# vfs.py - Mercurial 'vfs' classes

#

#  Copyright Matt Mackall <mpm@selenic.com>

#

# 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 contextlib

import errno

import os

import shutil

import stat

import tempfile

import threading

from .i18n import _

from . import (

    error,

    osutil,

    pathutil,

    pycompat,

    util,

)

class abstractvfs(object):

    """Abstract base class; cannot be instantiated"""

    def __init__(self, *args, **kwargs):

        '''Prevent instantiation; don't call this from subclasses.'''

        raise NotImplementedError('attempted instantiating ' + str(type(self)))

    def tryread(self, path):

        '''gracefully return an empty string for missing files'''

        try:

            return self.read(path)

        except IOError as inst:

            if inst.errno != errno.ENOENT:

                raise

        return ""

    def tryreadlines(self, path, mode='rb'):

        '''gracefully return an empty array for missing files'''

        try:

            return self.readlines(path, mode=mode)

        except IOError as inst:

            if inst.errno != errno.ENOENT:

                raise

        return []

    @util.propertycache

    def open(self):

        '''Open ``path`` file, which is relative to vfs root.

        Newly created directories are marked as "not to be indexed by

        the content indexing service", if ``notindexed`` is specified

        for "write" mode access.

        '''

        return self.__call__

    def read(self, path):

        with self(path, 'rb') as fp:

            return fp.read()

    def readlines(self, path, mode='rb'):

        with self(path, mode=mode) as fp:

            return fp.readlines()

    def write(self, path, data, backgroundclose=False):

        with self(path, 'wb', backgroundclose=backgroundclose) as fp:

            return fp.write(data)

    def writelines(self, path, data, mode='wb', notindexed=False):

        with self(path, mode=mode, notindexed=notindexed) as fp:

            return fp.writelines(data)

    def append(self, path, data):

        with self(path, 'ab') as fp:

            return fp.write(data)

    def basename(self, path):

        """return base element of a path (as os.path.basename would do)

        This exists to allow handling of strange encoding if needed."""

        return os.path.basename(path)

    def chmod(self, path, mode):

        return os.chmod(self.join(path), mode)

    def dirname(self, path):

        """return dirname element of a path (as os.path.dirname would do)

        This exists to allow handling of strange encoding if needed."""

        return os.path.dirname(path)

    def exists(self, path=None):

        return os.path.exists(self.join(path))

    def fstat(self, fp):

        return util.fstat(fp)

    def isdir(self, path=None):

        return os.path.isdir(self.join(path))

    def isfile(self, path=None):

        return os.path.isfile(self.join(path))

    def islink(self, path=None):

        return os.path.islink(self.join(path))

    def isfileorlink(self, path=None):

        '''return whether path is a regular file or a symlink

        Unlike isfile, this doesn't follow symlinks.'''

        try:

            st = self.lstat(path)

        except OSError:

            return False

        mode = st.st_mode

        return stat.S_ISREG(mode) or stat.S_ISLNK(mode)

    def reljoin(self, *paths):

        """join various elements of a path together (as os.path.join would do)

        The vfs base is not injected so that path stay relative. This exists

        to allow handling of strange encoding if needed."""

        return os.path.join(*paths)

    def split(self, path):

        """split top-most element of a path (as os.path.split would do)

        This exists to allow handling of strange encoding if needed."""

        return os.path.split(path)

    def lexists(self, path=None):

        return os.path.lexists(self.join(path))

    def lstat(self, path=None):

        return os.lstat(self.join(path))

    def listdir(self, path=None):

        return os.listdir(self.join(path))

    def makedir(self, path=None, notindexed=True):

        return util.makedir(self.join(path), notindexed)

    def makedirs(self, path=None, mode=None):

        return util.makedirs(self.join(path), mode)

    def makelock(self, info, path):

        return util.makelock(info, self.join(path))

    def mkdir(self, path=None):

        return os.mkdir(self.join(path))

    def mkstemp(self, suffix='', prefix='tmp', dir=None, text=False):

        fd, name = tempfile.mkstemp(suffix=suffix, prefix=prefix,

                                    dir=self.join(dir), text=text)

        dname, fname = util.split(name)

        if dir:

            return fd, os.path.join(dir, fname)

        else:

            return fd, fname

    def readdir(self, path=None, stat=None, skip=None):

        return osutil.listdir(self.join(path), stat, skip)

    def readlock(self, path):

        return util.readlock(self.join(path))

    def rename(self, src, dst, checkambig=False):

        """Rename from src to dst

        checkambig argument is used with util.filestat, and is useful

        only if destination file is guarded by any lock

        (e.g. repo.lock or repo.wlock).

        """

        dstpath = self.join(dst)

        oldstat = checkambig and util.filestat(dstpath)

        if oldstat and oldstat.stat:

            ret = util.rename(self.join(src), dstpath)

            newstat = util.filestat(dstpath)

            if newstat.isambig(oldstat):

                # stat of renamed file is ambiguous to original one

                newstat.avoidambig(dstpath, oldstat)

            return ret

        return util.rename(self.join(src), dstpath)

    def readlink(self, path):

        return os.readlink(self.join(path))

    def removedirs(self, path=None):

        """Remove a leaf directory and all empty intermediate ones

        """

        return util.removedirs(self.join(path))

    def rmtree(self, path=None, ignore_errors=False, forcibly=False):

        """Remove a directory tree recursively

        If ``forcibly``, this tries to remove READ-ONLY files, too.

