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[Emacs-diffs] master 9fc02ff: Fix accept-process-output/process-live-p c
From: |
Paul Eggert |
Subject: |
[Emacs-diffs] master 9fc02ff: Fix accept-process-output/process-live-p confusion |
Date: |
Tue, 15 Jan 2019 13:21:20 -0500 (EST) |
branch: master
commit 9fc02ff5ea95c31a8d81eabb5634aa135fcd8786
Author: Paul Eggert <address@hidden>
Commit: Paul Eggert <address@hidden>
Fix accept-process-output/process-live-p confusion
* doc/lispref/processes.texi (Accepting Output):
Document the issue.
* lisp/net/tramp-adb.el (tramp-adb-parse-device-names):
* lisp/net/tramp-rclone.el (tramp-rclone-parse-device-names):
* lisp/net/tramp-smb.el (tramp-smb-wait-for-output):
* lisp/net/tramp.el (tramp-interrupt-process):
* test/src/process-tests.el (make-process/mix-stderr):
Fix code that uses accept-process-output and process-live-p.
Add FIXME comments as necessary.
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-action-sudo):
* lisp/net/tramp.el (tramp-action-out-of-band):
Add FIXME comments as necessary.
---
doc/lispref/processes.texi | 20 ++++++++++++++++++++
lisp/net/tramp-adb.el | 6 +++---
lisp/net/tramp-rclone.el | 6 +++---
lisp/net/tramp-smb.el | 19 +++++++++++--------
lisp/net/tramp-sudoedit.el | 2 ++
lisp/net/tramp.el | 9 ++++++---
test/src/process-tests.el | 4 ++--
7 files changed, 47 insertions(+), 19 deletions(-)
diff --git a/doc/lispref/processes.texi b/doc/lispref/processes.texi
index 72b164c..afda8ae 100644
--- a/doc/lispref/processes.texi
+++ b/doc/lispref/processes.texi
@@ -1859,6 +1859,26 @@ corresponding connection contains buffered data. The
function returns
arrived.
@end defun
+If a connection from a process contains buffered data,
address@hidden can return address@hidden even after the
+process has exited. Therefore, although the following loop:
+
address@hidden
+;; This loop contains a bug.
+(while (process-live-p process)
+ (accept-process-output process))
address@hidden example
+
address@hidden
+will often work, it has a race condition and can miss some output if
address@hidden returns @code{nil} while the connection still
+contains data. Better is to write the loop like this:
+
address@hidden
+(while (or (accept-process-output process)
+ (process-live-p process)))
address@hidden example
+
@node Processes and Threads
@subsection Processes and Threads
@cindex processes, threads
diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index e2275be..ca47601 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -206,9 +206,9 @@ pass to the OPERATION."
(tramp-message v 6 "%s" (mapconcat 'identity (process-command p) " "))
(process-put p 'adjust-window-size-function 'ignore)
(set-process-query-on-exit-flag p nil)
- (while (process-live-p p)
- (accept-process-output p 0.1))
- (accept-process-output p 0.1)
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ (while (or (accept-process-output p 0.1)
+ (process-live-p p)))
(tramp-message v 6 "\n%s" (buffer-string))
(goto-char (point-min))
(while (search-forward-regexp "^\\(\\S-+\\)[[:space:]]+device$" nil t)
diff --git a/lisp/net/tramp-rclone.el b/lisp/net/tramp-rclone.el
index 0aa110d..7366057 100644
--- a/lisp/net/tramp-rclone.el
+++ b/lisp/net/tramp-rclone.el
@@ -183,9 +183,9 @@ pass to the OPERATION."
(tramp-message v 6 "%s" (mapconcat 'identity (process-command p) " "))
(process-put p 'adjust-window-size-function 'ignore)
(set-process-query-on-exit-flag p nil)
- (while (process-live-p p)
- (accept-process-output p 0.1))
- (accept-process-output p 0.1)
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ (while (or (accept-process-output p 0.1)
+ (process-live-p p)))
(tramp-message v 6 "\n%s" (buffer-string))
(goto-char (point-min))
(while (search-forward-regexp "^\\(\\S-+\\):$" nil t)
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index 0c42a5d..abf3248 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -2038,10 +2038,10 @@ Returns nil if an error message has appeared."
;; Algorithm: get waiting output. See if last line contains
;; `tramp-smb-prompt' sentinel or `tramp-smb-errors' strings.
;; If not, wait a bit and again get waiting output.
- (while (and (not found) (not err) (process-live-p p))
-
- ;; Accept pending output.
- (tramp-accept-process-output p 0.1)
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ (while (and (not found) (not err)
+ (or (tramp-accept-process-output p 0.1)
+ (process-live-p p)))
;; Search for prompt.
(goto-char (point-min))
@@ -2052,10 +2052,13 @@ Returns nil if an error message has appeared."
(setq err (re-search-forward tramp-smb-errors nil t)))
;; When the process is still alive, read pending output.
- (while (and (not found) (process-live-p p))
-
- ;; Accept pending output.
- (tramp-accept-process-output p 0.1)
+ ;; FIXME: This loop should be folded into the previous loop.
+ ;; Also, ERR should be set just once, after the combined
+ ;; loop has finished.
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ (while (and (not found)
+ (or (tramp-accept-process-output p 0.1)
+ (process-live-p p)))
;; Search for prompt.
(goto-char (point-min))
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index cab9b8d..e1e5ab0 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -746,6 +746,8 @@ ID-FORMAT valid values are `string' and `integer'."
(defun tramp-sudoedit-action-sudo (proc vec)
"Check, whether a sudo process copy has finished."
;; There might be pending output for the exit status.
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ ;; FIXME: There's a race here. Shouldn't the next two lines be interchanged?
(tramp-accept-process-output proc 0.1)
(when (not (process-live-p proc))
;; Delete narrowed region, it would be in the way reading a Lisp form.
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 437e2d1..7632d65 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -3977,6 +3977,8 @@ The terminal type can be configured with
`tramp-terminal-type'."
(defun tramp-action-out-of-band (proc vec)
"Check, whether an out-of-band copy has finished."
;; There might be pending output for the exit status.
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ ;; FIXME: Shouldn't the following line be wrapped inside (while ...)?
(tramp-accept-process-output proc 0.1)
(cond ((and (not (process-live-p proc))
(zerop (process-exit-status proc)))
@@ -4821,9 +4823,10 @@ Only works for Bourne-like shells."
;; Wait, until the process has disappeared. If it doesn't,
;; fall back to the default implementation.
(with-timeout (1 (ignore))
- (while (process-live-p proc)
- ;; We cannot run `tramp-accept-process-output', it blocks timers.
- (accept-process-output proc 0.1))
+ ;; We cannot run `tramp-accept-process-output', it blocks timers.
+ ;; FIXME: Either remove " 0.1", or comment why it's needed.
+ (while (or (accept-process-output proc 0.1)
+ (process-live-p proc)))
;; Report success.
proc)))))
diff --git a/test/src/process-tests.el b/test/src/process-tests.el
index 514bd04..5dbf441 100644
--- a/test/src/process-tests.el
+++ b/test/src/process-tests.el
@@ -207,8 +207,8 @@
:sentinel #'ignore
:noquery t
:connection-type 'pipe)))
- (while (process-live-p process)
- (accept-process-output process))
+ (while (or (accept-process-output process)
+ (process-live-p process)))
(should (eq (process-status process) 'exit))
(should (eq (process-exit-status process) 0))
(should (process-tests--mixable (string-to-list (buffer-string))
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