1 files changed, 395 insertions, 23 deletions

diff --git a/pack-revindex.c b/pack-revindex.c
index d28a7e4..a7624d8 100644
--- a/pack-revindex.c
+++ b/pack-revindex.c
@@ -1,7 +1,19 @@
-#include "cache.h"
+#include "git-compat-util.h"
+#include "gettext.h"
 #include "pack-revindex.h"
-#include "object-store.h"
+#include "object-file.h"
+#include "object-store-ll.h"
 #include "packfile.h"
+#include "strbuf.h"
+#include "trace2.h"
+#include "parse.h"
+#include "midx.h"
+#include "csum-file.h"
+
+struct revindex_entry {
+	off_t offset;
+	unsigned int nr;
+};
 
 /*
  * Pack index for existing packs give us easy access to the offsets into
@@ -130,7 +142,7 @@ static void create_pack_revindex(struct packed_git *p)
 
 	if (p->index_version > 1) {
 		const uint32_t *off_32 =
-			(uint32_t *)(index + 8 + p->num_objects * (hashsz + 4));
+			(uint32_t *)(index + 8 + (size_t)p->num_objects * (hashsz + 4));
 		const uint32_t *off_64 = off_32 + p->num_objects;
 		for (i = 0; i < num_ent; i++) {
 			const uint32_t off = ntohl(*off_32++);
@@ -159,27 +171,264 @@ static void create_pack_revindex(struct packed_git *p)
 	sort_revindex(p->revindex, num_ent, p->pack_size);
 }
 
