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-rw-r--r--pack-objects.c84
-rw-r--r--pack.h23
-rw-r--r--sha1_file.c75
-rw-r--r--unpack-objects.c65
4 files changed, 174 insertions, 73 deletions
diff --git a/pack-objects.c b/pack-objects.c
index e9764604f6..d1e62dc019 100644
--- a/pack-objects.c
+++ b/pack-objects.c
@@ -2,25 +2,18 @@
#include "cache.h"
#include "object.h"
#include "delta.h"
+#include "pack.h"
#include "csum-file.h"
static const char pack_usage[] = "git-pack-objects [--window=N] [--depth=N] {--stdout | base-name} < object-list";
-/*
- * The object type is a single-character shorthand:
- * - 'C' for "Commit"
- * - 'T' for "Tree"
- * - 'B' for "Blob"
- * - 'G' for "taG"
- * - 'D' for "Delta"
- */
struct object_entry {
unsigned char sha1[20];
unsigned long size;
unsigned long offset;
unsigned int depth;
unsigned int hash;
- unsigned char type;
+ enum object_type type;
unsigned long delta_size;
struct object_entry *delta;
};
@@ -49,13 +42,54 @@ static void *delta_against(void *buf, unsigned long size, struct object_entry *e
return delta_buf;
}
+/*
+ * The per-object header is a pretty dense thing, which is
+ * - first byte: low four bits are "size", then three bits of "type",
+ * and the high bit is "size continues".
+ * - each byte afterwards: low seven bits are size continuation,
+ * with the high bit being "size continues"
+ */
+static int encode_header(enum object_type type, unsigned long size, unsigned char *hdr)
+{
+ int n = 1, i;
+ unsigned char c;
+
+ if (type < OBJ_COMMIT || type > OBJ_DELTA)
+ die("bad type %d", type);
+
+ /*
+ * Shift the size up by 7 bits at a time,
+ * until you get bits in the "high four".
+ * That will be our beginning. We'll have
+ * four size bits in 28..31, then groups
+ * of seven in 21..27, 14..20, 7..13 and
+ * finally 0..6.
+ */
+ if (size) {
+ n = 5;
+ while (!(size & 0xfe000000)) {
+ size <<= 7;
+ n--;
+ }
+ }
+ c = (type << 4) | (size >> 28);
+ for (i = 1; i < n; i++) {
+ *hdr++ = c | 0x80;
+ c = (size >> 21) & 0x7f;
+ size <<= 7;
+ }
+ *hdr = c;
+ return n;
+}
+
static unsigned long write_object(struct sha1file *f, struct object_entry *entry)
{
unsigned long size;
char type[10];
void *buf = read_sha1_file(entry->sha1, type, &size);
- char header[25];
+ unsigned char header[10];
unsigned hdrlen, datalen;
+ enum object_type obj_type;
if (!buf)
die("unable to read %s", sha1_to_hex(entry->sha1));
@@ -67,18 +101,18 @@ static unsigned long write_object(struct sha1file *f, struct object_entry *entry
* length, except for deltas that has the 20 bytes of delta sha
* instead.
