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Diffstat (limited to 'src/libgit2/pack.h')
-rw-r--r-- | src/libgit2/pack.h | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/src/libgit2/pack.h b/src/libgit2/pack.h new file mode 100644 index 000000000..f87249ba6 --- /dev/null +++ b/src/libgit2/pack.h @@ -0,0 +1,200 @@ +/* + * Copyright (C) the libgit2 contributors. All rights reserved. + * + * This file is part of libgit2, distributed under the GNU GPL v2 with + * a Linking Exception. For full terms see the included COPYING file. + */ + +#ifndef INCLUDE_pack_h__ +#define INCLUDE_pack_h__ + +#include "common.h" + +#include "git2/oid.h" + +#include "array.h" +#include "map.h" +#include "mwindow.h" +#include "odb.h" +#include "offmap.h" +#include "oidmap.h" +#include "zstream.h" +#include "oid.h" + +/** + * Function type for callbacks from git_pack_foreach_entry_offset. + */ +typedef int git_pack_foreach_entry_offset_cb( + const git_oid *id, + off64_t offset, + void *payload); + +#define GIT_PACK_FILE_MODE 0444 + +#define PACK_SIGNATURE 0x5041434b /* "PACK" */ +#define PACK_VERSION 2 +#define pack_version_ok(v) ((v) == htonl(2) || (v) == htonl(3)) +struct git_pack_header { + uint32_t hdr_signature; + uint32_t hdr_version; + uint32_t hdr_entries; +}; + +/* + * The first four bytes of index formats later than version 1 should + * start with this signature, as all older git binaries would find this + * value illegal and abort reading the file. + * + * This is the case because the number of objects in a packfile + * cannot exceed 1,431,660,000 as every object would need at least + * 3 bytes of data and the overall packfile cannot exceed 4 GiB with + * version 1 of the index file due to the offsets limited to 32 bits. + * Clearly the signature exceeds this maximum. + * + * Very old git binaries will also compare the first 4 bytes to the + * next 4 bytes in the index and abort with a "non-monotonic index" + * error if the second 4 byte word is smaller than the first 4 + * byte word. This would be true in the proposed future index + * format as idx_signature would be greater than idx_version. + */ + +#define PACK_IDX_SIGNATURE 0xff744f63 /* "\377tOc" */ + +struct git_pack_idx_header { + uint32_t idx_signature; + uint32_t idx_version; +}; + +typedef struct git_pack_cache_entry { + size_t last_usage; /* enough? */ + git_atomic32 refcount; + git_rawobj raw; +} git_pack_cache_entry; + +struct pack_chain_elem { + off64_t base_key; + off64_t offset; + size_t size; + git_object_t type; +}; + +typedef git_array_t(struct pack_chain_elem) git_dependency_chain; + +#define GIT_PACK_CACHE_MEMORY_LIMIT 16 * 1024 * 1024 +#define GIT_PACK_CACHE_SIZE_LIMIT 1024 * 1024 /* don't bother caching anything over 1MB */ + +typedef struct { + size_t memory_used; + size_t memory_limit; + size_t use_ctr; + git_mutex lock; + git_offmap *entries; +} git_pack_cache; + +struct git_pack_file { + git_mwindow_file mwf; + git_map index_map; + git_mutex lock; /* protect updates to index_map */ + git_atomic32 refcount; + + uint32_t num_objects; + uint32_t num_bad_objects; + git_oid *bad_object_sha1; /* array of git_oid */ + + int index_version; + git_time_t mtime; + unsigned pack_local:1, pack_keep:1, has_cache:1; + git_oidmap *idx_cache; + unsigned char **oids; + + git_pack_cache bases; /* delta base cache */ + + time_t last_freshen; /* last time the packfile was freshened */ + + /* something like ".git/objects/pack/xxxxx.pack" */ + char pack_name[GIT_FLEX_ARRAY]; /* more */ +}; + +/** + * Return the position where an OID (or a prefix) would be inserted within the + * OID Lookup Table of an .idx file. This performs binary search between the lo + * and hi indices. + * + * The stride parameter is provided because .idx files version 1 store the OIDs + * interleaved with the 4-byte file offsets of the objects within the .pack + * file (stride = 24), whereas files with version 2 store them in a contiguous + * flat array (stride = 20). + */ +int git_pack__lookup_sha1(const void *oid_lookup_table, size_t stride, unsigned lo, + unsigned hi, const unsigned char *oid_prefix); + +struct git_pack_entry { + off64_t offset; + git_oid sha1; + struct git_pack_file *p; +}; + +typedef struct git_packfile_stream { + off64_t curpos; + int done; + git_zstream zstream; + struct git_pack_file *p; + git_mwindow *mw; +} git_packfile_stream; + +int git_packfile__object_header(size_t *out, unsigned char *hdr, size_t size, git_object_t type); + +int git_packfile__name(char **out, const char *path); + +int git_packfile_unpack_header( + size_t *size_p, + git_object_t *type_p, + struct git_pack_file *p, + git_mwindow **w_curs, + off64_t *curpos); + +int git_packfile_resolve_header( + size_t *size_p, + git_object_t *type_p, + struct git_pack_file *p, + off64_t offset); + +int git_packfile_unpack(git_rawobj *obj, struct git_pack_file *p, off64_t *obj_offset); + +int git_packfile_stream_open(git_packfile_stream *obj, struct git_pack_file *p, off64_t curpos); +ssize_t git_packfile_stream_read(git_packfile_stream *obj, void *buffer, size_t len); +void git_packfile_stream_dispose(git_packfile_stream *obj); + +int get_delta_base( + off64_t *delta_base_out, + struct git_pack_file *p, + git_mwindow **w_curs, + off64_t *curpos, + git_object_t type, + off64_t delta_obj_offset); + +void git_packfile_free(struct git_pack_file *p, bool unlink_packfile); +int git_packfile_alloc(struct git_pack_file **pack_out, const char *path); + +int git_pack_entry_find( + struct git_pack_entry *e, + struct git_pack_file *p, + const git_oid *short_oid, + size_t len); +int git_pack_foreach_entry( + struct git_pack_file *p, + git_odb_foreach_cb cb, + void *data); +/** + * Similar to git_pack_foreach_entry, but: + * - It also provides the offset of the object within the + * packfile. + * - It does not sort the objects in any order. + * - It retains the lock while invoking the callback. + */ +int git_pack_foreach_entry_offset( + struct git_pack_file *p, + git_pack_foreach_entry_offset_cb cb, + void *data); + +#endif |