commit-bot@chromium.org | 0ed9002 | 2014-01-30 22:12:30 +0000 | [diff] [blame] | 1 | # Copyright 2014 Google Inc. |
| 2 | # |
| 3 | # Use of this source code is governed by a BSD-style license that can be |
| 4 | # found in the LICENSE file. |
| 5 | |
| 6 | """Module to host the ChangeGitBranch class and test_git_executable function. |
| 7 | """ |
| 8 | |
| 9 | import os |
| 10 | import subprocess |
| 11 | |
| 12 | import misc_utils |
| 13 | |
| 14 | |
| 15 | class ChangeGitBranch(object): |
| 16 | """Class to manage git branches. |
| 17 | |
| 18 | This class allows one to create a new branch in a repository based |
| 19 | off of a given commit, and restore the original tree state. |
| 20 | |
| 21 | Assumes current working directory is a git repository. |
| 22 | |
| 23 | Example: |
| 24 | with ChangeGitBranch(): |
| 25 | edit_files(files) |
| 26 | git_add(files) |
| 27 | git_commit() |
| 28 | git_format_patch('HEAD~') |
| 29 | # At this point, the repository is returned to its original |
| 30 | # state. |
| 31 | |
| 32 | Constructor Args: |
| 33 | branch_name: (string) if not None, the name of the branch to |
| 34 | use. If None, then use a temporary branch that will be |
| 35 | deleted. If the branch already exists, then a different |
| 36 | branch name will be created. Use git_branch_name() to |
| 37 | find the actual branch name used. |
| 38 | upstream_branch: (string) if not None, the name of the branch or |
| 39 | commit to branch from. If None, then use origin/master |
| 40 | verbose: (boolean) if true, makes debugging easier. |
| 41 | |
| 42 | Raises: |
| 43 | OSError: the git executable disappeared. |
| 44 | subprocess.CalledProcessError: git returned unexpected status. |
| 45 | Exception: if the given branch name exists, or if the repository |
| 46 | isn't clean on exit, or git can't be found. |
| 47 | """ |
| 48 | # pylint: disable=I0011,R0903,R0902 |
| 49 | |
| 50 | def __init__(self, |
| 51 | branch_name=None, |
| 52 | upstream_branch=None, |
| 53 | verbose=False): |
| 54 | # pylint: disable=I0011,R0913 |
| 55 | if branch_name: |
| 56 | self._branch_name = branch_name |
| 57 | self._delete_branch = False |
| 58 | else: |
| 59 | self._branch_name = 'ChangeGitBranchTempBranch' |
| 60 | self._delete_branch = True |
| 61 | |
| 62 | if upstream_branch: |
| 63 | self._upstream_branch = upstream_branch |
| 64 | else: |
| 65 | self._upstream_branch = 'origin/master' |
| 66 | |
| 67 | self._git = git_executable() |
| 68 | if not self._git: |
| 69 | raise Exception('Git can\'t be found.') |
| 70 | |
| 71 | self._stash = None |
| 72 | self._original_branch = None |
| 73 | self._vsp = misc_utils.VerboseSubprocess(verbose) |
| 74 | |
| 75 | def _has_git_diff(self): |
| 76 | """Return true iff repository has uncommited changes.""" |
| 77 | return bool(self._vsp.call([self._git, 'diff', '--quiet', 'HEAD'])) |
| 78 | |
| 79 | def _branch_exists(self, branch): |
| 80 | """Return true iff branch exists.""" |
| 81 | return 0 == self._vsp.call([self._git, 'show-ref', '--quiet', branch]) |
| 82 | |
| 83 | def __enter__(self): |
| 84 | git, vsp = self._git, self._vsp |
| 85 | |
| 86 | if self._branch_exists(self._branch_name): |
| 87 | i, branch_name = 0, self._branch_name |
| 88 | while self._branch_exists(branch_name): |
| 89 | i += 1 |
| 90 | branch_name = '%s_%03d' % (self._branch_name, i) |
| 91 | self._branch_name = branch_name |
| 92 | |
| 93 | self._stash = self._has_git_diff() |
| 94 | if self._stash: |
| 95 | vsp.check_call([git, 'stash', 'save']) |
| 96 | self._original_branch = git_branch_name(vsp.verbose) |
| 97 | vsp.check_call( |
| 98 | [git, 'checkout', '-q', '-b', |
| 99 | self._branch_name, self._upstream_branch]) |
| 100 | |
| 101 | def __exit__(self, etype, value, traceback): |
| 102 | git, vsp = self._git, self._vsp |
| 103 | |
| 104 | if self._has_git_diff(): |
| 105 | status = vsp.check_output([git, 'status', '-s']) |
| 106 | raise Exception('git checkout not clean:\n%s' % status) |
| 107 | vsp.check_call([git, 'checkout', '-q', self._original_branch]) |
| 108 | if self._stash: |
| 109 | vsp.check_call([git, 'stash', 'pop']) |
| 110 | if self._delete_branch: |
| 111 | assert self._original_branch != self._branch_name |
| 112 | vsp.check_call([git, 'branch', '-D', self._branch_name]) |
| 113 | |
| 114 | |
| 115 | def git_branch_name(verbose=False): |
| 116 | """Return a description of the current branch. |
| 117 | |
| 118 | Args: |
| 119 | verbose: (boolean) makes debugging easier |
| 120 | |
| 121 | Returns: |
| 122 | A string suitable for passing to `git checkout` later. |
| 123 | """ |
| 124 | git = git_executable() |
| 125 | vsp = misc_utils.VerboseSubprocess(verbose) |
| 126 | try: |
| 127 | full_branch = vsp.strip_output([git, 'symbolic-ref', 'HEAD']) |
| 128 | return full_branch.split('/')[-1] |
| 129 | except (subprocess.CalledProcessError,): |
| 130 | # "fatal: ref HEAD is not a symbolic ref" |
| 131 | return vsp.strip_output([git, 'rev-parse', 'HEAD']) |
| 132 | |
| 133 | |
| 134 | def test_git_executable(git): |
| 135 | """Test the git executable. |
| 136 | |
| 137 | Args: |
| 138 | git: git executable path. |
| 139 | Returns: |
| 140 | True if test is successful. |
| 141 | """ |
| 142 | with open(os.devnull, 'w') as devnull: |
| 143 | try: |
| 144 | subprocess.call([git, '--version'], stdout=devnull) |
| 145 | except (OSError,): |
| 146 | return False |
| 147 | return True |
| 148 | |
| 149 | |
| 150 | def git_executable(): |
| 151 | """Find the git executable. |
| 152 | |
| 153 | If the GIT_EXECUTABLE environment variable is set, that will |
| 154 | override whatever is found in the PATH. |
| 155 | |
| 156 | If no suitable executable is found, return None |
| 157 | |
| 158 | Returns: |
| 159 | A string suiable for passing to subprocess functions, or None. |
| 160 | """ |
| 161 | env_git = os.environ.get('GIT_EXECUTABLE') |
| 162 | if env_git and test_git_executable(env_git): |
| 163 | return env_git |
| 164 | for git in ('git', 'git.exe', 'git.bat'): |
| 165 | if test_git_executable(git): |
| 166 | return git |
| 167 | return None |
| 168 | |