X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=read-cache.c;h=d2aebdd6bc6dbf7ae40f3a7600d76765f31b9a15;hb=750a09a7de63c92868cff41a3151eac320c77fa0;hp=8571ba2f0f72cbb45640a4832539520af4ad9646;hpb=b51ad4314078298194d23d46e2b4473ffd32a88a;p=git.git

diff --git a/read-cache.c b/read-cache.c
index 8571ba2f..d2aebdd6 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -3,315 +3,180 @@
  *
  * Copyright (C) Linus Torvalds, 2005
  */
-#include <stdarg.h>
 #include "cache.h"
 
-const char *sha1_file_directory = NULL;
 struct cache_entry **active_cache = NULL;
-unsigned int active_nr = 0, active_alloc = 0;
+unsigned int active_nr = 0, active_alloc = 0, active_cache_changed = 0;
 
-void usage(const char *err)
-{
-	fprintf(stderr, "usage: %s\n", err);
-	exit(1);
-}
-
-static void report(const char *prefix, const char *err, va_list params)
-{
-	fputs(prefix, stderr);
-	vfprintf(stderr, err, params);
-	fputs("\n", stderr);
-}
-
-void die(const char *err, ...)
-{
-	va_list params;
-
-	va_start(params, err);
-	report("fatal: ", err, params);
-	va_end(params);
-	exit(1);
-}
-
-int error(const char *err, ...)
+/*
+ * This only updates the "non-critical" parts of the directory
+ * cache, ie the parts that aren't tracked by GIT, and only used
+ * to validate the cache.
+ */
+void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 {
-	va_list params;
-
-	va_start(params, err);
-	report("error: ", err, params);
-	va_end(params);
-	return -1;
+	ce->ce_ctime.sec = htonl(st->st_ctime);
+	ce->ce_mtime.sec = htonl(st->st_mtime);
+#ifdef USE_NSEC
+	ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
+	ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
+#endif
+	ce->ce_dev = htonl(st->st_dev);
+	ce->ce_ino = htonl(st->st_ino);
+	ce->ce_uid = htonl(st->st_uid);
+	ce->ce_gid = htonl(st->st_gid);
+	ce->ce_size = htonl(st->st_size);
 }
 
-
-static unsigned hexval(char c)
+int ce_match_stat(struct cache_entry *ce, struct stat *st)
 {
-	if (c >= '0' && c <= '9')
-		return c - '0';
-	if (c >= 'a' && c <= 'f')
-		return c - 'a' + 10;
-	if (c >= 'A' && c <= 'F')
-		return c - 'A' + 10;
-	return ~0;
-}
+	unsigned int changed = 0;
 
-int get_sha1_hex(const char *hex, unsigned char *sha1)
-{
-	int i;
-	for (i = 0; i < 20; i++) {
-		unsigned int val = (hexval(hex[0]) << 4) | hexval(hex[1]);
-		if (val & ~0xff)
-			return -1;
-		*sha1++ = val;
-		hex += 2;
+	switch (ntohl(ce->ce_mode) & S_IFMT) {
+	case S_IFREG:
+		changed |= !S_ISREG(st->st_mode) ? TYPE_CHANGED : 0;
+		/* We consider only the owner x bit to be relevant for "mode changes" */
+		if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
+			changed |= MODE_CHANGED;
+		break;
+	case S_IFLNK:
+		changed |= !S_ISLNK(st->st_mode) ? TYPE_CHANGED : 0;
+		break;
+	default:
+		die("internal error: ce_mode is %o", ntohl(ce->ce_mode));
 	}
-	return 0;
-}
+	if (ce->ce_mtime.sec != htonl(st->st_mtime))
+		changed |= MTIME_CHANGED;
+	if (ce->ce_ctime.sec != htonl(st->st_ctime))
+		changed |= CTIME_CHANGED;
 
