mime: improve unbinding top multipart from easy handle.

Also avoid dangling pointers in referencing parts.

1 files changed, 41 insertions, 10 deletions

diff --git a/lib/mime.c b/lib/mime.c
index 7cfce6ae8..0759ad50e 100644
--- a/lib/mime.c
+++ b/lib/mime.c
@@ -1069,13 +1069,6 @@ static int mime_subparts_seek(void *instream, curl_off_t offset, int whence)
   return result;
 }
 
-static void mime_subparts_free(void *ptr)
-{
-  curl_mime *mime = (curl_mime *) ptr;
-  curl_mime_free(mime);
-}
-
-
 /* Release part content. */
 static void cleanup_part_content(curl_mimepart *part)
 {
@@ -1094,6 +1087,30 @@ static void cleanup_part_content(curl_mimepart *part)
   part->kind = MIMEKIND_NONE;
 }
 
+static void mime_subparts_free(void *ptr)
+{
+  curl_mime *mime = (curl_mime *) ptr;
+
+  if(mime && mime->parent) {
+    mime->parent->freefunc = NULL;  /* Be sure we won't be called again. */
+    cleanup_part_content(mime->parent);  /* Avoid dangling pointer in part. */
+  }
+  curl_mime_free(mime);
+}
+
+/* Do not free subparts: unbind them. This is used for the top level only. */
+static void mime_subparts_unbind(void *ptr)
+{
+  curl_mime *mime = (curl_mime *) ptr;
+
+  if(mime && mime->parent) {
+    mime->parent->freefunc = NULL;  /* Be sure we won't be called again. */
+    cleanup_part_content(mime->parent);  /* Avoid dangling pointer in part. */
+    mime->parent = NULL;
+  }
+}
+
+
 void Curl_mime_cleanpart(curl_mimepart *part)
 {
   cleanup_part_content(part);
@@ -1390,8 +1407,8 @@ CURLcode curl_mime_data_cb(curl_mimepart *part, curl_off_t datasize,
 }
 
 /* Set mime part content from subparts. */
-CURLcode curl_mime_subparts(curl_mimepart *part,
-                            curl_mime *subparts)
+CURLcode Curl_mime_set_subparts(curl_mimepart *part,
+                                curl_mime *subparts, int take_ownership)
 {
   if(!part)
     return CURLE_BAD_FUNCTION_ARGUMENT;
@@ -1414,7 +1431,7 @@ CURLcode curl_mime_subparts(curl_mimepart *part,
     subparts->parent = part;
     part->readfunc = mime_subparts_read;
     part->seekfunc = mime_subparts_seek;
-    part->freefunc = mime_subparts_free;
+    part->freefunc = take_ownership? mime_subparts_free: mime_subparts_unbind;
     part->arg = subparts;
     part->datasize = -1;
     part->kind = MIMEKIND_MULTIPART;
@@ -1423,6 +1440,11 @@ CURLcode curl_mime_subparts(curl_mimepart *part,
   return CURLE_OK;
 }
 
+CURLcode curl_mime_subparts(curl_mimepart *part, curl_mime *subparts)
+{
+  return Curl_mime_set_subparts(part, subparts, TRUE);
+}
+
 
 /* Readback from top mime. */
 /* Argument is the dummy top part. */
@@ -1817,6 +1839,15 @@ void Curl_mime_cleanpart(curl_mimepart *part)
   (void) part;
 }
 
+CURLcode Curl_mime_set_subparts(curl_mimepart *part,
+                                curl_mime *subparts, int take_ownership)
+{
+  (void) part;
+  (void) subparts;
+  (void) take_ownership;
+  return CURLE_NOT_BUILT_IN;
+}
+
 CURLcode Curl_mime_prepare_headers(curl_mimepart *part,
                                    const char *contenttype,
                                    const char *disposition,