make pack data reuse compatible with both delta types
This is the missing part to git-pack-objects allowing it to reuse delta
data to/from any of the two delta types. It can reuse delta from any
type, and it outputs base offsets when --allow-delta-base-offset is
provided and the base is also included in the pack. Otherwise it
outputs base sha1 references just like it always did.
Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/builtin-pack-objects.c b/builtin-pack-objects.c
index 2212649..6db97b6 100644
--- a/builtin-pack-objects.c
+++ b/builtin-pack-objects.c
@@ -29,6 +29,7 @@
enum object_type type;
enum object_type in_pack_type; /* could be delta */
unsigned long delta_size; /* delta data size (uncompressed) */
+#define in_pack_header_size delta_size /* only when reusing pack data */
struct object_entry *delta; /* delta base object */
struct packed_git *in_pack; /* already in pack */
unsigned int in_pack_offset;
@@ -86,17 +87,25 @@
* Pack index for existing packs give us easy access to the offsets into
* corresponding pack file where each object's data starts, but the entries
* do not store the size of the compressed representation (uncompressed
- * size is easily available by examining the pack entry header). We build
- * a hashtable of existing packs (pack_revindex), and keep reverse index
- * here -- pack index file is sorted by object name mapping to offset; this
- * pack_revindex[].revindex array is an ordered list of offsets, so if you
- * know the offset of an object, next offset is where its packed
- * representation ends.
+ * size is easily available by examining the pack entry header). It is
+ * also rather expensive to find the sha1 for an object given its offset.
+ *
+ * We build a hashtable of existing packs (pack_revindex), and keep reverse
+ * index here -- pack index file is sorted by object name mapping to offset;
+ * this pack_revindex[].revindex array is a list of offset/index_nr pairs
+ * ordered by offset, so if you know the offset of an object, next offset
+ * is where its packed representation ends and the index_nr can be used to
+ * get the object sha1 from the main index.
*/
+struct revindex_entry {
+ unsigned int offset;
+ unsigned int nr;
+};
struct pack_revindex {
struct packed_git *p;
- unsigned long *revindex;
-} *pack_revindex = NULL;
+ struct revindex_entry *revindex;
+};
+static struct pack_revindex *pack_revindex;
static int pack_revindex_hashsz;
/*
@@ -143,14 +152,9 @@
static int cmp_offset(const void *a_, const void *b_)
{
- unsigned long a = *(unsigned long *) a_;
- unsigned long b = *(unsigned long *) b_;
- if (a < b)
- return -1;
- else if (a == b)
- return 0;
- else
- return 1;
+ const struct revindex_entry *a = a_;
+ const struct revindex_entry *b = b_;
+ return (a->offset < b->offset) ? -1 : (a->offset > b->offset) ? 1 : 0;
}
/*
@@ -163,25 +167,27 @@
int i;
void *index = p->index_base + 256;
- rix->revindex = xmalloc(sizeof(unsigned long) * (num_ent + 1));
+ rix->revindex = xmalloc(sizeof(*rix->revindex) * (num_ent + 1));
for (i = 0; i < num_ent; i++) {
unsigned int hl = *((unsigned int *)((char *) index + 24*i));
- rix->revindex[i] = ntohl(hl);
+ rix->revindex[i].offset = ntohl(hl);
+ rix->revindex[i].nr = i;
}
/* This knows the pack format -- the 20-byte trailer
* follows immediately after the last object data.
*/
- rix->revindex[num_ent] = p->pack_size - 20;
- qsort(rix->revindex, num_ent, sizeof(unsigned long), cmp_offset);
+ rix->revindex[num_ent].offset = p->pack_size - 20;
+ rix->revindex[num_ent].nr = -1;
+ qsort(rix->revindex, num_ent, sizeof(*rix->revindex), cmp_offset);
}
-static unsigned long find_packed_object_size(struct packed_git *p,
- unsigned long ofs)
+static struct revindex_entry * find_packed_object(struct packed_git *p,
+ unsigned int ofs)
{
int num;
int lo, hi;
struct pack_revindex *rix;
- unsigned long *revindex;
+ struct revindex_entry *revindex;
num = pack_revindex_ix(p);
if (num < 0)
die("internal error: pack revindex uninitialized");
@@ -193,10 +199,10 @@
hi = num_packed_objects(p) + 1;
do {
int mi = (lo + hi) / 2;
- if (revindex[mi] == ofs) {
- return revindex[mi+1] - ofs;
+ if (revindex[mi].offset == ofs) {
+ return revindex + mi;
}
- else if (ofs < revindex[mi])
+ else if (ofs < revindex[mi].offset)
hi = mi;
else
lo = mi + 1;
@@ -204,6 +210,20 @@
die("internal error: pack revindex corrupt");
}
+static unsigned long find_packed_object_size(struct packed_git *p,
+ unsigned long ofs)
+{
+ struct revindex_entry *entry = find_packed_object(p, ofs);
+ return entry[1].offset - ofs;
+}
+
+static unsigned char *find_packed_object_name(struct packed_git *p,
+ unsigned long ofs)
+{
+ struct revindex_entry *entry = find_packed_object(p, ofs);
+ return (unsigned char *)(p->index_base + 256) + 24 * entry->nr + 4;
+}
+
static void *delta_against(void *buf, unsigned long size, struct object_entry *entry)
{
unsigned long othersize, delta_size;
@@ -249,6 +269,10 @@
return n;
}
+/*
+ * we are going to reuse the existing object data as is. make
+ * sure it is not corrupt.
