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authorJunio C Hamano <junkio@cox.net>2005-06-27 10:35:33 (GMT)
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-06-27 22:27:51 (GMT)
commit1f688557c0b4963d5e0b93ad5cddad31e5322709 (patch)
tree1012f836f129ee7cf52cc18a0e573449aa6e3170 /sha1_file.c
parent36e4d74a210ba618e1520f11ce7fc2f8baec5bb8 (diff)
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[PATCH] Teach read_sha1_file() and friends about packed git object store.
GIT_OBJECT_DIRECTORY and GIT_ALTERNATE_OBJECT_DIRECTORIES can have the "pack" subdirectory that houses "packed GIT" files produced by git-pack-objects (e.g. .git/objects/pack/foo.pack and .git/objects/pack/foo.idx; always store them as pairs). The following functions in sha1_file.c can then read object contents from such packed file: - sha1_object_info() - has_sha1_file() - read_sha1_file() Signed-off-by: Junio C Hamano <junkio@cox.net> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'sha1_file.c')
-rw-r--r--sha1_file.c422
1 files changed, 412 insertions, 10 deletions
diff --git a/sha1_file.c b/sha1_file.c
index 4225c67..7e4a3df 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -6,7 +6,10 @@
* This handles basic git sha1 object files - packing, unpacking,
* creation etc.
*/
+#include <sys/types.h>
+#include <dirent.h>
#include "cache.h"
+#include "delta.h"
#ifndef O_NOATIME
#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
@@ -265,6 +268,184 @@ static char *find_sha1_file(const unsigned char *sha1, struct stat *st)
return NULL;
}
+#define PACK_MAX_SZ (1<<26)
+static int pack_used_ctr;
+static unsigned long pack_mapped;
+static struct packed_git {
+ struct packed_git *next;
+ unsigned long index_size;
+ unsigned long pack_size;
+ unsigned int *index_base;
+ void *pack_base;
+ unsigned int pack_last_used;
+ char pack_name[0]; /* something like ".git/objects/pack/xxxxx.pack" */
+} *packed_git;
+
+struct pack_entry {
+ unsigned int offset;
+ unsigned char sha1[20];
+ struct packed_git *p;
+};
+
+static int check_packed_git_idx(const char *path, unsigned long *idx_size_,
+ void **idx_map_)
+{
+ void *idx_map;
+ unsigned int *index;
+ unsigned long idx_size;
+ int nr, i;
+ int fd = open(path, O_RDONLY);
+ struct stat st;
+ if (fd < 0)
+ return -1;
+ if (fstat(fd, &st)) {
+ close(fd);
+ return -1;
+ }
+ idx_size = st.st_size;
+ idx_map = mmap(NULL, idx_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ close(fd);
+ if (idx_map == MAP_FAILED)
+ return -1;
+
+ index = idx_map;
+
+ /* check index map */
+ if (idx_size < 4*256 + 20)
+ return error("index file too small");
+ nr = 0;
+ for (i = 0; i < 256; i++) {
+ unsigned int n = ntohl(index[i]);
+ if (n < nr)
+ return error("non-monotonic index");
+ nr = n;
+ }
+
+ /*
+ * 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)
+ return error("wrong index file size");
+
+ *idx_map_ = idx_map;
+ *idx_size_ = idx_size;
+ return 0;
+}
+
+static void unuse_one_packed_git(void)
+{
+ /* NOTYET */
+}
+
+static int use_packed_git(struct packed_git *p)
+{
+ if (!p->pack_base) {
+ int fd;
+ struct stat st;
+ void *map;
+
+ pack_mapped += p->pack_size;
+ while (PACK_MAX_SZ < pack_mapped)
+ unuse_one_packed_git();
+ fd = open(p->pack_name, O_RDONLY);
+ if (fd < 0)
+ return -1;
+ if (fstat(fd, &st)) {
+ close(fd);
+ return -1;
+ }
+ if (st.st_size != p->pack_size)
+ return -1;
+ map = mmap(NULL, p->pack_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ close(fd);
+ if (map == MAP_FAILED)
+ return -1;
+ p->pack_base = map;
+ }
+ p->pack_last_used = pack_used_ctr++;
+ return 0;
+}
+
+static struct packed_git *add_packed_git(char *path, int path_len)
+{
+ struct stat st;
+ struct packed_git *p;
+ unsigned long idx_size;
+ void *idx_map;
+
+ if (check_packed_git_idx(path, &idx_size, &idx_map))
+ return NULL;
+
+ /* do we have a corresponding .pack file? */
+ strcpy(path + path_len - 4, ".pack");
+ if (stat(path, &st) || !S_ISREG(st.st_mode)) {
+ munmap(idx_map, idx_size);
+ return NULL;
+ }
+ /* ok, it looks sane as far as we can check without
+ * actually mapping the pack file.
