hgext/largefiles/lfutil.py

largefiles: copy files into .hg/largefiles atomically

Copying from the user cache into .hg/largefiles could fail halfway
though with a partially written file.

# Copyright 2009-2010 Gregory P. Ward
# Copyright 2009-2010 Intelerad Medical Systems Incorporated
# Copyright 2010-2011 Fog Creek Software
# Copyright 2010-2011 Unity Technologies
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''largefiles utility code: must not import other modules in this package.'''

import os
import errno
import platform
import shutil
import stat
import tempfile

from mercurial import dirstate, httpconnection, match as match_, util, scmutil
from mercurial.i18n import _

shortname = '.hglf'
longname = 'largefiles'


# -- Portability wrappers ----------------------------------------------

def dirstate_walk(dirstate, matcher, unknown=False, ignored=False):
    return dirstate.walk(matcher, [], unknown, ignored)

def repo_add(repo, list):
    add = repo[None].add
    return add(list)

def repo_remove(repo, list, unlink=False):
    def remove(list, unlink):
        wlock = repo.wlock()
        try:
            if unlink:
                for f in list:
                    try:
                        util.unlinkpath(repo.wjoin(f))
                    except OSError, inst:
                        if inst.errno != errno.ENOENT:
                            raise
            repo[None].forget(list)
        finally:
            wlock.release()
    return remove(list, unlink=unlink)

def repo_forget(repo, list):
    forget = repo[None].forget
    return forget(list)

def findoutgoing(repo, remote, force):
    from mercurial import discovery
    common, _anyinc, _heads = discovery.findcommonincoming(repo,
        remote, force=force)
    return repo.changelog.findmissing(common)

# -- Private worker functions ------------------------------------------

def getminsize(ui, assumelfiles, opt, default=10):
    lfsize = opt
    if not lfsize and assumelfiles:
        lfsize = ui.config(longname, 'minsize', default=default)
    if lfsize:
        try:
            lfsize = float(lfsize)
        except ValueError:
            raise util.Abort(_('largefiles: size must be number (not %s)\n')
                             % lfsize)
    if lfsize is None:
        raise util.Abort(_('minimum size for largefiles must be specified'))
    return lfsize

def link(src, dest):
    try:
        util.oslink(src, dest)
    except OSError:
        # if hardlinks fail, fallback on atomic copy
        dst = util.atomictempfile(dest)
        for chunk in util.filechunkiter(open(src)):
            dst.write(chunk)
        dst.close()
        os.chmod(dest, os.stat(src).st_mode)

def usercachepath(ui, hash):
    path = ui.configpath(longname, 'usercache', None)
    if path:
        path = os.path.join(path, hash)
    else:
        if os.name == 'nt':
            appdata = os.getenv('LOCALAPPDATA', os.getenv('APPDATA'))
            path = os.path.join(appdata, longname, hash)
        elif platform.system() == 'Darwin':
            path = os.path.join(os.getenv('HOME'), 'Library', 'Caches',
                                longname, hash)
        elif os.name == 'posix':
            path = os.getenv('XDG_CACHE_HOME')
            if path:
                path = os.path.join(path, longname, hash)
            else:
                path = os.path.join(os.getenv('HOME'), '.cache', longname, hash)
        else:
            raise util.Abort(_('unknown operating system: %s\n') % os.name)
    return path

def inusercache(ui, hash):
    return os.path.exists(usercachepath(ui, hash))

def findfile(repo, hash):
    if instore(repo, hash):
        repo.ui.note(_('Found %s in store\n') % hash)
    elif inusercache(repo.ui, hash):
        repo.ui.note(_('Found %s in system cache\n') % hash)
        path = storepath(repo, hash)
        util.makedirs(os.path.dirname(path))
        link(usercachepath(repo.ui, hash), path)
    else:
        return None
    return storepath(repo, hash)

class largefiles_dirstate(dirstate.dirstate):
    def __getitem__(self, key):
        return super(largefiles_dirstate, self).__getitem__(unixpath(key))
    def normal(self, f):
        return super(largefiles_dirstate, self).normal(unixpath(f))
    def remove(self, f):
        return super(largefiles_dirstate, self).remove(unixpath(f))
    def add(self, f):
        return super(largefiles_dirstate, self).add(unixpath(f))
    def drop(self, f):
        return super(largefiles_dirstate, self).drop(unixpath(f))
    def forget(self, f):
        return super(largefiles_dirstate, self).forget(unixpath(f))

def openlfdirstate(ui, repo):
    '''
    Return a dirstate object that tracks largefiles: i.e. its root is
    the repo root, but it is saved in .hg/largefiles/dirstate.
    '''
    admin = repo.join(longname)
    opener = scmutil.opener(admin)
    lfdirstate = largefiles_dirstate(opener, ui, repo.root,
                                     repo.dirstate._validate)

