# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1714950849 -7200
# Node ID 5b77aef76beac37486d5337021df112dae5dcd6b
# Parent  4cc3e52e39fb014bd7b7e60310b8f98dbfac96e8
Fixed buffer descriptor register initialisation for currently supported usage.
Fixed handling of invalid received capabilities (again), leaving allocated
capabilities in place for use by valid received capabilities.

diff -r 4cc3e52e39fb -r 5b77aef76bea libipc/lib/src/message.c
--- a/libipc/lib/src/message.c	Mon May 06 01:09:30 2024 +0200
+++ b/libipc/lib/src/message.c	Mon May 06 01:14:09 2024 +0200
@@ -213,7 +213,12 @@
   msg->discarded_items = 0;
   msg->words = 0;
   msg->items = 0;
+
+  /* Initialise items to be received.
+     NOTE: This does not support item type mixing. */
+
   msg->import_item = 0;
+  msg->bregs.bdr = 0;
 
   /* Message label overriding. */
 
@@ -510,8 +515,16 @@
   if (local)
     return L4_EOK;
 
-  err = ipc_message_expect_capability(msg, msg->import_item);
-  msg->import_item += 1;
+  /* Only if the specified item yielded a valid capability, will an allocated
+     have been consumed. Otherwise, the next allocated capability will still be
+     available. */
+
+  if (l4_is_valid_cap(*ref))
+  {
+    err = ipc_message_expect_capability(msg, msg->import_item);
+    msg->import_item += 1;
+  }
+
   return err;
 }
 
diff -r 4cc3e52e39fb -r 5b77aef76bea libipc/lib/src/util_ipc.c
--- a/libipc/lib/src/util_ipc.c	Mon May 06 01:09:30 2024 +0200
+++ b/libipc/lib/src/util_ipc.c	Mon May 06 01:14:09 2024 +0200
@@ -60,7 +60,6 @@
 
   /* Indicate the expectation of a capability in return. */
 
-  bregs->bdr = 0;
   bregs->br[item] = L4_RCV_ITEM_SINGLE_CAP | future | L4_RCV_ITEM_LOCAL_ID;
 
   return L4_EOK;
@@ -70,7 +69,6 @@
 
 long _expect_fpage(l4_buf_regs_t *bregs, int item, l4_umword_t map_control, l4_fpage_t fpage)
 {
-  bregs->bdr = 0;
   bregs->br[item] = map_control;
   bregs->br[item + 1] = fpage.raw;