aboutsummaryrefslogtreecommitdiff
path: root/tools/patman/gitutil.py
blob: 5e4c1128dcb5c433ff8e2bf0a4fed047eefba7f4 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2011 The Chromium OS Authors.
#

import re
import os
import subprocess
import sys

from patman import command
from patman import settings
from patman import terminal
from patman import tools

# True to use --no-decorate - we check this in Setup()
use_no_decorate = True

def LogCmd(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 CountCommitsToBranch(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 = GetUpstream('.git', branch)
        rev_range = '%s..%s' % (us, branch)
    else:
        rev_range = '@{upstream}..'
    pipe = [LogCmd(rev_range, oneline=True)]
    result = command.RunPipe(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 NameRevision(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.RunPipe([pipe], capture=True, oneline=True).stdout

    # We expect a commit, a space, then a revision name
    name = stdout.split(' ')[1].strip()
    return name

def GuessUpstream(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 = [LogCmd(branch, git_dir=git_dir, oneline=True, count=100)]
    result = command.RunPipe(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 = NameRevision(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 GetUpstream(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.OutputOneLine('git', '--git-dir', git_dir, 'config',
                                       'branch.%s.remote' % branch)
        merge = command.OutputOneLine('git', '--git-dir', git_dir, 'config',
                                      'branch.%s.merge' % branch)
    except:
        upstream, msg = GuessUpstream(git_dir, branch)
        return upstream, msg

    if remote == '.':
        return merge, None
    elif remote and merge:
        leaf = merge.split('/')[-1]
        return '%s/%s' % (remote, leaf), None
    else:
        raise ValueError("Cannot determine upstream branch for branch "
                "'%s' remote='%s', merge='%s'" % (branch, remote, merge))


def GetRangeInBranch(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 = GetUpstream(git_dir, branch)
    if not upstream:
        return None, msg
    rstr = '%s%s..%s' % (upstream, '~' if include_upstream else '', branch)
    return rstr, msg

def CountCommitsInRange(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 = [LogCmd(range_expr, git_dir=git_dir, oneline=True)]
    result = command.RunPipe(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 CountCommitsInBranch(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 = GetRangeInBranch(git_dir, branch, include_upstream)
    if not range_expr:
        return None, msg
    return CountCommitsInRange(git_dir, range_expr)

def CountCommits(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 = [LogCmd(commit_range, oneline=True),
            ['wc', '-l']]
    stdout = command.RunPipe(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.RunPipe([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.RunPipe([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.RunPipe([pipe], capture=True, capture_stderr=True)
    if result.return_code != 0:
        raise OSError('git fetch: %s' % result.stderr)

def CheckWorktreeIsAvailable(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.RunPipe([pipe], capture=True, capture_stderr=True,
                             raise_on_error=False)
    return result.return_code == 0

def AddWorktree(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.RunPipe([pipe], capture=True, cwd=output_dir,
                             capture_stderr=True)
    if result.return_code != 0:
        raise OSError('git worktree add: %s' % result.stderr)

def PruneWorktrees(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.RunPipe([pipe], capture=True, capture_stderr=True)
    if result.return_code != 0:
        raise OSError('git worktree prune: %s' % result.stderr)

def CreatePatches(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
    """
    if series.get('version'):
        version = '%s ' % series['version']
    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.RunList(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 BuildEmailList(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   ']
    >>> BuildEmailList(['john', 'mary'], None, alias)
    ['j.bloggs@napier.co.nz', 'Mary Poppins <m.poppins@cloud.net>']
    >>> BuildEmailList(['john', 'mary'], '--to', alias)
    ['--to "j.bloggs@napier.co.nz"', \
'--to "Mary Poppins <m.poppins@cloud.net>"']
    >>> BuildEmailList(['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 += LookupEmail(item, alias, warn_on_error=warn_on_error)
    result = []
    for item in raw:
        if not item in result:
            result.append(item)
    if tag:
        return ['%s %s%s%s' % (tag, quote, email, quote) for email in result]
    return result

def CheckSuppressCCConfig():
    """Check if sendemail.suppresscc is configured correctly.

