Rewrite the hook template in python

pre_commit/resources/commit-msg-tmpl

@@ -1 +0,0 @@
-args="--hook-stage=commit-msg --commit-msg-filename=$1"

pre_commit/resources/hook-tmpl

@@ -1,55 +1,167 @@
-#!/usr/bin/env bash
-# This is a randomish md5 to identify this script
-# 138fd403232d2ddd5efb44317e38bf03
+#!/usr/bin/env python
+"""File generated by pre-commit: https://pre-commit.com"""
+from __future__ import print_function
 
-pushd "$(dirname "$0")" >& /dev/null
-HERE="$(pwd)"
-popd >& /dev/null
+import distutils.spawn
+import os
+import subprocess
+import sys
 
-retv=0
-args=""
+HERE = os.path.dirname(os.path.abspath(__file__))
+Z40 = '0' * 40
+ID_HASH = '138fd403232d2ddd5efb44317e38bf03'
+# start templated
+CONFIG = None
+HOOK_TYPE = None
+INSTALL_PYTHON = None
+SKIP_ON_MISSING_CONFIG = None
+# end templated
 
-ENV_PYTHON={sys_executable}
-SKIP_ON_MISSING_CONF={skip_on_missing_conf}
 
-if which pre-commit >& /dev/null; then
-    exe="pre-commit"
-    run_args=""
-elif "$ENV_PYTHON" -c 'import pre_commit.main' >& /dev/null; then
-    exe="$ENV_PYTHON"
-    run_args="-m pre_commit.main"
-elif python -c 'import pre_commit.main' >& /dev/null; then
-    exe="python"
-    run_args="-m pre_commit.main"
-else
-    echo '`pre-commit` not found.  Did you forget to activate your virtualenv?'
-    exit 1
-fi
+class EarlyExit(RuntimeError):
+    pass
 
-# Run the legacy pre-commit if it exists
-if [ -x "$HERE"/{hook_type}.legacy ] && ! "$HERE"/{hook_type}.legacy "$@"; then
-    retv=1
-fi
 
-CONF_FILE="$(git rev-parse --show-toplevel)/{config_file}"
-if [ ! -f "$CONF_FILE" ]; then
-    if [ "$SKIP_ON_MISSING_CONF" = true -o ! -z "$PRE_COMMIT_ALLOW_NO_CONFIG" ]; then
-        echo '`{config_file}` config file not found. Skipping `pre-commit`.'
-        exit $retv
-    else
-        echo 'No {config_file} file was found'
-        echo '- To temporarily silence this, run `PRE_COMMIT_ALLOW_NO_CONFIG=1 git ...`'
-        echo '- To permanently silence this, install pre-commit with the `--allow-missing-config` option'
-        echo '- To uninstall pre-commit run `pre-commit uninstall`'
-        exit 1
-	fi
-fi
+class FatalError(RuntimeError):
+    pass
 
-{hook_specific}
 
-# Run pre-commit
-if ! "$exe" $run_args run $args --config {config_file}; then
-    retv=1
-fi
+def _norm_exe(exe):
+    """Necessary for shebang support on windows.
 
