diff options
Diffstat (limited to 'src/pack.c')
| -rw-r--r-- | src/pack.c | 816 |
1 files changed, 816 insertions, 0 deletions
diff --git a/src/pack.c b/src/pack.c new file mode 100644 index 000000000..0db1069de --- /dev/null +++ b/src/pack.c @@ -0,0 +1,816 @@ +/* + * Copyright (C) 2009-2012 the libgit2 contributors + * + * This file is part of libgit2, distributed under the GNU GPL v2 with + * a Linking Exception. For full terms see the included COPYING file. + */ + +#include "common.h" +#include "odb.h" +#include "pack.h" +#include "delta-apply.h" +#include "sha1_lookup.h" +#include "mwindow.h" +#include "fileops.h" + +#include "git2/oid.h" +#include <zlib.h> + +static int packfile_open(struct git_pack_file *p); +static git_off_t nth_packed_object_offset(const struct git_pack_file *p, uint32_t n); +int packfile_unpack_compressed( + git_rawobj *obj, + struct git_pack_file *p, + git_mwindow **w_curs, + git_off_t *curpos, + size_t size, + git_otype type); + +/* Can find the offset of an object given + * a prefix of an identifier. + * Throws GIT_EAMBIGUOUSOIDPREFIX if short oid + * is ambiguous within the pack. + * This method assumes that len is between + * GIT_OID_MINPREFIXLEN and GIT_OID_HEXSZ. + */ +static int pack_entry_find_offset( + git_off_t *offset_out, + git_oid *found_oid, + struct git_pack_file *p, + const git_oid *short_oid, + unsigned int len); + +static int packfile_error(const char *message) +{ + giterr_set(GITERR_ODB, "Invalid pack file - %s", message); + return -1; +} + +/*********************************************************** + * + * PACK INDEX METHODS + * + ***********************************************************/ + +static void pack_index_free(struct git_pack_file *p) +{ + if (p->index_map.data) { + git_futils_mmap_free(&p->index_map); + p->index_map.data = NULL; + } +} + +static int pack_index_check(const char *path, struct git_pack_file *p) +{ + struct git_pack_idx_header *hdr; + uint32_t version, nr, i, *index; + void *idx_map; + size_t idx_size; + struct stat st; + int error; + /* TODO: properly open the file without access time using O_NOATIME */ + git_file fd = git_futils_open_ro(path); + if (fd < 0) + return fd; + + if (p_fstat(fd, &st) < 0 || + !S_ISREG(st.st_mode) || + !git__is_sizet(st.st_size) || + (idx_size = (size_t)st.st_size) < 4 * 256 + 20 + 20) + { + p_close(fd); + giterr_set(GITERR_OS, "Failed to check pack index."); + return -1; + } + + error = git_futils_mmap_ro(&p->index_map, fd, 0, idx_size); + + p_close(fd); + + if (error < 0) + return error; + + hdr = idx_map = p->index_map.data; + + if (hdr->idx_signature == htonl(PACK_IDX_SIGNATURE)) { + version = ntohl(hdr->idx_version); + + if (version < 2 || version > 2) { + git_futils_mmap_free(&p->index_map); + return packfile_error("unsupported index version"); + } + + } else + version = 1; + + nr = 0; + index = idx_map; + + if (version > 1) + index += 2; /* skip index header */ + + for (i = 0; i < 256; i++) { + uint32_t n = ntohl(index[i]); + if (n < nr) { + git_futils_mmap_free(&p->index_map); + return packfile_error("index is non-monotonic"); + } + nr = n; + } + + if (version == 1) { + /* + * Total size: + * - 256 index entries 4 bytes each + * - 24-byte entries * nr (20-byte sha1 + 4-byte offset) + * - 20-byte SHA1 of the packfile + * - 20-byte SHA1 file checksum + */ + if (idx_size != 4*256 + nr * 24 + 20 + 20) { + git_futils_mmap_free(&p->index_map); + return packfile_error("index is corrupted"); + } + } else if (version == 2) { + /* + * Minimum size: + * - 8 bytes of header + * - 256 index entries 4 bytes each + * - 20-byte sha1 entry * nr + * - 4-byte crc entry * nr + * - 4-byte offset entry * nr + * - 20-byte SHA1 of the packfile + * - 20-byte SHA1 file checksum + * And after the 4-byte offset table might be a + * variable sized table containing 8-byte entries + * for offsets larger than 2^31. + */ + unsigned long min_size = 8 + 4*256 + nr*(20 + 4 + 4) + 20 + 20; + unsigned long max_size = min_size; + + if (nr) + max_size += (nr - 1)*8; + + if (idx_size < min_size || idx_size > max_size) { + git_futils_mmap_free(&p->index_map); + return packfile_error("wrong index size"); + } + } + + p->index_version = version; + p->num_objects = nr; + return 0; +} + +static int pack_index_open(struct git_pack_file *p) +{ + char *idx_name; + int error; + size_t name_len, offset; + + if (p->index_map.data) + return 0; + + idx_name = git__strdup(p->pack_name); + GITERR_CHECK_ALLOC(idx_name); + + name_len = strlen(idx_name); + offset = name_len - strlen(".pack"); + assert(offset < name_len); /* make sure no underflow */ + + strncpy(idx_name + offset, ".idx", name_len - offset); + + error = pack_index_check(idx_name, p); + git__free(idx_name); + + return error; +} + +static unsigned char *pack_window_open( + struct git_pack_file *p, + git_mwindow **w_cursor, + git_off_t offset, + unsigned int *left) +{ + if (p->mwf.fd == -1 && packfile_open(p) < 0) + return NULL; + + /* Since packfiles end in a hash of their content and it's + * pointless to ask for an offset into the middle of that + * hash, and the pack_window_contains function above wouldn't match + * don't allow an offset too close to the end of the file. + */ + if (offset > (p->mwf.size - 20)) + return NULL; + + return git_mwindow_open(&p->mwf, w_cursor, offset, 20, left); + } + +static int packfile_unpack_header1( + unsigned long *usedp, + size_t *sizep, + git_otype *type, + const unsigned char *buf, + unsigned long len) +{ + unsigned shift; + unsigned long size, c; + unsigned long used = 0; + + c = buf[used++]; + *type = (c >> 4) & 7; + size = c & 15; + shift = 4; + while (c & 0x80) { + if (len <= used) + return GIT_EBUFS; + + if (bitsizeof(long) <= shift) { + *usedp = 0; + return -1; + } + + c = buf[used++]; + size += (c & 0x7f) << shift; + shift += 7; + } + + *sizep = (size_t)size; + *usedp = used; + return 0; +} + +int git_packfile_unpack_header( + size_t *size_p, + git_otype *type_p, + git_mwindow_file *mwf, + git_mwindow **w_curs, + git_off_t *curpos) +{ + unsigned char *base; + unsigned int left; + unsigned long used; + int ret; + + /* pack_window_open() assures us we have [base, base + 20) available + * as a range that we can look at at. (Its actually the hash + * size that is assured.) With our object header encoding + * the maximum deflated object size is 2^137, which is just + * insane, so we know won't exceed what we have been given. + */ +// base = pack_window_open(p, w_curs, *curpos, &left); + base = git_mwindow_open(mwf, w_curs, *curpos, 20, &left); + if (base == NULL) + return GIT_EBUFS; + + ret = packfile_unpack_header1(&used, size_p, type_p, base, left); + git_mwindow_close(w_curs); + if (ret == GIT_EBUFS) + return