view hgext/fastexport.py @ 50336:cf4d2f31660d stable

chg: populate CHGHG if not set

Normally, chg determines which `hg` executable to use by first consulting the
`$CHGHG` and `$HG` environment variables, and if neither are present defaults
to the `hg` found in the user's `$PATH`. If built with the `HGPATHREL` compiler
flag, chg will instead assume that there exists an `hg` executable in the same
directory as the `chg` binary and attempt to use that.

This can cause problems in situations where there are multiple actively-used
Mercurial installations on the same system. When a `chg` client connects to a
running command server, the server process performs some basic validation to
determine whether a new command server needs to be spawned. These checks include
things like checking certain "sensitive" environment variables and config
sections, as well as checking whether the mtime of the extensions, hg's
`__version__.py` module, and the Python interpreter have changed.

Crucially, the command server doesn't explicitly check whether the executable it
is running from matches the executable that the `chg` client would have
otherwise invoked had there been no existing command server process. Without
`HGPATHREL`, this still gets implicitly checked during the validation step,
because the only way to specify an alternate hg executable (apart from `$PATH`)
is via the `$CHGHG` and `$HG` environment variables, both of which are checked.

With `HGPATHREL`, however, the command server has no way of knowing which hg
executable the client would have run. This means that a client located at
`/version_B/bin/chg` will happily connect to a command server running
`/version_A/bin/hg` instead of `/version_B/bin/hg` as expected. A simple
solution is to have the client set `$CHGHG` itself, which then allows the
command server's environment validation to work as intended.

I have tested this manually using two locally built hg installations and it
seems to work with no ill effects. That said, I'm not sure how to write an
automated test for this since the `chg` available to the tests isn't even built
with the `HGPATHREL` compiler flag to begin with.

# Copyright 2020 Joerg Sonnenberger <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""export repositories as git fast-import stream"""

# The format specification for fast-import streams can be found at
# https://git-scm.com/docs/git-fast-import#_input_format

import re

from mercurial.i18n import _
from mercurial.node import hex, nullrev
from mercurial.utils import stringutil
from mercurial import (
    error,
    logcmdutil,
    pycompat,
    registrar,
    scmutil,
)
from .convert import convcmd

# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = b"ships-with-hg-core"

cmdtable = {}
command = registrar.command(cmdtable)

GIT_PERSON_PROHIBITED = re.compile(b'[<>\n"]')
GIT_EMAIL_PROHIBITED = re.compile(b"[<> \n]")


def convert_to_git_user(authormap, user, rev):
    mapped_user = authormap.get(user, user)
    user_person = stringutil.person(mapped_user)
    user_email = stringutil.email(mapped_user)
    if GIT_EMAIL_PROHIBITED.match(user_email) or GIT_PERSON_PROHIBITED.match(
        user_person
    ):
        raise error.Abort(
            _(b"Unable to parse user into person and email for revision %s")
            % rev
        )
    if user_person:
        return b'"' + user_person + b'" <' + user_email + b'>'
    else:
        return b"<" + user_email + b">"


def convert_to_git_date(date):
    timestamp, utcoff = date
    tzsign = b"+" if utcoff <= 0 else b"-"
    if utcoff % 60 != 0:
        raise error.Abort(
            _(b"UTC offset in %b is not an integer number of seconds") % (date,)
        )
    utcoff = abs(utcoff) // 60
    tzh = utcoff // 60
    tzmin = utcoff % 60
    return b"%d " % int(timestamp) + tzsign + b"%02d%02d" % (tzh, tzmin)


def convert_to_git_ref(branch):
    # XXX filter/map depending on git restrictions
    return b"refs/heads/" + branch


def write_data(buf, data, skip_newline):
    buf.append(b"data %d\n" % len(data))
    buf.append(data)
    if not skip_newline or data[-1:] != b"\n":
        buf.append(b"\n")


def export_commit(ui, repo, rev, marks, authormap):
    ctx = repo[rev]
    revid = ctx.hex()
    if revid in marks:
        ui.debug(b"warning: revision %s already exported, skipped\n" % revid)
        return
    parents = [p for p in ctx.parents() if p.rev() != nullrev]
    for p in parents:
        if p.hex() not in marks:
            ui.warn(
                _(b"warning: parent %s of %s has not been exported, skipped\n")
                % (p, revid)
            )
            return