-int load_pack_revindex(struct packed_git *p)
+static int create_pack_revindex_in_memory(struct packed_git *p)
+{
+	if (git_env_bool(GIT_TEST_REV_INDEX_DIE_IN_MEMORY, 0))
+		die("dying as requested by '%s'",
+		    GIT_TEST_REV_INDEX_DIE_IN_MEMORY);
+	if (open_pack_index(p))
+		return -1;
+	create_pack_revindex(p);
+	return 0;
+}
+
+static char *pack_revindex_filename(struct packed_git *p)
+{
+	size_t len;
+	if (!strip_suffix(p->pack_name, ".pack", &len))
+		BUG("pack_name does not end in .pack");
+	return xstrfmt("%.*s.rev", (int)len, p->pack_name);
+}
+
+#define RIDX_HEADER_SIZE (12)
+#define RIDX_MIN_SIZE (RIDX_HEADER_SIZE + (2 * the_hash_algo->rawsz))
+
+struct revindex_header {
+	uint32_t signature;
+	uint32_t version;
+	uint32_t hash_id;
+};
+
+static int load_revindex_from_disk(char *revindex_name,
+				   uint32_t num_objects,
+				   const uint32_t **data_p, size_t *len_p)
+{
+	int fd, ret = 0;
+	struct stat st;
+	void *data = NULL;
+	size_t revindex_size;
+	struct revindex_header *hdr;
+
+	if (git_env_bool(GIT_TEST_REV_INDEX_DIE_ON_DISK, 0))
+		die("dying as requested by '%s'", GIT_TEST_REV_INDEX_DIE_ON_DISK);
+
+	fd = git_open(revindex_name);
+
+	if (fd < 0) {
+		/* "No file" means return 1. */
+		ret = 1;
+		goto cleanup;
+	}
+	if (fstat(fd, &st)) {
+		ret = error_errno(_("failed to read %s"), revindex_name);
+		goto cleanup;
+	}
+
+	revindex_size = xsize_t(st.st_size);
+
+	if (revindex_size < RIDX_MIN_SIZE) {
+		ret = error(_("reverse-index file %s is too small"), revindex_name);
+		goto cleanup;
+	}
+
+	if (revindex_size - RIDX_MIN_SIZE != st_mult(sizeof(uint32_t), num_objects)) {
+		ret = error(_("reverse-index file %s is corrupt"), revindex_name);
+		goto cleanup;
+	}
+
+	data = xmmap(NULL, revindex_size, PROT_READ, MAP_PRIVATE, fd, 0);
+	hdr = data;
+
+	if (ntohl(hdr->signature) != RIDX_SIGNATURE) {
+		ret = error(_("reverse-index file %s has unknown signature"), revindex_name);
+		goto cleanup;
+	}
+	if (ntohl(hdr->version) != 1) {
+		ret = error(_("reverse-index file %s has unsupported version %"PRIu32),
+			    revindex_name, ntohl(hdr->version));
+		goto cleanup;
+	}
+	if (!(ntohl(hdr->hash_id) == 1 || ntohl(hdr->hash_id) == 2)) {
+		ret = error(_("reverse-index file %s has unsupported hash id %"PRIu32),
+			    revindex_name, ntohl(hdr->hash_id));
+		goto cleanup;
+	}
+
+cleanup:
+	if (ret) {
+		if (data)
+			munmap(data, revindex_size);
+	} else {
+		*len_p = revindex_size;
+		*data_p = (const uint32_t *)data;
+	}
+
+	if (fd >= 0)
+		close(fd);
+	return ret;
+}
+
+int load_pack_revindex_from_disk(struct packed_git *p)
+{
+	char *revindex_name;
+	int ret;
+	if (open_pack_index(p))
+		return -1;
+
+	revindex_name = pack_revindex_filename(p);
+
+	ret = load_revindex_from_disk(revindex_name,
+				      p->num_objects,
+				      &p->revindex_map,
+				      &p->revindex_size);
+	if (ret)
+		goto cleanup;
+
+	p->revindex_data = (const uint32_t *)((const char *)p->revindex_map + RIDX_HEADER_SIZE);
+
+cleanup:
+	free(revindex_name);
+	return ret;
+}
+
