cache.h: hide on-disk index details

The on-disk format of the index file is a detail whose implementation is
neatly encapsulated in read-cache.c; there is no need to expose it to the
general public that include the cache.h header file.

Also add a prominent mark to read-cache.c to delineate the parts that deal
with the index file I/O routines from the remainder of the file.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -115,48 +115,6 @@ struct cache_time {
 	unsigned int nsec;
 };
 
-/*
- * 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 ondisk_cache_entry {
-	struct cache_time ctime;
-	struct cache_time mtime;
-	unsigned int dev;
-	unsigned int ino;
-	unsigned int mode;
-	unsigned int uid;
-	unsigned int gid;
-	unsigned int size;
-	unsigned char sha1[20];
-	unsigned short flags;
-	char name[FLEX_ARRAY]; /* more */
-};
-
-/*
- * This struct is used when CE_EXTENDED bit is 1
- * The struct must match ondisk_cache_entry exactly from
- * ctime till flags
- */
-struct ondisk_cache_entry_extended {
-	struct cache_time ctime;
-	struct cache_time mtime;
-	unsigned int dev;
-	unsigned int ino;
-	unsigned int mode;
-	unsigned int uid;
-	unsigned int gid;
-	unsigned int size;
-	unsigned char sha1[20];
-	unsigned short flags;
-	unsigned short flags2;
-	char name[FLEX_ARRAY]; /* more */
-};
-
 struct cache_entry {
 	struct cache_time ce_ctime;
 	struct cache_time ce_mtime;
@@ -253,9 +211,6 @@ static inline size_t ce_namelen(const struct cache_entry *ce)
 }
 
 #define ce_size(ce) cache_entry_size(ce_namelen(ce))
-#define ondisk_ce_size(ce) (((ce)->ce_flags & CE_EXTENDED) ? \
-			    ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
-			    ondisk_cache_entry_size(ce_namelen(ce)))
 #define ce_stage(ce) ((CE_STAGEMASK & (ce)->ce_flags) >> CE_STAGESHIFT)
 #define ce_uptodate(ce) ((ce)->ce_flags & CE_UPTODATE)
 #define ce_skip_worktree(ce) ((ce)->ce_flags & CE_SKIP_WORKTREE)
@@ -306,10 +261,7 @@ static inline unsigned int canon_mode(unsigned int mode)
 	return S_IFGITLINK;
 }
 
-#define flexible_size(STRUCT,len) ((offsetof(struct STRUCT,name) + (len) + 8) & ~7)
 #define cache_entry_size(len) (offsetof(struct cache_entry,name) + (len) + 1)
-#define ondisk_cache_entry_size(len) flexible_size(ondisk_cache_entry,len)
-#define ondisk_cache_entry_extended_size(len) flexible_size(ondisk_cache_entry_extended,len)
 
 struct index_state {
 	struct cache_entry **cache;

read-cache.c

@@ -1189,6 +1189,60 @@ static struct cache_entry *refresh_cache_entry(struct cache_entry *ce, int reall
 	return refresh_cache_ent(&the_index, ce, really, NULL, NULL);
 }
 
+
+/*****************************************************************
+ * Index File I/O
+ *****************************************************************/
+
+/*
+ * 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 ondisk_cache_entry {
+	struct cache_time ctime;
+	struct cache_time mtime;
+	unsigned int dev;
+	unsigned int ino;
+	unsigned int mode;
+	unsigned int uid;
+	unsigned int gid;
+	unsigned int size;
+	unsigned char sha1[20];
+	unsigned short flags;
+	char name[FLEX_ARRAY]; /* more */
+};
+
+/*
+ * This struct is used when CE_EXTENDED bit is 1
+ * The struct must match ondisk_cache_entry exactly from
+ * ctime till flags
+ */
+struct ondisk_cache_entry_extended {
+	struct cache_time ctime;
+	struct cache_time mtime;
+	unsigned int dev;
+	unsigned int ino;
+	unsigned int mode;
+	unsigned int uid;
+	unsigned int gid;
+	unsigned int size;
+	unsigned char sha1[20];
+	unsigned short flags;
+	unsigned short flags2;
+	char name[FLEX_ARRAY]; /* more */
+};
+
+#define align_flex_name(STRUCT,len) ((offsetof(struct STRUCT,name) + (len) + 8) & ~7)
+#define ondisk_cache_entry_size(len) align_flex_name(ondisk_cache_entry,len)
+#define ondisk_cache_entry_extended_size(len) align_flex_name(ondisk_cache_entry_extended,len)
+#define ondisk_ce_size(ce) (((ce)->ce_flags & CE_EXTENDED) ? \
+			    ondisk_cache_entry_extended_size(ce_namelen(ce)) : \
+			    ondisk_cache_entry_size(ce_namelen(ce)))
+
 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 {
 	git_SHA_CTX c;