+ */
+ p = xmalloc(sizeof(*p) + path_len + 2);
+ strcpy(p->pack_name, path);
+ p->index_size = idx_size;
+ p->pack_size = st.st_size;
+ p->index_base = idx_map;
+ p->next = NULL;
+ p->pack_last_used = 0;
+ return p;
+}
+
+static void prepare_packed_git_one(char *objdir)
+{
+ char path[PATH_MAX];
+ int len;
+ DIR *dir;
+ struct dirent *de;
+
+ sprintf(path, "%s/pack", objdir);
+ len = strlen(path);
+ dir = opendir(path);
+ if (!dir)
+ return;
+ path[len++] = '/';
+ while ((de = readdir(dir)) != NULL) {
+ int namelen = strlen(de->d_name);
+ struct packed_git *p;
+
+ if (strcmp(de->d_name + namelen - 4, ".idx"))
+ continue;
+
+ /* we have .idx. Is it a file we can map? */
+ strcpy(path + len, de->d_name);
+ p = add_packed_git(path, len + namelen);
+ if (!p)
+ continue;
+ p->next = packed_git;
+ packed_git = p;
+ }
+}
+
+static void prepare_packed_git(void)
+{
+ int i;
+ static int run_once = 0;
+
+ if (run_once++)
+ return;
+
+ prepare_packed_git_one(get_object_directory());
+ if (!alt_odb)
+ prepare_alt_odb();
+ for (i = 0; alt_odb[i].base != NULL; i++) {
+ alt_odb[i].name[0] = 0;
+ prepare_packed_git_one(alt_odb[i].base);
+ }
+}
+
int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long size, const char *type)
{
char header[100];
@@ -278,7 +459,9 @@ int check_sha1_signature(const unsigned char *sha1, void *map, unsigned long siz
return memcmp(sha1, real_sha1, 20) ? -1 : 0;
}
-void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+static void *map_sha1_file_internal(const unsigned char *sha1,
+ unsigned long *size,
+ int say_error)
{
struct stat st;
void *map;
@@ -286,7 +469,8 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
char *filename = find_sha1_file(sha1, &st);
if (!filename) {
- error("cannot map sha1 file %s", sha1_to_hex(sha1));
+ if (say_error)
+ error("cannot map sha1 file %s", sha1_to_hex(sha1));
return NULL;
}
@@ -300,11 +484,14 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
break;
/* Fallthrough */
case 0:
- perror(filename);
+ if (say_error)
+ perror(filename);
return NULL;
}
- /* If it failed once, it will probably fail again. Stop using O_NOATIME */
+ /* If it failed once, it will probably fail again.
+ * Stop using O_NOATIME
+ */
sha1_file_open_flag = 0;
}
map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
@@ -315,6 +502,11 @@ void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
return map;
}
+void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+{
+ return map_sha1_file_internal(sha1, size, 1);
+}
+
int unpack_sha1_header(z_stream *stream, void *map, unsigned long mapsize, void *buffer, unsigned long size)
{
/* Get the data stream */
@@ -409,6 +601,191 @@ void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned l
return unpack_sha1_rest(&stream, hdr, *size);
}
+/* Returns 0 on fast-path success, returns 1 on deltified
+ * and need to unpack to see info.