    # If the largefiles dirstate does not exist, populate and create
    # it. This ensures that we create it on the first meaningful
    # largefiles operation in a new clone. It also gives us an easy
    # way to forcibly rebuild largefiles state:
    #   rm .hg/largefiles/dirstate && hg status
    # Or even, if things are really messed up:
    #   rm -rf .hg/largefiles && hg status
    if not os.path.exists(os.path.join(admin, 'dirstate')):
        util.makedirs(admin)
        matcher = getstandinmatcher(repo)
        for standin in dirstate_walk(repo.dirstate, matcher):
            lfile = splitstandin(standin)
            hash = readstandin(repo, lfile)
            lfdirstate.normallookup(lfile)
            try:
                if hash == hashfile(repo.wjoin(lfile)):
                    lfdirstate.normal(lfile)
            except OSError, err:
                if err.errno != errno.ENOENT:
                    raise

        lfdirstate.write()

    return lfdirstate

def lfdirstate_status(lfdirstate, repo, rev):
    wlock = repo.wlock()
    try:
        match = match_.always(repo.root, repo.getcwd())
        s = lfdirstate.status(match, [], False, False, False)
        unsure, modified, added, removed, missing, unknown, ignored, clean = s
        for lfile in unsure:
            if repo[rev][standin(lfile)].data().strip() != \
                    hashfile(repo.wjoin(lfile)):
                modified.append(lfile)
            else:
                clean.append(lfile)
                lfdirstate.normal(lfile)
        lfdirstate.write()
    finally:
        wlock.release()
    return (modified, added, removed, missing, unknown, ignored, clean)

def listlfiles(repo, rev=None, matcher=None):
    '''return a list of largefiles in the working copy or the
    specified changeset'''

    if matcher is None:
        matcher = getstandinmatcher(repo)

    # ignore unknown files in working directory
    return [splitstandin(f)
            for f in repo[rev].walk(matcher)
            if rev is not None or repo.dirstate[f] != '?']

def instore(repo, hash):
    return os.path.exists(storepath(repo, hash))

def storepath(repo, hash):
    return repo.join(os.path.join(longname, hash))

def copyfromcache(repo, hash, filename):
    '''Copy the specified largefile from the repo or system cache to
    filename in the repository. Return true on success or false if the
    file was not found in either cache (which should not happened:
    this is meant to be called only after ensuring that the needed
    largefile exists in the cache).'''
    path = findfile(repo, hash)
    if path is None:
        return False
    util.makedirs(os.path.dirname(repo.wjoin(filename)))
    # The write may fail before the file is fully written, but we
    # don't use atomic writes in the working copy.
    shutil.copy(path, repo.wjoin(filename))
    return True

def copytostore(repo, rev, file, uploaded=False):
    hash = readstandin(repo, file)
    if instore(repo, hash):
        return
    copytostoreabsolute(repo, repo.wjoin(file), hash)

def copytostoreabsolute(repo, file, hash):
    util.makedirs(os.path.dirname(storepath(repo, hash)))
    if inusercache(repo.ui, hash):
        link(usercachepath(repo.ui, hash), storepath(repo, hash))
    else:
        dst = util.atomictempfile(storepath(repo, hash))
        for chunk in util.filechunkiter(open(file)):
            dst.write(chunk)
        dst.close()
        util.copymode(file, storepath(repo, hash))
        linktousercache(repo, hash)

def linktousercache(repo, hash):
    util.makedirs(os.path.dirname(usercachepath(repo.ui, hash)))
    link(storepath(repo, hash), usercachepath(repo.ui, hash))

def getstandinmatcher(repo, pats=[], opts={}):
    '''Return a match object that applies pats to the standin directory'''
    standindir = repo.pathto(shortname)
    if pats:
        # patterns supplied: search standin directory relative to current dir
        cwd = repo.getcwd()
        if os.path.isabs(cwd):
            # cwd is an absolute path for hg -R <reponame>
            # work relative to the repository root in this case
            cwd = ''
        pats = [os.path.join(standindir, cwd, pat) for pat in pats]
    elif os.path.isdir(standindir):
        # no patterns: relative to repo root
        pats = [standindir]
    else:
        # no patterns and no standin dir: return matcher that matches nothing
        match = match_.match(repo.root, None, [], exact=True)
        match.matchfn = lambda f: False
        return match
    return getmatcher(repo, pats, opts, showbad=False)

def getmatcher(repo, pats=[], opts={}, showbad=True):
    '''Wrapper around scmutil.match() that adds showbad: if false,
    neuter the match object's bad() method so it does not print any
    warnings about missing files or directories.'''
    match = scmutil.match(repo[None], pats, opts)

    if not showbad:
        match.bad = lambda f, msg: None
    return match

def composestandinmatcher(repo, rmatcher):
    '''Return a matcher that accepts standins corresponding to the
    files accepted by rmatcher. Pass the list of files in the matcher
    as the paths specified by the user.'''
    smatcher = getstandinmatcher(repo, rmatcher.files())
    isstandin = smatcher.matchfn
    def composed_matchfn(f):
        return isstandin(f) and rmatcher.matchfn(splitstandin(f))
    smatcher.matchfn = composed_matchfn