ret; + else if (ret < 0) + return packfile_error("header length is zero"); + + *curpos += used; + return 0; +} + +static int packfile_unpack_delta( + git_rawobj *obj, + struct git_pack_file *p, + git_mwindow **w_curs, + git_off_t *curpos, + size_t delta_size, + git_otype delta_type, + git_off_t obj_offset) +{ + git_off_t base_offset; + git_rawobj base, delta; + int error; + + base_offset = get_delta_base(p, w_curs, curpos, delta_type, obj_offset); + git_mwindow_close(w_curs); + if (base_offset == 0) + return packfile_error("delta offset is zero"); + if (base_offset < 0) /* must actually be an error code */ + return (int)base_offset; + + error = git_packfile_unpack(&base, p, &base_offset); + + /* + * TODO: git.git tries to load the base from other packfiles + * or loose objects. + * + * We'll need to do this in order to support thin packs. + */ + if (error < 0) + return error; + + error = packfile_unpack_compressed(&delta, p, w_curs, curpos, delta_size, delta_type); + git_mwindow_close(w_curs); + if (error < 0) { + git__free(base.data); + return error; + } + + obj->type = base.type; + error = git__delta_apply(obj, base.data, base.len, delta.data, delta.len); + + git__free(base.data); + git__free(delta.data); + + /* TODO: we might want to cache this shit. eventually */ + //add_delta_base_cache(p, base_offset, base, base_size, *type); + + return error; /* error set by git__delta_apply */ +} + +int git_packfile_unpack( + git_rawobj *obj, + struct git_pack_file *p, + git_off_t *obj_offset) +{ + git_mwindow *w_curs = NULL; + git_off_t curpos = *obj_offset; + int error; + + size_t size = 0; + git_otype type; + + /* + * TODO: optionally check the CRC on the packfile + */ + + obj->data = NULL; + obj->len = 0; + obj->type = GIT_OBJ_BAD; + + error = git_packfile_unpack_header(&size, &type, &p->mwf, &w_curs, &curpos); + git_mwindow_close(&w_curs); + + if (error < 0) + return error; + + switch (type) { + case GIT_OBJ_OFS_DELTA: + case GIT_OBJ_REF_DELTA: + error = packfile_unpack_delta( + obj, p, &w_curs, &curpos, + size, type, *obj_offset); + break; + + case GIT_OBJ_COMMIT: + case GIT_OBJ_TREE: + case GIT_OBJ_BLOB: + case GIT_OBJ_TAG: + error = packfile_unpack_compressed( + obj, p, &w_curs, &curpos, + size, type); + break; + + default: + error = packfile_error("invalid packfile type in header");; + break; + } + + *obj_offset = curpos; + return error; +} + +static void *use_git_alloc(void *opaq, unsigned int count, unsigned int size) +{ + GIT_UNUSED(opaq); + return git__calloc(count, size); +} + +static void use_git_free(void *opaq, void *ptr) +{ + GIT_UNUSED(opaq); + git__free(ptr); +} + +int packfile_unpack_compressed( + git_rawobj *obj, + struct git_pack_file *p, + git_mwindow **w_curs, + git_off_t *curpos, + size_t size, + git_otype type) +{ + int st; + z_stream stream; + unsigned char *buffer, *in; + + buffer = git__calloc(1, size + 1); + GITERR_CHECK_ALLOC(buffer); + + memset(&stream, 0, sizeof(stream)); + stream.next_out = buffer; + stream.avail_out = (uInt)size + 1; + stream.zalloc = use_git_alloc; + stream.zfree = use_git_free; + + st = inflateInit(&stream); + if (st != Z_OK) { + git__free(buffer); + giterr_set(GITERR_ZLIB, "Failed to inflate packfile"); + + return -1; + } + + do { + in = pack_window_open(p, w_curs, *curpos, &stream.avail_in); + stream.next_in = in; + st = inflate(&stream, Z_FINISH); + git_mwindow_close(w_curs); + + if (!stream.avail_out) + break; /* the payload is larger than it should be */ + + if (st == Z_BUF_ERROR && in == NULL) { + inflateEnd(&stream); + git__free(buffer); + return GIT_EBUFS; + } + + *curpos += stream.next_in - in; + } while (st == Z_OK || st == Z_BUF_ERROR); + + inflateEnd(&stream); + + if ((st != Z_STREAM_END) || stream.total_out != size) { + git__free(buffer); + giterr_set(GITERR_ZLIB, "Failed to inflate packfile"); + return -1; + } + + obj->type = type; + obj->len = size; + obj->data = buffer; + return 0; +} + +/* + * curpos is where the data starts, delta_obj_offset is the where the + * header starts + */ +git_off_t get_delta_base( + struct git_pack_file *p, + git_mwindow **w_curs, + git_off_t *curpos, + git_otype type, + git_off_t delta_obj_offset) +{ + unsigned int left = 0; + unsigned char *base_info; + git_off_t base_offset; + git_oid unused; + + base_info = pack_window_open(p, w_curs, *curpos, &left); + /* Assumption: the only reason this would fail is because the file is too small */ + if (base_info == NULL) + return GIT_EBUFS; + /* pack_window_open() assured us we have [base_info, base_info + 20) + * as a range that we can look at without walking off the + * end of the mapped window. Its actually the hash size + * that is assured. An OFS_DELTA longer than the hash size + * is stupid, as then a REF_DELTA would be smaller to store. + */ + if (type == GIT_OBJ_OFS_DELTA) { + unsigned used = 0; + unsigned char c = base_info[used++]; + base_offset = c & 127; + while (c & 128) { + if (left <= used) + return GIT_EBUFS; + base_offset += 1; + if (!base_offset || MSB(base_offset, 7)) + return 0; /* overflow */ + c = base_info[used++]; + base_offset = (base_offset << 7) + (c & 127); + } + base_offset = delta_obj_offset - base_offset; + if (base_offset <= 0 || base_offset >= delta_obj_offset) + return 0; /* out of bound */ + *curpos += used; + } else if (type == GIT_OBJ_REF_DELTA) { + /* If we have the cooperative cache, search in it first */ + if (p->has_cache) { + int pos; + struct git_pack_entry key; + + git_oid_fromraw(&key.sha1, base_info); + pos = git_vector_bsearch(&p->cache, &key); + if (pos >= 0) { + *curpos += 20; + return ((struct git_pack_entry *)git_vector_get(&p->cache, pos))->offset; + } + } + /* The base entry _must_ be in the same pack */ + if (pack_entry_find_offset(&base_offset, &unused, p, (git_oid *)base_info, GIT_OID_HEXSZ) < 0) + return packfile_error("base entry delta is not in the same pack"); + *curpos += 20; + } else + return 0; + + return base_offset; +} + +/*********************************************************** + * + * PACKFILE METHODS + * + ***********************************************************/ + +static struct git_pack_file *packfile_alloc(size_t extra) +{ + struct git_pack_file *p = git__calloc(1, sizeof(*p) + extra); + if (p != NULL) + p->mwf.fd = -1; + return p; +} + + +void packfile_free(struct git_pack_file *p) +{ + assert(p); + + /* clear_delta_base_cache(); */ + git_mwindow_free_all(&p->mwf); + + if (p->mwf.fd != -1) + p_close(p->mwf.fd); + + pack_index_free(p); + + git__free(p->bad_object_sha1); + git__free(p); +} + +static int packfile_open(struct git_pack_file *p) +{ + struct stat st; + struct git_pack_header hdr; + git_oid sha1; + unsigned char *idx_sha1; + + assert(p->index_map.data); + + if (!p->index_map.data && pack_index_open(p) < 0) + return git_odb__error_notfound("failed to open packfile", NULL); + + /* TODO: open with noatime */ + p->mwf.fd = git_futils_open_ro(p->pack_name); + if (p->mwf.fd < 0) + return p->mwf.fd; + + if (p_fstat(p->mwf.fd, &st) < 0 || + git_mwindow_file_register(&p->mwf) < 0) + goto cleanup; + + /* If we created the struct before we had the pack we lack size. */ + if (!p->mwf.size) { + if (!S_ISREG(st.st_mode)) + goto cleanup; + p->mwf.size = (git_off_t)st.st_size; + } else if (p->mwf.size != st.st_size) + goto cleanup; + +#if 0 + /* We leave these file descriptors open with sliding mmap; + * there is no point keeping them open across exec(), though. + */ + fd_flag = fcntl(p->mwf.fd, F_GETFD, 0); + if (fd_flag < 0) + goto cleanup; + + fd_flag |= FD_CLOEXEC; + if (fcntl(p->pack_fd, F_SETFD, fd_flag) == -1) + goto cleanup; +#endif + + /* Verify we recognize this pack file format. */ + if (p_read(p->mwf.fd, &hdr, sizeof(hdr)) < 0 || + hdr.hdr_signature != htonl(PACK_SIGNATURE) || + !pack_version_ok(hdr.hdr_version)) + goto cleanup; + + /* Verify the pack matches its index. */ + if (p->num_objects != ntohl(hdr.hdr_entries) || + p_lseek(p->mwf.fd, p->mwf.size - GIT_OID_RAWSZ, SEEK_SET) == -1 || + p_read(p->mwf.fd, sha1.id, GIT_OID_RAWSZ) < 0) + goto cleanup; + + idx_sha1 = ((unsigned char *)p->index_map.data) + p->index_map.len - 40; + + if (git_oid_cmp(&sha1, (git_oid *)idx_sha1) == 0) + return 0; + +cleanup: + giterr_set(GITERR_OS, "Invalid packfile '%s'", p->pack_name); + p_close(p->mwf.fd); + p->mwf.fd = -1; + return -1; +} + +int git_packfile_check(struct git_pack_file **pack_out, const char *path) +{ + struct stat st; + struct git_pack_file *p; + size_t path_len; + + *pack_out = NULL; + path_len = strlen(path); + p = packfile_alloc(path_len + 2); + GITERR_CHECK_ALLOC(p); + + /* + * Make sure a corresponding .pack file exists and that + * the index looks sane. + */ + path_len -= strlen(".idx"); + if (path_len < 1) { + git__free(p); + return git_odb__error_notfound("invalid packfile path", NULL); + } + + memcpy(p->pack_name, path, path_len); + + strcpy(p->pack_name + path_len, ".keep"); + if (git_path_exists(p->pack_name) == true) + p->pack_keep = 1; + + strcpy(p->pack_name + path_len, ".pack"); + if (p_stat(p->pack_name, &st) < 0 || !S_ISREG(st.st_mode)) { + git__free(p); + return git_odb__error_notfound("packfile not found", NULL); + } + + /* ok, it looks sane as far as we can check without + * actually mapping the pack file. + */ + p->mwf.size = st.st_size; + p->pack_local = 1; + p->mtime = (git_time_t)st.st_mtime; + + /* see if we can parse the sha1 oid in the packfile name */ + if (path_len < 40 || + git_oid_fromstr(&p->sha1, path + path_len - GIT_OID_HEXSZ) < 0) + memset(&p->sha1, 0x0, GIT_OID_RAWSZ); + + *pack_out = p; + + return 0; +} + +/*********************************************************** + * + * PACKFILE ENTRY SEARCH INTERNALS + * + ***********************************************************/ + +static git_off_t nth_packed_object_offset(const struct git_pack_file *p, uint32_t n) +{ + const unsigned char *index = p->index_map.data; + index += 4 * 256; + if (p->index_version == 1) { + return ntohl(*((uint32_t *)(index + 24 * n))); + } else { + uint32_t off; + index += 8 + p->num_objects * (20 + 4); + off = ntohl(*((uint32_t *)(index + 4 * n))); + if (!