+ */
+static int packed_object_info(struct pack_entry *entry,
+ char *type, unsigned long *sizep)
+{
+ struct packed_git *p = entry->p;
+ unsigned long offset, size, left;
+ unsigned char *pack;
+
+ offset = entry->offset;
+ if (p->pack_size - 5 < offset)
+ die("object offset outside of pack file");
+ pack = p->pack_base + offset;
+ size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
+ left = p->pack_size - offset - 5;
+ switch (*pack) {
+ case 'D':
+ return 1;
+ break;
+ case 'C':
+ strcpy(type, "commit");
+ break;
+ case 'T':
+ strcpy(type, "tree");
+ break;
+ case 'B':
+ strcpy(type, "blob");
+ break;
+ default:
+ die("corrupted pack file");
+ }
+ *sizep = size;
+ return 0;
+}
+
+/* forward declaration for a mutually recursive function */
+static void *unpack_entry(struct pack_entry *, char *, unsigned long *);
+
+static void *unpack_delta_entry(unsigned char *base_sha1,
+ unsigned long delta_size,
+ unsigned long left,
+ char *type,
+ unsigned long *sizep)
+{
+ void *data, *delta_data, *result, *base;
+ unsigned long data_size, result_size, base_size;
+ z_stream stream;
+ int st;
+
+ if (left < 20)
+ die("truncated pack file");
+ data = base_sha1 + 20;
+ data_size = left - 20;
+ delta_data = xmalloc(delta_size);
+
+ memset(&stream, 0, sizeof(stream));
+
+ stream.next_in = data;
+ stream.avail_in = data_size;
+ stream.next_out = delta_data;
+ stream.avail_out = delta_size;
+
+ inflateInit(&stream);
+ st = inflate(&stream, Z_FINISH);
+ inflateEnd(&stream);
+ if ((st != Z_STREAM_END) || stream.total_out != delta_size)
+ die("delta data unpack failed");
+
+ /* This may recursively unpack the base, which is what we want */
+ base = read_sha1_file(base_sha1, type, &base_size);
+ if (!base)
+ die("failed to read delta-pack base object %s",
+ sha1_to_hex(base_sha1));
+ result = patch_delta(base, base_size,
+ delta_data, delta_size,
+ &result_size);
+ if (!result)
+ die("failed to apply delta");
+ free(delta_data);
+ free(base);
+ *sizep = result_size;
+ return result;
+}
+
+static void *unpack_non_delta_entry(unsigned char *data,
+ unsigned long size,
+ unsigned long left)
+{
+ int st;
+ z_stream stream;
+ char *buffer;
+
+ buffer = xmalloc(size + 1);
+ buffer[size] = 0;
+ memset(&stream, 0, sizeof(stream));
+ stream.next_in = data;
+ stream.avail_in = left;
+ stream.next_out = buffer;
+ stream.avail_out = size;
+
+ inflateInit(&stream);
+ st = inflate(&stream, Z_FINISH);
+ inflateEnd(&stream);
+ if ((st != Z_STREAM_END) || stream.total_out != size) {
+ free(buffer);
+ return NULL;
+ }
+
+ return buffer;
+}
+
+static void *unpack_entry(struct pack_entry *entry,
+ char *type, unsigned long *sizep)
+{
+ struct packed_git *p = entry->p;
+ unsigned long offset, size, left;
+ unsigned char *pack;
+
+ offset = entry->offset;
+ if (p->pack_size - 5 < offset)
+ die("object offset outside of pack file");
+
+ if (use_packed_git(p))
+ die("cannot map packed file");
+
+ pack = p->pack_base + offset;
+ size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
+ left = p->pack_size - offset - 5;
+ switch (*pack) {
