From patchwork Thu Mar 19 15:52:10 2020
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Subject: Improve error message when a user configured editor could not be found
From: mw-u2@posteo.de
X-Patchwork-Id: 45833
Message-Id: <e8adbcd80820f3992114336f794f7fb6@posteo.de>
To: mercurial-devel@mercurial-scm.org
Date: Thu, 19 Mar 2020 16:52:10 +0100

Hi,

Summary: I ran "hg histedit" and got a strange error message which was 
not helpful in tracking down the problem (I configured a non-existing 
editor). This patch improves the error message.

Details: The error message of a failed attempt to launch the user 
configured editor does not deal correctly with whitespace. Example 
message when "C:\Program Files\editor\editor.exe" does not exist:

> Abort: edit failed: Program exited with status 1

Here "Program" is not part of the error message but 
basename("C:\Program"). Instead it should have been "C:\Program 
Files\editor\editor.exe" (or possible "editor.exe" which is much less 
useful in tracking down the user error though).

The situation is still not ideal since "exited with status 1" refers to 
the exit code of "cmd.exe" and the real error ("File not found") gets 
swallowed in the process.

Regards,
Micha Wiedenmann

# HG changeset patch
# User Micha Wiedenmann
# Date 1584630384 -3600
#      Do Mrz 19 16:06:24 2020 +0100
# Node ID f66e7761209b675665a27765c2772eef697331bf
# Parent  ea40fea992e000fb32edcf41d57721601842a7f2
hg: Use "shlex()" to parse commandlines fowarded to "procutil.system()"

A commandline containing a space ('"C:\\Program Files\\bar.exe" "..."') 
must not
simply split at whitespace, instead quoting has to be taken into 
account. Use
"shlex.split()" to parse it instead.

This can improve the error message if we fail to launch a user 
configured
editor which does not exist. Consider

     [ui]
     editor = "C:\Program Files\editor\editor.exe"

where the path does not exist. "hg histedit" currently aborts with

> Abort: edit failed: Program exited with status 1

here "Program" is not part of the message but the name of the program 
that
failed (i.e. `basename("C:\\Program ")`). With this change the message 
instead
reads

> Abort: edit failed: C:\Program Files\editor\editor.exe exited with 
> status 1

which is also not ideal since infact "cmd.exe" exited with code 1 not 
the
editor. But the real error message ("File not found") gets swallowed by
`procutil` and including the correct path improves the error message
nevertheless.

              if errprefix:

diff -r ea40fea992e0 -r f66e7761209b mercurial/ui.py
--- a/mercurial/ui.py	Do Mrz 12 16:25:22 2020 -0700
+++ b/mercurial/ui.py	Do Mrz 19 16:06:24 2020 +0100
@@ -14,6 +14,7 @@
  import inspect
  import os
  import re
+import shlex
  import signal
  import socket
  import subprocess
@@ -1868,7 +1869,7 @@
              rc = self._runsystem(cmd, environ=environ, cwd=cwd, 
out=out)
          if rc and onerr:
              errmsg = b'%s %s' % (
-                os.path.basename(cmd.split(None, 1)[0]),
+                shlex.split(cmd)[0],
                  procutil.explainexit(rc),
              )