procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
# A minimal client for Mercurial's command server
import io
import os
import re
import signal
import socket
import struct
import subprocess
import sys
import time
if sys.version_info[0] >= 3:
stdout = sys.stdout.buffer
stderr = sys.stderr.buffer
stringio = io.BytesIO
def bprint(*args):
# remove b'' as well for ease of test migration
pargs = [re.sub(br'''\bb(['"])''', br'\1', b'%s' % a) for a in args]
stdout.write(b' '.join(pargs) + b'\n')
else:
import cStringIO
stdout = sys.stdout
stderr = sys.stderr
stringio = cStringIO.StringIO
bprint = print
def connectpipe(path=None, extraargs=()):
cmdline = [b'hg', b'serve', b'--cmdserver', b'pipe']
if path:
cmdline += [b'-R', path]
cmdline.extend(extraargs)
def tonative(cmdline):
if os.name != 'nt':
return cmdline
return [arg.decode("utf-8") for arg in cmdline]
server = subprocess.Popen(
tonative(cmdline), stdin=subprocess.PIPE, stdout=subprocess.PIPE
)
return server
class unixconnection:
def __init__(self, sockpath):
self.sock = sock = socket.socket(socket.AF_UNIX)
sock.connect(sockpath)
self.stdin = sock.makefile('wb')
self.stdout = sock.makefile('rb')
def wait(self):
self.stdin.close()
self.stdout.close()
self.sock.close()
class unixserver:
def __init__(self, sockpath, logpath=None, repopath=None):
self.sockpath = sockpath
cmdline = [b'hg', b'serve', b'--cmdserver', b'unix', b'-a', sockpath]
if repopath:
cmdline += [b'-R', repopath]
if logpath:
stdout = open(logpath, 'a')
stderr = subprocess.STDOUT
else:
stdout = stderr = None
self.server = subprocess.Popen(cmdline, stdout=stdout, stderr=stderr)
# wait for listen()
while self.server.poll() is None:
if os.path.exists(sockpath):
break
time.sleep(0.1)
def connect(self):
return unixconnection(self.sockpath)
def shutdown(self):
os.kill(self.server.pid, signal.SIGTERM)
self.server.wait()
def writeblock(server, data):
server.stdin.write(struct.pack(b'>I', len(data)))
server.stdin.write(data)
server.stdin.flush()
def readchannel(server):
data = server.stdout.read(5)
if not data:
raise EOFError
channel, length = struct.unpack('>cI', data)
if channel in b'IL':
return channel, length
else:
return channel, server.stdout.read(length)
def sep(text):
return text.replace(b'\\', b'/')
def runcommand(
server, args, output=stdout, error=stderr, input=None, outfilter=lambda x: x
):
bprint(b'*** runcommand', b' '.join(args))
stdout.flush()
server.stdin.write(b'runcommand\n')
writeblock(server, b'\0'.join(args))
if not input:
input = stringio()
while True:
ch, data = readchannel(server)
if ch == b'o':
output.write(outfilter(data))
output.flush()
elif ch == b'e':
error.write(data)
error.flush()
elif ch == b'I':
writeblock(server, input.read(data))
elif ch == b'L':
writeblock(server, input.readline(data))
elif ch == b'm':
bprint(b"message: %r" % data)
elif ch == b'r':
(ret,) = struct.unpack('>i', data)
if ret != 0:
bprint(b' [%d]' % ret)
return ret
else:
bprint(b"unexpected channel %c: %r" % (ch, data))
if ch.isupper():
return
def check(func, connect=connectpipe):
stdout.flush()
server = connect()
try:
return func(server)
finally:
server.stdin.close()
server.wait()
def checkwith(connect=connectpipe, **kwargs):
def wrap(func):
return check(func, lambda: connect(**kwargs))
return wrap