# posix.py - Posix utility function implementations for Mercurial

#

#  Copyright 2005-2009 Matt Mackall <mpm@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 i18n import _

import encoding

import os, sys, errno, stat, getpass, pwd, grp, socket, tempfile, unicodedata

posixfile = open

normpath = os.path.normpath

samestat = os.path.samestat

oslink = os.link

unlink = os.unlink

rename = os.rename

expandglobs = False

umask = os.umask(0)

os.umask(umask)

def split(p):

    '''Same as posixpath.split, but faster

    >>> import posixpath

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

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

    ...           'file_alone',

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

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

    ...           '/file_at_root',

    ...           '///multiple_leading_separators_at_root',

    ...           '']:

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

    '''

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

    if len(ht) == 1:

        return '', p

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

    if nh:

        return nh, ht[1]

    return ht[0] + '/', 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 os.sys.platform == 'OpenVMS':

        if pf[0] == '`':

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

    else:

        if pf.startswith("'") and pf.endswith("'") and " " 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 ("%s@%s" % (user, host)) or host

    return port and ("%s -p %s" % (args, port)) or args

def isexec(f):

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

    return (os.lstat(f).st_mode & 0100 != 0)

def setflags(f, l, x):

    s = os.lstat(f).st_mode

    if l:

        if not stat.S_ISLNK(s):

            # switch file to link

            fp = open(f)

            data = fp.read()

            fp.close()

            os.unlink(f)

            try:

                os.symlink(data, f)

            except OSError:

                # failed to make a link, rewrite file

                fp = open(f, "w")

                fp.write(data)

                fp.close()

        # no chmod needed at this point

        return

    if stat.S_ISLNK(s):

        # switch link to file

        data = os.readlink(f)

        os.unlink(f)

        fp = open(f, "w")

        fp.write(data)

        fp.close()

        s = 0666 & ~umask # avoid restatting for chmod

    sx = s & 0100

    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 & 0444) >> 2 & ~umask)

    elif not x and sx:

        # Turn off all +x bits

        os.chmod(f, s & 0666)

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

    '''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 & 0777

    except OSError, inst:

        if inst.errno != errno.ENOENT:

            raise

        st_mode = mode

        if st_mode is None:

            st_mode = ~umask

        st_mode &= 0666

    os.chmod(dst, st_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

        fh, fn = tempfile.mkstemp(dir=path, prefix='hg-checkexec-')

        try:

            os.close(fh)

            m = os.stat(fn).st_mode & 0777

            new_file_has_exec = m & EXECFLAGS

            os.chmod(fn, m ^ EXECFLAGS)

            exec_flags_cannot_flip = ((os.stat(fn).st_mode & 0777) == m)

        finally:

            os.unlink(fn)

    except (IOError, OSError):

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

        return False

    return not (new_file_has_exec or exec_flags_cannot_flip)

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

    name = tempfile.mktemp(dir=path, prefix='hg-checklink-')

    try:

        os.symlink(".", name)

        os.unlink(name)

        return True

    except (OSError, AttributeError):

        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.'''

    pass # on posix platforms, every path is ok

def setbinary(fd):

    pass

def pconvert(path):

    return path

def localpath(path):

    return path

def samefile(fpath1, fpath2):

    """Returns whether path1 and path2 refer to the same file. This is only

    guaranteed to work for files, not directories."""

    return os.path.samefile(fpath1, fpath2)

def samedevice(fpath1, fpath2):

    """Returns whether fpath1 and fpath2 are on the same device. This is only

    guaranteed to work for files, not directories."""

    st1 = os.lstat(fpath1)

    st2 = os.lstat(fpath2)

    return st1.st_dev == st2.st_dev

# os.path.normcase is a no-op, which doesn't help us on non-native filesystems

def normcase(path):

    return path.lower()

if sys.platform == 'darwin':

    import fcntl # only needed on darwin, missing on jython

    def normcase(path):

        try:

            path.decode('ascii') # throw exception for non-ASCII character

            return path.lower()

        except UnicodeDecodeError:

            pass

        try:

            u = path.decode('utf-8')

        except UnicodeDecodeError:

            # percent-encode any characters that don't round-trip

            p2 = path.decode('utf-8', 'ignore').encode('utf-8')

            s = ""

            pos = 0

            for c in path:

                if p2[pos:pos + 1] == c:

                    s += c

                    pos += 1

                else:

                    s += "%%%02X" % ord(c)

            u = s.decode('utf-8')

        # Decompose then lowercase (HFS+ technote specifies lower)

        return unicodedata.normalize('NFD', u).lower().encode('utf-8')

    def realpath(path):

        '''

        Returns the true, canonical file system path equivalent to the given

        path.

        Equivalent means, in this case, resulting in the same, unique

        file system link to the path. Every file system entry, whether a file,

        directory, hard link or symbolic link or special, will have a single

        path preferred by the system, but may allow multiple, differing path

        lookups to point to it.

