annotate mercurial/filemerge.py @ 26375:3686fa2b8eee

windows: insert file positioning call between reads and writes

fopen() and fdopen() have a unique-to-Windows requirement that
transitions between read and write operations in files opened
in modes r+, w+, and a+ perform a file positioning call
(fsetpos, fseek, or rewind) in between. While the MSDN docs don't
say what will happen if this is not done, observations reveal
that Python raises an IOError with errno 0. Furthermore, I
/think/ this behavior isn't deterministic. But I can reproduce
it reliably with subsequent patches applied that open revlogs
in a+ mode and perform both reads and writes.

This patch introduces a proxy class for file handles opened
in r+, w+, and a+ mode on Windows. The class intercepts calls
and audits whether a file positioning function has been called
between read and write operations. If not, a dummy, no-op seek
to the current file position is performed. This appears to be
sufficient to "trick" Windows into allowing transitions between
read and writes without raising errors.

# filemerge.py - file-level merge handling for Mercurial
#
# Copyright 2006, 2007, 2008 Matt Mackall <[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.

from __future__ import absolute_import

import filecmp
import os
import re
import tempfile

from .i18n import _
from .node import short

from . import (
    error,
    match,
    simplemerge,
    tagmerge,
    templatekw,
    templater,
    util,
)

def _toolstr(ui, tool, part, default=""):
    return ui.config("merge-tools", tool + "." + part, default)

def _toolbool(ui, tool, part, default=False):
    return ui.configbool("merge-tools", tool + "." + part, default)

def _toollist(ui, tool, part, default=[]):
    return ui.configlist("merge-tools", tool + "." + part, default)

internals = {}
# Merge tools to document.
internalsdoc = {}

def internaltool(name, trymerge, onfailure=None):
    '''return a decorator for populating internal merge tool table'''
    def decorator(func):
        fullname = ':' + name
        func.__doc__ = "``%s``\n" % fullname + func.__doc__.strip()
        internals[fullname] = func
        internals['internal:' + name] = func
        internalsdoc[fullname] = func
        func.trymerge = trymerge
        func.onfailure = onfailure
        return func
    return decorator

def _findtool(ui, tool):
    if tool in internals:
        return tool
    return findexternaltool(ui, tool)

def findexternaltool(ui, tool):
    for kn in ("regkey", "regkeyalt"):
        k = _toolstr(ui, tool, kn)
        if not k:
            continue
        p = util.lookupreg(k, _toolstr(ui, tool, "regname"))
        if p:
            p = util.findexe(p + _toolstr(ui, tool, "regappend"))
            if p:
                return p
    exe = _toolstr(ui, tool, "executable", tool)
    return util.findexe(util.expandpath(exe))

def _picktool(repo, ui, path, binary, symlink):
    def check(tool, pat, symlink, binary):
        tmsg = tool
        if pat:
            tmsg += " specified for " + pat
        if not _findtool(ui, tool):
            if pat: # explicitly requested tool deserves a warning
                ui.warn(_("couldn't find merge tool %s\n") % tmsg)
            else: # configured but non-existing tools are more silent
                ui.note(_("couldn't find merge tool %s\n") % tmsg)
        elif symlink and not _toolbool(ui, tool, "symlink"):
            ui.warn(_("tool %s can't handle symlinks\n") % tmsg)
        elif binary and not _toolbool(ui, tool, "binary"):
            ui.warn(_("tool %s can't handle binary\n") % tmsg)
        elif not util.gui() and _toolbool(ui, tool, "gui"):
            ui.warn(_("tool %s requires a GUI\n") % tmsg)
        else:
            return True
        return False

    # internal config: ui.forcemerge
    # forcemerge comes from command line arguments, highest priority
    force = ui.config('ui', 'forcemerge')
    if force:
        toolpath = _findtool(ui, force)
        if toolpath:
            return (force, util.shellquote(toolpath))
        else:
            # mimic HGMERGE if given tool not found
            return (force, force)

    # HGMERGE takes next precedence
    hgmerge = os.environ.get("HGMERGE")
    if hgmerge:
        return (hgmerge, hgmerge)

    # then patterns
    for pat, tool in ui.configitems("merge-patterns"):
        mf = match.match(repo.root, '', [pat])
        if mf(path) and check(tool, pat, symlink, False):
            toolpath = _findtool(ui, tool)
            return (tool, util.shellquote(toolpath))

    # then merge tools
    tools = {}
    for k, v in ui.configitems("merge-tools"):
        t = k.split('.')[0]
        if t not in tools:
            tools[t] = int(_toolstr(ui, t, "priority", "0"))
    names = tools.keys()
    tools = sorted([(-p, t) for t, p in tools.items()])
    uimerge = ui.config("ui", "merge")
    if uimerge:
        if uimerge not in names:
            return (uimerge, uimerge)
        tools.insert(0, (None, uimerge)) # highest priority
    tools.append((None, "hgmerge")) # the old default, if found
    for p, t in tools:
        if check(t, None, symlink, binary):
            toolpath = _findtool(ui, t)
            return (t, util.shellquote(toolpath))

