pager: avoid shell=True on subprocess.Popen for better errors (
issue5491)
man(1) behaves as poorly as Mercurial without this change. This cribs
from git's run-command[0], which has a list of characters that imply a
string that needs to be run using 'sh -c'. If none of those characters
are present in the command string, we can use shell=False mode on
subprocess and get significantly better error messages (see the test)
when the pager process is invalid. With a complicated pager command
(that contains one of the unsafe characters), we behave as we do today
(which is no worse than git manages.)
I briefly tried tapdancing in a thread to catch early pager exits, but
it's just too perilous: you get races between fd duping operations and
a bad pager exiting, and it's too hard to differentiate between a
slow-bad-pager result and a fast-human-quit-pager-early result.
I've observed some weird variation in exit code handling in the "bad
experience" case in test-pager.t: on my Mac hg predictably exits
nonzero, but on Linux hg always exits zero in that case. For now,
we'll work around it with || true. :(
0: https://github.com/git/git/blob/
cddbda4bc87b9d2c985b6749b1cf026b15e2d3e7/run-command.c#L201
#!/usr/bin/env python
# fixpax - fix ownership in bdist_mpkg output
#
# Copyright 2015 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# MIT license (http://opensource.org/licenses/MIT)
"""Set file ownership to 0 in an Archive.pax.gz.
Suitable for fixing files bdist_mpkg output:
*.mpkg/Contents/Packages/*.pkg/Contents/Archive.pax.gz
"""
from __future__ import absolute_import, print_function
import gzip
import os
import sys
def fixpax(iname, oname):
i = gzip.GzipFile(iname)
o = gzip.GzipFile(oname, "w")
while True:
magic = i.read(6)
dev = i.read(6)
ino = i.read(6)
mode = i.read(6)
i.read(6) # uid
i.read(6) # gid
nlink = i.read(6)
rdev = i.read(6)
mtime = i.read(11)
namesize = i.read(6)
filesize = i.read(11)
name = i.read(int(namesize, 8))
data = i.read(int(filesize, 8))
o.write(magic)
o.write(dev)
o.write(ino)
o.write(mode)
o.write("000000")
o.write("000000")
o.write(nlink)
o.write(rdev)
o.write(mtime)
o.write(namesize)
o.write(filesize)
o.write(name)
o.write(data)
if name.startswith("TRAILER!!!"):
o.write(i.read())
break
o.close()
i.close()
if __name__ == '__main__':
for iname in sys.argv[1:]:
print('fixing file ownership in %s' % iname)
oname = sys.argv[1] + '.tmp'
fixpax(iname, oname)
os.rename(oname, iname)