-char * sha1_to_hex(const unsigned char *sha1)
-{
-	static char buffer[50];
-	static const char hex[] = "0123456789abcdef";
-	char *buf = buffer;
-	int i;
-
-	for (i = 0; i < 20; i++) {
-		unsigned int val = *sha1++;
-		*buf++ = hex[val >> 4];
-		*buf++ = hex[val & 0xf];
-	}
-	return buffer;
-}
+#ifdef USE_NSEC
+	/*
+	 * nsec seems unreliable - not all filesystems support it, so
+	 * as long as it is in the inode cache you get right nsec
+	 * but after it gets flushed, you get zero nsec.
+	 */
+	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec))
+		changed |= MTIME_CHANGED;
+	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec))
+		changed |= CTIME_CHANGED;
+#endif	
 
-/*
- * NOTE! This returns a statically allocated buffer, so you have to be
- * careful about using it. Do a "strdup()" if you need to save the
- * filename.
- */
-char *sha1_file_name(const unsigned char *sha1)
-{
-	int i;
-	static char *name, *base;
-
-	if (!base) {
-		char *sha1_file_directory = getenv(DB_ENVIRONMENT) ? : DEFAULT_DB_ENVIRONMENT;
-		int len = strlen(sha1_file_directory);
-		base = malloc(len + 60);
-		memcpy(base, sha1_file_directory, len);
-		memset(base+len, 0, 60);
-		base[len] = '/';
-		base[len+3] = '/';
-		name = base + len + 1;
-	}
-	for (i = 0; i < 20; i++) {
-		static char hex[] = "0123456789abcdef";
-		unsigned int val = sha1[i];
-		char *pos = name + i*2 + (i > 0);
-		*pos++ = hex[val >> 4];
-		*pos = hex[val & 0xf];
-	}
-	return base;
-}
+	if (ce->ce_uid != htonl(st->st_uid) ||
+	    ce->ce_gid != htonl(st->st_gid))
+		changed |= OWNER_CHANGED;
+	if (ce->ce_ino != htonl(st->st_ino))
+		changed |= INODE_CHANGED;
 
-int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
-{
-	unsigned char real_sha1[20];
-	SHA_CTX c;
+#ifdef USE_STDEV
+	/*
+	 * st_dev breaks on network filesystems where different
+	 * clients will have different views of what "device"
+	 * the filesystem is on
+	 */
+	if (ce->ce_dev != htonl(st->st_dev))
+		changed |= INODE_CHANGED;
+#endif
 
-	SHA1_Init(&c);
-	SHA1_Update(&c, map, size);
-	SHA1_Final(real_sha1, &c);
-	return memcmp(sha1, real_sha1, 20) ? -1 : 0;
+	if (ce->ce_size != htonl(st->st_size))
+		changed |= DATA_CHANGED;
+	return changed;
 }
 
-void *map_sha1_file(const unsigned char *sha1, unsigned long *size)
+static int ce_compare_data(struct cache_entry *ce, struct stat *st)
 {
-	char *filename = sha1_file_name(sha1);
-	int fd = open(filename, O_RDONLY);
-	struct stat st;
-	void *map;
+	int match = -1;
+	int fd = open(ce->name, O_RDONLY);
 
-	if (fd < 0) {
-		perror(filename);
-		return NULL;
-	}
-	if (fstat(fd, &st) < 0) {
+	if (fd >= 0) {
+		unsigned char sha1[20];
+		if (!index_fd(sha1, fd, st, 0, NULL))
+			match = memcmp(sha1, ce->sha1, 20);
 		close(fd);
-		return NULL;
 	}
-	map = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
-	close(fd);
-	if (-1 == (int)(long)map)
-		return NULL;
-	*size = st.st_size;
-	return map;
+	return match;
 }
 
