u_boot_pylib: Move gitutil into the library

Move this file into U-Boot's Python library, so that it is no-longer
part of patman.

This makes a start on:

https://source.denx.de/u-boot/custodians/u-boot-dm/-/issues/35

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/u_boot_pylib/__init__.py b/tools/u_boot_pylib/__init__.py
index 63c88e8..807a62e 100644
--- a/tools/u_boot_pylib/__init__.py
+++ b/tools/u_boot_pylib/__init__.py
@@ -1,4 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
 
-__all__ = ['command', 'cros_subprocess','terminal', 'test_util', 'tools',
-	   'tout']
+__all__ = ['command', 'cros_subprocess', 'gitutil', 'terminal', 'test_util',
+           'tools', 'tout']
diff --git a/tools/u_boot_pylib/__main__.py b/tools/u_boot_pylib/__main__.py
index 8f98d7b..c0762bc 100755
--- a/tools/u_boot_pylib/__main__.py
+++ b/tools/u_boot_pylib/__main__.py
@@ -13,7 +13,6 @@
     sys.path.append(os.path.join(our_path, '..'))
 
     # Run tests
-    from u_boot_pylib import terminal
     from u_boot_pylib import test_util
 
     result = test_util.run_test_suites(
diff --git a/tools/u_boot_pylib/gitutil.py b/tools/u_boot_pylib/gitutil.py
new file mode 100644
index 0000000..10ea5ff
--- /dev/null
+++ b/tools/u_boot_pylib/gitutil.py
@@ -0,0 +1,706 @@
+# SPDX-License-Identifier: GPL-2.0+
+# Copyright (c) 2011 The Chromium OS Authors.
+#
+
+import os
+import sys
+
+from patman import settings
+from u_boot_pylib import command
+from u_boot_pylib import terminal
+
+# True to use --no-decorate - we check this in setup()
+use_no_decorate = True
+
+
+def log_cmd(commit_range, git_dir=None, oneline=False, reverse=False,
+            count=None):
+    """Create a command to perform a 'git log'
+
+    Args:
+        commit_range: Range expression to use for log, None for none
+        git_dir: Path to git repository (None to use default)
+        oneline: True to use --oneline, else False
+        reverse: True to reverse the log (--reverse)
+        count: Number of commits to list, or None for no limit
+    Return:
+        List containing command and arguments to run
+    """
+    cmd = ['git']
+    if git_dir:
+        cmd += ['--git-dir', git_dir]
+    cmd += ['--no-pager', 'log', '--no-color']
+    if oneline:
+        cmd.append('--oneline')
+    if use_no_decorate:
+        cmd.append('--no-decorate')
+    if reverse:
+        cmd.append('--reverse')
+    if count is not None:
+        cmd.append('-n%d' % count)
+    if commit_range:
+        cmd.append(commit_range)
+
+    # Add this in case we have a branch with the same name as a directory.
+    # This avoids messages like this, for example:
+    #   fatal: ambiguous argument 'test': both revision and filename
+    cmd.append('--')
+    return cmd
+
+
+def count_commits_to_branch(branch):
+    """Returns number of commits between HEAD and the tracking branch.
+
+    This looks back to the tracking branch and works out the number of commits
+    since then.
+
+    Args:
+        branch: Branch to count from (None for current branch)
+
+    Return:
+        Number of patches that exist on top of the branch
+    """
+    if branch:
+        us, msg = get_upstream('.git', branch)
+        rev_range = '%s..%s' % (us, branch)
+    else:
+        rev_range = '@{upstream}..'
