Make "write_cache()" and friends available as generic routines.

This is needed for the change to make "read-tree" just read into the
cache (and then you do a "checkout-cache" to update your current dir
contents).

cache.h

@@ -73,7 +73,10 @@ unsigned int active_nr, active_alloc;
 
 /* Initialize and use the cache information */
 extern int read_cache(void);
+extern int write_cache(int newfd, struct cache_entry **cache, int entries);
 extern int cache_name_pos(const char *name, int namelen);
+extern int add_cache_entry(struct cache_entry *ce);
+extern int remove_file_from_cache(char *path);
 extern int cache_match_stat(struct cache_entry *ce, struct stat *st);
 
 #define MTIME_CHANGED	0x0001
@@ -97,8 +100,8 @@ extern int write_sha1_file(char *buf, unsigned len);
 extern int check_sha1_signature(unsigned char *sha1, void *buf, unsigned long size);
 
 /* Convert to/from hex/sha1 representation */
-extern int get_sha1_hex(char *hex, unsigned char *sha1);
-extern char *sha1_to_hex(unsigned char *sha1);	/* static buffer! */
+extern int get_sha1_hex(const char *hex, unsigned char *sha1);
+extern char *sha1_to_hex(const unsigned char *sha1);	/* static buffer result! */
 
 /* General helper functions */
 extern void usage(const char *err);

read-cache.c

@@ -26,7 +26,7 @@ static unsigned hexval(char c)
 	return ~0;
 }
 
-int get_sha1_hex(char *hex, unsigned char *sha1)
+int get_sha1_hex(const char *hex, unsigned char *sha1)
 {
 	int i;
 	for (i = 0; i < 20; i++) {
@@ -39,7 +39,7 @@ int get_sha1_hex(char *hex, unsigned char *sha1)
 	return 0;
 }
 
-char * sha1_to_hex(unsigned char *sha1)
+char * sha1_to_hex(const unsigned char *sha1)
 {
 	static char buffer[50];
 	static const char hex[] = "0123456789abcdef";
@@ -281,6 +281,44 @@ int cache_name_pos(const char *name, int namelen)
 	return first;
 }
 
+int remove_file_from_cache(char *path)
+{
+	int pos = cache_name_pos(path, strlen(path));
+	if (pos < 0) {
+		pos = -pos-1;
+		active_nr--;
+		if (pos < active_nr)
+			memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *));
+	}
+	return 0;
+}
+
+int add_cache_entry(struct cache_entry *ce)
+{
+	int pos;
+
+	pos = cache_name_pos(ce->name, ce->namelen);
+
+	/* existing match? Just replace it */
+	if (pos < 0) {
+		active_cache[-pos-1] = ce;
+		return 0;
+	}
+
+	/* 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 *));
+	}
+
+	/* Add it in.. */
+	active_nr++;
+	if (active_nr > pos)
+		memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
+	active_cache[pos] = ce;
+	return 0;
+}
+
 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 {
 	SHA_CTX c;
@@ -354,3 +392,33 @@ unmap:
 	return error("verify header failed");
 }
 
+int write_cache(int newfd, struct cache_entry **cache, int entries)
+{
+	SHA_CTX c;
+	struct cache_header hdr;
+	int i;
+
+	hdr.signature = CACHE_SIGNATURE;
+	hdr.version = 1;
+	hdr.entries = entries;
+
+	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))
+		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)
+			return -1;
+	}
+	return 0;
+}

update-cache.c

@@ -5,44 +5,6 @@
  */
 #include "cache.h"
 
-static int remove_file_from_cache(char *path)
-{
-	int pos = cache_name_pos(path, strlen(path));
-	if (pos < 0) {
-		pos = -pos-1;
-		active_nr--;
-		if (pos < active_nr)
-			memmove(active_cache + pos, active_cache + pos + 1, (active_nr - pos - 1) * sizeof(struct cache_entry *));
-	}
-	return 0;
-}
-
-static int add_cache_entry(struct cache_entry *ce)
-{
-	int pos;
-
-	pos = cache_name_pos(ce->name, ce->namelen);
-
-	/* existing match? Just replace it */
-	if (pos < 0) {
-		active_cache[-pos-1] = ce;
-		return 0;
-	}
-
-	/* 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 *));
-	}
-
-	/* Add it in.. */
-	active_nr++;
-	if (active_nr > pos)
-		memmove(active_cache + pos + 1, active_cache + pos, (active_nr - pos - 1) * sizeof(ce));
-	active_cache[pos] = ce;
-	return 0;
-}
-
 static int index_fd(const char *path, int namelen, struct cache_entry *ce, int fd, struct stat *st)
 {
 	z_stream stream;
@@ -126,37 +88,6 @@ static int add_file_to_cache(char *path)
 	return add_cache_entry(ce);
 }
 
-static int write_cache(int newfd, struct cache_entry **cache, int entries)
-{
-	SHA_CTX c;
-	struct cache_header hdr;
-	int i;
-
-	hdr.signature = CACHE_SIGNATURE;
-	hdr.version = 1;
-	hdr.entries = entries;
-
-	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))
-		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)
-			return -1;
-	}
-	return 0;
-}		
-
 /*
  * We fundamentally don't like some paths: we don't want
  * dot or dot-dot anywhere, and in fact, we don't even want