text: /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #include "indexer.h"
  
  #include "git2/indexer.h"
  #include "git2/object.h"
  
  #include "pack.h"
  #include "mwindow.h"
  #include "posix.h"
  #include "pack.h"
  #include "filebuf.h"
  #include "oid.h"
  #include "oidmap.h"
  #include "zstream.h"
  #include "object.h"
  
  extern git_mutex git__mwindow_mutex;
  
  #define UINT31_MAX (0x7FFFFFFF)
  
  struct entry {
  	git_oid oid;
  	uint32_t crc;
  	uint32_t offset;
  	uint64_t offset_long;
  };
  
  struct git_indexer {
  	unsigned int parsed_header :1,
  		pack_committed :1,
  		have_stream :1,
  		have_delta :1,
  		do_fsync :1;
  	struct git_pack_header hdr;
  	struct git_pack_file *pack;
  	unsigned int mode;
  	git_off_t off;
  	git_off_t entry_start;
  	git_packfile_stream stream;
  	size_t nr_objects;
  	git_vector objects;
  	git_vector deltas;
  	unsigned int fanout[256];
  	git_hash_ctx hash_ctx;
  	git_oid hash;
  	git_transfer_progress_cb progress_cb;
  	void *progress_payload;
  	char objbuf[8*1024];
  
  	/* Needed to look up objects which we want to inject to fix a thin pack */
  	git_odb *odb;
  
  	/* Fields for calculating the packfile trailer (hash of everything before it) */
  	char inbuf[GIT_OID_RAWSZ];
  	size_t inbuf_len;
  	git_hash_ctx trailer;
  };
  
  struct delta_info {
  	git_off_t delta_off;
  };
  
  const git_oid *git_indexer_hash(const git_indexer *idx)
  {
  	return &idx->hash;
  }
  
  static int parse_header(struct git_pack_header *hdr, struct git_pack_file *pack)
  {
  	int error;
  	git_map map;
  
  	if ((error = p_mmap(&map, sizeof(*hdr), GIT_PROT_READ, GIT_MAP_SHARED, pack->mwf.fd, 0)) < 0)
  		return error;
  
  	memcpy(hdr, map.data, sizeof(*hdr));
  	p_munmap(&map);
  
  	/* Verify we recognize this pack file format. */
  	if (hdr->hdr_signature != ntohl(PACK_SIGNATURE)) {
  		giterr_set(GITERR_INDEXER, "wrong pack signature");
  		return -1;
  	}
  
  	if (!pack_version_ok(hdr->hdr_version)) {
  		giterr_set(GITERR_INDEXER, "wrong pack version");
  		return -1;
  	}
  
  	return 0;
  }
  
  static int objects_cmp(const void *a, const void *b)
  {
  	const struct entry *entrya = a;
  	const struct entry *entryb = b;
  
  	return git_oid__cmp(&entrya->oid, &entryb->oid);
  }
  
  int git_indexer_new(
  		git_indexer **out,
  		const char *prefix,
  		unsigned int mode,
  		git_odb *odb,
  		git_transfer_progress_cb progress_cb,
  		void *progress_payload)
  {
  	git_indexer *idx;
  	git_buf path = GIT_BUF_INIT, tmp_path = GIT_BUF_INIT;
  	static const char suff[] = "/pack";
  	int error, fd = -1;
  
  	idx = git__calloc(1, sizeof(git_indexer));
  	GITERR_CHECK_ALLOC(idx);
  	idx->odb = odb;
  	idx->progress_cb = progress_cb;
  	idx->progress_payload = progress_payload;
  	idx->mode = mode ? mode : GIT_PACK_FILE_MODE;
  	git_hash_ctx_init(&idx->hash_ctx);
  	git_hash_ctx_init(&idx->trailer);
  
  	if (git_repository__fsync_gitdir)
  		idx->do_fsync = 1;
  
  	error = git_buf_joinpath(&path, prefix, suff);
  	if (error < 0)
  		goto cleanup;
  
  	fd = git_futils_mktmp(&tmp_path, git_buf_cstr(&path), idx->mode);
  	git_buf_free(&path);
  	if (fd < 0)
  		goto cleanup;
  
  	error = git_packfile_alloc(&idx->pack, git_buf_cstr(&tmp_path));
  	git_buf_free(&tmp_path);
  
  	if (error < 0)
  		goto cleanup;
  
  	idx->pack->mwf.fd = fd;
  	if ((error = git_mwindow_file_register(&idx->pack->mwf)) < 0)
  		goto cleanup;
  