(off & 0x80000000)) + return off; + index += p->num_objects * 4 + (off & 0x7fffffff) * 8; + return (((uint64_t)ntohl(*((uint32_t *)(index + 0)))) << 32) | + ntohl(*((uint32_t *)(index + 4))); + } +} + +static int pack_entry_find_offset( + git_off_t *offset_out, + git_oid *found_oid, + struct git_pack_file *p, + const git_oid *short_oid, + unsigned int len) +{ + const uint32_t *level1_ofs = p->index_map.data; + const unsigned char *index = p->index_map.data; + unsigned hi, lo, stride; + int pos, found = 0; + const unsigned char *current = 0; + + *offset_out = 0; + + if (index == NULL) { + int error; + + if ((error = pack_index_open(p)) < 0) + return error; + + assert(p->index_map.data); + + index = p->index_map.data; + level1_ofs = p->index_map.data; + } + + if (p->index_version > 1) { + level1_ofs += 2; + index += 8; + } + + index += 4 * 256; + hi = ntohl(level1_ofs[(int)short_oid->id[0]]); + lo = ((short_oid->id[0] == 0x0) ? 0 : ntohl(level1_ofs[(int)short_oid->id[0] - 1])); + + if (p->index_version > 1) { + stride = 20; + } else { + stride = 24; + index += 4; + } + +#ifdef INDEX_DEBUG_LOOKUP + printf("%02x%02x%02x... lo %u hi %u nr %d\n", + short_oid->id[0], short_oid->id[1], short_oid->id[2], lo, hi, p->num_objects); +#endif + + /* Use git.git lookup code */ + pos = sha1_entry_pos(index, stride, 0, lo, hi, p->num_objects, short_oid->id); + + if (pos >= 0) { + /* An object matching exactly the oid was found */ + found = 1; + current = index + pos * stride; + } else { + /* No object was found */ + /* pos refers to the object with the "closest" oid to short_oid */ + pos = - 1 - pos; + if (pos < (int)p->num_objects) { + current = index + pos * stride; + + if (!git_oid_ncmp(short_oid, (const git_oid *)current, len)) + found = 1; + } + } + + if (found && len != GIT_OID_HEXSZ && pos + 1 < (int)p->num_objects) { + /* Check for ambiguousity */ + const unsigned char *next = current + stride; + + if (!git_oid_ncmp(short_oid, (const git_oid *)next, len)) { + found = 2; + } + } + + if (!found) + return git_odb__error_notfound("failed to find offset for pack entry", short_oid); + if (found > 1) + return git_odb__error_ambiguous("found multiple offsets for pack entry"); + *offset_out = nth_packed_object_offset(p, pos); + git_oid_fromraw(found_oid, current); + +#ifdef INDEX_DEBUG_LOOKUP + { + unsigned char hex_sha1[GIT_OID_HEXSZ + 1]; + git_oid_fmt(hex_sha1, found_oid); + hex_sha1[GIT_OID_HEXSZ] = '\0'; + printf("found lo=%d %s\n", lo, hex_sha1); + } +#endif + return 0; +} + +int git_pack_entry_find( + struct git_pack_entry *e, + struct git_pack_file *p, + const git_oid *short_oid, + unsigned int len) +{ + git_off_t offset; + git_oid found_oid; + int error; + + assert(p); + + if (len == GIT_OID_HEXSZ && p->num_bad_objects) { + unsigned i; + for (i = 0; i < p->num_bad_objects; i++) + if (git_oid_cmp(short_oid, &p->bad_object_sha1[i]) == 0) + return packfile_error("bad object found in packfile"); + } + + error = pack_entry_find_offset(&offset, &found_oid, p, short_oid, len); + if (error < 0) + return error; + + /* we found a unique entry in the index; + * make sure the packfile backing the index + * still exists on disk */ + if (p->mwf.fd == -1 && (error = packfile_open(p)) < 0) + return error; + + e->offset = offset; + e->p = p; + + git_oid_cpy(&e->sha1, &found_oid); + return 0; +} |