*/
- header[0] = entry->type;
- hdrlen = 5;
+ obj_type = entry->type;
if (entry->delta) {
- header[0] = 'D';
- memcpy(header+5, entry->delta, 20);
buf = delta_against(buf, size, entry);
size = entry->delta_size;
- hdrlen = 25;
+ obj_type = OBJ_DELTA;
}
- datalen = htonl(size);
- memcpy(header+1, &datalen, 4);
+ hdrlen = encode_header(obj_type, size, header);
sha1write(f, header, hdrlen);
+ if (entry->delta) {
+ sha1write(f, entry->delta, 20);
+ hdrlen += 20;
+ }
datalen = sha1write_compressed(f, buf, size);
free(buf);
return hdrlen + datalen;
@@ -88,13 +122,19 @@ static void write_pack_file(void)
{
int i;
struct sha1file *f;
- unsigned long offset = 0;
+ unsigned long offset;
unsigned long mb;
+ struct pack_header hdr;
if (!base_name)
f = sha1fd(1, "<stdout>");
else
f = sha1create("%s.%s", base_name, "pack");
+ hdr.hdr_signature = htonl(PACK_SIGNATURE);
+ hdr.hdr_version = htonl(1);
+ hdr.hdr_entries = htonl(nr_objects);
+ sha1write(f, &hdr, sizeof(hdr));
+ offset = sizeof(hdr);
for (i = 0; i < nr_objects; i++) {
struct object_entry *entry = objects + i;
entry->offset = offset;
@@ -168,13 +208,13 @@ static void check_object(struct object_entry *entry)
if (!sha1_object_info(entry->sha1, type, &entry->size)) {
if (!strcmp(type, "commit")) {
- entry->type = 'C';
+ entry->type = OBJ_COMMIT;
} else if (!strcmp(type, "tree")) {
- entry->type = 'T';
+ entry->type = OBJ_TREE;
} else if (!strcmp(type, "blob")) {
- entry->type = 'B';
+ entry->type = OBJ_BLOB;
} else if (!strcmp(type, "tag")) {
- entry->type = 'G';
+ entry->type = OBJ_TAG;
} else
die("unable to pack object %s of type %s",
sha1_to_hex(entry->sha1), type);
diff --git a/pack.h b/pack.h
new file mode 100644
index 0000000000..08e120dca6
--- /dev/null
+++ b/pack.h
@@ -0,0 +1,23 @@
+#ifndef PACK_H
+#define PACK_H
+
+enum object_type {
+ OBJ_NONE,
+ OBJ_COMMIT,
+ OBJ_TREE,
+ OBJ_BLOB,
+ OBJ_TAG,
+ OBJ_DELTA,
+};
+
+/*
+ * Packed object header
+ */
+#define PACK_SIGNATURE 0x5041434b /* "PACK" */
+struct pack_header {
+ unsigned int hdr_signature;
+ unsigned int hdr_version;
+ unsigned int hdr_entries;
+};
+
+#endif
diff --git a/sha1_file.c b/sha1_file.c
index e27affb288..6e3fd180f9 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -10,6 +10,7 @@
#include <dirent.h>
#include "cache.h"
#include "delta.h"
+#include "pack.h"
#ifndef O_NOATIME
#if defined(__linux__) && (defined(__i386__) || defined(__PPC__))
@@ -665,37 +666,60 @@ static int packed_delta_info(unsigned char *base_sha1,
return 0;
}
+static unsigned long unpack_object_header(struct packed_git *p, unsigned long offset,
+ enum object_type *type, unsigned long *sizep)
+{
+ unsigned char *pack, c;
+ unsigned long size;
+
+ if (offset >= p->pack_size)
+ die("object offset outside of pack file");
+
+ pack = p->pack_base + offset;
+ c = *pack++;
+ offset++;
+ *type = (c >> 4) & 7;
+ size = c & 15;
+ while (c & 0x80) {
+ if (offset >= p->pack_size)
+ die("object offset outside of pack file");
+ c = *pack++;
+ offset++;
+ size = (size << 7) | (c & 0x7f);
+ }
+ *sizep = size;
+ return offset;
+}
+
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");
+ enum object_type kind;
if (use_packed_git(p))
die("cannot map packed file");
+ offset = unpack_object_header(p, entry->offset, &kind, &size);
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 packed_delta_info(pack+5, size, left, type, sizep);
+ left = p->pack_size - offset;
+
+ switch (kind) {
+ case OBJ_DELTA:
+ return packed_delta_info(pack, size, left, type, sizep);
break;
- case 'C':
+ case OBJ_COMMIT:
strcpy(type, "commit");
break;
- case 'T':
+ case OBJ_TREE:
strcpy(type, "tree");
break;
- case 'B':
+ case OBJ_BLOB:
strcpy(type, "blob");
break;
- case 'G':
+ case OBJ_TAG:
strcpy(type, "tag");
break;
default:
@@ -787,37 +811,34 @@ static void *unpack_entry(struct pack_entry *entry,
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");