  	*out = idx;
  	return 0;
  
  cleanup:
  	if (fd != -1)
  		p_close(fd);
  
  	if (git_buf_len(&tmp_path) > 0)
  		p_unlink(git_buf_cstr(&tmp_path));
  
  	if (idx->pack != NULL)
  		p_unlink(idx->pack->pack_name);
  
  	git_buf_free(&path);
  	git_buf_free(&tmp_path);
  	git__free(idx);
  	return -1;
  }
  
  void git_indexer__set_fsync(git_indexer *idx, int do_fsync)
  {
  	idx->do_fsync = !!do_fsync;
  }
  
  /* Try to store the delta so we can try to resolve it later */
  static int store_delta(git_indexer *idx)
  {
  	struct delta_info *delta;
  
  	delta = git__calloc(1, sizeof(struct delta_info));
  	GITERR_CHECK_ALLOC(delta);
  	delta->delta_off = idx->entry_start;
  
  	if (git_vector_insert(&idx->deltas, delta) < 0)
  		return -1;
  
  	return 0;
  }
  
  static int hash_header(git_hash_ctx *ctx, git_off_t len, git_otype type)
  {
  	char buffer[64];
  	size_t hdrlen;
  	int error;
  
  	if ((error = git_odb__format_object_header(&hdrlen,
  		buffer, sizeof(buffer), (size_t)len, type)) < 0)
  		return error;
  
  	return git_hash_update(ctx, buffer, hdrlen);
  }
  
  static int hash_object_stream(git_indexer*idx, git_packfile_stream *stream)
  {
  	ssize_t read;
  
  	assert(idx && stream);
  
  	do {
  		if ((read = git_packfile_stream_read(stream, idx->objbuf, sizeof(idx->objbuf))) < 0)
  			break;
  
  		git_hash_update(&idx->hash_ctx, idx->objbuf, read);
  	} while (read > 0);
  
  	if (read < 0)
  		return (int)read;
  
  	return 0;
  }
  
  /* In order to create the packfile stream, we need to skip over the delta base description */
  static int advance_delta_offset(git_indexer *idx, git_otype type)
  {
  	git_mwindow *w = NULL;
  
  	assert(type == GIT_OBJ_REF_DELTA || type == GIT_OBJ_OFS_DELTA);
  
  	if (type == GIT_OBJ_REF_DELTA) {
  		idx->off += GIT_OID_RAWSZ;
  	} else {
  		git_off_t base_off = get_delta_base(idx->pack, &w, &idx->off, type, idx->entry_start);
  		git_mwindow_close(&w);
  		if (base_off < 0)
  			return (int)base_off;
  	}
  
  	return 0;
  }
  
  /* Read from the stream and discard any output */
  static int read_object_stream(git_indexer *idx, git_packfile_stream *stream)
  {
  	ssize_t read;
  
  	assert(stream);
  
  	do {
  		read = git_packfile_stream_read(stream, idx->objbuf, sizeof(idx->objbuf));
  	} while (read > 0);
  
  	if (read < 0)
  		return (int)read;
  
  	return 0;
  }
  
  static int crc_object(uint32_t *crc_out, git_mwindow_file *mwf, git_off_t start, git_off_t size)
  {
  	void *ptr;
  	uint32_t crc;
  	unsigned int left, len;
  	git_mwindow *w = NULL;
  
  	crc = crc32(0L, Z_NULL, 0);
  	while (size) {
  		ptr = git_mwindow_open(mwf, &w, start, (size_t)size, &left);
  		if (ptr == NULL)
  			return -1;
  
  		len = min(left, (unsigned int)size);
  		crc = crc32(crc, ptr, len);
  		size -= len;
  		start += len;
  		git_mwindow_close(&w);
  	}
  
  	*crc_out = htonl(crc);
  	return 0;
  }
  
  static int store_object(git_indexer *idx)
  {
  	int i, error;
  	khiter_t k;
  	git_oid oid;
  	struct entry *entry;
  	git_off_t entry_size;
  	struct git_pack_entry *pentry;
  	git_off_t entry_start = idx->entry_start;
  
  	entry = git__calloc(1, sizeof(*entry));
  	GITERR_CHECK_ALLOC(entry);
  
  	pentry = git__calloc(1, sizeof(struct git_pack_entry));
  	GITERR_CHECK_ALLOC(pentry);
  
  	git_hash_final(&oid, &idx->hash_ctx);
  	entry_size = idx->off - entry_start;
  	if (entry_start > UINT31_MAX) {
  		entry->offset = UINT32_MAX;
  		entry->offset_long = entry_start;
  	} else {
  		entry->offset = (uint32_t)entry_start;
  	}
  
  	git_oid_cpy(&pentry->sha1, &oid);
  	pentry->offset = entry_start;
  
  	k = git_oidmap_put(idx->pack->idx_cache, &pentry->sha1, &error);
  	if (error == -1) {
  		git__free(pentry);
  		giterr_set_oom();
  		goto on_error;
  	}
  
  	if (error == 0) {
  		giterr_set(GITERR_INDEXER, "duplicate object %s found in pack", git_oid_tostr_s(&pentry->sha1));
  		git__free(pentry);
  		goto on_error;
  	}
  
  
  	git_oidmap_set_value_at(idx->pack->idx_cache, k, pentry);
  
  	git_oid_cpy(&entry->oid, &oid);
  
  	if (crc_object(&entry->crc, &idx->pack->mwf, entry_start, entry_size) < 0)
  		goto on_error;
  
