view tests/f @ 35098:66c5a8cf2868

lfs: import the Facebook git-lfs client extension

The purpose of this is the same as the built-in largefiles extension- to handle
huge files outside of the normal storage system, generally to keep the amount of
data cloned to a lower amount.  There are several benefits of implementing the
git-lfs protocol, instead of using the largefiles extension:

  - Bitbucket and Github support (and probably wider support in 3rd party
    hosting sites in general). [1][2]

  - The number of hg internals monkey patched are several orders of magnitude
    lower, so it will be easier to reason about and maintain.  Future commands
    will likely just work, without requiring various wrappers.

  - The "standin" files are only written to the filelog, not the disk.  That
    should avoid weird edge cases where the largefile and standin files get out
    of sync. [3]  It also avoids the occasional printing of the "hidden" standin
    file in various messages.

  - Filesets like size() will work, even if the file isn't present.  (It always
    says 41 bytes for largefiles, whether present or not.)

The only place that I see where largefiles comes out on top is that it works
with `hg serve` for simple sharing, without external infrastructure.  Getting
lfs-test-server working was a hassle, and took awhile to figure out.  Maybe we
can do something to make it work in the future.

Long term, I expect that this will be highly preferred over largefiles.  But if
we are to recommend this to largefile users, there are some UI issues to
bikeshed.  Until they are resolved, I've marked this experimental, and am not
putting a pointer to this in the largefiles help.  The (non exhaustive) list of
issues I've seen so far are:

  - It isn't sufficient to just enable the largefiles extension- you have to
    explicitly add a file with --large before it will pay attention to the
    configured sizes and patterns on future adds.  The justification being that
    once you use it, you're stuck with it.  I've seen people confused by this,
    and haven't liked it myself.  But it's also saved me a few times.  Should we
    do something like have a specific enabling config setting that must be set
    in the local repo config, so that enabling this extension in the user or
    system hgrc doesn't silently start storing lfs files?

  - The largefiles extension adds a repo requirement when the first largefile is
    committed, so that the extension must always be enabled in the future.  This
    extension is not doing that, and since I only enabled it locally to avoid
    infecting other repos, I got a cryptic error about missing flag processors
    when I cloned.  Is there no repo requirement due to shallow/narrow clone
    considerations (or other future advanced things)?

  - In the (small amount of) reading I've done about the git implementation, it
    seems that the files and sizes are stored in a tracked .gitattributes file.
    I think a tracked file for this would be extremely useful for consistency
    across developers, but this kind of touches on the tracked hgrc file
    proposal a few months back.

  - The git client can specify file patterns, not just sizes.

  - The largefiles extension has a cache directory in the local repo, but also a
    system wide one.  We should probably implement a system wide cache too, so
    that multiple clones don't have to refetch the files from the server.

  - Jun mentioned other missing features, like SSH authentication, gc, etc.

The code corresponds to c0492b73c7ef in hg-experimental. [4]  The only tweaks
are to load the extension in the tests with 'lfs=' instead of
'lfs=$TESTDIR/../hgext3rd/lfs', change the import in the *.py test to hgext
(from hgext3rd), add the 'testedwith' declaration, and mark it experimental for
now.  The infinite-push, p4fastimport, and remotefilelog tests were left behind.

The devel-warnings for unregistered config options are not corrected yet, nor
are the import check warnings.

[1] https://www.mercurial-scm.org/pipermail/mercurial/2017-November/050699.html
[2] https://bitbucket.org/site/master/issues/3843/largefiles-support-bb-3903
[3] https://bz.mercurial-scm.org/show_bug.cgi?id=5738
[4] https://bitbucket.org/facebook/hg-experimental

#!/usr/bin/env python

"""
Utility for inspecting files in various ways.

This tool is like the collection of tools found in a unix environment but are
cross platform and stable and suitable for our needs in the test suite.

This can be used instead of tools like:
  [
  dd
  find
  head
  hexdump
  ls
  md5sum
  readlink
  sha1sum
  stat
  tail
  test
  readlink.py
  md5sum.py
"""

from __future__ import absolute_import

import glob
import hashlib
import optparse
import os
import re
import sys

# Python 3 adapters
ispy3 = (sys.version_info[0] >= 3)
if ispy3:
    def iterbytes(s):
        for i in range(len(s)):
            yield s[i:i + 1]
else:
    iterbytes = iter

