1 files changed, 196 insertions, 0 deletions
diff --git a/pre_commit/git.py b/pre_commit/git.py
new file mode 100644
index 0000000..7e757f2
--- /dev/null
+++ b/pre_commit/git.py
@@ -0,0 +1,196 @@
+import logging
+import os.path
+import sys
+from typing import Dict
+from typing import List
+from typing import Optional
+from typing import Set
+
+from pre_commit.util import cmd_output
+from pre_commit.util import cmd_output_b
+from pre_commit.util import EnvironT
+
+
+logger = logging.getLogger(__name__)
+
+
+def zsplit(s: str) -> List[str]:
+    s = s.strip('\0')
+    if s:
+        return s.split('\0')
+    else:
+        return []
+
+
+def no_git_env(_env: Optional[EnvironT] = None) -> Dict[str, str]:
+    # Too many bugs dealing with environment variables and GIT:
+    # https://github.com/pre-commit/pre-commit/issues/300
+    # In git 2.6.3 (maybe others), git exports GIT_WORK_TREE while running
+    # pre-commit hooks
+    # In git 1.9.1 (maybe others), git exports GIT_DIR and GIT_INDEX_FILE
+    # while running pre-commit hooks in submodules.
+    # GIT_DIR: Causes git clone to clone wrong thing
+    # GIT_INDEX_FILE: Causes 'error invalid object ...' during commit
+    _env = _env if _env is not None else os.environ
+    return {
+        k: v for k, v in _env.items()
+        if not k.startswith('GIT_') or
+        k in {
+            'GIT_EXEC_PATH', 'GIT_SSH', 'GIT_SSH_COMMAND', 'GIT_SSL_CAINFO',
+            'GIT_SSL_NO_VERIFY',
+        }
+    }
+
+
+def get_root() -> str:
+    return cmd_output('git', 'rev-parse', '--show-toplevel')[1].strip()
+
+
+def get_git_dir(git_root: str = '.') -> str:
+    opts = ('--git-common-dir', '--git-dir')
+    _, out, _ = cmd_output('git', 'rev-parse', *opts, cwd=git_root)
+    for line, opt in zip(out.splitlines(), opts):
+        if line != opt:  # pragma: no branch (git < 2.5)
+            return os.path.normpath(os.path.join(git_root, line))
+    else:
+        raise AssertionError('unreachable: no git dir')
+
+
+def get_remote_url(git_root: str) -> str:
+    _, out, _ = cmd_output('git', 'config', 'remote.origin.url', cwd=git_root)
+    return out.strip()
+
+
+def is_in_merge_conflict() -> bool:
+    git_dir = get_git_dir('.')
+    return (
+        os.path.exists(os.path.join(git_dir, 'MERGE_MSG')) and
+        os.path.exists(os.path.join(git_dir, 'MERGE_HEAD'))
+    )
+
+
+def parse_merge_msg_for_conflicts(merge_msg: bytes) -> List[str]:
+    # Conflicted files start with tabs
+    return [
+        line.lstrip(b'#').strip().decode()
+        for line in merge_msg.splitlines()
+        # '#\t' for git 2.4.1
+        if line.startswith((b'\t', b'#\t'))
+    ]
+
+
+def get_conflicted_files() -> Set[str]:
+    logger.info('Checking merge-conflict files only.')
+    # Need to get the conflicted files from the MERGE_MSG because they could
+    # have resolved the conflict by choosing one side or the other
+    with open(os.path.join(get_git_dir('.'), 'MERGE_MSG'), 'rb') as f:
+        merge_msg = f.read()
+    merge_conflict_filenames = parse_merge_msg_for_conflicts(merge_msg)
+
+    # This will get the rest of the changes made after the merge.
