Add "check_sha1_signature()" helper function

diff --git a/read-cache.c b/read-cache.c
index 4d750506e97af68013aa25e192c569da557701fd..2ede67dbe17530e5b6dd4893430327b9121751fb 100644 (file)
--- a/read-cache.c
+++ b/read-cache.c
@@ -84,6 +84,17 @@ char *sha1_file_name(unsigned char *sha1)
        return base;
 }
 
+int check_sha1_signature(unsigned char *sha1, void *map, unsigned long size)
+{
+       unsigned char real_sha1[20];
+       SHA_CTX c;
+
+       SHA1_Init(&c);
+       SHA1_Update(&c, map, size);
+       SHA1_Final(real_sha1, &c);
+       return memcmp(sha1, real_sha1, 20) ? -1 : 0;
+}
+
 void *map_sha1_file(unsigned char *sha1, unsigned long *size)
 {
        char *filename = sha1_file_name(sha1);