    return smatcher

def standin(filename):
    '''Return the repo-relative path to the standin for the specified big
    file.'''
    # Notes:
    # 1) Most callers want an absolute path, but _create_standin() needs
    #    it repo-relative so lfadd() can pass it to repo_add().  So leave
    #    it up to the caller to use repo.wjoin() to get an absolute path.
    # 2) Join with '/' because that's what dirstate always uses, even on
    #    Windows. Change existing separator to '/' first in case we are
    #    passed filenames from an external source (like the command line).
    return shortname + '/' + filename.replace(os.sep, '/')

def isstandin(filename):
    '''Return true if filename is a big file standin. filename must be
    in Mercurial's internal form (slash-separated).'''
    return filename.startswith(shortname + '/')

def splitstandin(filename):
    # Split on / because that's what dirstate always uses, even on Windows.
    # Change local separator to / first just in case we are passed filenames
    # from an external source (like the command line).
    bits = filename.replace(os.sep, '/').split('/', 1)
    if len(bits) == 2 and bits[0] == shortname:
        return bits[1]
    else:
        return None

def updatestandin(repo, standin):
    file = repo.wjoin(splitstandin(standin))
    if os.path.exists(file):
        hash = hashfile(file)
        executable = getexecutable(file)
        writestandin(repo, standin, hash, executable)

def readstandin(repo, filename, node=None):
    '''read hex hash from standin for filename at given node, or working
    directory if no node is given'''
    return repo[node][standin(filename)].data().strip()

def writestandin(repo, standin, hash, executable):
    '''write hash to <repo.root>/<standin>'''
    writehash(hash, repo.wjoin(standin), executable)

def copyandhash(instream, outfile):
    '''Read bytes from instream (iterable) and write them to outfile,
    computing the SHA-1 hash of the data along the way.  Close outfile
    when done and return the binary hash.'''
    hasher = util.sha1('')
    for data in instream:
        hasher.update(data)
        outfile.write(data)

    # Blecch: closing a file that somebody else opened is rude and
    # wrong. But it's so darn convenient and practical! After all,
    # outfile was opened just to copy and hash.
    outfile.close()

    return hasher.digest()

def hashrepofile(repo, file):
    return hashfile(repo.wjoin(file))

def hashfile(file):
    if not os.path.exists(file):
        return ''
    hasher = util.sha1('')
    fd = open(file, 'rb')
    for data in blockstream(fd):
        hasher.update(data)
    fd.close()
    return hasher.hexdigest()

class limitreader(object):
    def __init__(self, f, limit):
        self.f = f
        self.limit = limit

    def read(self, length):
        if self.limit == 0:
            return ''
        length = length > self.limit and self.limit or length
        self.limit -= length
        return self.f.read(length)

    def close(self):
        pass

def blockstream(infile, blocksize=128 * 1024):
    """Generator that yields blocks of data from infile and closes infile."""
    while True:
        data = infile.read(blocksize)
        if not data:
            break
        yield data
    # same blecch as copyandhash() above
    infile.close()

def readhash(filename):
    rfile = open(filename, 'rb')
    hash = rfile.read(40)
    rfile.close()
    if len(hash) < 40:
        raise util.Abort(_('bad hash in \'%s\' (only %d bytes long)')
                         % (filename, len(hash)))
    return hash

def writehash(hash, filename, executable):
    util.makedirs(os.path.dirname(filename))
    if os.path.exists(filename):
        os.unlink(filename)
    wfile = open(filename, 'wb')

    try:
        wfile.write(hash)
        wfile.write('\n')
    finally:
        wfile.close()
    if os.path.exists(filename):
        os.chmod(filename, getmode(executable))

def getexecutable(filename):
    mode = os.stat(filename).st_mode
    return ((mode & stat.S_IXUSR) and
            (mode & stat.S_IXGRP) and
            (mode & stat.S_IXOTH))

def getmode(executable):
    if executable:
        return 0755
    else:
        return 0644

def urljoin(first, second, *arg):
    def join(left, right):
        if not left.endswith('/'):
            left += '/'
        if right.startswith('/'):
            right = right[1:]
        return left + right

    url = join(first, second)
    for a in arg:
        url = join(url, a)
    return url

def hexsha1(data):
    """hexsha1 returns the hex-encoded sha1 sum of the data in the file-like
    object data"""
    h = util.sha1()
    for chunk in util.filechunkiter(data):
        h.update(chunk)
    return h.hexdigest()

def httpsendfile(ui, filename):
    return httpconnection.httpsendfile(ui, filename, 'rb')

def unixpath(path):
    '''Return a version of path normalized for use with the lfdirstate.'''
    return os.path.normpath(path).replace(os.sep, '/')

def islfilesrepo(repo):
    return ('largefiles' in repo.requirements and
            util.any(shortname + '/' in f[0] for f in repo.store.datafiles()))

def mkstemp(repo, prefix):
    '''Returns a file descriptor and a filename corresponding to a temporary
    file in the repo's largefiles store.'''
    path = repo.join(longname)
    util.makedirs(path)
    return tempfile.mkstemp(prefix=prefix, dir=path)

class storeprotonotcapable(Exception):
    def __init__(self, storetypes):
        self.storetypes = storetypes