A new flag, --fix-thin, instructs git-index-pack to append any missing
objects to a thin pack to make it self contained and indexable. Of course
objects missing from the pack must be present elsewhere in the local
repository.
Signed-off-by: Nicolas Pitre <nico@xxxxxxx>
---
Documentation/git-index-pack.txt | 14 ++-
index-pack.c | 254 +++++++++++++++++++++++++++++++-------
2 files changed, 224 insertions(+), 44 deletions(-)
diff --git a/Documentation/git-index-pack.txt b/Documentation/git-index-pack.txt
index db7af58..c58287d 100644
--- a/Documentation/git-index-pack.txt
+++ b/Documentation/git-index-pack.txt
@@ -8,7 +8,8 @@ git-index-pack - Build pack index file f
SYNOPSIS
--------
-'git-index-pack' [-o <index-file>] { <pack-file> | --stdin [<pack-file>] }
+'git-index-pack' [-o <index-file>] <pack-file>
+'git-index-pack' --stdin [--fix-thin] [-o <index-file>] [<pack-file>]
DESCRIPTION
@@ -36,6 +37,17 @@ OPTIONS
objects/pack/ directory of the current git repository with
a default name determined from the pack content.
+--fix-thin::
+ It is possible for gitlink:git-pack-objects[1] to build
+ "thin" pack, which records objects in deltified form based on
+ objects not included in the pack to reduce network traffic.
+ Those objects are expected to be present on the receiving end
+ and they must be included in the pack for that pack to be self
+ contained and indexable. Without this option any attempt to
+ index a thin pack will fail. This option only makes sense in
+ conjonction with --stdin.
+
+
Author
------
Written by Sergey Vlasov <vsu@xxxxxxxxxxx>
diff --git a/index-pack.c b/index-pack.c
index cecdd26..9086bbf 100644
--- a/index-pack.c
+++ b/index-pack.c
@@ -8,7 +8,7 @@
#include "tree.h"
static const char index_pack_usage[] =
-"git-index-pack [-o <index-file>] { <pack-file> | --stdin [<pack-file>] }";
+"git-index-pack [-o <index-file>] { <pack-file> | --stdin [--fix-thin] [<pack-file>] }";
struct object_entry
{
@@ -33,14 +33,15 @@ union delta_base {
struct delta_entry
{
- struct object_entry *obj;
union delta_base base;
+ int obj_no;
};
static struct object_entry *objects;
static struct delta_entry *deltas;
static int nr_objects;
static int nr_deltas;
+static int nr_resolved_deltas;
static int from_stdin;
@@ -50,6 +51,18 @@ static unsigned long input_offset, input
static SHA_CTX input_ctx;
static int input_fd, output_fd, mmap_fd;
+/* Discard current buffer used content. */
+static void flush()
+{
+ if (input_offset) {
+ if (output_fd >= 0)
+ write_or_die(output_fd, input_buffer, input_offset);
+ SHA1_Update(&input_ctx, input_buffer, input_offset);
+ memcpy(input_buffer, input_buffer + input_offset, input_len);
+ input_offset = 0;
+ }
+}
+
/*
* Make sure at least "min" bytes are available in the buffer, and
* return the pointer to the buffer.
