Make "cache_name_pos()" available to others.

It finds the cache entry position for a given name, and is
generally useful. Sure, everybody can just scan the active
cache array, but since it's sorted, you actually want to
search it with a binary search, so let's not duplicate that
logic all over the place.

cache.h

@@ -73,6 +73,7 @@ unsigned int active_nr, active_alloc;
 
 /* Initialize the cache information */
 extern int read_cache(void);
+extern int cache_name_pos(const char *name, int namelen);
 
 /* Return a statically allocated filename matching the sha1 signature */
 extern char *sha1_file_name(unsigned char *sha1);

read-cache.c

@@ -222,6 +222,42 @@ static int error(const char * string)
 	return -1;
 }
 
+static int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
+{
+	int len = len1 < len2 ? len1 : len2;
+	int cmp;
+
+	cmp = memcmp(name1, name2, len);
+	if (cmp)
+		return cmp;
+	if (len1 < len2)
+		return -1;
+	if (len1 > len2)
+		return 1;
+	return 0;
+}
+
+int cache_name_pos(const char *name, int namelen)
+{
+	int first, last;
+
+	first = 0;
+	last = active_nr;
+	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);
+		if (!cmp)
+			return -next-1;
+		if (cmp < 0) {
+			last = next;
+			continue;
+		}
+		first = next+1;
+	}
+	return first;
+}
+
 static int verify_hdr(struct cache_header *hdr, unsigned long size)
 {
 	SHA_CTX c;

update-cache.c

@@ -5,42 +5,6 @@
  */
 #include "cache.h"
 
-static int cache_name_compare(const char *name1, int len1, const char *name2, int len2)
-{
-	int len = len1 < len2 ? len1 : len2;
-	int cmp;
-
-	cmp = memcmp(name1, name2, len);
-	if (cmp)
-		return cmp;
-	if (len1 < len2)
-		return -1;
-	if (len1 > len2)
-		return 1;
-	return 0;
-}
-
-static int cache_name_pos(const char *name, int namelen)
-{
-	int first, last;
-
-	first = 0;
-	last = active_nr;
-	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);
-		if (!cmp)
-			return -next-1;
-		if (cmp < 0) {
-			last = next;
-			continue;
-		}
-		first = next+1;
-	}
-	return first;
-}
-
 static int remove_file_from_cache(char *path)
 {
 	int pos = cache_name_pos(path, strlen(path));