  	/* Add the object to the list */
  	if (git_vector_insert(&idx->objects, entry) < 0)
  		goto on_error;
  
  	for (i = oid.id[0]; i < 256; ++i) {
  		idx->fanout[i]++;
  	}
  
  	return 0;
  
  on_error:
  	git__free(entry);
  
  	return -1;
  }
  
  GIT_INLINE(bool) has_entry(git_indexer *idx, git_oid *id)
  {
  	return git_oidmap_exists(idx->pack->idx_cache, id);
  }
  
  static int save_entry(git_indexer *idx, struct entry *entry, struct git_pack_entry *pentry, git_off_t entry_start)
  {
  	int i, error;
  	khiter_t k;
  
  	if (entry_start > UINT31_MAX) {
  		entry->offset = UINT32_MAX;
  		entry->offset_long = entry_start;
  	} else {
  		entry->offset = (uint32_t)entry_start;
  	}
  
  	pentry->offset = entry_start;
  	k = git_oidmap_put(idx->pack->idx_cache, &pentry->sha1, &error);
  
  	if (error <= 0) {
  		giterr_set(GITERR_INDEXER, "cannot insert object into pack");
  		return -1;
  	}
  
  	git_oidmap_set_value_at(idx->pack->idx_cache, k, pentry);
  
  	/* Add the object to the list */
  	if (git_vector_insert(&idx->objects, entry) < 0)
  		return -1;
  
  	for (i = entry->oid.id[0]; i < 256; ++i) {
  		idx->fanout[i]++;
  	}
  
  	return 0;
  }
  
  static int hash_and_save(git_indexer *idx, git_rawobj *obj, git_off_t entry_start)
  {
  	git_oid oid;
  	size_t entry_size;
  	struct entry *entry;
  	struct git_pack_entry *pentry = NULL;
  
  	entry = git__calloc(1, sizeof(*entry));
  	GITERR_CHECK_ALLOC(entry);
  
  	if (git_odb__hashobj(&oid, obj) < 0) {
  		giterr_set(GITERR_INDEXER, "failed to hash object");
  		goto on_error;
  	}
  
  	pentry = git__calloc(1, sizeof(struct git_pack_entry));
  	GITERR_CHECK_ALLOC(pentry);
  
  	git_oid_cpy(&pentry->sha1, &oid);
  	git_oid_cpy(&entry->oid, &oid);
  	entry->crc = crc32(0L, Z_NULL, 0);
  
  	entry_size = (size_t)(idx->off - entry_start);
  	if (crc_object(&entry->crc, &idx->pack->mwf, entry_start, entry_size) < 0)
  		goto on_error;
  
  	return save_entry(idx, entry, pentry, entry_start);
  
  on_error:
  	git__free(pentry);
  	git__free(entry);
  	git__free(obj->data);
  	return -1;
  }
  
  static int do_progress_callback(git_indexer *idx, git_transfer_progress *stats)
  {
  	if (idx->progress_cb)
  		return giterr_set_after_callback_function(
  			idx->progress_cb(stats, idx->progress_payload),
  			"indexer progress");
  	return 0;
  }
  
  /* Hash everything but the last 20B of input */
  static void hash_partially(git_indexer *idx, const uint8_t *data, size_t size)
  {
  	size_t to_expell, to_keep;
  
  	if (size == 0)
  		return;
  
  	/* Easy case, dump the buffer and the data minus the last 20 bytes */
  	if (size >= GIT_OID_RAWSZ) {
  		git_hash_update(&idx->trailer, idx->inbuf, idx->inbuf_len);
  		git_hash_update(&idx->trailer, data, size - GIT_OID_RAWSZ);
  
  		data += size - GIT_OID_RAWSZ;
  		memcpy(idx->inbuf, data, GIT_OID_RAWSZ);
  		idx->inbuf_len = GIT_OID_RAWSZ;
  		return;
  	}
  
  	/* We can just append */
  	if (idx->inbuf_len + size <= GIT_OID_RAWSZ) {
  		memcpy(idx->inbuf + idx->inbuf_len, data, size);
  		idx->inbuf_len += size;
  		return;
  	}
  