+int load_pack_revindex(struct repository *r, struct packed_git *p)
+{
+	if (p->revindex || p->revindex_data)
+		return 0;
+
+	prepare_repo_settings(r);
+
+	if (r->settings.pack_read_reverse_index &&
+	    !load_pack_revindex_from_disk(p))
+		return 0;
+	else if (!create_pack_revindex_in_memory(p))
+		return 0;
+	return -1;
+}
+
+/*
+ * verify_pack_revindex verifies that the on-disk rev-index for the given
+ * pack-file is the same that would be created if written from scratch.
+ *
+ * A negative number is returned on error.
+ */
+int verify_pack_revindex(struct packed_git *p)
+{
+	int res = 0;
+
+	/* Do not bother checking if not initialized. */
+	if (!p->revindex_map || !p->revindex_data)
+		return res;
+
+	if (!hashfile_checksum_valid((const unsigned char *)p->revindex_map, p->revindex_size)) {
+		error(_("invalid checksum"));
+		res = -1;
+	}
+
+	/* This may fail due to a broken .idx. */
+	if (create_pack_revindex_in_memory(p))
+		return res;
+
+	for (size_t i = 0; i < p->num_objects; i++) {
+		uint32_t nr = p->revindex[i].nr;
+		uint32_t rev_val = get_be32(p->revindex_data + i);
+
+		if (nr != rev_val) {
+			error(_("invalid rev-index position at %"PRIu64": %"PRIu32" != %"PRIu32""),
+			      (uint64_t)i, nr, rev_val);
+			res = -1;
+		}
+	}
+
+	return res;
+}
+
+static int can_use_midx_ridx_chunk(struct multi_pack_index *m)
 {
-	if (!p->revindex) {
-		if (open_pack_index(p))
-			return -1;
-		create_pack_revindex(p);
+	if (!m->chunk_revindex)
+		return 0;
+	if (m->chunk_revindex_len != st_mult(sizeof(uint32_t), m->num_objects)) {
+		error(_("multi-pack-index reverse-index chunk is the wrong size"));
+		return 0;
 	}
+	return 1;
+}
+
+int load_midx_revindex(struct multi_pack_index *m)
+{
+	struct strbuf revindex_name = STRBUF_INIT;
+	int ret;
+
+	if (m->revindex_data)
+		return 0;
+
+	if (can_use_midx_ridx_chunk(m)) {
+		/*
+		 * If the MIDX `m` has a `RIDX` chunk, then use its contents for
+		 * the reverse index instead of trying to load a separate `.rev`
+		 * file.
+		 *
+		 * Note that we do *not* set `m->revindex_map` here, since we do
+		 * not want to accidentally call munmap() in the middle of the
+		 * MIDX.
+		 */
+		trace2_data_string("load_midx_revindex", the_repository,
+				   "source", "midx");
+		m->revindex_data = (const uint32_t *)m->chunk_revindex;
+		return 0;
+	}
+
+	trace2_data_string("load_midx_revindex", the_repository,
+			   "source", "rev");
+
+	get_midx_rev_filename(&revindex_name, m);
+
+	ret = load_revindex_from_disk(revindex_name.buf,
+				      m->num_objects,
+				      &m->revindex_map,
+				      &m->revindex_len);
+	if (ret)
+		goto cleanup;
+
+	m->revindex_data = (const uint32_t *)((const char *)m->revindex_map + RIDX_HEADER_SIZE);
+
+cleanup:
+	strbuf_release(&revindex_name);
+	return ret;
+}
+
+int close_midx_revindex(struct multi_pack_index *m)
+{
+	if (!m || !m->revindex_map)
+		return 0;
+
+	munmap((void*)m->revindex_map, m->revindex_len);
+
+	m->revindex_map = NULL;
+	m->revindex_data = NULL;
+	m->revindex_len = 0;
+
 	return 0;
 }
 
