Convert the index file reading/writing to use network byte order.

This allows using a git tree over NFS with different byte order, and
makes it possible to just copy a fully populated repository and have
the end result immediately usable (needing just a refresh to update
the stat information).

cache.h

@@ -10,6 +10,7 @@
 #include <string.h>
 #include <errno.h>
 #include <sys/mman.h>
+#include <netinet/in.h>
 
 #include <openssl/sha.h>
 #include <zlib.h>
@@ -24,9 +25,9 @@
 
 #define CACHE_SIGNATURE 0x44495243	/* "DIRC" */
 struct cache_header {
-	unsigned int signature;
-	unsigned int version;
-	unsigned int entries;
+	unsigned int hdr_signature;
+	unsigned int hdr_version;
+	unsigned int hdr_entries;
 	unsigned char sha1[20];
 };
 
@@ -44,18 +45,21 @@ struct cache_time {
  * dev/ino/uid/gid/size are also just tracked to the low 32 bits
  * Again - this is just a (very strong in practice) heuristic that
  * the inode hasn't changed.
+ *
+ * We save the fields in big-endian order to allow using the
+ * index file over NFS transparently.
  */
 struct cache_entry {
-	struct cache_time ctime;
-	struct cache_time mtime;
-	unsigned int st_dev;
-	unsigned int st_ino;
-	unsigned int st_mode;
-	unsigned int st_uid;
-	unsigned int st_gid;
-	unsigned int st_size;
+	struct cache_time ce_ctime;
+	struct cache_time ce_mtime;
+	unsigned int ce_dev;
+	unsigned int ce_ino;
+	unsigned int ce_mode;
+	unsigned int ce_uid;
+	unsigned int ce_gid;
+	unsigned int ce_size;
 	unsigned char sha1[20];
-	unsigned short namelen;
+	unsigned short ce_namelen;
 	char name[0];
 };
 
@@ -67,7 +71,8 @@ unsigned int active_nr, active_alloc;
 #define DEFAULT_DB_ENVIRONMENT ".git/objects"
 
 #define cache_entry_size(len) ((offsetof(struct cache_entry,name) + (len) + 8) & ~7)
-#define ce_size(ce) cache_entry_size((ce)->namelen)
+#define ce_namelen(ce) ntohs((ce)->ce_namelen)
+#define ce_size(ce) cache_entry_size(ce_namelen(ce))
 
 #define alloc_nr(x) (((x)+16)*3/2)
 

checkout-cache.c

@@ -77,7 +77,7 @@ static int write_entry(struct cache_entry *ce)
 		return error("checkout-cache: unable to read sha1 file of %s (%s)",
 			ce->name, sha1_to_hex(ce->sha1));
 	}
-	fd = create_file(ce->name, ce->st_mode);
+	fd = create_file(ce->name, ntohl(ce->ce_mode));
 	if (fd < 0) {
 		free(new);
 		return error("checkout-cache: unable to create %s (%s)",

read-cache.c

@@ -283,30 +283,32 @@ int cache_match_stat(struct cache_entry *ce, struct stat *st)
 {
 	unsigned int changed = 0;
 
-	/* 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->mtime.sec  != (unsigned int)st->st_mtim.tv_sec
-#ifdef NSEC
-	    || ce->mtime.nsec != (unsigned int)st->st_mtim.tv_nsec
-#endif
-	    )
+	if (ce->ce_mtime.sec != htonl(st->st_mtime))
 		changed |= MTIME_CHANGED;
-	if (ce->ctime.sec  != (unsigned int)st->st_ctim.tv_sec
-#ifdef NSEC
-	    || ce->ctime.nsec != (unsigned int)st->st_ctim.tv_nsec
-#endif
-	    )
+	if (ce->ce_ctime.sec != htonl(st->st_ctime))
 		changed |= CTIME_CHANGED;
-	if (ce->st_uid != (unsigned int)st->st_uid ||
-	    ce->st_gid != (unsigned int)st->st_gid)
+
+#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;
-	if (ce->st_mode != (unsigned int)st->st_mode)
+	if (ce->ce_mode != htonl(st->st_mode))
 		changed |= MODE_CHANGED;
-	if (ce->st_dev != (unsigned int)st->st_dev ||
-	    ce->st_ino != (unsigned int)st->st_ino)
+	if (ce->ce_dev != htonl(st->st_dev) ||
+	    ce->ce_ino != htonl(st->st_ino))
 		changed |= INODE_CHANGED;
-	if (ce->st_size != (unsigned int)st->st_size)
+	if (ce->ce_size != htonl(st->st_size))
 		changed |= DATA_CHANGED;
 	return changed;
 }
@@ -335,7 +337,7 @@ 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, ce->namelen);
+		int cmp = cache_name_compare(name, namelen, ce->name, ce_namelen(ce));
 		if (!cmp)
 			return next;
 		if (cmp < 0) {
@@ -362,7 +364,7 @@ int add_cache_entry(struct cache_entry *ce, int ok_to_add)
 {
 	int pos;
 
-	pos = cache_name_pos(ce->name, ce->namelen);
+	pos = cache_name_pos(ce->name, ce_namelen(ce));
 
 	/* existing match? Just replace it */
 	if (pos >= 0) {
@@ -393,9 +395,9 @@ static int verify_hdr(struct cache_header *hdr, unsigned long size)
 	SHA_CTX c;
 	unsigned char sha1[20];
 