@@ -60,13 +73,7 @@ static void * fill(int min)
return input_buffer + input_offset;
if (min > sizeof(input_buffer))
die("cannot fill %d bytes", min);
- if (input_offset) {
- if (output_fd >= 0)
- write_or_die(output_fd, input_buffer, input_offset);
- SHA1_Update(&input_ctx, input_buffer, input_offset);
- memcpy(input_buffer, input_buffer + input_offset, input_len);
- input_offset = 0;
- }
+ flush();
do {
int ret = xread(input_fd, input_buffer + input_len,
sizeof(input_buffer) - input_len);
@@ -323,10 +330,9 @@ static void sha1_object(const void *data
SHA1_Final(sha1, &ctx);
}
-static void resolve_delta(struct delta_entry *delta, void *base_data,
+static void resolve_delta(struct object_entry *delta_obj, void *base_data,
unsigned long base_size, enum object_type type)
{
- struct object_entry *obj = delta->obj;
void *delta_data;
unsigned long delta_size;
void *result;
@@ -334,29 +340,34 @@ static void resolve_delta(struct delta_e
union delta_base delta_base;
int j, first, last;
- obj->real_type = type;
- delta_data = get_data_from_pack(obj);
- delta_size = obj->size;
+ delta_obj->real_type = type;
+ delta_data = get_data_from_pack(delta_obj);
+ delta_size = delta_obj->size;
result = patch_delta(base_data, base_size, delta_data, delta_size,
&result_size);
free(delta_data);
if (!result)
- bad_object(obj->offset, "failed to apply delta");
- sha1_object(result, result_size, type, obj->sha1);
+ bad_object(delta_obj->offset, "failed to apply delta");
+ sha1_object(result, result_size, type, delta_obj->sha1);
+ nr_resolved_deltas++;
- hashcpy(delta_base.sha1, obj->sha1);
+ hashcpy(delta_base.sha1, delta_obj->sha1);
if (!find_delta_childs(&delta_base, &first, &last)) {
- for (j = first; j <= last; j++)
- if (deltas[j].obj->type == OBJ_REF_DELTA)
- resolve_delta(&deltas[j], result, result_size, type);
+ for (j = first; j <= last; j++) {
+ struct object_entry *child = objects + deltas[j].obj_no;
+ if (child->real_type == OBJ_REF_DELTA)
+ resolve_delta(child, result, result_size, type);
+ }
}
memset(&delta_base, 0, sizeof(delta_base));
- delta_base.offset = obj->offset;
+ delta_base.offset = delta_obj->offset;
if (!find_delta_childs(&delta_base, &first, &last)) {
- for (j = first; j <= last; j++)
- if (deltas[j].obj->type == OBJ_OFS_DELTA)
- resolve_delta(&deltas[j], result, result_size, type);
+ for (j = first; j <= last; j++) {
+ struct object_entry *child = objects + deltas[j].obj_no;
+ if (child->real_type == OBJ_OFS_DELTA)
+ resolve_delta(child, result, result_size, type);
+ }
}
free(result);
@@ -389,7 +400,7 @@ static void parse_pack_objects(unsigned
obj->real_type = obj->type;
if (obj->type == OBJ_REF_DELTA || obj->type == OBJ_OFS_DELTA) {
nr_deltas++;
- delta->obj = obj;
+ delta->obj_no = i;
delta++;
} else
sha1_object(data, obj->size, obj->type, obj->sha1);
@@ -398,18 +409,15 @@ static void parse_pack_objects(unsigned
objects[i].offset = consumed_bytes;
/* Check pack integrity */
- SHA1_Update(&input_ctx, input_buffer, input_offset);
+ flush();
SHA1_Final(sha1, &input_ctx);
if (hashcmp(fill(20), sha1))
die("pack is corrupted (SHA1 mismatch)");
- use(20);
- if (output_fd >= 0)
- write_or_die(output_fd, input_buffer, input_offset);
/* If input_fd is a file, we should have reached its end now. */
if (fstat(input_fd, &st))
die("cannot fstat packfile: %s", strerror(errno));
- if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes)
+ if (S_ISREG(st.st_mode) && st.st_size != consumed_bytes + 20)
die("pack has junk at the end");
/* Sort deltas by base SHA1/offset for fast searching */
