git/chunk-format.h
Taylor Blau d9fef9d90d chunk-format.h: extract oid_version()
There are three definitions of an identical function which converts
`the_hash_algo` into either 1 (for SHA-1) or 2 (for SHA-256). There is a
copy of this function for writing both the commit-graph and
multi-pack-index file, and another inline definition used to write the
.rev header.

Consolidate these into a single definition in chunk-format.h. It's not
clear that this is the best header to define this function in, but it
should do for now.

(Worth noting, the .rev caller expects a 4-byte unsigned, but the other
two callers work with a single unsigned byte. The consolidated version
uses the latter type, and lets the compiler widen it when required).

Another caller will be added in a subsequent patch.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-05-26 15:48:26 -07:00

71 lines
2 KiB
C

#ifndef CHUNK_FORMAT_H
#define CHUNK_FORMAT_H
#include "git-compat-util.h"
#include "hash.h"
struct hashfile;
struct chunkfile;
#define CHUNK_TOC_ENTRY_SIZE (sizeof(uint32_t) + sizeof(uint64_t))
/*
* Initialize a 'struct chunkfile' for writing _or_ reading a file
* with the chunk format.
*
* If writing a file, supply a non-NULL 'struct hashfile *' that will
* be used to write.
*
* If reading a file, use a NULL 'struct hashfile *' and then call
* read_table_of_contents(). Supply the memory-mapped data to the
* pair_chunk() or read_chunk() methods, as appropriate.
*
* DO NOT MIX THESE MODES. Use different 'struct chunkfile' instances
* for reading and writing.
*/
struct chunkfile *init_chunkfile(struct hashfile *f);
void free_chunkfile(struct chunkfile *cf);
int get_num_chunks(struct chunkfile *cf);
typedef int (*chunk_write_fn)(struct hashfile *f, void *data);
void add_chunk(struct chunkfile *cf,
uint32_t id,
size_t size,
chunk_write_fn fn);
int write_chunkfile(struct chunkfile *cf, void *data);
int read_table_of_contents(struct chunkfile *cf,
const unsigned char *mfile,
size_t mfile_size,
uint64_t toc_offset,
int toc_length);
#define CHUNK_NOT_FOUND (-2)
/*
* Find 'chunk_id' in the given chunkfile and assign the
* given pointer to the position in the mmap'd file where
* that chunk begins.
*
* Returns CHUNK_NOT_FOUND if the chunk does not exist.
*/
int pair_chunk(struct chunkfile *cf,
uint32_t chunk_id,
const unsigned char **p);
typedef int (*chunk_read_fn)(const unsigned char *chunk_start,
size_t chunk_size, void *data);
/*
* Find 'chunk_id' in the given chunkfile and call the
* given chunk_read_fn method with the information for
* that chunk.
*
* Returns CHUNK_NOT_FOUND if the chunk does not exist.
*/
int read_chunk(struct chunkfile *cf,
uint32_t chunk_id,
chunk_read_fn fn,
void *data);
uint8_t oid_version(const struct git_hash_algo *algop);
#endif