+    pipe = [log_cmd(rev_range, oneline=True)]
+    result = command.run_pipe(pipe, capture=True, capture_stderr=True,
+                              oneline=True, raise_on_error=False)
+    if result.return_code:
+        raise ValueError('Failed to determine upstream: %s' %
+                         result.stderr.strip())
+    patch_count = len(result.stdout.splitlines())
+    return patch_count
+
+
+def name_revision(commit_hash):
+    """Gets the revision name for a commit
+
+    Args:
+        commit_hash: Commit hash to look up
+
+    Return:
+        Name of revision, if any, else None
+    """
+    pipe = ['git', 'name-rev', commit_hash]
+    stdout = command.run_pipe([pipe], capture=True, oneline=True).stdout
+
+    # We expect a commit, a space, then a revision name
+    name = stdout.split(' ')[1].strip()
+    return name
+
+
+def guess_upstream(git_dir, branch):
+    """Tries to guess the upstream for a branch
+
+    This lists out top commits on a branch and tries to find a suitable
+    upstream. It does this by looking for the first commit where
+    'git name-rev' returns a plain branch name, with no ! or ^ modifiers.
+
+    Args:
+        git_dir: Git directory containing repo
+        branch: Name of branch
+
+    Returns:
+        Tuple:
+            Name of upstream branch (e.g. 'upstream/master') or None if none
+            Warning/error message, or None if none
+    """
+    pipe = [log_cmd(branch, git_dir=git_dir, oneline=True, count=100)]
+    result = command.run_pipe(pipe, capture=True, capture_stderr=True,
+                              raise_on_error=False)
+    if result.return_code:
+        return None, "Branch '%s' not found" % branch
+    for line in result.stdout.splitlines()[1:]:
+        commit_hash = line.split(' ')[0]
+        name = name_revision(commit_hash)
+        if '~' not in name and '^' not in name:
+            if name.startswith('remotes/'):
+                name = name[8:]
+            return name, "Guessing upstream as '%s'" % name
+    return None, "Cannot find a suitable upstream for branch '%s'" % branch
+
+
+def get_upstream(git_dir, branch):
+    """Returns the name of the upstream for a branch
+
+    Args:
+        git_dir: Git directory containing repo
+        branch: Name of branch
+
+    Returns:
+        Tuple:
+            Name of upstream branch (e.g. 'upstream/master') or None if none
+            Warning/error message, or None if none
+    """
+    try:
+        remote = command.output_one_line('git', '--git-dir', git_dir, 'config',
+                                         'branch.%s.remote' % branch)
+        merge = command.output_one_line('git', '--git-dir', git_dir, 'config',
+                                        'branch.%s.merge' % branch)
+    except Exception:
+        upstream, msg = guess_upstream(git_dir, branch)
+        return upstream, msg
+
+    if remote == '.':
+        return merge, None
+    elif remote and merge:
+        # Drop the initial refs/heads from merge
+        leaf = merge.split('/', maxsplit=2)[2:]
+        return '%s/%s' % (remote, '/'.join(leaf)), None
+    else:
+        raise ValueError("Cannot determine upstream branch for branch "
+                         "'%s' remote='%s', merge='%s'"
+                         % (branch, remote, merge))
+
+
+def get_range_in_branch(git_dir, branch, include_upstream=False):
+    """Returns an expression for the commits in the given branch.
+
+    Args:
+        git_dir: Directory containing git repo
+        branch: Name of branch
+    Return:
+        Expression in the form 'upstream..branch' which can be used to
+        access the commits. If the branch does not exist, returns None.
+    """
+    upstream, msg = get_upstream(git_dir, branch)
+    if not upstream:
+        return None, msg
+    rstr = '%s%s..%s' % (upstream, '~' if include_upstream else '', branch)
+    return rstr, msg
+
+
+def count_commits_in_range(git_dir, range_expr):
+    """Returns the number of commits in the given range.
