csync io: Fix UNC path conversion on Win #3748

Paths that were already in UNC form don't need to be prefixed.

csync/src/std/c_path.c

@@ -393,8 +393,8 @@ int c_parse_uri(const char *uri,
 
 /*
  * This function takes a path and converts it to a UNC representation of the
- * string. That means that it prepends a \\?\ and convertes all slashes to
- * backslashes.
+ * string. That means that it prepends a \\?\ (unless already UNC) and converts
+ * all slashes to backslashes.
  *
  * Note the following:
  *  - The string must be absolute.
@@ -408,27 +408,28 @@ int c_parse_uri(const char *uri,
  {
      int len = 0;
      char *longStr = NULL;
-     int i = 4; // index where to start changing "/"=>"\"
 
      len = strlen(str);
      longStr = c_malloc(len+5);
      *longStr = '\0';
 
      // prepend \\?\ and convert '/' => '\' to support long names
-     if( str[0] == '/' ) {
-         strncpy( longStr, "\\\\?", 4);
-         i=3;
+     if( str[0] == '/' || str[0] == '\\' ) {
+         // Don't prepend if already UNC
+         if( !(len > 1 && (str[1] == '/' || str[1] == '\\')) ) {
+            strcpy( longStr, "\\\\?");
+         }
      } else {
-         strncpy( longStr, "\\\\?\\", 5); // prepend string by this four magic chars.
+         strcpy( longStr, "\\\\?\\"); // prepend string by this four magic chars.
      }
      strncat( longStr, str, len );
 
      /* replace all occurences of / with the windows native \ */
-     while(longStr[i] != '\0') {
-         if(longStr[i] == '/') {
-             longStr[i] = '\\';
+     char *c = longStr;
+     for (; *c; ++c) {
+         if(*c == '/') {
+             *c = '\\';
          }
-         i++;
      }
      return longStr;
  }

csync/tests/encoding_tests/check_encoding.c

@@ -146,13 +146,47 @@ static void check_to_multibyte(void **state)
 
 static void check_long_win_path(void **state)
 {
-    const char *path = "C://DATA/FILES/MUSIC/MY_MUSIC.mp3"; // check a short path
-    const char *exp_path = "\\\\?\\C:\\\\DATA\\FILES\\MUSIC\\MY_MUSIC.mp3";
-    const char *new_short = c_path_to_UNC(path);
-
     (void) state; /* unused */
 
-    assert_string_equal(new_short, exp_path);
+    {
+        const char *path = "C://DATA/FILES/MUSIC/MY_MUSIC.mp3"; // check a short path
+        const char *exp_path = "\\\\?\\C:\\\\DATA\\FILES\\MUSIC\\MY_MUSIC.mp3";
+        const char *new_short = c_path_to_UNC(path);
+        assert_string_equal(new_short, exp_path);
+        SAFE_FREE(new_short);
+    }
+
+    {
+        const char *path = "\\\\foo\\bar/MY_MUSIC.mp3";
+        const char *exp_path = "\\\\foo\\bar\\MY_MUSIC.mp3";
+        const char *new_short = c_path_to_UNC(path);
+        assert_string_equal(new_short, exp_path);
+        SAFE_FREE(new_short);
+    }
+
+    {
+        const char *path = "//foo\\bar/MY_MUSIC.mp3";
+        const char *exp_path = "\\\\foo\\bar\\MY_MUSIC.mp3";
+        const char *new_short = c_path_to_UNC(path);
+        assert_string_equal(new_short, exp_path);
+        SAFE_FREE(new_short);
+    }
+
+    {
+        const char *path = "\\foo\\bar";
+        const char *exp_path = "\\\\?\\foo\\bar";
+        const char *new_short = c_path_to_UNC(path);
+        assert_string_equal(new_short, exp_path);
+        SAFE_FREE(new_short);
+    }
+
+    {
+        const char *path = "/foo/bar";
+        const char *exp_path = "\\\\?\\foo\\bar";
+        const char *new_short = c_path_to_UNC(path);
+        assert_string_equal(new_short, exp_path);
+        SAFE_FREE(new_short);
+    }
 
     const char *longPath = "D://alonglonglonglong/blonglonglonglong/clonglonglonglong/dlonglonglonglong/"
             "elonglonglonglong/flonglonglonglong/glonglonglonglong/hlonglonglonglong/ilonglonglonglong/"
@@ -170,7 +204,7 @@ static void check_long_win_path(void **state)
 
     // printf( "YYYYYYYYYYYY %ld\n", strlen(new_long));
     assert_int_equal( strlen(new_long), 286);
-
+    SAFE_FREE(new_long);
 }
 
 int torture_run_tests(void)