comparison mercurial/filemerge.py @ 35702:c0439e11af16

filemerge: fix backing up an in-memory file to a custom location

If the user specifies a ui.origbackuppath, we used to always copy the file
there, but if the source file is in memory we must write it instead of copying.

Differential Revision: https://phab.mercurial-scm.org/D1806

35701:c5d220a621e7

    In addition to preserving the user's pre-existing modifications to `fcd`
    (if any), the backup is used to undo certain premerges, confirm whether a
    merge changed anything, and determine what line endings the new file should
    have.
    """
    if fcd.isabsent():
        return None
    # TODO: Break this import cycle somehow. (filectx -> ctx -> fileset ->
    # merge -> filemerge). (I suspect the fileset import is the weakest link)
    from . import context
    a = _workingpath(repo, fcd)
    back = scmutil.origpath(ui, repo, a)
    inworkingdir = (back.startswith(repo.wvfs.base) and not
        back.startswith(repo.vfs.base))

    if isinstance(fcd, context.overlayworkingfilectx) and inworkingdir:
        # If the backup file is to be in the working directory, and we're
        # merging in-memory, we must redirect the backup to the memory context
        # so we don't disturb the working directory.
        relpath = back[len(repo.wvfs.base) + 1:]
        wctx[relpath].write(fcd.data(), fcd.flags())
        return wctx[relpath]
    else:
        # Otherwise, write to wherever the user specified the backups should go.
        #
        # A arbitraryfilectx is returned, so we can run the same functions on
        # the backup context regardless of where it lives.
        if premerge:
            util.copyfile(a, back)
        return context.arbitraryfilectx(back, repo=repo)

def _maketempfiles(repo, fco, fca):
    """Writes out `fco` and `fca` as temporary files, so an external merge
    tool may use them.

35702:c0439e11af16

    In addition to preserving the user's pre-existing modifications to `fcd`
    (if any), the backup is used to undo certain premerges, confirm whether a
    merge changed anything, and determine what line endings the new file should
    have.

    Backups only need to be written once (right before the premerge) since their
    content doesn't change afterwards.
    """
    if fcd.isabsent():
        return None
    # TODO: Break this import cycle somehow. (filectx -> ctx -> fileset ->
    # merge -> filemerge). (I suspect the fileset import is the weakest link)
    from . import context
    a = _workingpath(repo, fcd)
    back = scmutil.origpath(ui, repo, a)
    inworkingdir = (back.startswith(repo.wvfs.base) and not
        back.startswith(repo.vfs.base))
    if isinstance(fcd, context.overlayworkingfilectx) and inworkingdir:
        # If the backup file is to be in the working directory, and we're
        # merging in-memory, we must redirect the backup to the memory context
        # so we don't disturb the working directory.
        relpath = back[len(repo.wvfs.base) + 1:]
        wctx[relpath].write(fcd.data(), fcd.flags())
        return wctx[relpath]
    else:
        if premerge:
            # Otherwise, write to wherever path the user specified the backups
            # should go. We still need to switch based on whether the source is
            # in-memory so we can use the fast path of ``util.copy`` if both are
            # on disk.
            if isinstance(fcd, context.overlayworkingfilectx):
                util.writefile(back, fcd.data())
            else:
                util.copyfile(a, back)
        # A arbitraryfilectx is returned, so we can run the same functions on
        # the backup context regardless of where it lives.
        return context.arbitraryfilectx(back, repo=repo)

def _maketempfiles(repo, fco, fca):
    """Writes out `fco` and `fca` as temporary files, so an external merge
    tool may use them.