pack-check.c 5.63 KB
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#include "cache.h"
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#include "repository.h"
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#include "pack.h"
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#include "pack-revindex.h"
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#include "progress.h"
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#include "packfile.h"
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#include "object-store.h"
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struct idx_entry {
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	off_t                offset;
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	union idx_entry_object {
		const unsigned char *hash;
		struct object_id *oid;
	} oid;
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	unsigned int nr;
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};

static int compare_entries(const void *e1, const void *e2)
{
	const struct idx_entry *entry1 = e1;
	const struct idx_entry *entry2 = e2;
	if (entry1->offset < entry2->offset)
		return -1;
	if (entry1->offset > entry2->offset)
		return 1;
	return 0;
}

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int check_pack_crc(struct packed_git *p, struct pack_window **w_curs,
		   off_t offset, off_t len, unsigned int nr)
{
	const uint32_t *index_crc;
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	uint32_t data_crc = crc32(0, NULL, 0);
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	do {
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		unsigned long avail;
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		void *data = use_pack(p, w_curs, offset, &avail);
		if (avail > len)
			avail = len;
		data_crc = crc32(data_crc, data, avail);
		offset += avail;
		len -= avail;
	} while (len);

	index_crc = p->index_data;
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	index_crc += 2 + 256 + p->num_objects * (the_hash_algo->rawsz/4) + nr;
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	return data_crc != ntohl(*index_crc);
}

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static int verify_packfile(struct repository *r,
			   struct packed_git *p,
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			   struct pack_window **w_curs,
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			   verify_fn fn,
			   struct progress *progress, uint32_t base_count)

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{
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	off_t index_size = p->index_size;
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	const unsigned char *index_base = p->index_data;
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	git_hash_ctx ctx;
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	unsigned char hash[GIT_MAX_RAWSZ], *pack_sig;
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	off_t offset = 0, pack_sig_ofs = 0;
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	uint32_t nr_objects, i;
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	int err = 0;
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	struct idx_entry *entries;
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	if (!is_pack_valid(p))
		return error("packfile %s cannot be accessed", p->pack_name);
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	the_hash_algo->init_fn(&ctx);
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	do {
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		unsigned long remaining;
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		unsigned char *in = use_pack(p, w_curs, offset, &remaining);
		offset += remaining;
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		if (!pack_sig_ofs)
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			pack_sig_ofs = p->pack_size - the_hash_algo->rawsz;
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		if (offset > pack_sig_ofs)
			remaining -= (unsigned int)(offset - pack_sig_ofs);
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		the_hash_algo->update_fn(&ctx, in, remaining);
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	} while (offset < pack_sig_ofs);
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	the_hash_algo->final_fn(hash, &ctx);
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	pack_sig = use_pack(p, w_curs, pack_sig_ofs, NULL);
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	if (!hasheq(hash, pack_sig))
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		err = error("%s pack checksum mismatch",
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			    p->pack_name);
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	if (!hasheq(index_base + index_size - the_hash_algo->hexsz, pack_sig))
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		err = error("%s pack checksum does not match its index",
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			    p->pack_name);
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	unuse_pack(w_curs);
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	/* Make sure everything reachable from idx is valid.  Since we
	 * have verified that nr_objects matches between idx and pack,
	 * we do not do scan-streaming check on the pack file.
	 */
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	nr_objects = p->num_objects;
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	ALLOC_ARRAY(entries, nr_objects + 1);
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	entries[nr_objects].offset = pack_sig_ofs;
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	/* first sort entries by pack offset, since unpacking them is more efficient that way */
	for (i = 0; i < nr_objects; i++) {
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		entries[i].oid.hash = nth_packed_object_sha1(p, i);
		if (!entries[i].oid.hash)
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			die("internal error pack-check nth-packed-object");
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		entries[i].offset = nth_packed_object_offset(p, i);
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		entries[i].nr = i;
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	}
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	QSORT(entries, nr_objects, compare_entries);
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	for (i = 0; i < nr_objects; i++) {
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		void *data;
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		enum object_type type;
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		unsigned long size;
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		off_t curpos;
		int data_valid;
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		if (p->index_version > 1) {
			off_t offset = entries[i].offset;
			off_t len = entries[i+1].offset - offset;
			unsigned int nr = entries[i].nr;
			if (check_pack_crc(p, w_curs, offset, len, nr))
				err = error("index CRC mismatch for object %s "
					    "from %s at offset %"PRIuMAX"",
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					    oid_to_hex(entries[i].oid.oid),
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					    p->pack_name, (uintmax_t)offset);
		}
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		curpos = entries[i].offset;
		type = unpack_object_header(p, w_curs, &curpos, &size);
		unuse_pack(w_curs);

		if (type == OBJ_BLOB && big_file_threshold <= size) {
			/*
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			 * Let check_object_signature() check it with
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			 * the streaming interface; no point slurping
			 * the data in-core only to discard.
			 */
			data = NULL;
			data_valid = 0;
		} else {
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			data = unpack_entry(r, p, entries[i].offset, &type, &size);
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			data_valid = 1;
		}

		if (data_valid && !data)
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			err = error("cannot unpack %s from %s at offset %"PRIuMAX"",
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				    oid_to_hex(entries[i].oid.oid), p->pack_name,
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				    (uintmax_t)entries[i].offset);
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		else if (check_object_signature(entries[i].oid.oid, data, size, type_name(type)))
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			err = error("packed %s from %s is corrupt",
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				    oid_to_hex(entries[i].oid.oid), p->pack_name);
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		else if (fn) {
			int eaten = 0;
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			err |= fn(entries[i].oid.oid, type, size, data, &eaten);
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			if (eaten)
				data = NULL;
		}
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		if (((base_count + i) & 1023) == 0)
			display_progress(progress, base_count + i);
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		free(data);
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	}
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	display_progress(progress, base_count + i);
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	free(entries);
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	return err;
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}

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int verify_pack_index(struct packed_git *p)
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{
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	off_t index_size;
	const unsigned char *index_base;
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	git_hash_ctx ctx;
	unsigned char hash[GIT_MAX_RAWSZ];
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	int err = 0;
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	if (open_pack_index(p))
		return error("packfile %s index not opened", p->pack_name);
	index_size = p->index_size;
	index_base = p->index_data;

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	/* Verify SHA1 sum of the index file */
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	the_hash_algo->init_fn(&ctx);
	the_hash_algo->update_fn(&ctx, index_base, (unsigned int)(index_size - the_hash_algo->rawsz));
	the_hash_algo->final_fn(hash, &ctx);
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	if (!hasheq(hash, index_base + index_size - the_hash_algo->rawsz))
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		err = error("Packfile index for %s hash mismatch",
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			    p->pack_name);
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	return err;
}

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int verify_pack(struct repository *r, struct packed_git *p, verify_fn fn,
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		struct progress *progress, uint32_t base_count)
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{
	int err = 0;
	struct pack_window *w_curs = NULL;

	err |= verify_pack_index(p);
	if (!p->index_data)
		return -1;
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	err |= verify_packfile(r, p, &w_curs, fn, progress, base_count);
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	unuse_pack(&w_curs);
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	return err;
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}