Fix filenames with spaces in them.

pre_commit/languages/helpers.py

@@ -2,12 +2,12 @@ from __future__ import unicode_literals
 
 
 def file_args_to_stdin(file_args):
-    return '\n'.join(list(file_args) + [''])
+    return '\0'.join(list(file_args) + [''])
 
 
 def run_hook(env, hook, file_args):
     return env.run(
-        ' '.join(['xargs', hook['entry']] + hook['args']),
+        ' '.join(['xargs', '-0', hook['entry']] + hook['args']),
         stdin=file_args_to_stdin(file_args),
         retcode=None,
     )

pre_commit/languages/pcre.py

@@ -16,7 +16,7 @@ def run_hook(repo_cmd_runner, hook, file_args):
     # For PCRE the entry is the regular expression to match
     return repo_cmd_runner.run(
         [
-            'xargs', 'sh', '-c',
+            'xargs', '-0', 'sh', '-c',
             # Grep usually returns 0 for matches, and nonzero for non-matches
             # so we flip it here.
             '! grep -H -n -P {0} $@'.format(shell_escape(hook['entry'])),

pre_commit/languages/script.py

@@ -13,7 +13,7 @@ def install_environment(repo_cmd_runner, version='default'):
 
 def run_hook(repo_cmd_runner, hook, file_args):
     return repo_cmd_runner.run(
-        ['xargs', '{{prefix}}{0}'.format(hook['entry'])] + hook['args'],
+        ['xargs', '-0', '{{prefix}}{0}'.format(hook['entry'])] + hook['args'],
         # TODO: this is duplicated in pre_commit/languages/helpers.py
         stdin=file_args_to_stdin(file_args),
         retcode=None,

pre_commit/languages/system.py

@@ -15,7 +15,7 @@ def install_environment(repo_cmd_runner, version='default'):
 
 def run_hook(repo_cmd_runner, hook, file_args):
     return repo_cmd_runner.run(
-        ['xargs'] + shlex.split(hook['entry']) + hook['args'],
+        ['xargs', '-0'] + shlex.split(hook['entry']) + hook['args'],
         stdin=file_args_to_stdin(file_args),
         retcode=None,
     )

testing/resources/arg_per_line_hooks_repo/bin/hook.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+for i in "$@"; do
+    echo "arg: $i"
+done

testing/resources/arg_per_line_hooks_repo/hooks.yaml

@@ -0,0 +1,5 @@
+-   id: arg-per-line
+    name: Args per line hook
+    entry: bin/hook.sh
+    language: script
+    files: ''

tests/languages/helpers_test.py

@@ -9,8 +9,8 @@ def test_file_args_to_stdin_empty():
 
 
 def test_file_args_to_stdin_some():
-    assert file_args_to_stdin(['foo', 'bar']) == 'foo\nbar\n'
+    assert file_args_to_stdin(['foo', 'bar']) == 'foo\0bar\0'
 
 
 def test_file_args_to_stdin_tuple():
-    assert file_args_to_stdin(('foo', 'bar')) == 'foo\nbar\n'
+    assert file_args_to_stdin(('foo', 'bar')) == 'foo\0bar\0'

tests/repository_test.py

@@ -102,6 +102,14 @@ def test_run_a_script_hook(tmpdir_factory, store):
     )
 
 
+@pytest.mark.integration
+def test_run_hook_with_spaced_args(tmpdir_factory, store):
+    _test_hook_repo(
+        tmpdir_factory, store, 'arg_per_line_hooks_repo',
+        'arg-per-line', ['foo bar', 'baz'], 'arg: foo bar\narg: baz\n',
+    )
+
+
 @pytest.mark.integration
 def test_pcre_hook_no_match(tmpdir_factory, store):
     path = git_dir(tmpdir_factory)