# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1715345392 -7200
# Node ID bbb065eae48318fbae56af1ca5754ac73499918f
# Parent  569d90054efef1a06c889ed019a5acdcbb0ab33e
Added a synchronisation operation for streams when shared between programs.
Currently, it only really makes sense for output streams.

diff -r 569d90054efe -r bbb065eae483 libfsclient/include/fsclient/client.h
--- a/libfsclient/include/fsclient/client.h	Fri May 10 14:46:04 2024 +0200
+++ b/libfsclient/include/fsclient/client.h	Fri May 10 14:49:52 2024 +0200
@@ -36,6 +36,7 @@
 /* Stream access operations. */
 
 file_t *client_get_stream(const char *name, flags_t flags);
+long client_sync_stream(file_t *file);
 
 /* Opening and closing operations. */
 
diff -r 569d90054efe -r bbb065eae483 libfsclient/lib/src/client.cc
--- a/libfsclient/lib/src/client.cc	Fri May 10 14:46:04 2024 +0200
+++ b/libfsclient/lib/src/client.cc	Fri May 10 14:49:52 2024 +0200
@@ -140,12 +140,7 @@
 
     else if (position == file->end_pos)
     {
-      err = client_next_region(file);
-      if (err)
-        return err;
-
-      file->data_current = 0;
-      return L4_EOK;
+      return client_next_region(file);
     }
 
     /* Within the current pipe region, synchronise with the pipe object. */
@@ -283,10 +278,10 @@
   stream->flags = flags;
   stream->ref = ref;
 
-  /* Test for pipe-based access, switching to memory mapped access if not
-     supported. */
+  /* Synchronise the state of the stream, testing for pipe-based access and
+     switching to memory mapped access if not supported. */
 
-  long err = client_current_region(stream);
+  long err = client_sync_stream(stream);
 
   if (err == -L4_EBADPROTO)
     stream->object_flags |= OBJECT_SUPPORTS_MMAP;
@@ -310,6 +305,19 @@
   return stream;
 }
 
+/* Initialise the stream data position to the end of any existing data. */
+
+long client_sync_stream(file_t *file)
+{
+  long err = client_current_region(file);
+
+  if (err)
+    return err;
+
+  file->data_current = file->data_end;
+  return err;
+}
+
 
 
 /* Open a filesystem object. */
@@ -608,7 +616,13 @@
   if (!client_opened(file))
     return -L4_EINVAL;
 
-  return pipe_next(file);
+  long err = pipe_next(file);
+
+  if (err)
+    return err;
+
+  file->data_current = 0;
+  return L4_EOK;
 }