    Returns:
        True if the option is configured correctly, False otherwise.
    """
    suppresscc = command.OutputOneLine('git', 'config', 'sendemail.suppresscc',
                                       raise_on_error=False)

    # Other settings should be fine.
    if suppresscc == 'all' or suppresscc == 'cccmd':
        col = terminal.Color()

        print((col.Color(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 EmailPatches(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):
    """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

    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']
    >>> EmailPatches(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'
    >>> EmailPatches(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']
    >>> EmailPatches(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'
    >>> EmailPatches(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 = BuildEmailList(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 = BuildEmailList(list(set(series.get('cc')) - set(series.get('to'))),
                        '--cc', alias, warn_on_error)
    if self_only:
        to = BuildEmailList([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 LookupEmail(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   ']
    >>> LookupEmail('mary', alias)
    ['m.poppins@cloud.net']
    >>> LookupEmail('arthur.wellesley@howe.ro.uk', alias)
    ['arthur.wellesley@howe.ro.uk']
    >>> LookupEmail('boys', alias)
    ['f.bloggs@napier.co.nz', 'j.bloggs@napier.co.nz']
    >>> LookupEmail('all', alias)
    ['f.bloggs@napier.co.nz', 'j.bloggs@napier.co.nz', 'm.poppins@cloud.net']
    >>> LookupEmail('odd', alias)
    Alias 'odd' not found
    []
    >>> LookupEmail('loop', alias)
    Traceback (most recent call last):
    ...
    OSError: Recursive email alias at 'other'
    >>> LookupEmail('odd', alias, warn_on_error=False)
    []
    >>> # In this case the loop part will effectively be ignored.
    >>> LookupEmail('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.Color(col.RED, msg))
            return out_list

    if lookup_name:
        if not lookup_name in alias:
            msg = "Alias '%s' not found" % lookup_name
            if warn_on_error:
                print(col.Color(col.RED, msg))
            return out_list
        for item in alias[lookup_name]:
            todo = LookupEmail(item, alias, warn_on_error, level + 1)
            for new_item in todo:
                if not new_item in out_list:
                    out_list.append(new_item)

    return out_list

def GetTopLevel():
    """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(GetTopLevel(), 'tools', 'patman')
    True
    """
    return command.OutputOneLine('git', 'rev-parse', '--show-toplevel')

def GetAliasFile():
    """Gets the name of the git alias file.

    Returns:
        Filename of git alias file, or None if none
    """
    fname = command.OutputOneLine('git', 'config', 'sendemail.aliasesfile',
            raise_on_error=False)
    if fname:
        fname = os.path.join(GetTopLevel(), fname.strip())
    return fname

def GetDefaultUserName():
    """Gets the user.name from .gitconfig file.

    Returns:
        User name found in .gitconfig file, or None if none
    """
    uname = command.OutputOneLine('git', 'config', '--global', 'user.name')
    return uname

def GetDefaultUserEmail():
    """Gets the user.email from the global .gitconfig file.

    Returns:
        User's email found in .gitconfig file, or None if none
    """
    uemail = command.OutputOneLine('git', 'config', '--global', 'user.email')
    return uemail

def GetDefaultSubjectPrefix():
    """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.OutputOneLine('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 = GetAliasFile()
    if alias_fname:
        settings.ReadGitAliases(alias_fname)
    cmd = LogCmd(None, count=0)
    use_no_decorate = (command.RunPipe([cmd], raise_on_error=False)
                       .return_code == 0)

def GetHead():
    """Get the hash of the current HEAD

    Returns:
        Hash of HEAD
    """
    return command.OutputOneLine('git', 'show', '-s', '--pretty=format:%H')

if __name__ == "__main__":
    import doctest

    doctest.testmod()