+    # If they resolved the merge conflict by choosing a mesh of both sides
+    # this will also include the conflicted files
+    tree_hash = cmd_output('git', 'write-tree')[1].strip()
+    merge_diff_filenames = zsplit(
+        cmd_output(
+            'git', 'diff', '--name-only', '--no-ext-diff', '-z',
+            '-m', tree_hash, 'HEAD', 'MERGE_HEAD',
+        )[1],
+    )
+    return set(merge_conflict_filenames) | set(merge_diff_filenames)
+
+
+def get_staged_files(cwd: Optional[str] = None) -> List[str]:
+    return zsplit(
+        cmd_output(
+            'git', 'diff', '--staged', '--name-only', '--no-ext-diff', '-z',
+            # Everything except for D
+            '--diff-filter=ACMRTUXB',
+            cwd=cwd,
+        )[1],
+    )
+
+
+def intent_to_add_files() -> List[str]:
+    _, stdout, _ = cmd_output('git', 'status', '--porcelain', '-z')
+    parts = list(reversed(zsplit(stdout)))
+    intent_to_add = []
+    while parts:
+        line = parts.pop()
+        status, filename = line[:3], line[3:]
+        if status[0] in {'C', 'R'}:  # renames / moves have an additional arg
+            parts.pop()
+        if status[1] == 'A':
+            intent_to_add.append(filename)
+    return intent_to_add
+
+
+def get_all_files() -> List[str]:
+    return zsplit(cmd_output('git', 'ls-files', '-z')[1])
+
+
+def get_changed_files(old: str, new: str) -> List[str]:
+    return zsplit(
+        cmd_output(
+            'git', 'diff', '--name-only', '--no-ext-diff', '-z',
+            f'{old}...{new}',
+        )[1],
+    )
+
+
+def head_rev(remote: str) -> str:
+    _, out, _ = cmd_output('git', 'ls-remote', '--exit-code', remote, 'HEAD')
+    return out.split()[0]
+
+
+def has_diff(*args: str, repo: str = '.') -> bool:
+    cmd = ('git', 'diff', '--quiet', '--no-ext-diff', *args)
+    return cmd_output_b(*cmd, cwd=repo, retcode=None)[0] == 1
+
+
+def has_core_hookpaths_set() -> bool:
+    _, out, _ = cmd_output_b('git', 'config', 'core.hooksPath', retcode=None)
+    return bool(out.strip())
+
+
+def init_repo(path: str, remote: str) -> None:
+    if os.path.isdir(remote):
+        remote = os.path.abspath(remote)
+
+    env = no_git_env()
+    cmd_output_b('git', 'init', path, env=env)
+    cmd_output_b('git', 'remote', 'add', 'origin', remote, cwd=path, env=env)
+
+
+def commit(repo: str = '.') -> None:
+    env = no_git_env()
+    name, email = 'pre-commit', 'asottile+pre-commit@umich.edu'
+    env['GIT_AUTHOR_NAME'] = env['GIT_COMMITTER_NAME'] = name
+    env['GIT_AUTHOR_EMAIL'] = env['GIT_COMMITTER_EMAIL'] = email
+    cmd = ('git', 'commit', '--no-edit', '--no-gpg-sign', '-n', '-minit')
+    cmd_output_b(*cmd, cwd=repo, env=env)
+
+
+def git_path(name: str, repo: str = '.') -> str:
+    _, out, _ = cmd_output('git', 'rev-parse', '--git-path', name, cwd=repo)
+    return os.path.join(repo, out.strip())
+
+
+def check_for_cygwin_mismatch() -> None:
+    """See https://github.com/pre-commit/pre-commit/issues/354"""
+    if sys.platform in ('cygwin', 'win32'):  # pragma: no cover (windows)
+        is_cygwin_python = sys.platform == 'cygwin'
+        toplevel = cmd_output('git', 'rev-parse', '--show-toplevel')[1]
+        is_cygwin_git = toplevel.startswith('/')
+
+        if is_cygwin_python ^ is_cygwin_git:
+            exe_type = {True: '(cygwin)', False: '(windows)'}
+            logger.warn(
+                f'pre-commit has detected a mix of cygwin python / git\n'
+                f'This combination is not supported, it is likely you will '
+                f'receive an error later in the program.\n'
+                f'Make sure to use cygwin git+python while using cygwin\n'
+                f'These can be installed through the cygwin installer.\n'
+                f' - python {exe_type[is_cygwin_python]}\n'
+                f' - git {exe_type[is_cygwin_git]}\n',
+            )