simplemerge: let extension check for binary inputs (unless `--text`)

The `simplemerge` module does too much UI-related things. This patch
puts a specialized copy of `simplemerge._verifytext()` in the
simplemerge extension.

Differential Revision: https://phab.mercurial-scm.org/D12146

contrib/simplemerge

@@ -1,121 +1,140 b''
 #!/usr/bin/env python3
 from __future__ import absolute_import
 
 import getopt
 import sys
 
 import hgdemandimport
 
 hgdemandimport.enable()
 
 from mercurial.i18n import _
 from mercurial import (
     context,
     error,
     fancyopts,
     simplemerge,
     ui as uimod,
 )
 from mercurial.utils import procutil, stringutil
 
 options = [
     (b'L', b'label', [], _(b'labels to use on conflict markers')),
     (b'a', b'text', None, _(b'treat all files as text')),
     (b'p', b'print', None, _(b'print results instead of overwriting LOCAL')),
     (b'', b'no-minimal', None, _(b'no effect (DEPRECATED)')),
     (b'h', b'help', None, _(b'display help and exit')),
     (b'q', b'quiet', None, _(b'suppress output')),
 ]
 
 usage = _(
     b'''simplemerge [OPTS] LOCAL BASE OTHER
 
     Simple three-way file merge utility with a minimal feature set.
 
     Apply to LOCAL the changes necessary to go from BASE to OTHER.
 
     By default, LOCAL is overwritten with the results of this operation.
 '''
 )
 
 
 class ParseError(Exception):
     """Exception raised on errors in parsing the command line."""
 
 
 def showhelp():
     procutil.stdout.write(usage)
     procutil.stdout.write(b'\noptions:\n')
 
     out_opts = []
     for shortopt, longopt, default, desc in options:
         out_opts.append(
             (
                 b'%2s%s'
                 % (
                     shortopt and b'-%s' % shortopt,
                     longopt and b' --%s' % longopt,
                 ),
                 b'%s' % desc,
             )
         )
     opts_len = max([len(opt[0]) for opt in out_opts])
     for first, second in out_opts:
         procutil.stdout.write(b' %-*s  %s\n' % (opts_len, first, second))
 
 
+def _verifytext(input, ui, quiet=False, allow_binary=False):
+    """verifies that text is non-binary (unless opts[text] is passed,
+    then we just warn)"""
+    if stringutil.binary(input.text()):
+        msg = _(b"%s looks like a binary file.") % input.fctx.path()
+        if not quiet:
+            ui.warn(_(b'warning: %s\n') % msg)
+        if not allow_binary:
+            sys.exit(1)
+
+
 try:
     for fp in (sys.stdin, procutil.stdout, sys.stderr):
         procutil.setbinary(fp)
 
     opts = {}
     try:
         bargv = [a.encode('utf8') for a in sys.argv[1:]]
         args = fancyopts.fancyopts(bargv, options, opts)
     except getopt.GetoptError as e:
         raise ParseError(e)
     if opts[b'help']:
         showhelp()
         sys.exit(0)
     if len(args) != 3:
         raise ParseError(_(b'wrong number of arguments').decode('utf8'))
     mode = b'merge'
     if len(opts[b'label']) > 2:
         mode = b'merge3'
     local, base, other = args
     overrides = opts[b'label']
     if len(overrides) > 3:
         raise error.InputError(b'can only specify three labels.')
     labels = [local, other, base]
     labels[: len(overrides)] = overrides
     local_input = simplemerge.MergeInput(
         context.arbitraryfilectx(local), labels[0]
     )
     other_input = simplemerge.MergeInput(
         context.arbitraryfilectx(other), labels[1]
     )
     base_input = simplemerge.MergeInput(
         context.arbitraryfilectx(base), labels[2]
     )
+
+    quiet = opts.get(b'quiet')
+    allow_binary = opts.get(b'text')
+    ui = uimod.ui.load()
+    _verifytext(local_input, ui, quiet=quiet, allow_binary=allow_binary)
+    _verifytext(base_input, ui, quiet=quiet, allow_binary=allow_binary)
+    _verifytext(other_input, ui, quiet=quiet, allow_binary=allow_binary)
+
     sys.exit(
         simplemerge.simplemerge(
-            uimod.ui.load(),
+            ui,
             local_input,
             base_input,
             other_input,
             mode,
-            quiet=opts.get(b'quiet'),
-            allow_binary=opts.get(b'text'),
+            quiet=True,
+            allow_binary=allow_binary,
             print_result=opts.get(b'print'),
         )
     )
 except ParseError as e:
     e = stringutil.forcebytestr(e)
     procutil.stdout.write(b"%s: %s\n" % (sys.argv[0].encode('utf8'), e))
     showhelp()
     sys.exit(1)
 except error.Abort as e:
     procutil.stderr.write(b"abort: %s\n" % e)
     sys.exit(255)
 except KeyboardInterrupt:
     sys.exit(255)