dynbuf: introduce internal generic dynamic buffer functions

A common set of functions instead of many separate implementations for
creating buffers that can grow when appending data to them. Existing
functionality has been ported over.

In my early basic testing, the total number of allocations seem at
roughly the same amount as before, possibly a few less.

See docs/DYNBUF.md for a description of the API.

Closes #5300

1 files changed, 16 insertions, 31 deletions

diff --git a/lib/escape.c b/lib/escape.c
index 7121db31c..97352a91d 100644
--- a/lib/escape.c
+++ b/lib/escape.c
@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -79,57 +79,42 @@ char *curl_unescape(const char *string, int length)
 char *curl_easy_escape(struct Curl_easy *data, const char *string,
                        int inlength)
 {
-  size_t alloc;
-  char *ns;
-  char *testing_ptr = NULL;
-  size_t newlen;
-  size_t strindex = 0;
   size_t length;
   CURLcode result;
+  struct dynbuf d;
 
   if(inlength < 0)
     return NULL;
 
-  alloc = (inlength?(size_t)inlength:strlen(string)) + 1;
-  newlen = alloc;
-
-  ns = malloc(alloc);
-  if(!ns)
-    return NULL;
+  Curl_dyn_init(&d, CURL_MAX_INPUT_LENGTH);
 
-  length = alloc-1;
+  length = (inlength?(size_t)inlength:strlen(string));
   while(length--) {
     unsigned char in = *string; /* we need to treat the characters unsigned */
 
-    if(Curl_isunreserved(in))
-      /* just copy this */
-      ns[strindex++] = in;
+    if(Curl_isunreserved(in)) {
+      /* append this */
+      if(Curl_dyn_addn(&d, &in, 1))
+        return NULL;
+    }
     else {
       /* encode it */
-      newlen += 2; /* the size grows with two, since this'll become a %XX */
-      if(newlen > alloc) {
-        alloc *= 2;
-        testing_ptr = Curl_saferealloc(ns, alloc);
-        if(!testing_ptr)
-          return NULL;
-        ns = testing_ptr;
-      }
-
+      char encoded[4];
       result = Curl_convert_to_network(data, (char *)&in, 1);
       if(result) {
         /* Curl_convert_to_network calls failf if unsuccessful */
-        free(ns);
+        Curl_dyn_free(&d);
         return NULL;
       }
 
-      msnprintf(&ns[strindex], 4, "%%%02X", in);
-
-      strindex += 3;
+      msnprintf(encoded, sizeof(encoded), "%%%02X", in);
+      if(Curl_dyn_add(&d, encoded))
+        return NULL;
     }
     string++;
   }
-  ns[strindex] = 0; /* terminate it */
-  return ns;
+
+  return Curl_dyn_ptr(&d);
 }
 
 /*