+
+    Args:
+        git_dir: Directory containing git repo
+        range_expr: Range to check
+    Return:
+        Number of patches that exist in the supplied range or None if none
+        were found
+    """
+    pipe = [log_cmd(range_expr, git_dir=git_dir, oneline=True)]
+    result = command.run_pipe(pipe, capture=True, capture_stderr=True,
+                              raise_on_error=False)
+    if result.return_code:
+        return None, "Range '%s' not found or is invalid" % range_expr
+    patch_count = len(result.stdout.splitlines())
+    return patch_count, None
+
+
+def count_commits_in_branch(git_dir, branch, include_upstream=False):
+    """Returns the number of commits in the given branch.
+
+    Args:
+        git_dir: Directory containing git repo
+        branch: Name of branch
+    Return:
+        Number of patches that exist on top of the branch, or None if the
+        branch does not exist.
+    """
+    range_expr, msg = get_range_in_branch(git_dir, branch, include_upstream)
+    if not range_expr:
+        return None, msg
+    return count_commits_in_range(git_dir, range_expr)
+
+
+def count_commits(commit_range):
+    """Returns the number of commits in the given range.
+
+    Args:
+        commit_range: Range of commits to count (e.g. 'HEAD..base')
+    Return:
+        Number of patches that exist on top of the branch
+    """
+    pipe = [log_cmd(commit_range, oneline=True),
+            ['wc', '-l']]
+    stdout = command.run_pipe(pipe, capture=True, oneline=True).stdout
+    patch_count = int(stdout)
+    return patch_count
+
+
+def checkout(commit_hash, git_dir=None, work_tree=None, force=False):
+    """Checkout the selected commit for this build
+
+    Args:
+        commit_hash: Commit hash to check out
+    """
+    pipe = ['git']
+    if git_dir:
+        pipe.extend(['--git-dir', git_dir])
+    if work_tree:
+        pipe.extend(['--work-tree', work_tree])
+    pipe.append('checkout')
+    if force:
+        pipe.append('-f')
+    pipe.append(commit_hash)
+    result = command.run_pipe([pipe], capture=True, raise_on_error=False,
+                              capture_stderr=True)
+    if result.return_code != 0:
+        raise OSError('git checkout (%s): %s' % (pipe, result.stderr))
+
+
+def clone(git_dir, output_dir):
+    """Checkout the selected commit for this build
+
+    Args:
+        commit_hash: Commit hash to check out
+    """
+    pipe = ['git', 'clone', git_dir, '.']
+    result = command.run_pipe([pipe], capture=True, cwd=output_dir,
+                              capture_stderr=True)
+    if result.return_code != 0:
+        raise OSError('git clone: %s' % result.stderr)
+
+
+def fetch(git_dir=None, work_tree=None):
+    """Fetch from the origin repo
+
+    Args:
+        commit_hash: Commit hash to check out
+    """
+    pipe = ['git']
+    if git_dir:
+        pipe.extend(['--git-dir', git_dir])
+    if work_tree:
+        pipe.extend(['--work-tree', work_tree])
+    pipe.append('fetch')
+    result = command.run_pipe([pipe], capture=True, capture_stderr=True)
+    if result.return_code != 0:
+        raise OSError('git fetch: %s' % result.stderr)
+
+
+def check_worktree_is_available(git_dir):
+    """Check if git-worktree functionality is available
+
+    Args:
+        git_dir: The repository to test in
+
+    Returns:
+        True if git-worktree commands will work, False otherwise.
