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fix backing up FIFOs. fixes #4394 

The O_NONBLOCK caused EAGAIN errors borg did not deal with, so we
better block and wait until read data is available from e.g. a fifo.

Fixed the --read-special test so it creates a FIFO, feeds it from a
thread and backs it up with borg. Then extracts and checks if correct
data has been backed up.

Also: renamed flags_follow to flags_special_follow (its only intended
use is on symlinks to special files with --read-special).
This commit is contained in:
Thomas Waldmann 2019-03-02 19:14:47 +01:00
parent 382875692b
commit cd857b6d8f
3 changed files with 42 additions and 19 deletions
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13
src/borg/archiver.py
View File

@ -66,7 +66,7 @@ from .helpers import ChunkIteratorFileWrapper
from .helpers import popen_with_error_handling, prepare_subprocess_env
from .helpers import dash_open
from .helpers import umount
from .helpers import flags_root, flags_dir, flags_follow
from .helpers import flags_root, flags_dir, flags_special_follow, flags_special
from .helpers import msgpack
from .nanorst import rst_to_terminal
from .patterns import ArgparsePatternAction, ArgparseExcludeFileAction, ArgparsePatternFileAction, parse_exclude_pattern
@ -646,7 +646,7 @@ class Archiver:
special = is_special(st_target.st_mode)
if special:
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st_target,
cache=cache, flags=flags_follow)
cache=cache, flags=flags_special_follow)
else:
status = fso.process_symlink(path=path, parent_fd=parent_fd, name=name, st=st)
elif stat.S_ISFIFO(st.st_mode):
@ -654,19 +654,22 @@ class Archiver:
if not read_special:
status = fso.process_fifo(path=path, parent_fd=parent_fd, name=name, st=st)
else:
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st, cache=cache)
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st,
cache=cache, flags=flags_special)
elif stat.S_ISCHR(st.st_mode):
if not dry_run:
if not read_special:
status = fso.process_dev(path=path, parent_fd=parent_fd, name=name, st=st, dev_type='c')
else:
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st, cache=cache)
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st,
cache=cache, flags=flags_special)
elif stat.S_ISBLK(st.st_mode):
if not dry_run:
if not read_special:
status = fso.process_dev(path=path, parent_fd=parent_fd, name=name, st=st, dev_type='b')
else:
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st, cache=cache)
status = fso.process_file(path=path, parent_fd=parent_fd, name=name, st=st,
cache=cache, flags=flags_special)
elif stat.S_ISSOCK(st.st_mode):
# Ignore unix sockets
return

7
src/borg/helpers/fs.py
View File

@ -202,9 +202,10 @@ def O_(*flags):
return result
flags_base = O_('BINARY', 'NONBLOCK', 'NOCTTY')
flags_follow = flags_base | O_('RDONLY')
flags_normal = flags_base | O_('RDONLY', 'NOFOLLOW')
flags_base = O_('BINARY', 'NOCTTY', 'RDONLY')
flags_special = flags_base | O_('NOFOLLOW') # BLOCK == wait when reading devices or fifos
flags_special_follow = flags_base # BLOCK == wait when reading symlinked devices or fifos
flags_normal = flags_base | O_('NONBLOCK', 'NOFOLLOW')
flags_noatime = flags_normal | O_('NOATIME')
flags_root = O_('RDONLY')
flags_dir = O_('DIRECTORY', 'RDONLY', 'NOFOLLOW')

41
src/borg/testsuite/archiver.py
View File

@ -1780,19 +1780,38 @@ class ArchiverTestCase(ArchiverTestCaseBase):
output = self.cmd('create', '--list', '--filter=AM', self.repository_location + '::test3', 'input')
self.assert_in('file1', output)
def test_create_read_special(self):
self.create_regular_file('regular', size=1024)
os.symlink(os.path.join(self.input_path, 'file'), os.path.join(self.input_path, 'link_regular'))
if are_fifos_supported():
os.mkfifo(os.path.join(self.input_path, 'fifo'))
os.symlink(os.path.join(self.input_path, 'fifo'), os.path.join(self.input_path, 'link_fifo'))
@pytest.mark.skipif(not are_fifos_supported(), reason='FIFOs not supported')
def test_create_read_special_symlink(self):
from threading import Thread
def fifo_feeder(fifo_fn, data):
fd = os.open(fifo_fn, os.O_WRONLY)
try:
os.write(fd, data)
finally:
os.close(fd)
self.cmd('init', '--encryption=repokey', self.repository_location)
archive = self.repository_location + '::test'
self.cmd('create', '--read-special', archive, 'input')
output = self.cmd('list', archive)
assert 'input/link_regular -> ' in output # not pointing to special file: archived as symlink
if are_fifos_supported():
assert 'input/link_fifo\n' in output # pointing to a special file: archived following symlink
data = b'foobar' * 1000
fifo_fn = os.path.join(self.input_path, 'fifo')
link_fn = os.path.join(self.input_path, 'link_fifo')
os.mkfifo(fifo_fn)
os.symlink(fifo_fn, link_fn)
t = Thread(target=fifo_feeder, args=(fifo_fn, data))
t.start()
try:
self.cmd('create', '--read-special', archive, 'input/link_fifo')
finally:
t.join()
with changedir('output'):
self.cmd('extract', archive)
fifo_fn = 'input/link_fifo'
with open(fifo_fn, 'rb') as f:
extracted_data = f.read()
assert extracted_data == data
def test_create_read_special_broken_symlink(self):
os.symlink('somewhere doesnt exist', os.path.join(self.input_path, 'link'))