Free chunk/step user data on context free

So far, users had no way to free user-defined data allocated inside the
chunk/step function pointers whenever an error occurred.

Now, the free callback can be also used in conjunction with chunk/step,
so that user-defined data is now deallocated when the operation
finishes (in the case of chunk-encoded data) or an error occurs.

2 files changed, 18 insertions, 2 deletions

diff --git a/doc/man7/libweb_http.7 b/doc/man7/libweb_http.7
index 0963828..39fd4a5 100644
--- a/doc/man7/libweb_http.7
+++ b/doc/man7/libweb_http.7
@@ -675,9 +675,14 @@ object accordingly.
 .I free
 is a pointer to a function that frees the memory used by
 .I rw
+or
+.I args
 .B only if
 .I rw
-is a valid pointer. Otherwise,
+or
+.I args
+are valid pointers.
+Otherwise,
 .I free
 must be a null pointer.
 
@@ -710,6 +715,12 @@ pointed to by
 .I done
 to
 .IR true .
+If not null,
+.I free
+shall be called when either all chunks have been transferred
+or whenever an error occurs, with
+.I args
+as its argument.
 
 .I step
 allows implementations to deal with responses asynchronously
@@ -723,6 +734,11 @@ must be assigned to a function that can generate it later.
 .I libweb
 shall then call this function immediately later,
 without blocking other clients.
+If not null,
+.I free
+shall be called whenever an error occurs, with
+.I args
+as its argument.
 Do not confuse
 .I step
 with
diff --git a/http.c b/http.c
index 21966bc..6410192 100644
--- a/http.c
+++ b/http.c
@@ -792,7 +792,7 @@ static int write_ctx_free(struct write_ctx *const w)
     const struct http_response *const r = &w->r;
 
     if (r->free)
-        r->free(r->buf.rw);
+        r->free(r->args ? r->args : r->buf.rw);
 
     if (r->f && (ret = fclose(r->f)))
         fprintf(stderr, "%s: fclose(3): %s\n", __func__, strerror(errno));