+ */
static int check_inflate(unsigned char *data, unsigned long len, unsigned long expect)
{
z_stream stream;
@@ -280,32 +304,6 @@
return st;
}
-/*
- * we are going to reuse the existing pack entry data. make
- * sure it is not corrupt.
- */
-static int revalidate_pack_entry(struct object_entry *entry, unsigned char *data, unsigned long len)
-{
- enum object_type type;
- unsigned long size, used;
-
- if (pack_to_stdout)
- return 0;
-
- /* the caller has already called use_packed_git() for us,
- * so it is safe to access the pack data from mmapped location.
- * make sure the entry inflates correctly.
- */
- used = unpack_object_header_gently(data, len, &type, &size);
- if (!used)
- return -1;
- if (type == OBJ_REF_DELTA)
- used += 20; /* skip base object name */
- data += used;
- len -= used;
- return check_inflate(data, len, entry->size);
-}
-
static int revalidate_loose_object(struct object_entry *entry,
unsigned char *map,
unsigned long mapsize)
@@ -339,7 +337,7 @@
obj_type = entry->type;
if (! entry->in_pack)
to_reuse = 0; /* can't reuse what we don't have */
- else if (obj_type == OBJ_REF_DELTA)
+ else if (obj_type == OBJ_REF_DELTA || obj_type == OBJ_OFS_DELTA)
to_reuse = 1; /* check_object() decided it for us */
else if (obj_type != entry->in_pack_type)
to_reuse = 0; /* pack has delta which is unusable */
@@ -415,18 +413,38 @@
}
else {
struct packed_git *p = entry->in_pack;
+
+ if (entry->delta) {
+ obj_type = (allow_ofs_delta && entry->delta->offset) ?
+ OBJ_OFS_DELTA : OBJ_REF_DELTA;
+ reused_delta++;
+ }
+ hdrlen = encode_header(obj_type, entry->size, header);
+ sha1write(f, header, hdrlen);
+ if (obj_type == OBJ_OFS_DELTA) {
+ unsigned long ofs = entry->offset - entry->delta->offset;
+ unsigned pos = sizeof(header) - 1;
+ header[pos] = ofs & 127;
+ while (ofs >>= 7)
+ header[--pos] = 128 | (--ofs & 127);
+ sha1write(f, header + pos, sizeof(header) - pos);
+ hdrlen += sizeof(header) - pos;
+ } else if (obj_type == OBJ_REF_DELTA) {
+ sha1write(f, entry->delta->sha1, 20);
+ hdrlen += 20;
+ }
+
use_packed_git(p);
-
- datalen = find_packed_object_size(p, entry->in_pack_offset);
- buf = (char *) p->pack_base + entry->in_pack_offset;
-
- if (revalidate_pack_entry(entry, buf, datalen))
+ buf = (char *) p->pack_base
+ + entry->in_pack_offset
+ + entry->in_pack_header_size;
+ datalen = find_packed_object_size(p, entry->in_pack_offset)
+ - entry->in_pack_header_size;
+//fprintf(stderr, "reusing %d at %d header %d size %d\n", obj_type, entry->in_pack_offset, entry->in_pack_header_size, datalen);
+ if (!pack_to_stdout && check_inflate(buf, datalen, entry->size))
die("corrupt delta in pack %s", sha1_to_hex(entry->sha1));
sha1write(f, buf, datalen);
unuse_packed_git(p);
- hdrlen = 0; /* not really */
- if (obj_type == OBJ_REF_DELTA)
- reused_delta++;
reused++;
}
if (entry->delta)
@@ -914,26 +932,64 @@
char type[20];
if (entry->in_pack && !entry->preferred_base) {
- unsigned char base[20];
- unsigned long size;
- struct object_entry *base_entry;
+ struct packed_git *p = entry->in_pack;
+ unsigned long left = p->pack_size - entry->in_pack_offset;
+ unsigned long size, used;
+ unsigned char *buf;
+ struct object_entry *base_entry = NULL;
+
+ use_packed_git(p);
+ buf = p->pack_base;
+ buf += entry->in_pack_offset;
/* We want in_pack_type even if we do not reuse delta.