-exit $retv
+    roughly lifted from `identify.identify.parse_shebang`
+    """
+    with open(exe, 'rb') as f:
+        if f.read(2) != b'#!':
+            return ()
+        try:
+            first_line = f.readline().decode('UTF-8')
+        except UnicodeDecodeError:
+            return ()
+
+        cmd = first_line.split()
+        if cmd[0] == '/usr/bin/env':
+            del cmd[0]
+        return tuple(cmd)
+
+
+def _run_legacy():
+    if HOOK_TYPE == 'pre-push':
+        stdin = getattr(sys.stdin, 'buffer', sys.stdin).read()
+    else:
+        stdin = None
+
+    legacy_hook = os.path.join(HERE, '{}.legacy'.format(HOOK_TYPE))
+    if os.access(legacy_hook, os.X_OK):
+        cmd = _norm_exe(legacy_hook) + (legacy_hook,) + tuple(sys.argv[1:])
+        proc = subprocess.Popen(cmd, stdin=subprocess.PIPE if stdin else None)
+        proc.communicate(stdin)
+        return proc.returncode, stdin
+    else:
+        return 0, stdin
+
+
+def _validate_config():
+    cmd = ('git', 'rev-parse', '--show-toplevel')
+    top_level = subprocess.check_output(cmd).decode('UTF-8').strip()
+    cfg = os.path.join(top_level, CONFIG)
+    if os.path.isfile(cfg):
+        pass
+    elif SKIP_ON_MISSING_CONFIG or os.getenv('PRE_COMMIT_ALLOW_NO_CONFIG'):
+        print(
+            '`{}` config file not found. '
+            'Skipping `pre-commit`.'.format(CONFIG),
+        )
+        raise EarlyExit()
+    else:
+        raise FatalError(
+            'No {} file was found\n'
+            '- To temporarily silence this, run '
+            '`PRE_COMMIT_ALLOW_NO_CONFIG=1 git ...`\n'
+            '- To permanently silence this, install pre-commit with the '
+            '--allow-missing-config option\n'
+            '- To uninstall pre-commit run '
+            '`pre-commit uninstall`'.format(CONFIG),
+        )
+
+
+def _exe():
+    with open(os.devnull, 'wb') as devnull:
+        for exe in (INSTALL_PYTHON, sys.executable):
+            try:
+                if not subprocess.call(
+                        (exe, '-c', 'import pre_commit.main'),
+                        stdout=devnull, stderr=devnull,
+                ):
+                    return (exe, '-m', 'pre_commit.main', 'run')
+            except OSError:
+                pass
+
+    if distutils.spawn.find_executable('pre-commit'):
+        return ('pre-commit', 'run')
+
+    raise FatalError(
+        '`pre-commit` not found.  Did you forget to activate your virtualenv?',
+    )
+
+
+def _pre_push(stdin):
+    remote = sys.argv[1]
+
+    opts = ()
+    for line in stdin.decode('UTF-8').splitlines():
+        _, local_sha, _, remote_sha = line.split()
+        if local_sha == Z40:
+            continue
+        elif remote_sha != Z40:
+            opts = ('--origin', local_sha, '--source', remote_sha)
+        else:
+            # First ancestor not found in remote
+            first_ancestor = subprocess.check_output((
+                'git', 'rev-list', '--max-count=1', '--topo-order',
+                '--reverse', local_sha, '--not', '--remotes={}'.format(remote),
+            )).decode().strip()
+            if not first_ancestor:
+                continue
+            else:
+                cmd = ('git', 'rev-list', '--max-parents=0', local_sha)
+                roots = set(subprocess.check_output(cmd).decode().splitlines())
+                if first_ancestor in roots:
+                    # pushing the whole tree including root commit
+                    opts = ('--all-files',)
+                else:
+                    cmd = ('git', 'rev-parse', '{}^'.format(first_ancestor))
+                    source = subprocess.check_output(cmd).decode().strip()
+                    opts = ('--origin', local_sha, '--source', source)
+
+    if opts:
+        return opts
+    else:
+        # An attempt to push an empty changeset
+        raise EarlyExit()
+
+
+def _opts(stdin):
+    fns = {
+        'commit-msg': lambda _: ('--commit-msg-filename', sys.argv[1]),
+        'pre-commit': lambda _: (),
+        'pre-push': _pre_push,
+    }
+    stage = HOOK_TYPE.replace('pre-', '')
+    return ('--config', CONFIG, '--hook-stage', stage) + fns[HOOK_TYPE](stdin)
+
+
+def main():
+    retv, stdin = _run_legacy()
+    try:
+        _validate_config()
+        return retv | subprocess.call(_exe() + _opts(stdin))
+    except EarlyExit:
+        return retv
+    except FatalError as e:
+        print(e.args[0])
+        return 1
+
+
+if __name__ == '__main__':
+    exit(main())

pre_commit/resources/pre-push-tmpl

@@ -1,31 +0,0 @@
-z40=0000000000000000000000000000000000000000
-while read local_ref local_sha remote_ref remote_sha
-do
-    if [ "$local_sha" != $z40 ]; then
-        if [ "$remote_sha" = $z40 ]; then
-            # First ancestor not found in remote
-            first_ancestor=$(git rev-list --topo-order --reverse "$local_sha" --not --remotes="$1" | head -n 1)
-            if [ -n "$first_ancestor" ]; then
-                # Check that the ancestor has at least one parent
-                git rev-list --max-parents=0 "$local_sha" | grep "$first_ancestor" > /dev/null
-                if [ $? -eq 0 ]; then
-                    # Pushing the whole tree, including the root commit, so run on all files
-                    args="--all-files"
-                else
-                    source=$(git rev-parse "$first_ancestor"^)
-                    args="--origin $local_sha --source $source"
-                fi
-            fi
-        else
-            args="--origin $local_sha --source $remote_sha"
-        fi
-    fi
-done
-
-if [ "$args" != "" ]; then
-    args="$args --hook-stage push"
-else
-    # If args is empty, then an attempt to push on an empty
-    # changeset is being made. In this case, just exit cleanly
-    exit 0
-fi