  	/* We need to partially drain the buffer and then append */
  	to_keep   = GIT_OID_RAWSZ - size;
  	to_expell = idx->inbuf_len - to_keep;
  
  	git_hash_update(&idx->trailer, idx->inbuf, to_expell);
  
  	memmove(idx->inbuf, idx->inbuf + to_expell, to_keep);
  	memcpy(idx->inbuf + to_keep, data, size);
  	idx->inbuf_len += size - to_expell;
  }
  
  static int write_at(git_indexer *idx, const void *data, git_off_t offset, size_t size)
  {
  	git_file fd = idx->pack->mwf.fd;
  	size_t mmap_alignment;
  	size_t page_offset;
  	git_off_t page_start;
  	unsigned char *map_data;
  	git_map map;
  	int error;
  
  	assert(data && size);
  
  	if ((error = git__mmap_alignment(&mmap_alignment)) < 0)
  		return error;
  
  	/* the offset needs to be at the mmap boundary for the platform */
  	page_offset = offset % mmap_alignment;
  	page_start = offset - page_offset;
  
  	if ((error = p_mmap(&map, page_offset + size, GIT_PROT_WRITE, GIT_MAP_SHARED, fd, page_start)) < 0)
  		return error;
  
  	map_data = (unsigned char *)map.data;
  	memcpy(map_data + page_offset, data, size);
  	p_munmap(&map);
  
  	return 0;
  }
  
  static int append_to_pack(git_indexer *idx, const void *data, size_t size)
  {
  	git_off_t new_size;
  	size_t mmap_alignment;
  	size_t page_offset;
  	git_off_t page_start;
  	git_off_t current_size = idx->pack->mwf.size;
  	int fd = idx->pack->mwf.fd;
  	int error;
  
  	if (!size)
  		return 0;
  
  	if ((error = git__mmap_alignment(&mmap_alignment)) < 0)
  		return error;
  
  	/* Write a single byte to force the file system to allocate space now or
  	 * report an error, since we can't report errors when writing using mmap.
  	 * Round the size up to the nearest page so that we only need to perform file
  	 * I/O when we add a page, instead of whenever we write even a single byte. */
  	new_size = current_size + size;
  	page_offset = new_size % mmap_alignment;
  	page_start = new_size - page_offset;
  
  	if (p_lseek(fd, page_start + mmap_alignment - 1, SEEK_SET) < 0 ||
  	    p_write(idx->pack->mwf.fd, data, 1) < 0) {
  		giterr_set(GITERR_OS, "cannot extend packfile '%s'", idx->pack->pack_name);
  		return -1;
  	}
  
  	return write_at(idx, data, idx->pack->mwf.size, size);
  }
  
  int git_indexer_append(git_indexer *idx, const void *data, size_t size, git_transfer_progress *stats)
  {
  	int error = -1;
  	size_t processed;
  	struct git_pack_header *hdr = &idx->hdr;
  	git_mwindow_file *mwf = &idx->pack->mwf;
  
  	assert(idx && data && stats);
  
  	processed = stats->indexed_objects;
  
  	if ((error = append_to_pack(idx, data, size)) < 0)
  		return error;
  
  	hash_partially(idx, data, (int)size);
  
  	/* Make sure we set the new size of the pack */
  	idx->pack->mwf.size += size;
  
  	if (!idx->parsed_header) {
  		unsigned int total_objects;
  
  		if ((unsigned)idx->pack->mwf.size < sizeof(struct git_pack_header))
  			return 0;
  
  		if ((error = parse_header(&idx->hdr, idx->pack)) < 0)
  			return error;
  
  		idx->parsed_header = 1;
  		idx->nr_objects = ntohl(hdr->hdr_entries);
  		idx->off = sizeof(struct git_pack_header);
  
  		/* for now, limit to 2^32 objects */
  		assert(idx->nr_objects == (size_t)((unsigned int)idx->nr_objects));
  		if (idx->nr_objects == (size_t)((unsigned int)idx->nr_objects))
  			total_objects = (unsigned int)idx->nr_objects;
  		else
  			total_objects = UINT_MAX;
  
  		idx->pack->idx_cache = git_oidmap_alloc();
  		GITERR_CHECK_ALLOC(idx->pack->idx_cache);
  
  		idx->pack->has_cache = 1;
  		if (git_vector_init(&idx->objects, total_objects, objects_cmp) < 0)
  			return -1;
  
  		if (git_vector_init(&idx->deltas, total_objects / 2, NULL) < 0)
  			return -1;
  
  		stats->received_objects = 0;
  		stats->local_objects = 0;
  		stats->total_deltas = 0;
  		stats->indexed_deltas = 0;
  		processed = stats->indexed_objects = 0;
  		stats->total_objects = total_objects;
  
  		if ((error = do_progress_callback(idx, stats)) != 0)
  			return error;
  	}
  
  	/* Now that we have data in the pack, let's try to parse it */
  
  	/* As the file grows any windows we try to use will be out of date */
  	git_mwindow_free_all(mwf);
  
  	while (processed < idx->nr_objects) {
  		git_packfile_stream *stream = &idx->stream;
  		git_off_t entry_start = idx->off;
  		size_t entry_size;
  		git_otype type;
  		git_mwindow *w = NULL;
  
