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, 9 insertions, 10 deletions

diff --git a/lib/easy.c b/lib/easy.c
index d08c6066c..3cb3579f7 100644
--- a/lib/easy.c
+++ b/lib/easy.c
@@ -77,6 +77,7 @@
 #include "http_digest.h"
 #include "system_win32.h"
 #include "http2.h"
+#include "dynbuf.h"
 
 /* The last 3 #include files should be in this order */
 #include "curl_printf.h"
@@ -820,15 +821,12 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
   if(!outcurl->state.buffer)
     goto fail;
 
-  outcurl->state.headerbuff = malloc(HEADERSIZE);
-  if(!outcurl->state.headerbuff)
-    goto fail;
-  outcurl->state.headersize = HEADERSIZE;
-
   /* copy all userdefined values */
   if(dupset(outcurl, data))
     goto fail;
 
+  Curl_dyn_init(&outcurl->state.headerb, CURL_MAX_HTTP_HEADER);
+
   /* the connection cache is setup on demand */
   outcurl->state.conn_cache = NULL;
 
@@ -921,7 +919,7 @@ struct Curl_easy *curl_easy_duphandle(struct Curl_easy *data)
     curl_slist_free_all(outcurl->change.cookielist);
     outcurl->change.cookielist = NULL;
     Curl_safefree(outcurl->state.buffer);
-    Curl_safefree(outcurl->state.headerbuff);
+    Curl_dyn_free(&outcurl->state.headerb);
     Curl_safefree(outcurl->change.url);
     Curl_safefree(outcurl->change.referer);
     Curl_freeset(outcurl);
@@ -1040,7 +1038,7 @@ CURLcode curl_easy_pause(struct Curl_easy *data, int action)
       /* copy the structs to allow for immediate re-pausing */
       for(i = 0; i < data->state.tempcount; i++) {
         writebuf[i] = data->state.tempwrite[i];
-        data->state.tempwrite[i].buf = NULL;
+        Curl_dyn_init(&data->state.tempwrite[i].b, DYN_PAUSE_BUFFER);
       }
       data->state.tempcount = 0;
 
@@ -1054,9 +1052,10 @@ CURLcode curl_easy_pause(struct Curl_easy *data, int action)
         /* even if one function returns error, this loops through and frees
            all buffers */
         if(!result)
-          result = Curl_client_write(conn, writebuf[i].type, writebuf[i].buf,
-                                     writebuf[i].len);
-        free(writebuf[i].buf);
+          result = Curl_client_write(conn, writebuf[i].type,
+                                     Curl_dyn_ptr(&writebuf[i].b),
+                                     Curl_dyn_len(&writebuf[i].b));
+        Curl_dyn_free(&writebuf[i].b);
       }
 
       /* recover previous owner of the connection */