+    """
+    pipe = ['git', '--git-dir', git_dir, 'worktree', 'list']
+    result = command.run_pipe([pipe], capture=True, capture_stderr=True,
+                              raise_on_error=False)
+    return result.return_code == 0
+
+
+def add_worktree(git_dir, output_dir, commit_hash=None):
+    """Create and checkout a new git worktree for this build
+
+    Args:
+        git_dir: The repository to checkout the worktree from
+        output_dir: Path for the new worktree
+        commit_hash: Commit hash to checkout
+    """
+    # We need to pass --detach to avoid creating a new branch
+    pipe = ['git', '--git-dir', git_dir, 'worktree', 'add', '.', '--detach']
+    if commit_hash:
+        pipe.append(commit_hash)
+    result = command.run_pipe([pipe], capture=True, cwd=output_dir,
+                              capture_stderr=True)
+    if result.return_code != 0:
+        raise OSError('git worktree add: %s' % result.stderr)
+
+
+def prune_worktrees(git_dir):
+    """Remove administrative files for deleted worktrees
+
+    Args:
+        git_dir: The repository whose deleted worktrees should be pruned
+    """
+    pipe = ['git', '--git-dir', git_dir, 'worktree', 'prune']
+    result = command.run_pipe([pipe], capture=True, capture_stderr=True)
+    if result.return_code != 0:
+        raise OSError('git worktree prune: %s' % result.stderr)
+
+
+def create_patches(branch, start, count, ignore_binary, series, signoff=True):
+    """Create a series of patches from the top of the current branch.
+
+    The patch files are written to the current directory using
+    git format-patch.
+
+    Args:
+        branch: Branch to create patches from (None for current branch)
+        start: Commit to start from: 0=HEAD, 1=next one, etc.
+        count: number of commits to include
+        ignore_binary: Don't generate patches for binary files
+        series: Series object for this series (set of patches)
+    Return:
+        Filename of cover letter (None if none)
+        List of filenames of patch files
+    """
+    cmd = ['git', 'format-patch', '-M']
+    if signoff:
+        cmd.append('--signoff')
+    if ignore_binary:
+        cmd.append('--no-binary')
+    if series.get('cover'):
+        cmd.append('--cover-letter')
+    prefix = series.GetPatchPrefix()
+    if prefix:
+        cmd += ['--subject-prefix=%s' % prefix]
+    brname = branch or 'HEAD'
+    cmd += ['%s~%d..%s~%d' % (brname, start + count, brname, start)]
+
+    stdout = command.run_list(cmd)
+    files = stdout.splitlines()
+
+    # We have an extra file if there is a cover letter
+    if series.get('cover'):
+        return files[0], files[1:]
+    else:
+        return None, files
+
+
+def build_email_list(in_list, tag=None, alias=None, warn_on_error=True):
+    """Build a list of email addresses based on an input list.
+
+    Takes a list of email addresses and aliases, and turns this into a list
+    of only email address, by resolving any aliases that are present.
+
+    If the tag is given, then each email address is prepended with this
+    tag and a space. If the tag starts with a minus sign (indicating a
+    command line parameter) then the email address is quoted.
+
+    Args:
+        in_list:        List of aliases/email addresses
+        tag:            Text to put before each address
+        alias:          Alias dictionary
+        warn_on_error: True to raise an error when an alias fails to match,
+                False to just print a message.
+
+    Returns:
+        List of email addresses
+
+    >>> alias = {}
+    >>> alias['fred'] = ['f.bloggs@napier.co.nz']
+    >>> alias['john'] = ['j.bloggs@napier.co.nz']
+    >>> alias['mary'] = ['Mary Poppins <m.poppins@cloud.net>']
+    >>> alias['boys'] = ['fred', ' john']
+    >>> alias['all'] = ['fred ', 'john', '   mary   ']
+    >>> build_email_list(['john', 'mary'], None, alias)
+    ['j.bloggs@napier.co.nz', 'Mary Poppins <m.poppins@cloud.net>']
+    >>> build_email_list(['john', 'mary'], '--to', alias)
+    ['--to "j.bloggs@napier.co.nz"', \
+'--to "Mary Poppins <m.poppins@cloud.net>"']
+    >>> build_email_list(['john', 'mary'], 'Cc', alias)
+    ['Cc j.bloggs@napier.co.nz', 'Cc Mary Poppins <m.poppins@cloud.net>']
+    """
+    quote = '"' if tag and tag[0] == '-' else ''
+    raw = []
+    for item in in_list:
+        raw += lookup_email(item, alias, warn_on_error=warn_on_error)
+    result = []
+    for item in raw:
+        if item not in result:
+            result.append(item)
+    if tag:
+        return ['%s %s%s%s' % (tag, quote, email, quote) for email in result]
+    return result
+
+
+def check_suppress_cc_config():
+    """Check if sendemail.suppresscc is configured correctly.
