fnmatch: optimize processing of consecutive *s and ?s pattern characters

Reported-By: Daniel Stenberg
Fixes #2291
Closes #2293

1 files changed, 18 insertions, 13 deletions

diff --git a/lib/curl_fnmatch.c b/lib/curl_fnmatch.c
index f303881d3..0179a4f71 100644
--- a/lib/curl_fnmatch.c
+++ b/lib/curl_fnmatch.c
@@ -256,7 +256,6 @@ static int loop(const unsigned char *pattern, const unsigned char *string,
   unsigned char *p = (unsigned char *)pattern;
   unsigned char *s = (unsigned char *)string;
   unsigned char charset[CURLFNM_CHSET_SIZE] = { 0 };
-  int rc = 0;
 
   for(;;) {
     unsigned char *pp;
@@ -265,18 +264,24 @@ static int loop(const unsigned char *pattern, const unsigned char *string,
     case '*':
       if(!maxstars)
         return CURL_FNMATCH_NOMATCH;
-      while(p[1] == '*') /* eliminate multiple stars */
-        p++;
-      if(*s == '\0' && p[1] == '\0')
-        return CURL_FNMATCH_MATCH;
-      rc = loop(p + 1, s, maxstars - 1); /* *.txt matches .txt <=>
-                                            .txt matches .txt */
-      if(rc == CURL_FNMATCH_MATCH)
-        return CURL_FNMATCH_MATCH;
-      if(!*s)
-        return CURL_FNMATCH_NOMATCH;
-      s++; /* let the star eat up one character */
-      break;
+      /* Regroup consecutive stars and question marks. This can be done because
+         '*?*?*' can be expressed as '??*'. */
+      for(;;) {
+        if(*++p == '\0')
+          return CURL_FNMATCH_MATCH;
+        if(*p == '?') {
+          if(!*s++)
+            return CURL_FNMATCH_NOMATCH;
+        }
+        else if(*p != '*')
+          break;
+      }
+      /* Skip string characters until we find a match with pattern suffix. */
+      for(maxstars--; *s; s++) {
+        if(loop(p, s, maxstars) == CURL_FNMATCH_MATCH)
+          return CURL_FNMATCH_MATCH;
+      }
+      return CURL_FNMATCH_NOMATCH;
     case '?':
       if(!*s)
         return CURL_FNMATCH_NOMATCH;