chunks(struct chunkfile *cf)
{
return cf->chunks_nr;
}
void add_chunk(struct chunkfile *cf,
uint32_t id,
size_t size,
chunk_write_fn fn)
{
ALLOC_GROW(cf->chunks, cf->chunks_nr + 1, cf->chunks_alloc);
cf->chunks[cf->chunks_nr].id = id;
cf->chunks[cf->chunks_nr].write_fn = fn;
cf->chunks[cf->chunks_nr].size = size;
cf->chunks_nr++;
}
int write_chunkfile(struct chunkfile *cf, void *data)
{
int i, result = 0;
uint64_t cur_offset = hashfile_total(cf->f);
trace2_region_enter("chunkfile", "write", the_repository);
/* Add the table of contents to the current offset */
cur_offset += (cf->chunks_nr + 1) * CHUNK_TOC_ENTRY_SIZE;
for (i = 0; i < cf->chunks_nr; i++) {
hashwrite_be32(cf->f, cf->chunks[i].id);
hashwrite_be64(cf->f, cur_offset);
cur_offset += cf->chunks[i].size;
}
/* Trailing entry marks the end of the chunks */
hashwrite_be32(cf->f, 0);
hashwrite_be64(cf->f, cur_offset);
for (i = 0; i < cf->chunks_nr; i++) {
off_t start_offset = hashfile_total(cf->f);
result = cf->chunks[i].write_fn(cf->f, data);
if (result)
goto cleanup;
if (hashfile_total(cf->f) - start_offset != cf->chunks[i].size)
BUG("expected to write %"PRId64" bytes to chunk %"PRIx32", but wrote %"PRId64" instead",
cf->chunks[i].size, cf->chunks[i].id,
hashfile_total(cf->f) - start_offset);
}
cleanup:
trace2_region_leave("chunkfile", "write", the_repository);
return result;
}
int read_table_of_contents(struct chunkfile *cf,
const unsigned char *mfile,
size_t mfile_size,
uint64_t toc_offset,
int toc_length)
{
int i;
uint32_t chunk_id;
const unsigned char *table_of_contents = mfile + toc_offset;
ALLOC_GROW(cf->chunks, toc_length, cf->chunks_alloc);
while (toc_length--) {
uint64_t chunk_offset, next_chunk_offset;
chunk_id = get_be32(table_of_contents);
chunk_offset = get_be64(table_of_contents + 4);
if (!chunk_id) {
error(_("terminating chunk id appears earlier than expected"));
return 1;
}
table_of_contents += CHUNK_TOC_ENTRY_SIZE;
next_chunk_offset = get_be64(table_of_contents + 4);
if (next_chunk_offset < chunk_offset ||
next_chunk_offset > mfile_size - the_hash_algo->rawsz) {
error(_("improper chunk offset(s) %"PRIx64" and %"PRIx64""),
chunk_offset, next_chunk_offset);
return -1;
}
for (i = 0; i < cf->chunks_nr; i++) {
if (cf->chunks[i].id == chunk_id) {
error(_("duplicate chunk ID %"PRIx32" found"),
chunk_id);
return -1;
}
}
cf->chunks[cf->chunks_nr].id = chunk_id;
cf->chunks[cf->chunks_nr].start = mfile + chunk_offset;
cf->chunks[cf->chunks_nr].size = next_chunk_offset - chunk_offset;
cf->chunks_nr++;
}
chunk_id = get_be32(table_of_contents);
if (chunk_id) {
error(_("final chunk has non-zero id %"PRIx32""), chunk_id);
return -1;
}
return 0;
}
static int pair_chunk_fn(const unsigned char *chunk_start,
size_t chunk_size,
void *data)
{
const unsigned char **p = data;
*p = chunk_start;
return 0;
}
int pair_chunk(struct chunkfile *cf,
uint32_t chunk_id,
const unsigned char **p)
{
return read_chunk(cf, chunk_id, pair_chunk_fn, p);
}
int read_chunk(struct chunkfile *cf,
uint32_t chunk_id,
chunk_read_fn fn,
void *data)
{
int i;
for (i = 0; i < cf->chunks_nr; i++) {
if (cf->chunks[i].id == chunk_id)
return fn(cf->chunks[i].start, cf->chunks[i].size, data);
}
return CHUNK_NOT_FOUND;
}
uint8_t oid_version(const struct git_hash_algo *algop)
{
switch (hash_algo_by_ptr(algop)) {
case GIT_HASH_SHA1:
return 1;
case GIT_HASH_SHA256:
return 2;
default:
die(_("invalid hash version"));
}
}