+ case 'D':
+ return unpack_delta_entry(pack+5, size, left, type, sizep);
+ case 'C':
+ strcpy(type, "commit");
+ break;
+ case 'T':
+ strcpy(type, "tree");
+ break;
+ case 'B':
+ strcpy(type, "blob");
+ break;
+ default:
+ die("corrupted pack file");
+ }
+ *sizep = size;
+ return unpack_non_delta_entry(pack+5, size, left);
+}
+
+static int find_pack_entry_1(const unsigned char *sha1,
+ struct pack_entry *e, struct packed_git *p)
+{
+ int *level1_ofs = p->index_base;
+ int hi = ntohl(level1_ofs[*sha1]);
+ int lo = ((*sha1 == 0x0) ? 0 : ntohl(level1_ofs[*sha1 - 1]));
+ void *index = p->index_base + 256;
+
+ do {
+ int mi = (lo + hi) / 2;
+ int cmp = memcmp(index + 24 * mi + 4, sha1, 20);
+ if (!cmp) {
+ e->offset = ntohl(*((int*)(index + 24 * mi)));
+ memcpy(e->sha1, sha1, 20);
+ e->p = p;
+ return 1;
+ }
+ if (cmp > 0)
+ hi = mi;
+ else
+ lo = mi+1;
+ } while (lo < hi);
+ return 0;
+}
+
+static int find_pack_entry(const unsigned char *sha1, struct pack_entry *e)
+{
+ struct packed_git *p;
+ prepare_packed_git();
+
+ for (p = packed_git; p; p = p->next) {
+ if (find_pack_entry_1(sha1, e, p))
+ return 1;
+ }
+ return 0;
+}
+
int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep)
{
int status;
@@ -417,9 +794,19 @@ int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep
z_stream stream;
char hdr[128];
- map = map_sha1_file(sha1, &mapsize);
- if (!map)
- return error("unable to map %s", sha1_to_hex(sha1));
+ map = map_sha1_file_internal(sha1, &mapsize, 0);
+ if (!map) {
+ struct pack_entry e;
+
+ if (!find_pack_entry(sha1, &e))
+ return error("unable to find %s", sha1_to_hex(sha1));
+ if (!packed_object_info(&e, type, sizep))
+ return 0;
+ /* sheesh */
+ map = unpack_entry(&e, type, sizep);
+ free(map);
+ return (map == NULL) ? 0 : -1;
+ }
if (unpack_sha1_header(&stream, map, mapsize, hdr, sizeof(hdr)) < 0)
status = error("unable to unpack %s header",
sha1_to_hex(sha1));
@@ -434,18 +821,29 @@ int sha1_object_info(const unsigned char *sha1, char *type, unsigned long *sizep
return status;
}
+static void *read_packed_sha1(const unsigned char *sha1, char *type, unsigned long *size)
+{
+ struct pack_entry e;
+
+ if (!find_pack_entry(sha1, &e)) {
+ error("cannot read sha1_file for %s", sha1_to_hex(sha1));
+ return NULL;
+ }
+ return unpack_entry(&e, type, size);
+}
+
void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
{
unsigned long mapsize;
void *map, *buf;
- map = map_sha1_file(sha1, &mapsize);
+ map = map_sha1_file_internal(sha1, &mapsize, 0);
if (map) {
buf = unpack_sha1_file(map, mapsize, type, size);
munmap(map, mapsize);
return buf;
}
- return NULL;
+ return read_packed_sha1(sha1, type, size);
}
void *read_object_with_reference(const unsigned char *sha1,
@@ -664,7 +1062,11 @@ int write_sha1_from_fd(const unsigned char *sha1, int fd)
int has_sha1_file(const unsigned char *sha1)
{
struct stat st;
- return !!find_sha1_file(sha1, &st);
+ struct pack_entry e;
+
+ if (find_sha1_file(sha1, &st))
+ return 1;
+ return find_pack_entry(sha1, &e);
}
int index_fd(unsigned char *sha1, int fd, struct stat *st)