+
+    Returns:
+        True if the option is configured correctly, False otherwise.
+    """
+    suppresscc = command.output_one_line(
+        'git', 'config', 'sendemail.suppresscc', raise_on_error=False)
+
+    # Other settings should be fine.
+    if suppresscc == 'all' or suppresscc == 'cccmd':
+        col = terminal.Color()
+
+        print((col.build(col.RED, "error") +
+               ": git config sendemail.suppresscc set to %s\n"
+               % (suppresscc)) +
+              "  patman needs --cc-cmd to be run to set the cc list.\n" +
+              "  Please run:\n" +
+              "    git config --unset sendemail.suppresscc\n" +
+              "  Or read the man page:\n" +
+              "    git send-email --help\n" +
+              "  and set an option that runs --cc-cmd\n")
+        return False
+
+    return True
+
+
+def email_patches(series, cover_fname, args, dry_run, warn_on_error, cc_fname,
+                  self_only=False, alias=None, in_reply_to=None, thread=False,
+                  smtp_server=None, get_maintainer_script=None):
+    """Email a patch series.
+
+    Args:
+        series: Series object containing destination info
+        cover_fname: filename of cover letter
+        args: list of filenames of patch files
+        dry_run: Just return the command that would be run
+        warn_on_error: True to print a warning when an alias fails to match,
+                False to ignore it.
+        cc_fname: Filename of Cc file for per-commit Cc
+        self_only: True to just email to yourself as a test
+        in_reply_to: If set we'll pass this to git as --in-reply-to.
+            Should be a message ID that this is in reply to.
+        thread: True to add --thread to git send-email (make
+            all patches reply to cover-letter or first patch in series)
+        smtp_server: SMTP server to use to send patches
+        get_maintainer_script: File name of script to get maintainers emails
+
+    Returns:
+        Git command that was/would be run
+
+    # For the duration of this doctest pretend that we ran patman with ./patman
+    >>> _old_argv0 = sys.argv[0]
+    >>> sys.argv[0] = './patman'
+
+    >>> alias = {}
+    >>> alias['fred'] = ['f.bloggs@napier.co.nz']
+    >>> alias['john'] = ['j.bloggs@napier.co.nz']
+    >>> alias['mary'] = ['m.poppins@cloud.net']
+    >>> alias['boys'] = ['fred', ' john']
+    >>> alias['all'] = ['fred ', 'john', '   mary   ']
+    >>> alias[os.getenv('USER')] = ['this-is-me@me.com']
+    >>> series = {}
+    >>> series['to'] = ['fred']
+    >>> series['cc'] = ['mary']
+    >>> email_patches(series, 'cover', ['p1', 'p2'], True, True, 'cc-fname', \
+            False, alias)
+    'git send-email --annotate --to "f.bloggs@napier.co.nz" --cc \
+"m.poppins@cloud.net" --cc-cmd "./patman send --cc-cmd cc-fname" cover p1 p2'
+    >>> email_patches(series, None, ['p1'], True, True, 'cc-fname', False, \
+            alias)
+    'git send-email --annotate --to "f.bloggs@napier.co.nz" --cc \
+"m.poppins@cloud.net" --cc-cmd "./patman send --cc-cmd cc-fname" p1'
+    >>> series['cc'] = ['all']
+    >>> email_patches(series, 'cover', ['p1', 'p2'], True, True, 'cc-fname', \
+            True, alias)
+    'git send-email --annotate --to "this-is-me@me.com" --cc-cmd "./patman \
+send --cc-cmd cc-fname" cover p1 p2'
+    >>> email_patches(series, 'cover', ['p1', 'p2'], True, True, 'cc-fname', \
+            False, alias)
+    'git send-email --annotate --to "f.bloggs@napier.co.nz" --cc \
+"f.bloggs@napier.co.nz" --cc "j.bloggs@napier.co.nz" --cc \
+"m.poppins@cloud.net" --cc-cmd "./patman send --cc-cmd cc-fname" cover p1 p2'
+
+    # Restore argv[0] since we clobbered it.
