Add mbuf_append_and_free() and mbuf_move()

CL: Add mbuf_append_and_free() and mbuf_move()

PUBLISHED_FROM=bdf73906dd93b2ebeace160596508e15480b54b4

docs/c-api/mbuf.h/intro.md

@@ -4,10 +4,12 @@ symbol_kind: "intro"
 decl_name: "mbuf.h"
 items:
   - { name: mbuf_append.md }
+  - { name: mbuf_append_and_free.md }
   - { name: mbuf_clear.md }
   - { name: mbuf_free.md }
   - { name: mbuf_init.md }
   - { name: mbuf_insert.md }
+  - { name: mbuf_move.md }
   - { name: mbuf_remove.md }
   - { name: mbuf_resize.md }
   - { name: mbuf_trim.md }

docs/c-api/mbuf.h/mbuf_append_and_free.md

+---
+title: "mbuf_append_and_free()"
+decl_name: "mbuf_append_and_free"
+symbol_kind: "func"
+signature: |
+  size_t mbuf_append_and_free(struct mbuf *, void *data, size_t data_size);
+---
+
+Appends data to the Mbuf and frees it (data must be heap-allocated).
+
+Returns the number of bytes appended or 0 if out of memory.
+data is freed irrespective of return value. 
+

docs/c-api/mbuf.h/mbuf_move.md

+---
+title: "mbuf_move()"
+decl_name: "mbuf_move"
+symbol_kind: "func"
+signature: |
+  void mbuf_move(struct mbuf *from, struct mbuf *to);
+---
+
+Moves the state from one mbuf to the other. 
+

mongoose.c

@@ -1612,6 +1612,22 @@ size_t mbuf_append(struct mbuf *a, const void *buf, size_t len) {
   return mbuf_insert(a, a->len, buf, len);
 }
 
+size_t mbuf_append_and_free(struct mbuf *a, void *buf, size_t len) WEAK;
+size_t mbuf_append_and_free(struct mbuf *a, void *data, size_t len) {
+  size_t ret;
+  /* Optimization: if the buffer is currently empty,
+   * take over the user-provided buffer. */
+  if (a->len == 0) {
+    if (a->buf != NULL) free(a->buf);
+    a->buf = (char *) data;
+    a->len = a->size = len;
+    return len;
+  }
+  ret = mbuf_insert(a, a->len, data, len);
+  free(data);
+  return ret;
+}
+
 void mbuf_remove(struct mbuf *mb, size_t n) WEAK;
 void mbuf_remove(struct mbuf *mb, size_t n) {
   if (n > 0 && n <= mb->len) {
@@ -1625,6 +1641,12 @@ void mbuf_clear(struct mbuf *mb) {
   mb->len = 0;
 }
 
+void mbuf_move(struct mbuf *from, struct mbuf *to) WEAK;
+void mbuf_move(struct mbuf *from, struct mbuf *to) {
+  memcpy(to, from, sizeof(*to));
+  memset(from, 0, sizeof(*from));
+}
+
 #endif /* EXCLUDE_COMMON */
 #ifdef MG_MODULE_LINES
 #line 1 "common/mg_str.c"

mongoose.h

@@ -2368,6 +2368,14 @@ void mbuf_free(struct mbuf *);
  */
 size_t mbuf_append(struct mbuf *, const void *data, size_t data_size);
 
+/*
+ * Appends data to the Mbuf and frees it (data must be heap-allocated).
+ *
+ * Returns the number of bytes appended or 0 if out of memory.
+ * data is freed irrespective of return value.
+ */
+size_t mbuf_append_and_free(struct mbuf *, void *data, size_t data_size);
+
 /*
  * Inserts data at a specified offset in the Mbuf.
  *
@@ -2388,6 +2396,9 @@ void mbuf_remove(struct mbuf *, size_t data_size);
  */
 void mbuf_resize(struct mbuf *, size_t new_size);
 
+/* Moves the state from one mbuf to the other. */
+void mbuf_move(struct mbuf *from, struct mbuf *to);
+
 /* Removes all the data from mbuf (if any). */
 void mbuf_clear(struct mbuf *);