    # For all files modified by the commit, check if they have already
    # been exported and otherwise dump the blob with the new mark.
    for fname in ctx.files():
        if fname not in ctx:
            continue
        filectx = ctx.filectx(fname)
        filerev = hex(filectx.filenode())
        if filerev not in marks:
            mark = len(marks) + 1
            marks[filerev] = mark
            data = filectx.data()
            buf = [b"blob\n", b"mark :%d\n" % mark]
            write_data(buf, data, False)
            ui.write(*buf, keepprogressbar=True)
            del buf

    # Assign a mark for the current revision for references by
    # latter merge commits.
    mark = len(marks) + 1
    marks[revid] = mark

    ref = convert_to_git_ref(ctx.branch())
    buf = [
        b"commit %s\n" % ref,
        b"mark :%d\n" % mark,
        b"committer %s %s\n"
        % (
            convert_to_git_user(authormap, ctx.user(), revid),
            convert_to_git_date(ctx.date()),
        ),
    ]
    write_data(buf, ctx.description(), True)
    if parents:
        buf.append(b"from :%d\n" % marks[parents[0].hex()])
    if len(parents) == 2:
        buf.append(b"merge :%d\n" % marks[parents[1].hex()])
        p0ctx = repo[parents[0]]
        files = ctx.manifest().diff(p0ctx.manifest())
    else:
        files = ctx.files()
    filebuf = []
    for fname in files:
        if fname not in ctx:
            filebuf.append((fname, b"D %s\n" % fname))
        else:
            filectx = ctx.filectx(fname)
            filerev = filectx.filenode()
            fileperm = b"755" if filectx.isexec() else b"644"
            changed = b"M %s :%d %s\n" % (fileperm, marks[hex(filerev)], fname)
            filebuf.append((fname, changed))
    filebuf.sort()
    buf.extend(changed for (fname, changed) in filebuf)
    del filebuf
    buf.append(b"\n")
    ui.write(*buf, keepprogressbar=True)
    del buf


isrev = re.compile(b"^[0-9a-f]{40}$")


@command(
    b"fastexport",
    [
        (b"r", b"rev", [], _(b"revisions to export"), _(b"REV")),
        (b"i", b"import-marks", b"", _(b"old marks file to read"), _(b"FILE")),
        (b"e", b"export-marks", b"", _(b"new marks file to write"), _(b"FILE")),
        (
            b"A",
            b"authormap",
            b"",
            _(b"remap usernames using this file"),
            _(b"FILE"),
        ),
    ],
    _(b"[OPTION]... [REV]..."),
    helpcategory=command.CATEGORY_IMPORT_EXPORT,
)
def fastexport(ui, repo, *revs, **opts):
    """export repository as git fast-import stream

    This command lets you dump a repository as a human-readable text stream.
    It can be piped into corresponding import routines like "git fast-import".
    Incremental dumps can be created by using marks files.
    """
    opts = pycompat.byteskwargs(opts)

    revs += tuple(opts.get(b"rev", []))
    if not revs:
        revs = scmutil.revrange(repo, [b":"])
    else:
        revs = logcmdutil.revrange(repo, revs)
    if not revs:
        raise error.Abort(_(b"no revisions matched"))
    authorfile = opts.get(b"authormap")
    if authorfile:
        authormap = convcmd.readauthormap(ui, authorfile)
    else:
        authormap = {}

    import_marks = opts.get(b"import_marks")
    marks = {}
    if import_marks:
        with open(import_marks, "rb") as import_marks_file:
            for line in import_marks_file:
                line = line.strip()
                if not isrev.match(line) or line in marks:
                    raise error.Abort(_(b"Corrupted marks file"))
                marks[line] = len(marks) + 1

    revs.sort()
    with ui.makeprogress(
        _(b"exporting"), unit=_(b"revisions"), total=len(revs)
    ) as progress:
        for rev in revs:
            export_commit(ui, repo, rev, marks, authormap)
            progress.increment()

    export_marks = opts.get(b"export_marks")
    if export_marks:
        with open(export_marks, "wb") as export_marks_file:
            output_marks = [None] * len(marks)
            for k, v in marks.items():
                output_marks[v - 1] = k
            for k in output_marks:
                export_marks_file.write(k + b"\n")