+ enum object_type kind;
if (use_packed_git(p))
die("cannot map packed file");
+ offset = unpack_object_header(p, entry->offset, &kind, &size);
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':
+ left = p->pack_size - offset;
+ switch (kind) {
+ case OBJ_DELTA:
+ return unpack_delta_entry(pack, size, left, type, sizep);
+ case OBJ_COMMIT:
strcpy(type, "commit");
break;
- case 'T':
+ case OBJ_TREE:
strcpy(type, "tree");
break;
- case 'B':
+ case OBJ_BLOB:
strcpy(type, "blob");
break;
- case 'G':
+ case OBJ_TAG:
strcpy(type, "tag");
break;
default:
die("corrupted pack file");
}
*sizep = size;
- return unpack_non_delta_entry(pack+5, size, left);
+ return unpack_non_delta_entry(pack, size, left);
}
static int find_pack_entry_1(const unsigned char *sha1,
diff --git a/unpack-objects.c b/unpack-objects.c
index 57f3c9b6bb..98b696cf2c 100644
--- a/unpack-objects.c
+++ b/unpack-objects.c
@@ -1,6 +1,7 @@
#include "cache.h"
#include "object.h"
#include "delta.h"
+#include "pack.h"
static int dry_run;
static int nr_entries;
@@ -92,7 +93,7 @@ static int check_index(void)
}
static int unpack_non_delta_entry(struct pack_entry *entry,
- int kind,
+ enum object_type kind,
unsigned char *data,
unsigned long size,
unsigned long left)
@@ -101,9 +102,9 @@ static int unpack_non_delta_entry(struct pack_entry *entry,
z_stream stream;
char *buffer;
unsigned char sha1[20];
- char *type_s;
+ char *type;
- printf("%s %c %lu\n", sha1_to_hex(entry->sha1), kind, size);
+ printf("%s %c %lu\n", sha1_to_hex(entry->sha1), ".CTBGD"[kind], size);
if (dry_run)
return 0;
@@ -121,18 +122,18 @@ static int unpack_non_delta_entry(struct pack_entry *entry,
if ((st != Z_STREAM_END) || stream.total_out != size)
goto err_finish;
switch (kind) {
- case 'C': type_s = "commit"; break;
- case 'T': type_s = "tree"; break;
- case 'B': type_s = "blob"; break;
- case 'G': type_s = "tag"; break;
+ case OBJ_COMMIT: type = "commit"; break;
+ case OBJ_TREE: type = "tree"; break;
+ case OBJ_BLOB: type = "blob"; break;
+ case OBJ_TAG: type = "tag"; break;
default: goto err_finish;
}
- if (write_sha1_file(buffer, size, type_s, sha1) < 0)
+ if (write_sha1_file(buffer, size, type, sha1) < 0)
die("failed to write %s (%s)",
- sha1_to_hex(entry->sha1), type_s);
- printf("%s %s\n", sha1_to_hex(sha1), type_s);
+ sha1_to_hex(entry->sha1), type);
+ printf("%s %s\n", sha1_to_hex(sha1), type);
if (memcmp(sha1, entry->sha1, 20))
- die("resulting %s have wrong SHA1", type_s);
+ die("resulting %s have wrong SHA1", type);
finish:
st = 0;
@@ -237,28 +238,44 @@ static int unpack_delta_entry(struct pack_entry *entry,
static void unpack_entry(struct pack_entry *entry)
{
unsigned long offset, size, left;
- unsigned char *pack;
+ unsigned char *pack, c;
+ int type;
/* Have we done this one already due to deltas based on it? */
if (lookup_object(entry->sha1))
return;
offset = ntohl(entry->offset);
- if (offset > pack_size - 5)
- die("object offset outside of pack file");
+ if (offset >= pack_size)
+ goto bad;
+
pack = pack_base + offset;
- size = (pack[1] << 24) + (pack[2] << 16) + (pack[3] << 8) + pack[4];
- left = pack_size - offset - 5;
- switch (*pack) {
- case 'C': case 'T': case 'B': case 'G':
- unpack_non_delta_entry(entry, *pack, pack+5, size, left);
- break;
- case 'D':
+ c = *pack++;
+ offset++;
+ type = (c >> 4) & 7;
+ size = (c & 15);
+ while (c & 0x80) {
+ if (offset >= pack_size)
+ goto bad;
+ offset++;
+ c = *pack++;
+ size = (size << 7) + (c & 0x7f);
+
+ }
+ left = pack_size - offset;
+ switch (type) {
+ case OBJ_COMMIT:
+ case OBJ_TREE:
+ case OBJ_BLOB:
+ case OBJ_TAG:
+ unpack_non_delta_entry(entry, type, pack, size, left);
+ return;
+ case OBJ_DELTA:
unpack_delta_entry(entry, pack+5, size, left);
- break;
- default:
- die("corrupted pack file");
+ return;
}
+bad:
+ die("corrupted pack file");
}
/*
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-12 22:13:21 +0000