  		if (idx->pack->mwf.size <= idx->off + 20)
  			return 0;
  
  		if (!idx->have_stream) {
  			error = git_packfile_unpack_header(&entry_size, &type, mwf, &w, &idx->off);
  			if (error == GIT_EBUFS) {
  				idx->off = entry_start;
  				return 0;
  			}
  			if (error < 0)
  				goto on_error;
  
  			git_mwindow_close(&w);
  			idx->entry_start = entry_start;
  			git_hash_init(&idx->hash_ctx);
  
  			if (type == GIT_OBJ_REF_DELTA || type == GIT_OBJ_OFS_DELTA) {
  				error = advance_delta_offset(idx, type);
  				if (error == GIT_EBUFS) {
  					idx->off = entry_start;
  					return 0;
  				}
  				if (error < 0)
  					goto on_error;
  
  				idx->have_delta = 1;
  			} else {
  				idx->have_delta = 0;
  
  				error = hash_header(&idx->hash_ctx, entry_size, type);
  				if (error < 0)
  					goto on_error;
  			}
  
  			idx->have_stream = 1;
  
  			error = git_packfile_stream_open(stream, idx->pack, idx->off);
  			if (error < 0)
  				goto on_error;
  		}
  
  		if (idx->have_delta) {
  			error = read_object_stream(idx, stream);
  		} else {
  			error = hash_object_stream(idx, stream);
  		}
  
  		idx->off = stream->curpos;
  		if (error == GIT_EBUFS)
  			return 0;
  
  		/* We want to free the stream reasorces no matter what here */
  		idx->have_stream = 0;
  		git_packfile_stream_free(stream);
  
  		if (error < 0)
  			goto on_error;
  
  		if (idx->have_delta) {
  			error = store_delta(idx);
  		} else {
  			error = store_object(idx);
  		}
  
  		if (error < 0)
  			goto on_error;
  
  		if (!idx->have_delta) {
  			stats->indexed_objects = (unsigned int)++processed;
  		}
  		stats->received_objects++;
  
  		if ((error = do_progress_callback(idx, stats)) != 0)
  			goto on_error;
  	}
  
  	return 0;
  
  on_error:
  	git_mwindow_free_all(mwf);
  	return error;
  }
  
  static int index_path(git_buf *path, git_indexer *idx, const char *suffix)
  {
  	const char prefix[] = "pack-";
  	size_t slash = (size_t)path->size;
  
  	/* search backwards for '/' */
  	while (slash > 0 && path->ptr[slash - 1] != '/')
  		slash--;
  
  	if (git_buf_grow(path, slash + 1 + strlen(prefix) +
  					 GIT_OID_HEXSZ + strlen(suffix) + 1) < 0)
  		return -1;
  
  	git_buf_truncate(path, slash);
  	git_buf_puts(path, prefix);
  	git_oid_fmt(path->ptr + git_buf_len(path), &idx->hash);
  	path->size += GIT_OID_HEXSZ;
  	git_buf_puts(path, suffix);
  
  	return git_buf_oom(path) ? -1 : 0;
  }
  
  /**
   * Rewind the packfile by the trailer, as we might need to fix the
   * packfile by injecting objects at the tail and must overwrite it.
   */
  static void seek_back_trailer(git_indexer *idx)
  {
  	idx->pack->mwf.size -= GIT_OID_RAWSZ;
  	git_mwindow_free_all(&idx->pack->mwf);
  }
  
  static int inject_object(git_indexer *idx, git_oid *id)
  {
  	git_odb_object *obj;
  	struct entry *entry;
  	struct git_pack_entry *pentry = NULL;
  	git_oid foo = {{0}};
  	unsigned char hdr[64];
  	git_buf buf = GIT_BUF_INIT;
  	git_off_t entry_start;
  	const void *data;
  	size_t len, hdr_len;
  	int error;
  
  	seek_back_trailer(idx);
  	entry_start = idx->pack->mwf.size;
  
  	if (git_odb_read(&obj, idx->odb, id) < 0) {
  		giterr_set(GITERR_INDEXER, "missing delta bases");
  		return -1;
  	}
  
  	data = git_odb_object_data(obj);
  	len = git_odb_object_size(obj);
  
  	entry = git__calloc(1, sizeof(*entry));
  	GITERR_CHECK_ALLOC(entry);
  
  	entry->crc = crc32(0L, Z_NULL, 0);
  
  	/* Write out the object header */
  	hdr_len = git_packfile__object_header(hdr, len, git_odb_object_type(obj));
  	if ((error = append_to_pack(idx, hdr, hdr_len)) < 0)
  		goto cleanup;
  
  	idx->pack->mwf.size += hdr_len;
  	entry->crc = crc32(entry->crc, hdr, (uInt)hdr_len);
  
  	if ((error = git_zstream_deflatebuf(&buf, data, len)) < 0)
  		goto cleanup;
  