    # internal merge or prompt as last resort
    if symlink or binary:
        return ":prompt", None
    return ":merge", None

def _eoltype(data):
    "Guess the EOL type of a file"
    if '\0' in data: # binary
        return None
    if '\r\n' in data: # Windows
        return '\r\n'
    if '\r' in data: # Old Mac
        return '\r'
    if '\n' in data: # UNIX
        return '\n'
    return None # unknown

def _matcheol(file, origfile):
    "Convert EOL markers in a file to match origfile"
    tostyle = _eoltype(util.readfile(origfile))
    if tostyle:
        data = util.readfile(file)
        style = _eoltype(data)
        if style:
            newdata = data.replace(style, tostyle)
            if newdata != data:
                util.writefile(file, newdata)

@internaltool('prompt', False)
def _iprompt(repo, mynode, orig, fcd, fco, fca, toolconf):
    """Asks the user which of the local or the other version to keep as
    the merged version."""
    ui = repo.ui
    fd = fcd.path()

    if ui.promptchoice(_(" no tool found to merge %s\n"
                         "keep (l)ocal or take (o)ther?"
                         "$$ &Local $$ &Other") % fd, 0):
        return _iother(repo, mynode, orig, fcd, fco, fca, toolconf)
    else:
        return _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf)

@internaltool('local', False)
def _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf):
    """Uses the local version of files as the merged version."""
    return 0

@internaltool('other', False)
def _iother(repo, mynode, orig, fcd, fco, fca, toolconf):
    """Uses the other version of files as the merged version."""
    repo.wwrite(fcd.path(), fco.data(), fco.flags())
    return 0

@internaltool('fail', False)
def _ifail(repo, mynode, orig, fcd, fco, fca, toolconf):
    """
    Rather than attempting to merge files that were modified on both
    branches, it marks them as unresolved. The resolve command must be
    used to resolve these conflicts."""
    return 1

def _premerge(repo, toolconf, files, labels=None):
    tool, toolpath, binary, symlink = toolconf
    if symlink:
        return 1
    a, b, c, back = files

    ui = repo.ui

    validkeep = ['keep', 'keep-merge3']

    # do we attempt to simplemerge first?
    try:
        premerge = _toolbool(ui, tool, "premerge", not binary)
    except error.ConfigError:
        premerge = _toolstr(ui, tool, "premerge").lower()
        if premerge not in validkeep:
            _valid = ', '.join(["'" + v + "'" for v in validkeep])
            raise error.ConfigError(_("%s.premerge not valid "
                                      "('%s' is neither boolean nor %s)") %
                                    (tool, premerge, _valid))

    if premerge:
        if premerge == 'keep-merge3':
            if not labels:
                labels = _defaultconflictlabels
            if len(labels) < 3:
                labels.append('base')
        r = simplemerge.simplemerge(ui, a, b, c, quiet=True, label=labels)
        if not r:
            ui.debug(" premerge successful\n")
            return 0
        if premerge not in validkeep:
            util.copyfile(back, a) # restore from backup and try again
    return 1 # continue merging

def _merge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels, mode):
    """
    Uses the internal non-interactive simple merge algorithm for merging
    files. It will fail if there are any conflicts and leave markers in
    the partially merged file. Markers will have two sections, one for each side
    of merge, unless mode equals 'union' which suppresses the markers."""
    tool, toolpath, binary, symlink = toolconf
    if symlink:
        repo.ui.warn(_('warning: internal :merge cannot merge symlinks '
                       'for %s\n') % fcd.path())
        return False, 1
    r = _premerge(repo, toolconf, files, labels=labels)
    if r:
        a, b, c, back = files

        ui = repo.ui

        r = simplemerge.simplemerge(ui, a, b, c, label=labels, mode=mode)
        return True, r
    return False, 0

@internaltool('union', True,
              _("merging %s incomplete! "
                "(edit conflicts, then use 'hg resolve --mark')\n"))
def _iunion(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    """
    Uses the internal non-interactive simple merge algorithm for merging
    files. It will use both left and right sides for conflict regions.
    No markers are inserted."""
    return _merge(repo, mynode, orig, fcd, fco, fca, toolconf,
                  files, labels, 'union')

@internaltool('merge', True,
              _("merging %s incomplete! "
                "(edit conflicts, then use 'hg resolve --mark')\n"))
def _imerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    """
    Uses the internal non-interactive simple merge algorithm for merging
    files. It will fail if there are any conflicts and leave markers in
    the partially merged file. Markers will have two sections, one for each side
    of merge."""
    return _merge(repo, mynode, orig, fcd, fco, fca, toolconf,
                  files, labels, 'merge')