-void * unpack_sha1_file(void *map, unsigned long mapsize, char *type, unsigned long *size)
+static int ce_compare_link(struct cache_entry *ce, unsigned long expected_size)
 {
-	int ret, bytes;
-	z_stream stream;
-	char buffer[8192];
-	char *buf;
-
-	/* Get the data stream */
-	memset(&stream, 0, sizeof(stream));
-	stream.next_in = map;
-	stream.avail_in = mapsize;
-	stream.next_out = buffer;
-	stream.avail_out = sizeof(buffer);
-
-	inflateInit(&stream);
-	ret = inflate(&stream, 0);
-	if (sscanf(buffer, "%10s %lu", type, size) != 2)
-		return NULL;
-
-	bytes = strlen(buffer) + 1;
-	buf = malloc(*size);
-	if (!buf)
-		return NULL;
-
-	memcpy(buf, buffer + bytes, stream.total_out - bytes);
-	bytes = stream.total_out - bytes;
-	if (bytes < *size && ret == Z_OK) {
-		stream.next_out = buf + bytes;
-		stream.avail_out = *size - bytes;
-		while (inflate(&stream, Z_FINISH) == Z_OK)
-			/* nothing */;
+	int match = -1;
+	char *target;
+	void *buffer;
+	unsigned long size;
+	char type[10];
+	int len;
+
+	target = xmalloc(expected_size);
+	len = readlink(ce->name, target, expected_size);
+	if (len != expected_size) {
+		free(target);
+		return -1;
 	}
-	inflateEnd(&stream);
-	return buf;
-}
-
-void * read_sha1_file(const unsigned char *sha1, char *type, unsigned long *size)
-{
-	unsigned long mapsize;
-	void *map, *buf;
-
-	map = map_sha1_file(sha1, &mapsize);
-	if (map) {
-		buf = unpack_sha1_file(map, mapsize, type, size);
-		munmap(map, mapsize);
-		return buf;
+	buffer = read_sha1_file(ce->sha1, type, &size);
+	if (!buffer) {
+		free(target);
+		return -1;
 	}
-	return NULL;
+	if (size == expected_size)
+		match = memcmp(buffer, target, size);
+	free(buffer);
+	free(target);
+	return match;
 }
 
-int write_sha1_file(char *buf, unsigned len, unsigned char *returnsha1)
+int ce_modified(struct cache_entry *ce, struct stat *st)
 {
-	int size;
-	char *compressed;
-	z_stream stream;
-	unsigned char sha1[20];
-	SHA_CTX c;
+	int changed;
+	changed = ce_match_stat(ce, st);
+	if (!changed)
+		return 0;
 
-	/* Set it up */
-	memset(&stream, 0, sizeof(stream));
-	deflateInit(&stream, Z_BEST_COMPRESSION);
-	size = deflateBound(&stream, len);
-	compressed = malloc(size);
-
-	/* Compress it */
-	stream.next_in = buf;
-	stream.avail_in = len;
-	stream.next_out = compressed;
-	stream.avail_out = size;
-	while (deflate(&stream, Z_FINISH) == Z_OK)
-		/* nothing */;
-	deflateEnd(&stream);
-	size = stream.total_out;
-
-	/* Sha1.. */
-	SHA1_Init(&c);
-	SHA1_Update(&c, compressed, size);
-	SHA1_Final(sha1, &c);
+	/*
+	 * If the mode or type has changed, there's no point in trying
+	 * to refresh the entry - it's not going to match
+	 */
+	if (changed & (MODE_CHANGED | TYPE_CHANGED))
+		return changed;
 
-	if (write_sha1_buffer(sha1, compressed, size) < 0)
-		return -1;
-	if (returnsha1)
-		memcpy(returnsha1, sha1, 20);
+	/* Immediately after read-tree or update-index --cacheinfo,
+	 * the length field is zero.  For other cases the ce_size
+	 * should match the SHA1 recorded in the index entry.
+	 */
+	if ((changed & DATA_CHANGED) && ce->ce_size != htonl(0))
+		return changed;
+
+	switch (st->st_mode & S_IFMT) {
+	case S_IFREG:
+		if (ce_compare_data(ce, st))
+			return changed | DATA_CHANGED;
+		break;
+	case S_IFLNK:
+		if (ce_compare_link(ce, st->st_size))
+			return changed | DATA_CHANGED;
+		break;
+	default:
+		return changed | TYPE_CHANGED;
+	}
 	return 0;
 }
 
-static inline int collision_check(char *filename, void *buf, unsigned int size)
+int base_name_compare(const char *name1, int len1, int mode1,
+		      const char *name2, int len2, int mode2)
 {
-#ifdef COLLISION_CHECK
-	void *map;
-	int fd = open(filename, O_RDONLY);
-	struct stat st;
+	unsigned char c1, c2;
+	int len = len1 < len2 ? len1 : len2;
 	int cmp;
 
