bug#33389: 26.1.90; Emacs occasionally fails to receive asynchronous subprocess output in batch mode
Paul Eggert <[email protected]>
| Newsgroups | gmane.comp.gnu.parted.bugs |
|---|---|
| Organization | UCLA Computer Science Department |
| Message-ID | <[email protected]> |
> I don't think the manual states that output can > arrive after the process has finished, but if that's the case, then it > should do so. Good point, and I installed the attached patch into emacs-26 to try to do that. As this bug report seems to stem from a misunderstanding of accept-process-output (quite understandable, as its functionality is obscure) I'm taking the liberty of closing the report. If I'm wrong please feel free to reopen it.
0001-Improve-accept-process-process-doc.patch
(text/x-patch, 3 KB)
From c9fdd1b4965ebd02aa408f878320c4955f5e2cc7 Mon Sep 17 00:00:00 2001 From: Paul Eggert <[email protected]> Date: Thu, 27 Dec 2018 12:52:45 -0800 Subject: [PATCH] Improve accept-process-process doc * doc/lispref/processes.texi (Accepting Output): * src/process.c (Faccept_process_output): Document that (accept-process-output P) can return non-nil even after P has exited, and that it can return nil even if P is still running (Bug#33839). --- doc/lispref/processes.texi | 7 +++++-- src/process.c | 7 ++++--- 2 files changed, 9 insertions(+), 5 deletions(-) diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi index 623be09cc6..2aca7f82a1 100644 --- a/doc/lispref/processes.texi +++ b/doc/lispref/processes.texi @@ -1795,7 +1795,8 @@ Accepting Output This function allows Emacs to read pending output from processes. The output is given to their filter functions. If @var{process} is non-@code{nil} then this function does not return until some output -has been received from @var{process}. +has been received from @var{process} or @var{process} has closed the +connection. The arguments @var{seconds} and @var{millisec} let you specify timeout periods. The former specifies a period measured in seconds and the @@ -1820,7 +1821,9 @@ Accepting Output The function @code{accept-process-output} returns non-@code{nil} if it got output from @var{process}, or from any process if @var{process} is -@code{nil}. It returns @code{nil} if the timeout expired before output +@code{nil}; this can occur even after a process has exited if the +corresponding connection contains buffered data. The function returns +@code{nil} if the timeout expired or the connection was closed before output arrived. @end defun diff --git a/src/process.c b/src/process.c index e306b2ae9e..4dafee8cbe 100644 --- a/src/process.c +++ b/src/process.c @@ -4581,8 +4581,8 @@ DEFUN ("accept-process-output", Faccept_process_output, Saccept_process_output, 0, 4, 0, doc: /* Allow any pending output from subprocesses to be read by Emacs. It is given to their filter functions. -Optional argument PROCESS means do not return until output has been -received from PROCESS. +Optional argument PROCESS means to return only after output is +received from PROCESS or PROCESS closes the connection. Optional second argument SECONDS and third argument MILLISEC specify a timeout; return after that much time even if there is @@ -4594,7 +4594,8 @@ If optional fourth argument JUST-THIS-ONE is non-nil, accept output from PROCESS only, suspending reading output from other processes. If JUST-THIS-ONE is an integer, don't run any timers either. Return non-nil if we received any output from PROCESS (or, if PROCESS -is nil, from any process) before the timeout expired. */) +is nil, from any process) before the timeout expired or the +corresponding connection was closed. */) (Lisp_Object process, Lisp_Object seconds, Lisp_Object millisec, Lisp_Object just_this_one) { -- 2.17.1