# posix.py - Posix utility function implementations for Mercurial

#

#  Copyright 2005-2009 Olivia Mackall <olivia@selenic.com> and others

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import errno

import fcntl

import getpass

import grp

import os

import pwd

import re

import select

import stat

import sys

import tempfile

import unicodedata

from .i18n import _

from .pycompat import (

    getattr,

    open,

)

from . import (

    encoding,

    error,

    policy,

    pycompat,

)

osutil = policy.importmod('osutil')

normpath = os.path.normpath

samestat = os.path.samestat

abspath = os.path.abspath  # re-exports

try:

    oslink = os.link

except AttributeError:

    # Some platforms build Python without os.link on systems that are

    # vaguely unix-like but don't have hardlink support. For those

    # poor souls, just say we tried and that it failed so we fall back

    # to copies.

    def oslink(src, dst):

        raise OSError(

            errno.EINVAL, b'hardlinks not supported: %s to %s' % (src, dst)

        )

readlink = os.readlink

unlink = os.unlink

rename = os.rename

removedirs = os.removedirs

expandglobs = False

umask = os.umask(0)

os.umask(umask)

if not pycompat.ispy3:

    def posixfile(name, mode='r', buffering=-1):

        fp = open(name, mode=mode, buffering=buffering)

        # The position when opening in append mode is implementation defined, so

        # make it consistent by always seeking to the end.

        if 'a' in mode:

            fp.seek(0, os.SEEK_END)

        return fp

else:

    # The underlying file object seeks as required in Python 3:

    # https://github.com/python/cpython/blob/v3.7.3/Modules/_io/fileio.c#L474

    posixfile = open

def split(p):

    """Same as posixpath.split, but faster

    >>> import posixpath

    >>> for f in [b'/absolute/path/to/file',

    ...           b'relative/path/to/file',

    ...           b'file_alone',

    ...           b'path/to/directory/',

    ...           b'/multiple/path//separators',

    ...           b'/file_at_root',

    ...           b'///multiple_leading_separators_at_root',

    ...           b'']:

    ...     assert split(f) == posixpath.split(f), f

    """

    ht = p.rsplit(b'/', 1)

    if len(ht) == 1:

        return b'', p

    nh = ht[0].rstrip(b'/')

    if nh:

        return nh, ht[1]

    return ht[0] + b'/', ht[1]

def openhardlinks():

    '''return true if it is safe to hold open file handles to hardlinks'''

    return True

def nlinks(name):

    '''return number of hardlinks for the given file'''

    return os.lstat(name).st_nlink

def parsepatchoutput(output_line):

    """parses the output produced by patch and returns the filename"""

    pf = output_line[14:]

    if pycompat.sysplatform == b'OpenVMS':

        if pf[0] == b'`':

            pf = pf[1:-1]  # Remove the quotes

    else:

        if pf.startswith(b"'") and pf.endswith(b"'") and b" " in pf:

            pf = pf[1:-1]  # Remove the quotes

    return pf

def sshargs(sshcmd, host, user, port):

    '''Build argument list for ssh'''

    args = user and (b"%s@%s" % (user, host)) or host

    if b'-' in args[:1]:

        raise error.Abort(

            _(b'illegal ssh hostname or username starting with -: %s') % args

        )

    args = shellquote(args)

    if port:

        args = b'-p %s %s' % (shellquote(port), args)

    return args

def isexec(f):

    """check whether a file is executable"""

    return os.lstat(f).st_mode & 0o100 != 0

def setflags(f, l, x):

    st = os.lstat(f)

    s = st.st_mode

    if l:

        if not stat.S_ISLNK(s):

            # switch file to link

            with open(f, b'rb') as fp:

                data = fp.read()

            unlink(f)

            try:

                os.symlink(data, f)

            except OSError:

                # failed to make a link, rewrite file

                with open(f, b"wb") as fp:

                    fp.write(data)

        # no chmod needed at this point

        return

    if stat.S_ISLNK(s):

        # switch link to file

        data = os.readlink(f)

        unlink(f)

        with open(f, b"wb") as fp:

            fp.write(data)

        s = 0o666 & ~umask  # avoid restatting for chmod

    sx = s & 0o100

    if st.st_nlink > 1 and bool(x) != bool(sx):

        # the file is a hardlink, break it

        with open(f, b"rb") as fp:

            data = fp.read()

        unlink(f)

        with open(f, b"wb") as fp:

            fp.write(data)

    if x and not sx:

        # Turn on +x for every +r bit when making a file executable

        # and obey umask.

        os.chmod(f, s | (s & 0o444) >> 2 & ~umask)

    elif not x and sx:

        # Turn off all +x bits

        os.chmod(f, s & 0o666)

def copymode(src, dst, mode=None, enforcewritable=False):

    """Copy the file mode from the file at path src to dst.