-	/* Unreadable object, or object went away? Strange. */
-	if (fd < 0)
-		return -1;
-
-	if (fstat(fd, &st) < 0 || size != st.st_size)
-		return -1;
-
-	map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
-	close(fd);
-	if (map == MAP_FAILED)
-		return -1;
-	cmp = memcmp(buf, map, size);
-	munmap(map, size);
+	cmp = memcmp(name1, name2, len);
 	if (cmp)
-		return -1;
-#endif
-	return 0;
-}
-
-int write_sha1_buffer(const unsigned char *sha1, void *buf, unsigned int size)
-{
-	char *filename = sha1_file_name(sha1);
-	int fd;
-
-	fd = open(filename, O_WRONLY | O_CREAT | O_EXCL, 0666);
-	if (fd < 0) {
-		if (errno != EEXIST)
-			return -1;
-		if (collision_check(filename, buf, size))
-			return error("SHA1 collision detected!"
-					" This is bad, bad, BAD!\a\n");
-		return 0;
-	}
-	write(fd, buf, size);
-	close(fd);
-	return 0;
-}
-
-int cache_match_stat(struct cache_entry *ce, struct stat *st)
-{
-	unsigned int changed = 0;
-
-	if (ce->ce_mtime.sec != htonl(st->st_mtime))
-		changed |= MTIME_CHANGED;
-	if (ce->ce_ctime.sec != htonl(st->st_ctime))
-		changed |= CTIME_CHANGED;
-
-#ifdef NSEC
-	/*
-	 * nsec seems unreliable - not all filesystems support it, so
-	 * as long as it is in the inode cache you get right nsec
-	 * but after it gets flushed, you get zero nsec.
-	 */
-	if (ce->ce_mtime.nsec != htonl(st->st_mtim.tv_nsec)
-		changed |= MTIME_CHANGED;
-	if (ce->ce_ctime.nsec != htonl(st->st_ctim.tv_nsec)
-		changed |= CTIME_CHANGED;
-#endif	
-
-	if (ce->ce_uid != htonl(st->st_uid) ||
-	    ce->ce_gid != htonl(st->st_gid))
-		changed |= OWNER_CHANGED;
-	/* We consider only the owner x bit to be relevant for "mode changes" */
-	if (0100 & (ntohl(ce->ce_mode) ^ st->st_mode))
-		changed |= MODE_CHANGED;
-	if (ce->ce_dev != htonl(st->st_dev) ||
-	    ce->ce_ino != htonl(st->st_ino))
-		changed |= INODE_CHANGED;
-	if (ce->ce_size != htonl(st->st_size))
-		changed |= DATA_CHANGED;
-	return changed;
+		return cmp;
+	c1 = name1[len];
+	c2 = name2[len];
+	if (!c1 && S_ISDIR(mode1))
+		c1 = '/';
+	if (!c2 && S_ISDIR(mode2))
+		c2 = '/';
+	return (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
 }
 
 int cache_name_compare(const char *name1, int flags1, const char *name2, int flags2)
@@ -344,7 +209,7 @@ int cache_name_pos(const char *name, int namelen)
 	while (last > first) {
 		int next = (last + first) >> 1;
 		struct cache_entry *ce = active_cache[next];
-		int cmp = cache_name_compare(name, namelen, ce->name, htons(ce->ce_flags));
+		int cmp = cache_name_compare(name, namelen, ce->name, ntohs(ce->ce_flags));
 		if (!cmp)
 			return next;
 		if (cmp < 0) {
@@ -357,8 +222,9 @@ int cache_name_pos(const char *name, int namelen)
 }
 
 /* Remove entry, return true if there are more entries to go.. */
-static int remove_entry_at(int pos)
+int remove_cache_entry_at(int pos)
 {
+	active_cache_changed = 1;
 	active_nr--;
 	if (pos >= active_nr)
 		return 0;
@@ -366,30 +232,169 @@ static int remove_entry_at(int pos)
 	return 1;
 }
 
