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, 61 insertions, 0 deletions

diff --git a/lib/dynbuf.h b/lib/dynbuf.h
new file mode 100644
index 000000000..96e2fce8a
--- /dev/null
+++ b/lib/dynbuf.h
@@ -0,0 +1,61 @@
+#ifndef HEADER_CURL_DYNBUF_H
+#define HEADER_CURL_DYNBUF_H
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 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
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+
+struct dynbuf {
+  char *bufr;    /* point to a zero terminated allocated buffer */
+  size_t leng;   /* number of bytes *EXCLUDING* the zero terminator */
+  size_t allc;   /* size of the current allocation */
+  size_t toobig; /* size limit for the buffer */
+#ifdef DEBUGBUILD
+  int init;     /* detect API usage mistakes */
+#endif
+};
+
+void Curl_dyn_init(struct dynbuf *s, size_t toobig);
+void Curl_dyn_free(struct dynbuf *s);
+CURLcode Curl_dyn_addn(struct dynbuf *s, const void *mem, size_t len)
+  WARN_UNUSED_RESULT;
+CURLcode Curl_dyn_add(struct dynbuf *s, const char *str)
+  WARN_UNUSED_RESULT;
+CURLcode Curl_dyn_addf(struct dynbuf *s, const char *fmt, ...)
+  WARN_UNUSED_RESULT;
+void Curl_dyn_reset(struct dynbuf *s);
+CURLcode Curl_dyn_tail(struct dynbuf *s, size_t trail);
+char *Curl_dyn_ptr(const struct dynbuf *s);
+unsigned char *Curl_dyn_uptr(const struct dynbuf *s);
+size_t Curl_dyn_len(const struct dynbuf *s);
+
+/* Dynamic buffer max sizes */
+#define DYN_DOH_RESPONSE    3000
+#define DYN_DOH_CNAME       256
+#define DYN_PAUSE_BUFFER    (64 * 1024 * 1024)
+#define DYN_HAXPROXY        2048
+#define DYN_HTTP_REQUEST    (128*1024)
+#define DYN_H2_HEADERS      (128*1024)
+#define DYN_H2_TRAILERS     (128*1024)
+#define DYN_APRINTF         8000000
+#define DYN_RTSP_REQ_HEADER (64*1024)
+#define DYN_TRAILERS        (64*1024)
+
+#endif