* There is no point not reusing non-delta representations.
*/
- check_reuse_pack_delta(entry->in_pack,
- entry->in_pack_offset,
- base, &size,
- &entry->in_pack_type);
+ used = unpack_object_header_gently(buf, left,
+ &entry->in_pack_type, &size);
+ if (!used || left - used <= 20)
+ die("corrupt pack for %s", sha1_to_hex(entry->sha1));
/* Check if it is delta, and the base is also an object
* we are going to pack. If so we will reuse the existing
* delta.
*/
- if (!no_reuse_delta &&
- entry->in_pack_type == OBJ_REF_DELTA &&
- (base_entry = locate_object_entry(base)) &&
- (!base_entry->preferred_base)) {
+ if (!no_reuse_delta) {
+ unsigned char c, *base_name;
+ unsigned long ofs;
+ /* there is at least 20 bytes left in the pack */
+ switch (entry->in_pack_type) {
+ case OBJ_REF_DELTA:
+ base_name = buf + used;
+ used += 20;
+ break;
+ case OBJ_OFS_DELTA:
+ c = buf[used++];
+ ofs = c & 127;
+ while (c & 128) {
+ ofs += 1;
+ if (!ofs || ofs & ~(~0UL >> 7))
+ die("delta base offset overflow in pack for %s",
+ sha1_to_hex(entry->sha1));
+ c = buf[used++];
+ ofs = (ofs << 7) + (c & 127);
+ }
+ if (ofs >= entry->in_pack_offset)
+ die("delta base offset out of bound for %s",
+ sha1_to_hex(entry->sha1));
+ ofs = entry->in_pack_offset - ofs;
+ base_name = find_packed_object_name(p, ofs);
+ break;
+ default:
+ base_name = NULL;
+ }
+ if (base_name)
+ base_entry = locate_object_entry(base_name);
+ }
+ unuse_packed_git(p);
+ entry->in_pack_header_size = used;
+
+ if (base_entry && !base_entry->preferred_base) {
/* Depth value does not matter - find_deltas()
* will never consider reused delta as the
@@ -942,9 +998,9 @@
*/
/* uncompressed size of the delta data */
- entry->size = entry->delta_size = size;
+ entry->size = size;
entry->delta = base_entry;
- entry->type = OBJ_REF_DELTA;
+ entry->type = entry->in_pack_type;
entry->delta_sibling = base_entry->delta_child;
base_entry->delta_child = entry;
@@ -1500,7 +1556,7 @@
continue;
}
if (!strcmp("--delta-base-offset", arg)) {
- allow_ofs_delta = no_reuse_delta = 1;
+ allow_ofs_delta = 1;
continue;
}
if (!strcmp("--stdout", arg)) {
diff --git a/pack.h b/pack.h
index 05557da..4c9bddd 100644
--- a/pack.h
+++ b/pack.h
@@ -16,7 +16,4 @@
};
extern int verify_pack(struct packed_git *, int);
-extern int check_reuse_pack_delta(struct packed_git *, unsigned long,
- unsigned char *, unsigned long *,
- enum object_type *);
#endif
diff --git a/sha1_file.c b/sha1_file.c
index fdb4588..18c2f88 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1000,25 +1000,6 @@
return offset + used;
}
-int check_reuse_pack_delta(struct packed_git *p, unsigned long offset,
- unsigned char *base, unsigned long *sizep,
- enum object_type *kindp)
-{
- unsigned long ptr;
- int status = -1;
-
- use_packed_git(p);
- ptr = offset;
- ptr = unpack_object_header(p, ptr, kindp, sizep);
- if (*kindp != OBJ_REF_DELTA)
- goto done;
- hashcpy(base, (unsigned char *) p->pack_base + ptr);
- status = 0;
- done:
- unuse_packed_git(p);
- return status;
-}
-
void packed_object_info_detail(struct packed_git *p,
unsigned long offset,
char *type,
