lib: Optimize str_tabunescape()

diff --git a/src/lib/strescape.c b/src/lib/strescape.c
index 99482a570055ed99b03d632afdd3b20e69955b13..012689b8b705bf09aeb070a2e5eb740d6d80f08a 100644 (file)
--- a/src/lib/strescape.c
+++ b/src/lib/strescape.c
@@ -229,46 +229,54 @@ void str_append_tabunescaped(string_t *dest, const void *src, size_t src_size)
 char *str_tabunescape(char *str)
 {
        /* @UNSAFE */
-       char *dest, *start = str;
+       char *dest, *src, *p;
 
-       str = strchr(str, '\001');
-       if (str == NULL) {
+       src = strchr(str, '\001');
+       if (src == NULL) {
                /* no unescaping needed */
-               return start;
+               return str;
        }
 
-       for (dest = str; *str != '\0'; str++) {
-               if (*str != '\001')
-                       *dest++ = *str;
-               else {
-                       str++;
-                       if (*str == '\0')
-                               break;
-                       switch (*str) {
-                       case '0':
-                               *dest++ = '\000';
-                               break;
-                       case '1':
-                               *dest++ = '\001';
-                               break;
-                       case 't':
-                               *dest++ = '\t';
-                               break;
-                       case 'r':
-                               *dest++ = '\r';
-                               break;
-                       case 'n':
-                               *dest++ = '\n';
-                               break;
-                       default:
-                               *dest++ = *str;
-                               break;
-                       }
+       dest = src;
+       for (;;) {
+               switch (src[1]) {
+               case '\0':
+                       /* truncated input */
+                       *dest = '\0';
+                       return str;
+               case '0':
+                       *dest++ = '\000';
+                       break;
+               case '1':
+                       *dest++ = '\001';
+                       break;
+               case 't':
+                       *dest++ = '\t';
+                       break;
+               case 'r':
+                       *dest++ = '\r';
+                       break;
+               case 'n':
+                       *dest++ = '\n';
+                       break;
+               default:
+                       *dest++ = src[1];
+                       break;
                }
-       }
+               src += 2;
 
-       *dest = '\0';
-       return start;
+               p = strchr(src, '\001');
+               if (p == NULL) {
+                       memmove(dest, src, strlen(src)+1);
+                       break;
+               }
+
+               size_t copy_len = p - src;
+               memmove(dest, src, copy_len);
+               dest += copy_len;
+               src = p;
+       }
+       return str;
 }
 
 const char *t_str_tabunescape(const char *str)