        """

        if forcibly:

            def onerror(function, path, excinfo):

                if function is not os.remove:

                    raise

                # read-only files cannot be unlinked under Windows

                s = os.stat(path)

                if (s.st_mode & stat.S_IWRITE) != 0:

                    raise

                os.chmod(path, stat.S_IMODE(s.st_mode) | stat.S_IWRITE)

                os.remove(path)

        else:

            onerror = None

        return shutil.rmtree(self.join(path),

                             ignore_errors=ignore_errors, onerror=onerror)

    def setflags(self, path, l, x):

        return util.setflags(self.join(path), l, x)

    def stat(self, path=None):

        return os.stat(self.join(path))

    def unlink(self, path=None):

        return util.unlink(self.join(path))

    def tryunlink(self, path=None):

        """Attempt to remove a file, ignoring missing file errors."""

        util.tryunlink(self.join(path))

    def unlinkpath(self, path=None, ignoremissing=False):

        return util.unlinkpath(self.join(path), ignoremissing=ignoremissing)

    def utime(self, path=None, t=None):

        return os.utime(self.join(path), t)

    def walk(self, path=None, onerror=None):

        """Yield (dirpath, dirs, files) tuple for each directories under path

        ``dirpath`` is relative one from the root of this vfs. This

        uses ``os.sep`` as path separator, even you specify POSIX

        style ``path``.

        "The root of this vfs" is represented as empty ``dirpath``.

        """

        root = os.path.normpath(self.join(None))

        # when dirpath == root, dirpath[prefixlen:] becomes empty

        # because len(dirpath) < prefixlen.

        prefixlen = len(pathutil.normasprefix(root))

        for dirpath, dirs, files in os.walk(self.join(path), onerror=onerror):

            yield (dirpath[prefixlen:], dirs, files)

    @contextlib.contextmanager

    def backgroundclosing(self, ui, expectedcount=-1):

        """Allow files to be closed asynchronously.

        When this context manager is active, ``backgroundclose`` can be passed

        to ``__call__``/``open`` to result in the file possibly being closed

        asynchronously, on a background thread.

        """

        # This is an arbitrary restriction and could be changed if we ever

        # have a use case.

        vfs = getattr(self, 'vfs', self)

        if getattr(vfs, '_backgroundfilecloser', None):

            raise error.Abort(

                _('can only have 1 active background file closer'))

        with backgroundfilecloser(ui, expectedcount=expectedcount) as bfc:

            try:

                vfs._backgroundfilecloser = bfc

                yield bfc

            finally:

                vfs._backgroundfilecloser = None

class vfs(abstractvfs):

    '''Operate files relative to a base directory

    This class is used to hide the details of COW semantics and

    remote file access from higher level code.

    '''

    def __init__(self, base, audit=True, expandpath=False, realpath=False):

        if expandpath:

            base = util.expandpath(base)

        if realpath:

            base = os.path.realpath(base)

        self.base = base

        self.mustaudit = audit

        self.createmode = None

        self._trustnlink = None

    @property

    def mustaudit(self):

        return self._audit

    @mustaudit.setter

    def mustaudit(self, onoff):

        self._audit = onoff

        if onoff:

            self.audit = pathutil.pathauditor(self.base)

        else:

            self.audit = util.always

    @util.propertycache

    def _cansymlink(self):

        return util.checklink(self.base)

    @util.propertycache

    def _chmod(self):

        return util.checkexec(self.base)

    def _fixfilemode(self, name):

        if self.createmode is None or not self._chmod:

            return

        os.chmod(name, self.createmode & 0o666)

    def __call__(self, path, mode="r", text=False, atomictemp=False,

                 notindexed=False, backgroundclose=False, checkambig=False):

        '''Open ``path`` file, which is relative to vfs root.

        Newly created directories are marked as "not to be indexed by

        the content indexing service", if ``notindexed`` is specified

        for "write" mode access.

        If ``backgroundclose`` is passed, the file may be closed asynchronously.

        It can only be used if the ``self.backgroundclosing()`` context manager

        is active. This should only be specified if the following criteria hold:

        1. There is a potential for writing thousands of files. Unless you

           are writing thousands of files, the performance benefits of

           asynchronously closing files is not realized.

        2. Files are opened exactly once for the ``backgroundclosing``

           active duration and are therefore free of race conditions between

           closing a file on a background thread and reopening it. (If the

           file were opened multiple times, there could be unflushed data

           because the original file handle hasn't been flushed/closed yet.)

        ``checkambig`` argument is passed to atomictemplfile (valid

        only for writing), and is useful only if target file is

        guarded by any lock (e.g. repo.lock or repo.wlock).

        '''

        if self._audit:

            r = util.checkosfilename(path)

            if r:

                raise error.Abort("%s: %r" % (r, path))

        self.audit(path)

        f = self.join(path)

        if not text and "b" not in mode:

            mode += "b" # for that other OS

        nlink = -1

        if mode not in ('r', 'rb'):

            dirname, basename = util.split(f)

            # If basename is empty, then the path is malformed because it points

            # to a directory. Let the posixfile() call below raise IOError.

            if basename:

                if atomictemp:

                    util.makedirs(dirname, self.createmode, notindexed)

                    return util.atomictempfile(f, mode, self.createmode,

                                               checkambig=checkambig)

                try:

                    if 'w' in mode:

                        util.unlink(f)

                        nlink = 0

                    else:

                        # nlinks() may behave differently for files on Windows

                        # shares if the file is open.

                        with util.posixfile(f):

                            nlink = util.nlinks(f)

                            if nlink < 1:

                                nlink = 2 # force mktempcopy (issue1922)

                except (OSError, IOError) as e:

                    if e.errno != errno.ENOENT:

                        raise

                    nlink = 0

                    util.makedirs(dirname, self.createmode, notindexed)