-	if (hdr->signature != CACHE_SIGNATURE)
+	if (hdr->hdr_signature != htonl(CACHE_SIGNATURE))
 		return error("bad signature");
-	if (hdr->version != 1)
+	if (hdr->hdr_version != htonl(1))
 		return error("bad version");
 	SHA1_Init(&c);
 	SHA1_Update(&c, hdr, offsetof(struct cache_header, sha1));
@@ -443,12 +445,12 @@ int read_cache(void)
 	if (verify_hdr(hdr, size) < 0)
 		goto unmap;
 
-	active_nr = hdr->entries;
+	active_nr = ntohl(hdr->hdr_entries);
 	active_alloc = alloc_nr(active_nr);
 	active_cache = calloc(active_alloc, sizeof(struct cache_entry *));
 
 	offset = sizeof(*hdr);
-	for (i = 0; i < hdr->entries; i++) {
+	for (i = 0; i < active_nr; i++) {
 		struct cache_entry *ce = map + offset;
 		offset = offset + ce_size(ce);
 		active_cache[i] = ce;
@@ -467,9 +469,9 @@ int write_cache(int newfd, struct cache_entry **cache, int entries)
 	struct cache_header hdr;
 	int i;
 
-	hdr.signature = CACHE_SIGNATURE;
-	hdr.version = 1;
-	hdr.entries = entries;
+	hdr.hdr_signature = htonl(CACHE_SIGNATURE);
+	hdr.hdr_version = htonl(1);
+	hdr.hdr_entries = htonl(entries);
 
 	SHA1_Init(&c);
 	SHA1_Update(&c, &hdr, offsetof(struct cache_header, sha1));

read-tree.c

@@ -13,8 +13,8 @@ static int read_one_entry(unsigned char *sha1, const char *base, int baselen, co
 
 	memset(ce, 0, size);
 
-	ce->st_mode = mode;
-	ce->namelen = baselen + len;
+	ce->ce_mode = htonl(mode);
+	ce->ce_namelen = htons(baselen + len);
 	memcpy(ce->name, base, baselen);
 	memcpy(ce->name + baselen, pathname, len+1);
 	memcpy(ce->sha1, sha1, 20);

show-diff.c

@@ -90,7 +90,7 @@ int main(int argc, char **argv)
 		changed = cache_match_stat(ce, &st);
 		if (!changed)
 			continue;
-		printf("%.*s:  ", ce->namelen, ce->name);
+		printf("%.*s:  ", ce_namelen(ce), ce->name);
 		for (n = 0; n < 20; n++)
 			printf("%02x", ce->sha1[n]);
 		printf("\n");

update-cache.c

@@ -68,18 +68,17 @@ static int index_fd(const char *path, int namelen, struct cache_entry *ce, int f
  */
 static void fill_stat_cache_info(struct cache_entry *ce, struct stat *st)
 {
-	ce->ctime.sec = st->st_ctime;
+	ce->ce_ctime.sec = htonl(st->st_ctime);
+	ce->ce_mtime.sec = htonl(st->st_mtime);
 #ifdef NSEC
-	ce->ctime.nsec = st->st_ctim.tv_nsec;
+	ce->ce_ctime.nsec = htonl(st->st_ctim.tv_nsec);
+	ce->ce_mtime.nsec = htonl(st->st_mtim.tv_nsec);
 #endif
-	ce->mtime.sec = st->st_mtime;
-#ifdef NSEC
-	ce->mtime.nsec = st->st_mtim.tv_nsec;
-#endif
-	ce->st_dev = st->st_dev;
-	ce->st_ino = st->st_ino;
-	ce->st_uid = st->st_uid;
-	ce->st_gid = st->st_gid;
+	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 int add_file_to_cache(char *path)
@@ -107,9 +106,8 @@ static int add_file_to_cache(char *path)
 	memset(ce, 0, size);
 	memcpy(ce->name, path, namelen);
 	fill_stat_cache_info(ce, &st);
-	ce->st_mode = st.st_mode;
-	ce->st_size = st.st_size;
-	ce->namelen = namelen;
+	ce->ce_mode = htonl(st.st_mode);
+	ce->ce_namelen = htons(namelen);
 
 	if (index_fd(path, namelen, ce, fd, &st) < 0)
 		return -1;
@@ -190,7 +188,6 @@ static struct cache_entry *refresh_entry(struct cache_entry *ce)
 	updated = malloc(size);
 	memcpy(updated, ce, size);
 	fill_stat_cache_info(updated, &st);
-	updated->st_size = st.st_size;
 	return updated;
 }
 

write-tree.c

@@ -45,7 +45,7 @@ static int write_tree(struct cache_entry **cachep, int maxentries, const char *b
 	do {
 		struct cache_entry *ce = cachep[nr];
 		const char *pathname = ce->name, *filename, *dirname;
-		int pathlen = ce->namelen, entrylen;
+		int pathlen = ce_namelen(ce), entrylen;
 		unsigned char *sha1;
 		unsigned int mode;
 
@@ -54,7 +54,7 @@ static int write_tree(struct cache_entry **cachep, int maxentries, const char *b
 			break;
 
 		sha1 = ce->sha1;
-		mode = ce->st_mode;
+		mode = ntohl(ce->ce_mode);
 
 		/* Do we have _further_ subdirectories? */
 		filename = pathname + baselen;