    If src doesn't exist, we're using mode instead. If mode is None, we're

    using umask."""

    try:

        st_mode = os.lstat(src).st_mode & 0o777

    except OSError as inst:

        if inst.errno != errno.ENOENT:

            raise

        st_mode = mode

        if st_mode is None:

            st_mode = ~umask

        st_mode &= 0o666

    new_mode = st_mode

    if enforcewritable:

        new_mode |= stat.S_IWUSR

    os.chmod(dst, new_mode)

def checkexec(path):

    """

    Check whether the given path is on a filesystem with UNIX-like exec flags

    Requires a directory (like /foo/.hg)

    """

    # VFAT on some Linux versions can flip mode but it doesn't persist

    # a FS remount. Frequently we can detect it if files are created

    # with exec bit on.

    try:

        EXECFLAGS = stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH

        basedir = os.path.join(path, b'.hg')

        cachedir = os.path.join(basedir, b'wcache')

        storedir = os.path.join(basedir, b'store')

        if not os.path.exists(cachedir):

            try:

                # we want to create the 'cache' directory, not the '.hg' one.

                # Automatically creating '.hg' directory could silently spawn

                # invalid Mercurial repositories. That seems like a bad idea.

                os.mkdir(cachedir)

                if os.path.exists(storedir):

                    copymode(storedir, cachedir)

                else:

                    copymode(basedir, cachedir)

            except (IOError, OSError):

                # we other fallback logic triggers

                pass

        if os.path.isdir(cachedir):

            checkisexec = os.path.join(cachedir, b'checkisexec')

            checknoexec = os.path.join(cachedir, b'checknoexec')

            try:

                m = os.stat(checkisexec).st_mode

            except OSError as e:

                if e.errno != errno.ENOENT:

                    raise

                # checkisexec does not exist - fall through ...

            else:

                # checkisexec exists, check if it actually is exec

                if m & EXECFLAGS != 0:

                    # ensure checkisexec exists, check it isn't exec

                    try:

                        m = os.stat(checknoexec).st_mode

                    except OSError as e:

                        if e.errno != errno.ENOENT:

                            raise

                        open(checknoexec, b'w').close()  # might fail

                        m = os.stat(checknoexec).st_mode

                    if m & EXECFLAGS == 0:

                        # check-exec is exec and check-no-exec is not exec

                        return True

                    # checknoexec exists but is exec - delete it

                    unlink(checknoexec)

                # checkisexec exists but is not exec - delete it

                unlink(checkisexec)

            # check using one file, leave it as checkisexec

            checkdir = cachedir

        else:

            # check directly in path and don't leave checkisexec behind

            checkdir = path

            checkisexec = None

        fh, fn = pycompat.mkstemp(dir=checkdir, prefix=b'hg-checkexec-')

        try:

            os.close(fh)

            m = os.stat(fn).st_mode

            if m & EXECFLAGS == 0:

                os.chmod(fn, m & 0o777 | EXECFLAGS)

                if os.stat(fn).st_mode & EXECFLAGS != 0:

                    if checkisexec is not None:

                        os.rename(fn, checkisexec)

                        fn = None

                    return True

        finally:

            if fn is not None:

                unlink(fn)

    except (IOError, OSError):

        # we don't care, the user probably won't be able to commit anyway

        return False

def checklink(path):

    """check whether the given path is on a symlink-capable filesystem"""

    # mktemp is not racy because symlink creation will fail if the

    # file already exists

    while True:

        cachedir = os.path.join(path, b'.hg', b'wcache')

        checklink = os.path.join(cachedir, b'checklink')

        # try fast path, read only

        if os.path.islink(checklink):

            return True

        if os.path.isdir(cachedir):

            checkdir = cachedir

        else:

            checkdir = path

            cachedir = None

        name = tempfile.mktemp(

            dir=pycompat.fsdecode(checkdir), prefix=r'checklink-'

        )

        name = pycompat.fsencode(name)

        try:

            fd = None

            if cachedir is None:

                fd = pycompat.namedtempfile(

                    dir=checkdir, prefix=b'hg-checklink-'

                )

                target = os.path.basename(fd.name)

            else:

                # create a fixed file to link to; doesn't matter if it

                # already exists.

                target = b'checklink-target'

                try:

                    fullpath = os.path.join(cachedir, target)

                    open(fullpath, b'w').close()

                except IOError as inst:

                    # pytype: disable=unsupported-operands

                    if inst[0] == errno.EACCES:

                        # pytype: enable=unsupported-operands

                        # If we can't write to cachedir, just pretend

                        # that the fs is readonly and by association

                        # that the fs won't support symlinks. This

                        # seems like the least dangerous way to avoid

                        # data loss.

                        return False

                    raise

            try:

                os.symlink(target, name)

                if cachedir is None:

                    unlink(name)

                else:

                    try:

                        os.rename(name, checklink)

                    except OSError:

                        unlink(name)

                return True

            except OSError as inst:

                # link creation might race, try again

                if inst.errno == errno.EEXIST:

                    continue

                raise

            finally:

                if fd is not None:

                    fd.close()

        except AttributeError:

            return False

        except OSError as inst:

            # sshfs might report failure while successfully creating the link

            if inst.errno == errno.EIO and os.path.exists(name):

                unlink(name)

            return False

def checkosfilename(path):

    """Check that the base-relative path is a valid filename on this platform.

    Returns None if the path is ok, or a UI string describing the problem."""

    return None  # on posix platforms, every path is ok

def getfsmountpoint(dirpath):

    """Get the filesystem mount point from a directory (best-effort)

    Returns None if we are unsure. Raises OSError on ENOENT, EPERM, etc.

    """

    return getattr(osutil, 'getfsmountpoint', lambda x: None)(dirpath)

def getfstype(dirpath):

    """Get the filesystem type name from a directory (best-effort)

    Returns None if we are unsure. Raises OSError on ENOENT, EPERM, etc.

    """

    return getattr(osutil, 'getfstype', lambda x: None)(dirpath)

def get_password():

    return encoding.strtolocal(getpass.getpass(''))