@@ -440,24 +448,161 @@ static void parse_pack_objects(unsigned
continue;
data = get_data_from_pack(obj);
if (ref)
- for (j = ref_first; j <= ref_last; j++)
- if (deltas[j].obj->type == OBJ_REF_DELTA)
- resolve_delta(&deltas[j], data,
+ for (j = ref_first; j <= ref_last; j++) {
+ struct object_entry *child = objects + deltas[j].obj_no;
+ if (child->real_type == OBJ_REF_DELTA)
+ resolve_delta(child, data,
obj->size, obj->type);
+ }
if (ofs)
- for (j = ofs_first; j <= ofs_last; j++)
- if (deltas[j].obj->type == OBJ_OFS_DELTA)
- resolve_delta(&deltas[j], data,
+ for (j = ofs_first; j <= ofs_last; j++) {
+ struct object_entry *child = objects + deltas[j].obj_no;
+ if (child->real_type == OBJ_OFS_DELTA)
+ resolve_delta(child, data,
obj->size, obj->type);
+ }
free(data);
}
+}
+
+static int write_compressed(int fd, void *in, unsigned int size)
+{
+ z_stream stream;
+ unsigned long maxsize;
+ void *out;
+
+ memset(&stream, 0, sizeof(stream));
+ deflateInit(&stream, zlib_compression_level);
+ maxsize = deflateBound(&stream, size);
+ out = xmalloc(maxsize);
+
+ /* Compress it */
+ stream.next_in = in;
+ stream.avail_in = size;
+ stream.next_out = out;
+ stream.avail_out = maxsize;
+ while (deflate(&stream, Z_FINISH) == Z_OK);
+ deflateEnd(&stream);
+
+ size = stream.total_out;
+ write_or_die(fd, out, size);
+ free(out);
+ return size;
+}
+
+static void append_obj_to_pack(void *buf,
+ unsigned long size, enum object_type type)
+{
+ struct object_entry *obj = &objects[nr_objects++];
+ unsigned char header[10];
+ unsigned long s = size;
+ int n = 0;
+ unsigned char c = (type << 4) | (s & 15);
+ s >>= 4;
+ while (s) {
+ header[n++] = c | 0x80;
+ c = s & 0x7f;
+ s >>= 7;
+ }
+ header[n++] = c;
+ write_or_die(output_fd, header, n);
+ obj[1].offset = obj[0].offset + n;
+ obj[1].offset += write_compressed(output_fd, buf, size);
+ sha1_object(buf, size, type, obj->sha1);
+}
+
+static int delta_pos_compare(const void *_a, const void *_b)
+{
+ struct delta_entry *a = *(struct delta_entry **)_a;
+ struct delta_entry *b = *(struct delta_entry **)_b;
+ return a->obj_no - b->obj_no;
+}
- /* Check for unresolved deltas */
+static void fix_unresolved_deltas(int nr_unresolved)
+{
+ struct delta_entry **sorted_by_pos;
+ int i, n = 0;
+
+ /*
+ * Since many unresolved deltas may well be themselves base objects
+ * for more unresolved deltas, we really want to include the
+ * smallest number of base objects that would cover as much delta
+ * as possible by picking the
+ * trunc deltas first, allowing for other deltas to resolve without
+ * additional base objects. Since most base objects are to be found
+ * before deltas depending on them, a good heuristic is to start
+ * resolving deltas in the same order as their position in the pack.
+ */
+ sorted_by_pos = xmalloc(nr_unresolved * sizeof(*sorted_by_pos));
for (i = 0; i < nr_deltas; i++) {
- if (deltas[i].obj->real_type == OBJ_REF_DELTA ||
- deltas[i].obj->real_type == OBJ_OFS_DELTA)
- die("pack has unresolved deltas");
+ if (objects[deltas[i].obj_no].real_type != OBJ_REF_DELTA)
+ continue;
+ sorted_by_pos[n++] = &deltas[i];
}
+ qsort(sorted_by_pos, n, sizeof(*sorted_by_pos), delta_pos_compare);
+
+ for (i = 0; i < n; i++) {
+ struct delta_entry *d = sorted_by_pos[i];
+ void *data;
+ unsigned long size;
+ char type[10];
+ enum object_type obj_type;
+ int j, first, last;
+
+ if (objects[d->obj_no].real_type != OBJ_REF_DELTA)
+ continue;
+ data = read_sha1_file(d->base.sha1, type, &size);
+ if (!data)
+ continue;
+ if (!strcmp(type, blob_type)) obj_type = OBJ_BLOB;
+ else if (!strcmp(type, tree_type)) obj_type = OBJ_TREE;