        Most regular UNIX file systems only allow a file system entry to be

        looked up by its distinct path. Obviously, this does not apply to case

        insensitive file systems, whether case preserving or not. The most

        complex issue to deal with is file systems transparently reencoding the

        path, such as the non-standard Unicode normalisation required for HFS+

        and HFSX.

        '''

        # Constants copied from /usr/include/sys/fcntl.h

        F_GETPATH = 50

        O_SYMLINK = 0x200000

        try:

            fd = os.open(path, O_SYMLINK)

        except OSError, err:

            if err.errno == errno.ENOENT:

                return path

            raise

        try:

            return fcntl.fcntl(fd, F_GETPATH, '\0' * 1024).rstrip('\0')

        finally:

            os.close(fd)

elif sys.version_info < (2, 4, 2, 'final'):

    # Workaround for http://bugs.python.org/issue1213894 (os.path.realpath

    # didn't resolve symlinks that were the first component of the path.)

    def realpath(path):

        if os.path.isabs(path):

            return os.path.realpath(path)

        else:

            return os.path.realpath('./' + path)

else:

    # Fallback to the likely inadequate Python builtin function.

    realpath = os.path.realpath

if sys.platform == 'cygwin':

    # workaround for cygwin, in which mount point part of path is

    # treated as case sensitive, even though underlying NTFS is case

    # insensitive.

    # default mount points

    cygwinmountpoints = sorted([

            "/usr/bin",

            "/usr/lib",

            "/cygdrive",

            ], reverse=True)

    # use upper-ing as normcase as same as NTFS workaround

    def normcase(path):

        pathlen = len(path)

        if (pathlen == 0) or (path[0] != os.sep):

            # treat as relative

            return encoding.upper(path)

        # to preserve case of mountpoint part

        for mp in cygwinmountpoints:

            if not path.startswith(mp):

                continue

            mplen = len(mp)

            if mplen == pathlen: # mount point itself

                return mp

            if path[mplen] == os.sep:

                return mp + encoding.upper(path[mplen:])

        return encoding.upper(path)

    # Cygwin translates native ACLs to POSIX permissions,

    # but these translations are not supported by native

    # tools, so the exec bit tends to be set erroneously.

    # Therefore, disable executable bit access on Cygwin.

    def checkexec(path):

        return False

    # Similarly, Cygwin's symlink emulation is likely to create

    # problems when Mercurial is used from both Cygwin and native

    # Windows, with other native tools, or on shared volumes

    def checklink(path):

        return False

def shellquote(s):

    if os.sys.platform == 'OpenVMS':

        return '"%s"' % s

    else:

        return "'%s'" % s.replace("'", "'\\''")

def quotecommand(cmd):

    return cmd

def popen(command, mode='r'):

    return os.popen(command, mode)

def testpid(pid):

    '''return False if pid dead, True if running or not sure'''

    if os.sys.platform == 'OpenVMS':

        return True

    try:

        os.kill(pid, 0)

        return True

    except OSError, inst:

        return inst.errno != errno.ESRCH

def explainexit(code):

    """return a 2-tuple (desc, code) describing a subprocess status

    (codes from kill are negative - not os.system/wait encoding)"""

    if code >= 0:

        return _("exited with status %d") % code, code

    return _("killed by signal %d") % -code, -code

def isowner(st):

    """Return True if the stat object st is from the current user."""

    return st.st_uid == os.getuid()

def findexe(command):

    '''Find executable for command searching like which does.

    If command is a basename then PATH is searched for command.

    PATH isn't searched if command is an absolute or relative path.

    If command isn't found None is returned.'''

    if sys.platform == 'OpenVMS':

        return command

    def findexisting(executable):

        'Will return executable if existing file'

        if os.path.isfile(executable) and os.access(executable, os.X_OK):

            return executable

        return None

    if os.sep in command:

        return findexisting(command)

    if sys.platform == 'plan9':

        return findexisting(os.path.join('/bin', command))

    for path in os.environ.get('PATH', '').split(os.pathsep):

        executable = findexisting(os.path.join(path, command))

        if executable is not None:

            return executable

    return None

def setsignalhandler():

    pass

_wantedkinds = set([stat.S_IFREG, stat.S_IFLNK])

def statfiles(files):

    '''Stat each file in files. Yield each stat, or None if a file does not

    exist or has a type we don't care about.'''

    lstat = os.lstat

    getkind = stat.S_IFMT

    for nf in files:

        try:

            st = lstat(nf)

            if getkind(st.st_mode) not in _wantedkinds:

                st = None

        except OSError, err:

            if err.errno not in (errno.ENOENT, errno.ENOTDIR):

                raise

            st = None

        yield st

def getuser():

    '''return name of current user'''

    return getpass.getuser()

def username(uid=None):

    """Return the name of the user with the given uid.