  	/* And then the compressed object */
  	if ((error = append_to_pack(idx, buf.ptr, buf.size)) < 0)
  		goto cleanup;
  
  	idx->pack->mwf.size += buf.size;
  	entry->crc = htonl(crc32(entry->crc, (unsigned char *)buf.ptr, (uInt)buf.size));
  	git_buf_free(&buf);
  
  	/* Write a fake trailer so the pack functions play ball */
  
  	if ((error = append_to_pack(idx, &foo, GIT_OID_RAWSZ)) < 0)
  		goto cleanup;
  
  	idx->pack->mwf.size += GIT_OID_RAWSZ;
  
  	pentry = git__calloc(1, sizeof(struct git_pack_entry));
  	GITERR_CHECK_ALLOC(pentry);
  
  	git_oid_cpy(&pentry->sha1, id);
  	git_oid_cpy(&entry->oid, id);
  	idx->off = entry_start + hdr_len + len;
  
  	error = save_entry(idx, entry, pentry, entry_start);
  
  cleanup:
  	if (error) {
  		git__free(entry);
  		git__free(pentry);
  	}
  
  	git_odb_object_free(obj);
  	return error;
  }
  
  static int fix_thin_pack(git_indexer *idx, git_transfer_progress *stats)
  {
  	int error, found_ref_delta = 0;
  	unsigned int i;
  	struct delta_info *delta;
  	size_t size;
  	git_otype type;
  	git_mwindow *w = NULL;
  	git_off_t curpos = 0;
  	unsigned char *base_info;
  	unsigned int left = 0;
  	git_oid base;
  
  	assert(git_vector_length(&idx->deltas) > 0);
  
  	if (idx->odb == NULL) {
  		giterr_set(GITERR_INDEXER, "cannot fix a thin pack without an ODB");
  		return -1;
  	}
  
  	/* Loop until we find the first REF delta */
  	git_vector_foreach(&idx->deltas, i, delta) {
  		if (!delta)
  			continue;
  
  		curpos = delta->delta_off;
  		error = git_packfile_unpack_header(&size, &type, &idx->pack->mwf, &w, &curpos);
  		if (error < 0)
  			return error;
  
  		if (type == GIT_OBJ_REF_DELTA) {
  			found_ref_delta = 1;
  			break;
  		}
  	}
  
  	if (!found_ref_delta) {
  		giterr_set(GITERR_INDEXER, "no REF_DELTA found, cannot inject object");
  		return -1;
  	}
  
  	/* curpos now points to the base information, which is an OID */
  	base_info = git_mwindow_open(&idx->pack->mwf, &w, curpos, GIT_OID_RAWSZ, &left);
  	if (base_info == NULL) {
  		giterr_set(GITERR_INDEXER, "failed to map delta information");
  		return -1;
  	}
  
  	git_oid_fromraw(&base, base_info);
  	git_mwindow_close(&w);
  
  	if (has_entry(idx, &base))
  		return 0;
  
  	if (inject_object(idx, &base) < 0)
  		return -1;
  
  	stats->local_objects++;
  
  	return 0;
  }
  
  static int resolve_deltas(git_indexer *idx, git_transfer_progress *stats)
  {
  	unsigned int i;
  	int error;
  	struct delta_info *delta;
  	int progressed = 0, non_null = 0, progress_cb_result;
  
  	while (idx->deltas.length > 0) {
  		progressed = 0;
  		non_null = 0;
  		git_vector_foreach(&idx->deltas, i, delta) {
  			git_rawobj obj = {NULL};
  
  			if (!delta)
  				continue;
  
  			non_null = 1;
  			idx->off = delta->delta_off;
  			if ((error = git_packfile_unpack(&obj, idx->pack, &idx->off)) < 0) {
  				if (error == GIT_PASSTHROUGH) {
  					/* We have not seen the base object, we'll try again later. */
  					continue;
  				}
  				return -1;
  			}
  
  			if (hash_and_save(idx, &obj, delta->delta_off) < 0)
  				continue;
  
  			git__free(obj.data);
  			stats->indexed_objects++;
  			stats->indexed_deltas++;
  			progressed = 1;
  			if ((progress_cb_result = do_progress_callback(idx, stats)) < 0)
  				return progress_cb_result;
  
  			/* remove from the list */
  			git_vector_set(NULL, &idx->deltas, i, NULL);
  			git__free(delta);
  		}
  