-int remove_file_from_cache(char *path)
+int remove_file_from_cache(const char *path)
 {
 	int pos = cache_name_pos(path, strlen(path));
 	if (pos < 0)
 		pos = -pos-1;
 	while (pos < active_nr && !strcmp(active_cache[pos]->name, path))
-		remove_entry_at(pos);
+		remove_cache_entry_at(pos);
 	return 0;
 }
 
-static int same_name(struct cache_entry *a, struct cache_entry *b)
+int ce_same_name(struct cache_entry *a, struct cache_entry *b)
 {
 	int len = ce_namelen(a);
 	return ce_namelen(b) == len && !memcmp(a->name, b->name, len);
 }
 
-int add_cache_entry(struct cache_entry *ce, int ok_to_add)
+int ce_path_match(const struct cache_entry *ce, const char **pathspec)
 {
-	int pos;
+	const char *match, *name;
+	int len;
 
-	pos = cache_name_pos(ce->name, htons(ce->ce_flags));
+	if (!pathspec)
+		return 1;
+
+	len = ce_namelen(ce);
+	name = ce->name;
+	while ((match = *pathspec++) != NULL) {
+		int matchlen = strlen(match);
+		if (matchlen > len)
+			continue;
+		if (memcmp(name, match, matchlen))
+			continue;
+		if (matchlen && name[matchlen-1] == '/')
+			return 1;
+		if (name[matchlen] == '/' || !name[matchlen])
+			return 1;
+		if (!matchlen)
+			return 1;
+	}
+	return 0;
+}
+
+/*
+ * Do we have another file that has the beginning components being a
+ * proper superset of the name we're trying to add?
+ */
+static int has_file_name(const struct cache_entry *ce, int pos, int ok_to_replace)
+{
+	int retval = 0;
+	int len = ce_namelen(ce);
+	int stage = ce_stage(ce);
+	const char *name = ce->name;
+
+	while (pos < active_nr) {
+		struct cache_entry *p = active_cache[pos++];
+
+		if (len >= ce_namelen(p))
+			break;
+		if (memcmp(name, p->name, len))
+			break;
+		if (ce_stage(p) != stage)
+			continue;
+		if (p->name[len] != '/')
+			continue;
+		retval = -1;
+		if (!ok_to_replace)
+			break;
+		remove_cache_entry_at(--pos);
+	}
+	return retval;
+}
+
+/*
+ * Do we have another file with a pathname that is a proper
+ * subset of the name we're trying to add?
+ */
+static int has_dir_name(const struct cache_entry *ce, int pos, int ok_to_replace)
+{
+	int retval = 0;
+	int stage = ce_stage(ce);
+	const char *name = ce->name;
+	const char *slash = name + ce_namelen(ce);
+
+	for (;;) {
+		int len;
+
+		for (;;) {
+			if (*--slash == '/')
+				break;
+			if (slash <= ce->name)
+				return retval;
+		}
+		len = slash - name;
+
+		pos = cache_name_pos(name, ntohs(create_ce_flags(len, stage)));
+		if (pos >= 0) {
+			retval = -1;
+			if (ok_to_replace)
+				break;
+			remove_cache_entry_at(pos);
+			continue;
+		}
+
+		/*
+		 * Trivial optimization: if we find an entry that
+		 * already matches the sub-directory, then we know
+		 * we're ok, and we can exit.
+		 */
+		pos = -pos-1;
+		while (pos < active_nr) {
+			struct cache_entry *p = active_cache[pos];
+			if ((ce_namelen(p) <= len) ||
+			    (p->name[len] != '/') ||
+			    memcmp(p->name, name, len))
+				break; /* not our subdirectory */
+			if (ce_stage(p) == stage)
+				/* p is at the same stage as our entry, and
+				 * is a subdirectory of what we are looking
+				 * at, so we cannot have conflicts at our
+				 * level or anything shorter.
+				 */
+				return retval;
+			pos++;
+		}
+	}
+	return retval;
+}
+
+/* We may be in a situation where we already have path/file and path
+ * is being added, or we already have path and path/file is being
+ * added.  Either one would result in a nonsense tree that has path
+ * twice when git-write-tree tries to write it out.  Prevent it.
+ * 
+ * If ok-to-replace is specified, we remove the conflicting entries
+ * from the cache so the caller should recompute the insert position.
+ * When this happens, we return non-zero.
+ */
+static int check_file_directory_conflict(const struct cache_entry *ce, int pos, int ok_to_replace)
+{
+	/*
+	 * We check if the path is a sub-path of a subsequent pathname
+	 * first, since removing those will not change the position
+	 * in the array
+	 */
+	int retval = has_file_name(ce, pos, ok_to_replace);
+	/*
+	 * Then check if the path might have a clashing sub-directory
+	 * before it.
+	 */
+	return retval + has_dir_name(ce, pos, ok_to_replace);
+}
+
+int add_cache_entry(struct cache_entry *ce, int option)
+{
+	int pos;
+	int ok_to_add = option & ADD_CACHE_OK_TO_ADD;
+	int ok_to_replace = option & ADD_CACHE_OK_TO_REPLACE;
+	int skip_df_check = option & ADD_CACHE_SKIP_DFCHECK;
+	pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
 
