[Notes] [Git][BuildStream/buildstream][richardmaw/subprocess-PWD] subprocesses: Ensure PWD is set in process environment

[richardmaw-codethink <gitlab mg gitlab com>]

Title: GitLab

richardmaw-codethink pushed to branch richardmaw/subprocess-PWD at BuildStream / buildstream

Commits:

• 5b09dac7
  by Richard Maw at 2018-09-06T09:11:14Z

  subprocesses: Ensure PWD is set in process environment
  
  Naive getcwd implementations (such as in bash 4.4) can break
  when bind-mounts to different paths on the same filesystem are present,
  since the algorithm needs to know whether it's a mount-point
  to know whether it can trust the inode value from the readdir result
  or to use stat on the directory.
  
  Less naive implementations (such as in glibc) iterate again using stat
  in the case of not finding the directory because the inode in readdir was wrong,
  though a Linux-specific implementation could use name_to_handle_at.
  
  Letting the command know what directory it is in makes it unnecessary
  for it to call the faulty getcwd in the first place.
  

3 changed files:

• buildstream/sandbox/_sandboxbwrap.py
• buildstream/sandbox/_sandboxchroot.py
• tests/testutils/repo/git.py

Changes:

buildstream/sandbox/_sandboxbwrap.py

---

...	...	@@ -69,6 +69,15 @@ class SandboxBwrap(Sandbox):
69	69	if env is None:
70	70	env = self._get_environment()
71	71
	72	+ if cwd is None:
	73	+ cwd = '/'
	74	+
	75	+ # Naive getcwd implementations can break when bind-mounts to different
	76	+ # paths on the same filesystem are present. Letting the command know
	77	+ # what directory it is in makes it unnecessary to call the faulty
	78	+ # getcwd.
	79	+ env['PWD'] = cwd
	80	+
72	81	if not self._has_command(command[0], env):
73	82	raise SandboxError("Staged artifacts do not provide command "
74	83	"'{}'".format(command[0]),
...	...	@@ -83,9 +92,6 @@ class SandboxBwrap(Sandbox):
83	92	mount_map = MountMap(self, flags & SandboxFlags.ROOT_READ_ONLY)
84	93	root_mount_source = mount_map.get_mount_source('/')
85	94
86		- if cwd is None:
87		- cwd = '/'
88		-
89	95	# Grab the full path of the bwrap binary
90	96	bwrap_command = [utils.get_host_tool('bwrap')]
91	97

buildstream/sandbox/_sandboxchroot.py

---

...	...	@@ -58,6 +58,12 @@ class SandboxChroot(Sandbox):
58	58	if env is None:
59	59	env = self._get_environment()
60	60
	61	+ # Naive getcwd implementations can break when bind-mounts to different
	62	+ # paths on the same filesystem are present. Letting the command know
	63	+ # what directory it is in makes it unnecessary to call the faulty
	64	+ # getcwd.
	65	+ env['PWD'] = cwd
	66	+
61	67	if not self._has_command(command[0], env):
62	68	raise SandboxError("Staged artifacts do not provide command "
63	69	"'{}'".format(command[0]),

tests/testutils/repo/git.py

---

...	...	@@ -26,24 +26,30 @@ class Git(Repo):
26	26
27	27	super(Git, self).__init__(directory, subdir)
28	28
	29	+ def _run_git(self, *args, **kwargs):
	30	+ argv = ['git']
	31	+ argv.extend(args)
	32	+ if 'env' not in kwargs:
	33	+ kwargs['env'] = dict(GIT_ENV, PWD=self.repo)
	34	+ kwargs.setdefault('cwd', self.repo)
	35	+ kwargs.setdefault('check', True)
	36	+ return subprocess.run(argv, **kwargs)
	37	+
29	38	def create(self, directory):
30	39	self.copy_directory(directory, self.repo)
31		- subprocess.call(['git', 'init', '.'], env=GIT_ENV, cwd=self.repo)
32		- subprocess.call(['git', 'add', '.'], env=GIT_ENV, cwd=self.repo)
33		- subprocess.call(['git', 'commit', '-m', 'Initial commit'], env=GIT_ENV, cwd=self.repo)
	40	+ self._run_git('init', '.')
	41	+ self._run_git('add', '.')
	42	+ self._run_git('commit', '-m', 'Initial commit')
34	43	return self.latest_commit()
35	44
36	45	def add_commit(self):
37		- subprocess.call(['git', 'commit', '--allow-empty', '-m', 'Additional commit'],
38		- env=GIT_ENV, cwd=self.repo)
	46	+ self._run_git('commit', '--allow-empty', '-m', 'Additional commit')
39	47	return self.latest_commit()
40	48
41	49	def add_file(self, filename):
42	50	shutil.copy(filename, self.repo)
43		- subprocess.call(['git', 'add', os.path.basename(filename)], env=GIT_ENV, cwd=self.repo)
44		- subprocess.call([
45		- 'git', 'commit', '-m', 'Added {}'.format(os.path.basename(filename))
46		- ], env=GIT_ENV, cwd=self.repo)
	51	+ self._run_git('add', os.path.basename(filename))
	52	+ self._run_git('commit', '-m', 'Added {}'.format(os.path.basename(filename)))
47	53	return self.latest_commit()
48	54
49	55	def add_submodule(self, subdir, url=None, checkout=None):
...	...	@@ -53,8 +59,8 @@ class Git(Repo):
53	59	if url is not None:
54	60	submodule['url'] = url
55	61	self.submodules[subdir] = submodule
56		- subprocess.call(['git', 'submodule', 'add', url, subdir], env=GIT_ENV, cwd=self.repo)
57		- subprocess.call(['git', 'commit', '-m', 'Added the submodule'], env=GIT_ENV, cwd=self.repo)
	62	+ self._run_git('submodule', 'add', url, subdir)
	63	+ self._run_git('commit', '-m', 'Added the submodule')
58	64	return self.latest_commit()
59	65
60	66	def source_config(self, ref=None, checkout_submodules=None):
...	...	@@ -74,10 +80,8 @@ class Git(Repo):
74	80	return config
75	81
76	82	def latest_commit(self):
77		- output = subprocess.check_output([
78		- 'git', 'rev-parse', 'master'
79		- ], env=GIT_ENV, cwd=self.repo)
	83	+ output = self._run_git('rev-parse', 'master', stdout=subprocess.PIPE).stdout
80	84	return output.decode('UTF-8').strip()
81	85
82	86	def branch(self, branch_name):
83		- subprocess.call(['git', 'checkout', '-b', branch_name], env=GIT_ENV, cwd=self.repo)
	87	+ self._run_git('checkout', '-b', branch_name)

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