  		/* if none were actually set, we're done */
  		if (!non_null)
  			break;
  
  		if (!progressed && (fix_thin_pack(idx, stats) < 0)) {
  			return -1;
  		}
  	}
  
  	return 0;
  }
  
  static int update_header_and_rehash(git_indexer *idx, git_transfer_progress *stats)
  {
  	void *ptr;
  	size_t chunk = 1024*1024;
  	git_off_t hashed = 0;
  	git_mwindow *w = NULL;
  	git_mwindow_file *mwf;
  	unsigned int left;
  
  	mwf = &idx->pack->mwf;
  
  	git_hash_init(&idx->trailer);
  
  
  	/* Update the header to include the numer of local objects we injected */
  	idx->hdr.hdr_entries = htonl(stats->total_objects + stats->local_objects);
  	if (write_at(idx, &idx->hdr, 0, sizeof(struct git_pack_header)) < 0)
  		return -1;
  
  	/*
  	 * We now use the same technique as before to determine the
  	 * hash. We keep reading up to the end and let
  	 * hash_partially() keep the existing trailer out of the
  	 * calculation.
  	 */
  	git_mwindow_free_all(mwf);
  	idx->inbuf_len = 0;
  	while (hashed < mwf->size) {
  		ptr = git_mwindow_open(mwf, &w, hashed, chunk, &left);
  		if (ptr == NULL)
  			return -1;
  
  		hash_partially(idx, ptr, left);
  		hashed += left;
  
  		git_mwindow_close(&w);
  	}
  
  	return 0;
  }
  
  int git_indexer_commit(git_indexer *idx, git_transfer_progress *stats)
  {
  	git_mwindow *w = NULL;
  	unsigned int i, long_offsets = 0, left;
  	int error;
  	struct git_pack_idx_header hdr;
  	git_buf filename = GIT_BUF_INIT;
  	struct entry *entry;
  	git_oid trailer_hash, file_hash;
  	git_filebuf index_file = {0};
  	void *packfile_trailer;
  
  	if (!idx->parsed_header) {
  		giterr_set(GITERR_INDEXER, "incomplete pack header");
  		return -1;
  	}
  
  	/* Test for this before resolve_deltas(), as it plays with idx->off */
  	if (idx->off + 20 < idx->pack->mwf.size) {
  		giterr_set(GITERR_INDEXER, "unexpected data at the end of the pack");
  		return -1;
  	}
  	if (idx->off + 20 > idx->pack->mwf.size) {
  		giterr_set(GITERR_INDEXER, "missing trailer at the end of the pack");
  		return -1;
  	}
  
  	packfile_trailer = git_mwindow_open(&idx->pack->mwf, &w, idx->pack->mwf.size - GIT_OID_RAWSZ, GIT_OID_RAWSZ, &left);
  	if (packfile_trailer == NULL) {
  		git_mwindow_close(&w);
  		goto on_error;
  	}
  
  	/* Compare the packfile trailer as it was sent to us and what we calculated */
  	git_oid_fromraw(&file_hash, packfile_trailer);
  	git_mwindow_close(&w);
  
  	git_hash_final(&trailer_hash, &idx->trailer);
  	if (git_oid_cmp(&file_hash, &trailer_hash)) {
  		giterr_set(GITERR_INDEXER, "packfile trailer mismatch");
  		return -1;
  	}
  
  	/* Freeze the number of deltas */
  	stats->total_deltas = stats->total_objects - stats->indexed_objects;
  
  	if ((error = resolve_deltas(idx, stats)) < 0)
  		return error;
  
  	if (stats->indexed_objects != stats->total_objects) {
  		giterr_set(GITERR_INDEXER, "early EOF");
  		return -1;
  	}
  
  	if (stats->local_objects > 0) {
  		if (update_header_and_rehash(idx, stats) < 0)
  			return -1;
  
  		git_hash_final(&trailer_hash, &idx->trailer);
  		write_at(idx, &trailer_hash, idx->pack->mwf.size - GIT_OID_RAWSZ, GIT_OID_RAWSZ);
  	}
  
  	git_vector_sort(&idx->objects);
  
  	/* Use the trailer hash as the pack file name to ensure
  	 * files with different contents have different names */
  	git_oid_cpy(&idx->hash, &trailer_hash);
  
  	git_buf_sets(&filename, idx->pack->pack_name);
  	git_buf_shorten(&filename, strlen("pack"));
  	git_buf_puts(&filename, "idx");
  	if (git_buf_oom(&filename))
  		return -1;
  
  	if (git_filebuf_open(&index_file, filename.ptr,
  		GIT_FILEBUF_HASH_CONTENTS |
  		(idx->do_fsync ? GIT_FILEBUF_FSYNC : 0),
  		idx->mode) < 0)
  		goto on_error;
  
  	/* Write out the header */
  	hdr.idx_signature = htonl(PACK_IDX_SIGNATURE);
  	hdr.idx_version = htonl(2);
  	git_filebuf_write(&index_file, &hdr, sizeof(hdr));
  