 	/* existing match? Just replace it */
 	if (pos >= 0) {
+		active_cache_changed = 1;
 		active_cache[pos] = ce;
 		return 0;
 	}
@@ -400,9 +405,9 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 	 * will always replace all non-merged entries..
 	 */
 	if (pos < active_nr && ce_stage(ce) == 0) {
-		while (same_name(active_cache[pos], ce)) {
+		while (ce_same_name(active_cache[pos], ce)) {
 			ok_to_add = 1;
-			if (!remove_entry_at(pos))
+			if (!remove_cache_entry_at(pos))
 				break;
 		}
 	}
@@ -410,10 +415,17 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 	if (!ok_to_add)
 		return -1;
 
+	if (!skip_df_check && check_file_directory_conflict(ce, pos, ok_to_replace)) {
+		if (!ok_to_replace)
+			return -1;
+		pos = cache_name_pos(ce->name, ntohs(ce->ce_flags));
+		pos = -pos-1;
+	}
+
 	/* Make sure the array is big enough .. */
 	if (active_nr == active_alloc) {
 		active_alloc = alloc_nr(active_alloc);
-		active_cache = realloc(active_cache, active_alloc * sizeof(struct cache_entry *));
+		active_cache = xrealloc(active_cache, active_alloc * sizeof(struct cache_entry *));
 	}
 
 	/* Add it in.. */
@@ -421,6 +433,7 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 	if (active_nr > pos)
 		memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
 	active_cache[pos] = ce;
+	active_cache_changed = 1;
 	return 0;
 }
 
@@ -431,14 +444,13 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
 
 	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 		return error("bad signature");
-	if (hdr->hdr_version != htonl(1))
-		return error("bad version");
+	if (hdr->hdr_version != htonl(2))
+		return error("bad index version");
 	SHA1_Init(&c);
-	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
-	SHA1_Update(&c, hdr+1, size - sizeof(*hdr));
+	SHA1_Update(&c, hdr, size - 20);
 	SHA1_Final(sha1, &c);
-	if (memcmp(sha1, hdr->sha1, 20))
-		return error("bad header sha1");
+	if (memcmp(sha1, (void *)hdr + size - 20, 20))
+		return error("bad index file sha1 signature");
 	return 0;
 }
 
@@ -452,28 +464,27 @@ int read_cache(void)
 
 	errno = EBUSY;
 	if (active_cache)
-		return error("more than one cachefile");
+		return active_nr;
+
 	errno = ENOENT;
-	sha1_file_directory = getenv(DB_ENVIRONMENT);
-	if (!sha1_file_directory)
-		sha1_file_directory = DEFAULT_DB_ENVIRONMENT;
-	if (access(sha1_file_directory, X_OK) < 0)
-		return error("no access to SHA1 file directory");
-	fd = open(".git/index", O_RDONLY);
-	if (fd < 0)
-		return (errno == ENOENT) ? 0 : error("open failed");
+	fd = open(get_index_file(), O_RDONLY);
+	if (fd < 0) {
+		if (errno == ENOENT)
+			return 0;
+		die("index file open failed (%s)", strerror(errno));
+	}
 