@internaltool('merge3', True,
              _("merging %s incomplete! "
                "(edit conflicts, then use 'hg resolve --mark')\n"))
def _imerge3(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    """
    Uses the internal non-interactive simple merge algorithm for merging
    files. It will fail if there are any conflicts and leave markers in
    the partially merged file. Marker will have three sections, one from each
    side of the merge and one for the base content."""
    if not labels:
        labels = _defaultconflictlabels
    if len(labels) < 3:
        labels.append('base')
    return _imerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels)

def _imergeauto(repo, mynode, orig, fcd, fco, fca, toolconf, files,
                labels=None, localorother=None):
    """
    Generic driver for _imergelocal and _imergeother
    """
    assert localorother is not None
    tool, toolpath, binary, symlink = toolconf
    if symlink:
        repo.ui.warn(_('warning: :merge-%s cannot merge symlinks '
                       'for %s\n') % (localorother, fcd.path()))
        return False, 1
    a, b, c, back = files
    r = simplemerge.simplemerge(repo.ui, a, b, c, label=labels,
                                localorother=localorother)
    return True, r

@internaltool('merge-local', True)
def _imergelocal(*args, **kwargs):
    """
    Like :merge, but resolve all conflicts non-interactively in favor
    of the local changes."""
    success, status = _imergeauto(localorother='local', *args, **kwargs)
    return success, status

@internaltool('merge-other', True)
def _imergeother(*args, **kwargs):
    """
    Like :merge, but resolve all conflicts non-interactively in favor
    of the other changes."""
    success, status = _imergeauto(localorother='other', *args, **kwargs)
    return success, status

@internaltool('tagmerge', True,
              _("automatic tag merging of %s failed! "
                "(use 'hg resolve --tool :merge' or another merge "
                "tool of your choice)\n"))
def _itagmerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    """
    Uses the internal tag merge algorithm (experimental).
    """
    return tagmerge.merge(repo, fcd, fco, fca)

@internaltool('dump', True)
def _idump(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    """
    Creates three versions of the files to merge, containing the
    contents of local, other and base. These files can then be used to
    perform a merge manually. If the file to be merged is named
    ``a.txt``, these files will accordingly be named ``a.txt.local``,
    ``a.txt.other`` and ``a.txt.base`` and they will be placed in the
    same directory as ``a.txt``."""
    r = _premerge(repo, toolconf, files, labels=labels)
    if r:
        a, b, c, back = files

        fd = fcd.path()

        util.copyfile(a, a + ".local")
        repo.wwrite(fd + ".other", fco.data(), fco.flags())
        repo.wwrite(fd + ".base", fca.data(), fca.flags())
    return False, r

def _xmerge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
    r = _premerge(repo, toolconf, files, labels=labels)
    if r:
        tool, toolpath, binary, symlink = toolconf
        a, b, c, back = files
        out = ""
        env = {'HG_FILE': fcd.path(),
               'HG_MY_NODE': short(mynode),
               'HG_OTHER_NODE': str(fco.changectx()),
               'HG_BASE_NODE': str(fca.changectx()),
               'HG_MY_ISLINK': 'l' in fcd.flags(),
               'HG_OTHER_ISLINK': 'l' in fco.flags(),
               'HG_BASE_ISLINK': 'l' in fca.flags(),
               }

        ui = repo.ui

        args = _toolstr(ui, tool, "args", '$local $base $other')
        if "$output" in args:
            out, a = a, back # read input from backup, write to original
        replace = {'local': a, 'base': b, 'other': c, 'output': out}
        args = util.interpolate(r'\$', replace, args,
                                lambda s: util.shellquote(util.localpath(s)))
        cmd = toolpath + ' ' + args
        repo.ui.debug('launching merge tool: %s\n' % cmd)
        r = ui.system(cmd, cwd=repo.root, environ=env)
        repo.ui.debug('merge tool returned: %s\n' % r)
        return True, r
    return False, 0

def _formatconflictmarker(repo, ctx, template, label, pad):
    """Applies the given template to the ctx, prefixed by the label.

    Pad is the minimum width of the label prefix, so that multiple markers
    can have aligned templated parts.
    """
    if ctx.node() is None:
        ctx = ctx.p1()

    props = templatekw.keywords.copy()
    props['templ'] = template
    props['ctx'] = ctx
    props['repo'] = repo
    templateresult = template('conflictmarker', **props)

    label = ('%s:' % label).ljust(pad + 1)
    mark = '%s %s' % (label, templater.stringify(templateresult))

    if mark:
        mark = mark.splitlines()[0] # split for safety

    # 8 for the prefix of conflict marker lines (e.g. '<<<<<<< ')
    return util.ellipsis(mark, 80 - 8)

_defaultconflictmarker = ('{node|short} ' +
    '{ifeq(tags, "tip", "", "{tags} ")}' +
    '{if(bookmarks, "{bookmarks} ")}' +
    '{ifeq(branch, "default", "", "{branch} ")}' +
    '- {author|user}: {desc|firstline}')

_defaultconflictlabels = ['local', 'other']

def _formatlabels(repo, fcd, fco, fca, labels):
    """Formats the given labels using the conflict marker template.

