channel.scm (make-channel): Accept optional flags

* modules/ssh/channel.scm (make-channel): Accept optional flags that allow to
  create an input, output or input/output channel.  The procedure creates a
  bidirectional tunnel by default.
* libguile-ssh/channel-type.c (guile_ssh_make_channel): Likewise.  Rename the
  Scheme procedure to '%make-channel'.  All callers updated.
  (_scm_from_channel_data): Accept flags.  Assert flags value.
  (print_channel): Print the direction of a channel.
  (init_channel_type): Define 'RDNG' and 'WRTNG' symbols.
* libguile-ssh/channel-type.h: Update.
* libguile-ssh/message-func.c
  (guile_ssh_message_channel_request_open_reply_accept): Update.
* doc/api-channels.texi: Update description of 'make-channel'.

1 files changed, 7 insertions, 3 deletions

diff --git a/doc/api-channels.texi b/doc/api-channels.texi
index 6123027..03c5b7b 100644
--- a/doc/api-channels.texi
+++ b/doc/api-channels.texi
@@ -33,9 +33,13 @@ Return @code{#t} if @var{x} is a Guile-SSH channel, @code{#f}
 otherwise.
 @end deffn
 
-@deffn {Scheme Procedure} make-channel session
-Allocate a new Guile-SSH channel for the @var{session}
-(@pxref{Sessions}).
+@deffn {Scheme Procedure} make-channel session [flags]
+Allocate a new Guile-SSH channel for the @var{session} (@pxref{Sessions}).
+
+@var{flags} are determine what kind of a channel should be created.  Possible
+flags are: @code{O_RDONLY}, @code{O_WRONLY}, @code{O_RDWR}.  They play similar
+role to @code{open} procedure flags, and allow to create an ihput channel,
+output channel or input/output channel respectively.
 @end deffn
 
 @deffn {Scheme Procedure} channel-open-session channel