 	size = 0; // avoid gcc warning
-	map = (void *)-1;
+	map = MAP_FAILED;
 	if (!fstat(fd, &st)) {
 		size = st.st_size;
 		errno = EINVAL;
-		if (size >= sizeof(struct cache_header))
-			map = mmap(NULL, size, PROT_READ, MAP_PRIVATE, fd, 0);
+		if (size >= sizeof(struct cache_header) + 20)
+			map = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 	}
 	close(fd);
-	if (-1 == (int)(long)map)
-		return error("mmap failed");
+	if (map == MAP_FAILED)
+		die("index file mmap failed (%s)", strerror(errno));
 
 	hdr = map;
 	if (verify_hdr(hdr, size) < 0)
@@ -494,36 +505,83 @@ int read_cache(void)
 unmap:
 	munmap(map, size);
 	errno = EINVAL;
-	return error("verify header failed");
+	die("index file corrupt");
+}
+
+#define WRITE_BUFFER_SIZE 8192
+static unsigned char write_buffer[WRITE_BUFFER_SIZE];
+static unsigned long write_buffer_len;
+
+static int ce_write(SHA_CTX *context, int fd, void *data, unsigned int len)
+{
+	while (len) {
+		unsigned int buffered = write_buffer_len;
+		unsigned int partial = WRITE_BUFFER_SIZE - buffered;
+		if (partial > len)
+			partial = len;
+		memcpy(write_buffer + buffered, data, partial);
+		buffered += partial;
+		if (buffered == WRITE_BUFFER_SIZE) {
+			SHA1_Update(context, write_buffer, WRITE_BUFFER_SIZE);
+			if (write(fd, write_buffer, WRITE_BUFFER_SIZE) != WRITE_BUFFER_SIZE)
+				return -1;
+			buffered = 0;
+		}
+		write_buffer_len = buffered;
+		len -= partial;
+		data += partial;
+ 	}
+ 	return 0;
+}
+
+static int ce_flush(SHA_CTX *context, int fd)
+{
+	unsigned int left = write_buffer_len;
+
+	if (left) {
+		write_buffer_len = 0;
+		SHA1_Update(context, write_buffer, left);
+	}
+
+	/* Flush first if not enough space for SHA1 signature */
+	if (left + 20 > WRITE_BUFFER_SIZE) {
+		if (write(fd, write_buffer, left) != left)
+			return -1;
+		left = 0;
+	}
+
+	/* Append the SHA1 signature at the end */
+	SHA1_Final(write_buffer + left, context);
+	left += 20;
+	if (write(fd, write_buffer, left) != left)
+		return -1;
+	return 0;
 }
 
 int write_cache(int newfd, struct cache_entry **cache, int entries)
 {
 	SHA_CTX c;
 	struct cache_header hdr;
-	int i;
+	int i, removed;
+
+	for (i = removed = 0; i < entries; i++)
+		if (!cache[i]->ce_mode)
+			removed++;
 
 	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
-	hdr.hdr_version = htonl(1);
-	hdr.hdr_entries = htonl(entries);
+	hdr.hdr_version = htonl(2);
+	hdr.hdr_entries = htonl(entries - removed);
 
 	SHA1_Init(&c);
-	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));
-	for (i = 0; i < entries; i++) {
-		struct cache_entry *ce = cache[i];
-		int size = ce_size(ce);
-		SHA1_Update(&c, ce, size);
-	}
-	SHA1_Final(hdr.sha1, &c);
-
-	if (write(newfd, &hdr, sizeof(hdr)) != sizeof(hdr))
+	if (ce_write(&c, newfd, &hdr, sizeof(hdr)) < 0)
 		return -1;
 
 	for (i = 0; i < entries; i++) {
 		struct cache_entry *ce = cache[i];
-		int size = ce_size(ce);
-		if (write(newfd, ce, size) != size)
+		if (!ce->ce_mode)
+			continue;
+		if (ce_write(&c, newfd, ce, ce_size(ce)) < 0)
 			return -1;
 	}
-	return 0;
+	return ce_flush(&c, newfd);
 }