def visit(opts, filenames, outfile):
    """Process filenames in the way specified in opts, writing output to
    outfile."""
    for f in sorted(filenames):
        isstdin = f == '-'
        if not isstdin and not os.path.lexists(f):
            outfile.write(b'%s: file not found\n' % f.encode('utf-8'))
            continue
        quiet = opts.quiet and not opts.recurse or isstdin
        isdir = os.path.isdir(f)
        islink = os.path.islink(f)
        isfile = os.path.isfile(f) and not islink
        dirfiles = None
        content = None
        facts = []
        if isfile:
            if opts.type:
                facts.append('file')
            if opts.hexdump or opts.dump or opts.md5:
                content = open(f, 'rb').read()
        elif islink:
            if opts.type:
                facts.append('link')
            content = os.readlink(f)
        elif isstdin:
            content = getattr(sys.stdin, 'buffer', sys.stdin).read()
            if opts.size:
                facts.append('size=%s' % len(content))
        elif isdir:
            if opts.recurse or opts.type:
                dirfiles = glob.glob(f + '/*')
                facts.append('directory with %s files' % len(dirfiles))
        elif opts.type:
            facts.append('type unknown')
        if not isstdin:
            stat = os.lstat(f)
            if opts.size and not isdir:
                facts.append('size=%s' % stat.st_size)
            if opts.mode and not islink:
                facts.append('mode=%o' % (stat.st_mode & 0o777))
            if opts.links:
                facts.append('links=%s' % stat.st_nlink)
            if opts.newer:
                # mtime might be in whole seconds so newer file might be same
                if stat.st_mtime >= os.stat(opts.newer).st_mtime:
                    facts.append('newer than %s' % opts.newer)
                else:
                    facts.append('older than %s' % opts.newer)
        if opts.md5 and content is not None:
            h = hashlib.md5(content)
            facts.append('md5=%s' % h.hexdigest()[:opts.bytes])
        if opts.sha1 and content is not None:
            h = hashlib.sha1(content)
            facts.append('sha1=%s' % h.hexdigest()[:opts.bytes])
        if isstdin:
            outfile.write(b', '.join(facts) + b'\n')
        elif facts:
            outfile.write(b'%s: %s\n' % (f.encode('utf-8'), b', '.join(facts)))
        elif not quiet:
            outfile.write(b'%s:\n' % f.encode('utf-8'))
        if content is not None:
            chunk = content
            if not islink:
                if opts.lines:
                    if opts.lines >= 0:
                        chunk = b''.join(chunk.splitlines(True)[:opts.lines])
                    else:
                        chunk = b''.join(chunk.splitlines(True)[opts.lines:])
                if opts.bytes:
                    if opts.bytes >= 0:
                        chunk = chunk[:opts.bytes]
                    else:
                        chunk = chunk[opts.bytes:]
            if opts.hexdump:
                for i in range(0, len(chunk), 16):
                    s = chunk[i:i + 16]
                    outfile.write(b'%04x: %-47s |%s|\n' %
                                  (i, b' '.join(
                                      b'%02x' % ord(c) for c in iterbytes(s)),
                                   re.sub(b'[^ -~]', b'.', s)))
            if opts.dump:
                if not quiet:
                    outfile.write(b'>>>\n')
                outfile.write(chunk)
                if not quiet:
                    if chunk.endswith(b'\n'):
                        outfile.write(b'<<<\n')
                    else:
                        outfile.write(b'\n<<< no trailing newline\n')
        if opts.recurse and dirfiles:
            assert not isstdin
            visit(opts, dirfiles, outfile)

if __name__ == "__main__":
    parser = optparse.OptionParser("%prog [options] [filenames]")
    parser.add_option("-t", "--type", action="store_true",
                      help="show file type (file or directory)")
    parser.add_option("-m", "--mode", action="store_true",
                      help="show file mode")
    parser.add_option("-l", "--links", action="store_true",
                      help="show number of links")
    parser.add_option("-s", "--size", action="store_true",
                      help="show size of file")
    parser.add_option("-n", "--newer", action="store",
                      help="check if file is newer (or same)")
    parser.add_option("-r", "--recurse", action="store_true",
                      help="recurse into directories")
    parser.add_option("-S", "--sha1", action="store_true",
                      help="show sha1 hash of the content")
    parser.add_option("-M", "--md5", action="store_true",
                      help="show md5 hash of the content")
    parser.add_option("-D", "--dump", action="store_true",
                      help="dump file content")
    parser.add_option("-H", "--hexdump", action="store_true",
                      help="hexdump file content")
    parser.add_option("-B", "--bytes", type="int",
                      help="number of characters to dump")
    parser.add_option("-L", "--lines", type="int",
                      help="number of lines to dump")
    parser.add_option("-q", "--quiet", action="store_true",
                      help="no default output")
    (opts, filenames) = parser.parse_args(sys.argv[1:])
    if not filenames:
        filenames = ['-']

    visit(opts, filenames, getattr(sys.stdout, 'buffer', sys.stdout))