pager: fix the invocation of `more` on Windows
After 9335dc6b2a9c, with 'shell' being (mostly) set to False, invoking `more` no
longer worked. Instead, a warning was printed and the pager was disabled.
Invoking `more.com` works. Since a user may have configured 'pager.pager=more',
do this substitution at the end. Surprisingly, `more` does allow for arguments,
so those are preserved. This also allows `more` to work in MSYS.
Setting 'shell=False' runs the executable via CreateProcess(), which has rather
wonky rules for resolving an executable without an extension [1]. Resolving to
*.com is not among them. Since 'shell=True' yields a cryptic error for a bad
$PAGER, and a *.exe program will work without specifying the extension, sticking
with current 'shell=False' seems like the right thing to do. I don't think
there are any other *.com pagers out there, so this one special case seems OK.
If somebody wants to do something crazy that requires cmd.exe, I was able to get
normal paged output with 'pager.pager="cmd.exe /c more"'. I assume you can
replace `more` with *.bat, *.vbs or various other creatures listed in $PATHEXT.
[1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms682425(v=vs.85).aspx
--- a/mercurial/ui.py Wed Mar 22 16:36:53 2017 -0700
+++ b/mercurial/ui.py Mon Mar 20 00:19:33 2017 -0400
@@ -846,6 +846,15 @@
if not pagercmd:
return
+ if pycompat.osname == 'nt':
+ # `more` cannot be invoked with shell=False, but `more.com` can.
+ # Hide this implementation detail from the user, so we can also get
+ # sane bad PAGER behavior. If args are also given, the space in the
+ # command line forces shell=True, so that case doesn't need to be
+ # handled here.
+ if pagercmd == 'more':
+ pagercmd = 'more.com'
+
self.debug('starting pager for command %r\n' % command)
self.flush()
self.pageractive = True