+    >>> sys.argv[0] = _old_argv0
+    """
+    to = build_email_list(series.get('to'), '--to', alias, warn_on_error)
+    if not to:
+        git_config_to = command.output('git', 'config', 'sendemail.to',
+                                       raise_on_error=False)
+        if not git_config_to:
+            print("No recipient.\n"
+                  "Please add something like this to a commit\n"
+                  "Series-to: Fred Bloggs <f.blogs@napier.co.nz>\n"
+                  "Or do something like this\n"
+                  "git config sendemail.to u-boot@lists.denx.de")
+            return
+    cc = build_email_list(list(set(series.get('cc')) - set(series.get('to'))),
+                          '--cc', alias, warn_on_error)
+    if self_only:
+        to = build_email_list([os.getenv('USER')], '--to',
+                              alias, warn_on_error)
+        cc = []
+    cmd = ['git', 'send-email', '--annotate']
+    if smtp_server:
+        cmd.append('--smtp-server=%s' % smtp_server)
+    if in_reply_to:
+        cmd.append('--in-reply-to="%s"' % in_reply_to)
+    if thread:
+        cmd.append('--thread')
+
+    cmd += to
+    cmd += cc
+    cmd += ['--cc-cmd', '"%s send --cc-cmd %s"' % (sys.argv[0], cc_fname)]
+    if cover_fname:
+        cmd.append(cover_fname)
+    cmd += args
+    cmdstr = ' '.join(cmd)
+    if not dry_run:
+        os.system(cmdstr)
+    return cmdstr
+
+
+def lookup_email(lookup_name, alias=None, warn_on_error=True, level=0):
+    """If an email address is an alias, look it up and return the full name
+
+    TODO: Why not just use git's own alias feature?
+
+    Args:
+        lookup_name: Alias or email address to look up
+        alias: Dictionary containing aliases (None to use settings default)
+        warn_on_error: True to print a warning when an alias fails to match,
+                False to ignore it.
+
+    Returns:
+        tuple:
+            list containing a list of email addresses
+
+    Raises:
+        OSError if a recursive alias reference was found
+        ValueError if an alias was not found
+
+    >>> alias = {}
+    >>> alias['fred'] = ['f.bloggs@napier.co.nz']
+    >>> alias['john'] = ['j.bloggs@napier.co.nz']
+    >>> alias['mary'] = ['m.poppins@cloud.net']
+    >>> alias['boys'] = ['fred', ' john', 'f.bloggs@napier.co.nz']
+    >>> alias['all'] = ['fred ', 'john', '   mary   ']
+    >>> alias['loop'] = ['other', 'john', '   mary   ']
+    >>> alias['other'] = ['loop', 'john', '   mary   ']
+    >>> lookup_email('mary', alias)
+    ['m.poppins@cloud.net']
+    >>> lookup_email('arthur.wellesley@howe.ro.uk', alias)
+    ['arthur.wellesley@howe.ro.uk']
+    >>> lookup_email('boys', alias)
+    ['f.bloggs@napier.co.nz', 'j.bloggs@napier.co.nz']
+    >>> lookup_email('all', alias)
+    ['f.bloggs@napier.co.nz', 'j.bloggs@napier.co.nz', 'm.poppins@cloud.net']
+    >>> lookup_email('odd', alias)
+    Alias 'odd' not found
+    []
+    >>> lookup_email('loop', alias)
+    Traceback (most recent call last):
+    ...
