Merge branch 'jc/maint-simpler-common-prefix'

* jc/maint-simpler-common-prefix:
  common_prefix: simplify and fix scanning for prefixes

diff --combined dir.c
index 5e36f8e616d63f8a9c5950897e0f06235d8e9acf,7f912c76f268e2f27857a67d565e77be0e43660d..151ea670d961d39394990f122469557b6f217de3
--- 1/dir.c
--- 2/dir.c
+++ b/dir.c
@@@ -31,22 -31,22 +31,22 @@@ static int common_prefix(const char **p
        if (!slash)
                return 0;
  
+       /*
+        * The first 'prefix' characters of 'path' are common leading
+        * path components among the pathspecs we have seen so far,
+        * including the trailing slash.
+        */
        prefix = slash - path + 1;
        while ((next = *++pathspec) != NULL) {
-               int len = strlen(next);
-               if (len >= prefix && !memcmp(path, next, prefix))
+               int len, last_matching_slash = -1;
+               for (len = 0; len < prefix && next[len] == path[len]; len++)
+                       if (next[len] == '/')
+                               last_matching_slash = len;
+               if (len == prefix)
                        continue;
-               len = prefix - 1;
-               for (;;) {
-                       if (!len)
-                               return 0;
-                       if (next[--len] != '/')
-                               continue;
-                       if (memcmp(path, next, len+1))
-                               continue;
-                       prefix = len + 1;
-                       break;
-               }
+               if (last_matching_slash < 0)
+                       return 0;
+               prefix = last_matching_slash + 1;
        }
        return prefix;
  }
@@@ -465,7 -465,7 +465,7 @@@ static struct dir_entry *dir_add_ignore
  enum exist_status {
        index_nonexistent = 0,
        index_directory,
 -      index_gitdir,
 +      index_gitdir
  };
  
  /*
@@@ -533,7 -533,7 +533,7 @@@ static enum exist_status directory_exis
  enum directory_treatment {
        show_directory,
        ignore_directory,
 -      recurse_into_directory,
 +      recurse_into_directory
  };
  
  static enum directory_treatment treat_directory(struct dir_struct *dir,
@@@ -684,7 -684,7 +684,7 @@@ static int get_dtype(struct dirent *de
  enum path_treatment {
        path_ignored,
        path_handled,
 -      path_recurse,
 +      path_recurse
  };
  
  static enum path_treatment treat_one_path(struct dir_struct *dir,