+ else if (!strcmp(type, commit_type)) obj_type = OBJ_COMMIT;
+ else if (!strcmp(type, tag_type)) obj_type = OBJ_TAG;
+ else die("base object %s is of type '%s'",
+ sha1_to_hex(d->base.sha1), type);
+
+ find_delta_childs(&d->base, &first, &last);
+ for (j = first; j <= last; j++) {
+ struct object_entry *child = objects + deltas[j].obj_no;
+ if (child->real_type == OBJ_REF_DELTA)
+ resolve_delta(child, data, size, obj_type);
+ }
+
+ append_obj_to_pack(data, size, obj_type);
+ free(data);
+ }
+ free(sorted_by_pos);
+}
+
+static void readjust_pack_header_and_sha1(unsigned char *sha1)
+{
+ struct pack_header hdr;
+ SHA_CTX ctx;
+ int size;
+
+ /* Rewrite pack header with updated object number */
+ if (lseek(output_fd, 0, SEEK_SET) != 0)
+ die("cannot seek back: %s", strerror(errno));
+ if (xread(output_fd, &hdr, sizeof(hdr)) != sizeof(hdr))
+ die("cannot read pack header back: %s", strerror(errno));
+ hdr.hdr_entries = htonl(nr_objects);
+ if (lseek(output_fd, 0, SEEK_SET) != 0)
+ die("cannot seek back: %s", strerror(errno));
+ write_or_die(output_fd, &hdr, sizeof(hdr));
+ if (lseek(output_fd, 0, SEEK_SET) != 0)
+ die("cannot seek back: %s", strerror(errno));
+
+ /* Recompute and store the new pack's SHA1 */
+ SHA1_Init(&ctx);
+ do {
+ unsigned char *buf[4096];
+ size = xread(output_fd, buf, sizeof(buf));
+ if (size < 0)
+ die("cannot read pack data back: %s", strerror(errno));
+ SHA1_Update(&ctx, buf, size);
+ } while (size > 0);
+ SHA1_Final(sha1, &ctx);
+ write_or_die(output_fd, sha1, 20);
}
static int sha1_compare(const void *_a, const void *_b)
@@ -588,7 +733,7 @@ static void final(const char *final_pack
int main(int argc, char **argv)
{
- int i;
+ int i, fix_thin_pack = 0;
const char *curr_pack, *pack_name = NULL;
const char *curr_index, *index_name = NULL;
char *index_name_buf = NULL;
@@ -600,6 +745,8 @@ int main(int argc, char **argv)
if (*arg == '-') {
if (!strcmp(arg, "--stdin")) {
from_stdin = 1;
+ } else if (!strcmp(arg, "--fix-thin")) {
+ fix_thin_pack = 1;
} else if (!strcmp(arg, "-o")) {
if (index_name || (i+1) >= argc)
usage(index_pack_usage);
@@ -616,6 +763,8 @@ int main(int argc, char **argv)
if (!pack_name && !from_stdin)
usage(index_pack_usage);
+ if (fix_thin_pack && !from_stdin)
+ die("--fix-thin cannot be used without --stdin");
if (!index_name && pack_name) {
int len = strlen(pack_name);
if (!has_extension(pack_name, ".pack"))
@@ -629,9 +778,28 @@ int main(int argc, char **argv)
curr_pack = open_pack_file(pack_name);
parse_pack_header();
- objects = xcalloc(nr_objects + 1, sizeof(struct object_entry));
- deltas = xcalloc(nr_objects, sizeof(struct delta_entry));
+ objects = xmalloc((nr_objects + 1) * sizeof(struct object_entry));
+ deltas = xmalloc(nr_objects * sizeof(struct delta_entry));
parse_pack_objects(sha1);
+ if (nr_deltas != nr_resolved_deltas) {
+ if (fix_thin_pack) {
+ int nr_unresolved = nr_deltas - nr_resolved_deltas;
+ if (nr_unresolved <= 0)
+ die("confusion beyond insanity");
+ objects = xrealloc(objects,
+ (nr_objects + nr_unresolved + 1)
+ * sizeof(*objects));
+ fix_unresolved_deltas(nr_unresolved);
+ readjust_pack_header_and_sha1(sha1);
+ }
+ if (nr_deltas != nr_resolved_deltas)
+ die("pack has %d unresolved deltas",
+ nr_deltas - nr_resolved_deltas);
+ } else {
+ /* Flush remaining pack final 20-byte SHA1. */
+ use(20);
+ flush();
+ }
free(deltas);
curr_index = write_index_file(index_name, sha1);
final(pack_name, curr_pack, index_name, curr_index, sha1);
--
1.4.3.3.g10cf-dirty
-
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