+    OSError: Recursive email alias at 'other'
+    >>> lookup_email('odd', alias, warn_on_error=False)
+    []
+    >>> # In this case the loop part will effectively be ignored.
+    >>> lookup_email('loop', alias, warn_on_error=False)
+    Recursive email alias at 'other'
+    Recursive email alias at 'john'
+    Recursive email alias at 'mary'
+    ['j.bloggs@napier.co.nz', 'm.poppins@cloud.net']
+    """
+    if not alias:
+        alias = settings.alias
+    lookup_name = lookup_name.strip()
+    if '@' in lookup_name:      # Perhaps a real email address
+        return [lookup_name]
+
+    lookup_name = lookup_name.lower()
+    col = terminal.Color()
+
+    out_list = []
+    if level > 10:
+        msg = "Recursive email alias at '%s'" % lookup_name
+        if warn_on_error:
+            raise OSError(msg)
+        else:
+            print(col.build(col.RED, msg))
+            return out_list
+
+    if lookup_name:
+        if lookup_name not in alias:
+            msg = "Alias '%s' not found" % lookup_name
+            if warn_on_error:
+                print(col.build(col.RED, msg))
+            return out_list
+        for item in alias[lookup_name]:
+            todo = lookup_email(item, alias, warn_on_error, level + 1)
+            for new_item in todo:
+                if new_item not in out_list:
+                    out_list.append(new_item)
+
+    return out_list
+
+
+def get_top_level():
+    """Return name of top-level directory for this git repo.
+
+    Returns:
+        Full path to git top-level directory
+
+    This test makes sure that we are running tests in the right subdir
+
+    >>> os.path.realpath(os.path.dirname(__file__)) == \
+            os.path.join(get_top_level(), 'tools', 'patman')
+    True
+    """
+    return command.output_one_line('git', 'rev-parse', '--show-toplevel')
+
+
+def get_alias_file():
+    """Gets the name of the git alias file.
+
+    Returns:
+        Filename of git alias file, or None if none
+    """
+    fname = command.output_one_line('git', 'config', 'sendemail.aliasesfile',
+                                    raise_on_error=False)
+    if not fname:
+        return None
+
+    fname = os.path.expanduser(fname.strip())
+    if os.path.isabs(fname):
+        return fname
+
+    return os.path.join(get_top_level(), fname)
+
+
+def get_default_user_name():
+    """Gets the user.name from .gitconfig file.
+
+    Returns:
+        User name found in .gitconfig file, or None if none
+    """
+    uname = command.output_one_line('git', 'config', '--global', '--includes', 'user.name')
+    return uname
+
+
+def get_default_user_email():
+    """Gets the user.email from the global .gitconfig file.
+
+    Returns:
+        User's email found in .gitconfig file, or None if none
+    """
+    uemail = command.output_one_line('git', 'config', '--global', '--includes', 'user.email')
+    return uemail
+
+
+def get_default_subject_prefix():
+    """Gets the format.subjectprefix from local .git/config file.
+
+    Returns:
+        Subject prefix found in local .git/config file, or None if none
+    """
+    sub_prefix = command.output_one_line(
+        'git', 'config', 'format.subjectprefix', raise_on_error=False)
+
+    return sub_prefix
+
+
+def setup():
+    """Set up git utils, by reading the alias files."""
+    # Check for a git alias file also
+    global use_no_decorate
+
+    alias_fname = get_alias_file()
+    if alias_fname:
+        settings.ReadGitAliases(alias_fname)
+    cmd = log_cmd(None, count=0)
+    use_no_decorate = (command.run_pipe([cmd], raise_on_error=False)
+                       .return_code == 0)
+
+
+def get_head():
+    """Get the hash of the current HEAD
+
+    Returns:
+        Hash of HEAD
+    """
+    return command.output_one_line('git', 'show', '-s', '--pretty=format:%H')
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()