-int find_revindex_position(struct packed_git *p, off_t ofs)
+int offset_to_pack_pos(struct packed_git *p, off_t ofs, uint32_t *pos)
 {
-	int lo = 0;
-	int hi = p->num_objects + 1;
-	const struct revindex_entry *revindex = p->revindex;
+	unsigned lo, hi;
+
+	if (load_pack_revindex(the_repository, p) < 0)
+		return -1;
+
+	lo = 0;
+	hi = p->num_objects + 1;
 
 	do {
 		const unsigned mi = lo + (hi - lo) / 2;
-		if (revindex[mi].offset == ofs) {
-			return mi;
-		} else if (ofs < revindex[mi].offset)
+		off_t got = pack_pos_to_offset(p, mi);
+
+		if (got == ofs) {
+			*pos = mi;
+			return 0;
+		} else if (ofs < got)
 			hi = mi;
 		else
 			lo = mi + 1;
@@ -189,17 +438,140 @@ int find_revindex_position(struct packed_git *p, off_t ofs)
 	return -1;
 }
 
-struct revindex_entry *find_pack_revindex(struct packed_git *p, off_t ofs)
+uint32_t pack_pos_to_index(struct packed_git *p, uint32_t pos)
+{
+	if (!(p->revindex || p->revindex_data))
+		BUG("pack_pos_to_index: reverse index not yet loaded");
+	if (p->num_objects <= pos)
+		BUG("pack_pos_to_index: out-of-bounds object at %"PRIu32, pos);
+
+	if (p->revindex)
+		return p->revindex[pos].nr;
+	else
+		return get_be32(p->revindex_data + pos);
+}
+
+off_t pack_pos_to_offset(struct packed_git *p, uint32_t pos)
+{
+	if (!(p->revindex || p->revindex_data))
+		BUG("pack_pos_to_index: reverse index not yet loaded");
+	if (p->num_objects < pos)
+		BUG("pack_pos_to_offset: out-of-bounds object at %"PRIu32, pos);
+
+	if (p->revindex)
+		return p->revindex[pos].offset;
+	else if (pos == p->num_objects)
+		return p->pack_size - the_hash_algo->rawsz;
+	else
+		return nth_packed_object_offset(p, pack_pos_to_index(p, pos));
+}
+
+uint32_t pack_pos_to_midx(struct multi_pack_index *m, uint32_t pos)
+{
+	if (!m->revindex_data)
+		BUG("pack_pos_to_midx: reverse index not yet loaded");
+	if (m->num_objects <= pos)
+		BUG("pack_pos_to_midx: out-of-bounds object at %"PRIu32, pos);
+	return get_be32(m->revindex_data + pos);
+}
+
+struct midx_pack_key {
+	uint32_t pack;
+	off_t offset;
+
+	uint32_t preferred_pack;
+	struct multi_pack_index *midx;
+};
+
+static int midx_pack_order_cmp(const void *va, const void *vb)
+{
+	const struct midx_pack_key *key = va;
+	struct multi_pack_index *midx = key->midx;
+
+	uint32_t versus = pack_pos_to_midx(midx, (uint32_t*)vb - (const uint32_t *)midx->revindex_data);
+	uint32_t versus_pack = nth_midxed_pack_int_id(midx, versus);
+	off_t versus_offset;
+
+	uint32_t key_preferred = key->pack == key->preferred_pack;
+	uint32_t versus_preferred = versus_pack == key->preferred_pack;
+
+	/*
+	 * First, compare the preferred-ness, noting that the preferred pack
+	 * comes first.
+	 */
+	if (key_preferred && !versus_preferred)
+		return -1;
+	else if (!key_preferred && versus_preferred)
+		return 1;
+
+	/* Then, break ties first by comparing the pack IDs. */
+	if (key->pack < versus_pack)
+		return -1;
+	else if (key->pack > versus_pack)
+		return 1;
+
+	/* Finally, break ties by comparing offsets within a pack. */
+	versus_offset = nth_midxed_offset(midx, versus);
+	if (key->offset < versus_offset)
+		return -1;
+	else if (key->offset > versus_offset)
+		return 1;
+
+	return 0;
+}
+
+static int midx_key_to_pack_pos(struct multi_pack_index *m,
+				struct midx_pack_key *key,
+				uint32_t *pos)
 {
-	int pos;
+	uint32_t *found;
+
+	/*
+	 * The preferred pack sorts first, so determine its identifier by
+	 * looking at the first object in pseudo-pack order.
+	 *
+	 * Note that if no --preferred-pack is explicitly given when writing a
+	 * multi-pack index, then whichever pack has the lowest identifier
+	 * implicitly is preferred (and includes all its objects, since ties are
+	 * broken first by pack identifier).
+	 */
+	if (midx_preferred_pack(key->midx, &key->preferred_pack) < 0)
+		return error(_("could not determine preferred pack"));
 
-	if (load_pack_revindex(p))
-		return NULL;
+	found = bsearch(key, m->revindex_data, m->num_objects,
+			sizeof(*m->revindex_data),
+			midx_pack_order_cmp);
 
-	pos = find_revindex_position(p, ofs);
+	if (!found)
+		return -1;
 
-	if (pos < 0)
-		return NULL;
+	*pos = found - m->revindex_data;
+	return 0;
+}
 
-	return p->revindex + pos;
+int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos)
+{
+	struct midx_pack_key key;
+
+	if (!m->revindex_data)
+		BUG("midx_to_pack_pos: reverse index not yet loaded");
+	if (m->num_objects <= at)
+		BUG("midx_to_pack_pos: out-of-bounds object at %"PRIu32, at);
+
+	key.pack = nth_midxed_pack_int_id(m, at);
+	key.offset = nth_midxed_offset(m, at);
+	key.midx = m;
+
+	return midx_key_to_pack_pos(m, &key, pos);
+}
+
+int midx_pair_to_pack_pos(struct multi_pack_index *m, uint32_t pack_int_id,
+			  off_t ofs, uint32_t *pos)
+{
+	struct midx_pack_key key = {
+		.pack = pack_int_id,
+		.offset = ofs,
+		.midx = m,
+	};
+	return midx_key_to_pack_pos(m, &key, pos);
 }