  	/* Write out the fanout table */
  	for (i = 0; i < 256; ++i) {
  		uint32_t n = htonl(idx->fanout[i]);
  		git_filebuf_write(&index_file, &n, sizeof(n));
  	}
  
  	/* Write out the object names (SHA-1 hashes) */
  	git_vector_foreach(&idx->objects, i, entry) {
  		git_filebuf_write(&index_file, &entry->oid, sizeof(git_oid));
  	}
  
  	/* Write out the CRC32 values */
  	git_vector_foreach(&idx->objects, i, entry) {
  		git_filebuf_write(&index_file, &entry->crc, sizeof(uint32_t));
  	}
  
  	/* Write out the offsets */
  	git_vector_foreach(&idx->objects, i, entry) {
  		uint32_t n;
  
  		if (entry->offset == UINT32_MAX)
  			n = htonl(0x80000000 | long_offsets++);
  		else
  			n = htonl(entry->offset);
  
  		git_filebuf_write(&index_file, &n, sizeof(uint32_t));
  	}
  
  	/* Write out the long offsets */
  	git_vector_foreach(&idx->objects, i, entry) {
  		uint32_t split[2];
  
  		if (entry->offset != UINT32_MAX)
  			continue;
  
  		split[0] = htonl(entry->offset_long >> 32);
  		split[1] = htonl(entry->offset_long & 0xffffffff);
  
  		git_filebuf_write(&index_file, &split, sizeof(uint32_t) * 2);
  	}
  
  	/* Write out the packfile trailer to the index */
  	if (git_filebuf_write(&index_file, &trailer_hash, GIT_OID_RAWSZ) < 0)
  		goto on_error;
  
  	/* Write out the hash of the idx */
  	if (git_filebuf_hash(&trailer_hash, &index_file) < 0)
  		goto on_error;
  
  	git_filebuf_write(&index_file, &trailer_hash, sizeof(git_oid));
  
  	/* Figure out what the final name should be */
  	if (index_path(&filename, idx, ".idx") < 0)
  		goto on_error;
  
  	/* Commit file */
  	if (git_filebuf_commit_at(&index_file, filename.ptr) < 0)
  		goto on_error;
  
  	git_mwindow_free_all(&idx->pack->mwf);
  
  	/* Truncate file to undo rounding up to next page_size in append_to_pack */
  	if (p_ftruncate(idx->pack->mwf.fd, idx->pack->mwf.size) < 0) {
  		giterr_set(GITERR_OS, "failed to truncate pack file '%s'", idx->pack->pack_name);
  		return -1;
  	}
  
  	if (idx->do_fsync && p_fsync(idx->pack->mwf.fd) < 0) {
  		giterr_set(GITERR_OS, "failed to fsync packfile");
  		goto on_error;
  	}
  
  	/* We need to close the descriptor here so Windows doesn't choke on commit_at */
  	if (p_close(idx->pack->mwf.fd) < 0) {
  		giterr_set(GITERR_OS, "failed to close packfile");
  		goto on_error;
  	}
  
  	idx->pack->mwf.fd = -1;
  
  	if (index_path(&filename, idx, ".pack") < 0)
  		goto on_error;
  
  	/* And don't forget to rename the packfile to its new place. */
  	if (p_rename(idx->pack->pack_name, git_buf_cstr(&filename)) < 0)
  		goto on_error;
  
  	/* And fsync the parent directory if we're asked to. */
  	if (idx->do_fsync &&
  		git_futils_fsync_parent(git_buf_cstr(&filename)) < 0)
  		goto on_error;
  
  	idx->pack_committed = 1;
  
  	git_buf_free(&filename);
  	return 0;
  
  on_error:
  	git_mwindow_free_all(&idx->pack->mwf);
  	git_filebuf_cleanup(&index_file);
  	git_buf_free(&filename);
  	return -1;
  }
  
  void git_indexer_free(git_indexer *idx)
  {
  	if (idx == NULL)
  		return;
  
  	if (idx->have_stream)
  		git_packfile_stream_free(&idx->stream);
  
  	git_vector_free_deep(&idx->objects);
  
  	if (idx->pack->idx_cache) {
  		struct git_pack_entry *pentry;
  		git_oidmap_foreach_value(idx->pack->idx_cache, pentry, {
  			git__free(pentry);
  		});
  
  		git_oidmap_free(idx->pack->idx_cache);
  	}
  
  	git_vector_free_deep(&idx->deltas);
  
  	if (!git_mutex_lock(&git__mwindow_mutex)) {
  		if (!idx->pack_committed)
  			git_packfile_close(idx->pack, true);
  
  		git_packfile_free(idx->pack);
  		git_mutex_unlock(&git__mwindow_mutex);
  	}
  
  	git_hash_ctx_cleanup(&idx->trailer);
  	git_hash_ctx_cleanup(&idx->hash_ctx);
  	git__free(idx);
  }
  