archive: refactor file extension format-guessing

diff --git a/archive.c b/archive.c
index 7d0ca323c277d28da7b82d913facb3457ec71766..41065a8e2c8362b95c039b7493f842f791f6858b 100644 (file)
--- a/archive.c
+++ b/archive.c
@@ -419,13 +419,26 @@ int write_archive(int argc, const char **argv, const char *prefix,
        return ar->write_archive(ar, &args);
 }
 
+static int match_extension(const char *filename, const char *ext)
+{
+       int prefixlen = strlen(filename) - strlen(ext);
+
+       /*
+        * We need 1 character for the '.', and 1 character to ensure that the
+        * prefix is non-empty (k.e., we don't match .tar.gz with no actual
+        * filename).
+        */
+       if (prefixlen < 2 || filename[prefixlen-1] != '.')
+               return 0;
+       return !strcmp(filename + prefixlen, ext);
+}
+
 const char *archive_format_from_filename(const char *filename)
 {
-       const char *ext = strrchr(filename, '.');
-       if (!ext)
-               return NULL;
-       ext++;
-       if (!strcasecmp(ext, "zip"))
-               return "zip";
+       int i;
+
+       for (i = 0; i < nr_archivers; i++)
+               if (match_extension(filename, archivers[i]->name))
+                       return archivers[i]->name;
        return NULL;
 }