    Returns a list of formatted labels.
    """
    cd = fcd.changectx()
    co = fco.changectx()
    ca = fca.changectx()

    ui = repo.ui
    template = ui.config('ui', 'mergemarkertemplate', _defaultconflictmarker)
    tmpl = templater.templater(None, cache={'conflictmarker': template})

    pad = max(len(l) for l in labels)

    newlabels = [_formatconflictmarker(repo, cd, tmpl, labels[0], pad),
                 _formatconflictmarker(repo, co, tmpl, labels[1], pad)]
    if len(labels) > 2:
        newlabels.append(_formatconflictmarker(repo, ca, tmpl, labels[2], pad))
    return newlabels

def filemerge(repo, mynode, orig, fcd, fco, fca, labels=None):
    """perform a 3-way merge in the working directory

    mynode = parent node before merge
    orig = original local filename before merge
    fco = other file context
    fca = ancestor file context
    fcd = local file context for current/destination file
    """

    def temp(prefix, ctx):
        pre = "%s~%s." % (os.path.basename(ctx.path()), prefix)
        (fd, name) = tempfile.mkstemp(prefix=pre)
        data = repo.wwritedata(ctx.path(), ctx.data())
        f = os.fdopen(fd, "wb")
        f.write(data)
        f.close()
        return name

    if not fco.cmp(fcd): # files identical?
        return None

    ui = repo.ui
    fd = fcd.path()
    binary = fcd.isbinary() or fco.isbinary() or fca.isbinary()
    symlink = 'l' in fcd.flags() + fco.flags()
    tool, toolpath = _picktool(repo, ui, fd, binary, symlink)
    ui.debug("picked tool '%s' for %s (binary %s symlink %s)\n" %
               (tool, fd, binary, symlink))

    if tool in internals:
        func = internals[tool]
        trymerge = func.trymerge
        onfailure = func.onfailure
    else:
        func = _xmerge
        trymerge = True
        onfailure = _("merging %s failed!\n")

    toolconf = tool, toolpath, binary, symlink

    if not trymerge:
        return func(repo, mynode, orig, fcd, fco, fca, toolconf)

    a = repo.wjoin(fd)
    b = temp("base", fca)
    c = temp("other", fco)
    back = a + ".orig"
    util.copyfile(a, back)

    if orig != fco.path():
        ui.status(_("merging %s and %s to %s\n") % (orig, fco.path(), fd))
    else:
        ui.status(_("merging %s\n") % fd)

    ui.debug("my %s other %s ancestor %s\n" % (fcd, fco, fca))

    markerstyle = ui.config('ui', 'mergemarkers', 'basic')
    if not labels:
        labels = _defaultconflictlabels
    if markerstyle != 'basic':
        labels = _formatlabels(repo, fcd, fco, fca, labels)

    needcheck, r = func(repo, mynode, orig, fcd, fco, fca, toolconf,
                        (a, b, c, back), labels=labels)
    if not needcheck:
        if r:
            if onfailure:
                ui.warn(onfailure % fd)
        else:
            util.unlink(back)

        util.unlink(b)
        util.unlink(c)
        return r

    if not r and (_toolbool(ui, tool, "checkconflicts") or
                  'conflicts' in _toollist(ui, tool, "check")):
        if re.search("^(<<<<<<< .*|=======|>>>>>>> .*)$", fcd.data(),
                     re.MULTILINE):
            r = 1

    checked = False
    if 'prompt' in _toollist(ui, tool, "check"):
        checked = True
        if ui.promptchoice(_("was merge of '%s' successful (yn)?"
                             "$$ &Yes $$ &No") % fd, 1):
            r = 1

    if not r and not checked and (_toolbool(ui, tool, "checkchanged") or
                                  'changed' in _toollist(ui, tool, "check")):
        if filecmp.cmp(a, back):
            if ui.promptchoice(_(" output file %s appears unchanged\n"
                                 "was merge successful (yn)?"
                                 "$$ &Yes $$ &No") % fd, 1):
                r = 1

    if _toolbool(ui, tool, "fixeol"):
        _matcheol(a, back)

    if r:
        if onfailure:
            ui.warn(onfailure % fd)
    else:
        util.unlink(back)

    util.unlink(b)
    util.unlink(c)
    return r

# tell hggettext to extract docstrings from these functions:
i18nfunctions = internals.values()