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import ctypes
from ctypes.util import find_library
import os
from contextlib import contextmanager
# Looks like ctypes is having trouble with dependencies, so just force them to
# load with RTLD_GLOBAL until I figure that out.
api = ctypes.CDLL(find_library("gfapi"), ctypes.RTLD_GLOBAL, use_errno=True)
# Wow, the Linux kernel folks really play nasty games with this structure. If
# you look at the man page for stat(2) and then at this definition you'll note
# two discrepancies. First, we seem to have st_nlink and st_mode reversed. In
# fact that's exactly how they're defined *for 64-bit systems*; for 32-bit
# they're in the man-page order. Even uglier, the man page makes no mention of
# the *nsec fields, but they are very much present and if they're not included
# then we get memory corruption because libgfapi has a structure definition
# that's longer than ours and they overwrite some random bit of memory after
# the space we allocated. Yes, that's all very disgusting, and I'm still not
# sure this will really work on 32-bit because all of the field types are so
# obfuscated behind macros and feature checks.
class Stat (ctypes.Structure):
_fields_ = [
("st_dev", ctypes.c_ulong),
("st_ino", ctypes.c_ulong),
("st_nlink", ctypes.c_ulong),
("st_mode", ctypes.c_uint),
("st_uid", ctypes.c_uint),
("st_gid", ctypes.c_uint),
("st_rdev", ctypes.c_ulong),
("st_size", ctypes.c_ulong),
("st_blksize", ctypes.c_ulong),
("st_blocks", ctypes.c_ulong),
("st_atime", ctypes.c_ulong),
("st_atimensec", ctypes.c_ulong),
("st_mtime", ctypes.c_ulong),
("st_mtimensec", ctypes.c_ulong),
("st_ctime", ctypes.c_ulong),
("st_ctimensec", ctypes.c_ulong),
]
class Dirent (ctypes.Structure):
_fields_ = [
("d_ino", ctypes.c_ulong),
("d_off", ctypes.c_ulong),
("d_reclen", ctypes.c_ushort),
("d_type", ctypes.c_char),
("d_name", ctypes.c_char * 256),
]
api.glfs_creat.restype = ctypes.c_void_p
api.glfs_open.restype = ctypes.c_void_p
api.glfs_lstat.restype = ctypes.c_int
api.glfs_lstat.argtypes = [ctypes.c_void_p, ctypes.c_char_p,
ctypes.POINTER(Stat)]
api.glfs_opendir.restype = ctypes.c_void_p
api.glfs_readdir_r.restype = ctypes.c_int
api.glfs_readdir_r.argtypes = [ctypes.c_void_p, ctypes.POINTER(Dirent),
ctypes.POINTER(ctypes.POINTER(Dirent))]
class File(object):
def __init__(self, fd):
self.fd = fd
# File operations, in alphabetical order.
def close(self):
ret = api.glfs_close(self.fd)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def discard(self, offset, len):
ret = api.glfs_discard(self.fd, offset, len)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def fallocate(self, mode, offset, len):
ret = api.glfs_fallocate(self.fd, mode, offset, len)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def fsync(self):
ret = api.glfs_fsync(self.fd)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def read(self, buflen, flags=0):
rbuf = ctypes.create_string_buffer(buflen)
ret = api.glfs_read(self.fd, rbuf, buflen, flags)
if ret > 0:
return rbuf.value[:ret]
elif ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
else:
return ret
def write(self, data, flags=0):
ret = api.glfs_write(self.fd, data, len(data), flags)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
class Dir(object):
def __init__(self, fd):
# Add a reference so the module-level variable "api" doesn't
# get yanked out from under us (see comment above File def'n).
self._api = api
self.fd = fd
self.cursor = ctypes.POINTER(Dirent)()
def __del__(self):
self._api.glfs_closedir(self.fd)
self._api = None
def next(self):
entry = Dirent()
entry.d_reclen = 256
rc = api.glfs_readdir_r(self.fd, ctypes.byref(entry),
ctypes.byref(self.cursor))
if (rc < 0) or (not self.cursor) or (not self.cursor.contents):
return rc
return entry
class Volume(object):
# Housekeeping functions.
def __init__(self, host, volid, proto="tcp", port=24007):
# Add a reference so the module-level variable "api" doesn't
# get yanked out from under us (see comment above File def'n).
self._api = api
self.fs = api.glfs_new(volid)
api.glfs_set_volfile_server(self.fs, proto, host, port)
def __del__(self):
self._api.glfs_fini(self.fs)
self._api = None
def set_logging(self, path, level):
api.glfs_set_logging(self.fs, path, level)
def mount(self):
return api.glfs_init(self.fs)
# File operations, in alphabetical order.
@contextmanager
def creat(self, path, flags, mode):
fd = api.glfs_creat(self.fs, path, flags, mode)
if not fd:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
fileobj = None
try:
fileobj = File(fd)
yield fileobj
finally:
fileobj.close()
def getxattr(self, path, key, maxlen):
buf = ctypes.create_string_buffer(maxlen)
rc = api.glfs_getxattr(self.fs, path, key, buf, maxlen)
if rc < 0:
err = ctypes.get_errno()
raise IOError(err, os.strerror(err))
return buf.value[:rc]
def listxattr(self, path):
buf = ctypes.create_string_buffer(512)
rc = api.glfs_listxattr(self.fs, path, buf, 512)
if rc < 0:
err = ctypes.get_errno()
raise IOError(err, os.strerror(err))
xattrs = []
# Parsing character by character is ugly, but it seems like the
# easiest way to deal with the "strings separated by NUL in one
# buffer" format.
i = 0
while i < rc:
new_xa = buf.raw[i]
i += 1
while i < rc:
next_char = buf.raw[i]
i += 1
if next_char == '\0':
xattrs.append(new_xa)
break
new_xa += next_char
xattrs.sort()
return xattrs
def lstat(self, path):
x = Stat()
rc = api.glfs_lstat(self.fs, path, ctypes.byref(x))
if rc < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return x
def mkdir(self, path, mode):
ret = api.glfs_mkdir(self.fs, path, mode)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
@contextmanager
def open(self, path, flags):
fd = api.glfs_open(self.fs, path, flags)
if not fd:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
fileobj = None
try:
fileobj = File(fd)
yield fileobj
finally:
fileobj.close()
def opendir(self, path):
fd = api.glfs_opendir(self.fs, path)
if not fd:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return Dir(fd)
def rename(self, opath, npath):
ret = api.glfs_rename(self.fs, opath, npath)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def rmdir(self, path):
ret = api.glfs_rmdir(self.fs, path)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
def setxattr(self, path, key, value, vlen):
ret = api.glfs_setxattr(self.fs, path, key, value, vlen, 0)
if ret < 0:
err = ctypes.get_errno()
raise IOError(err, os.strerror(err))
return ret
def unlink(self, path):
ret = api.glfs_unlink(self.fs, path)
if ret < 0:
err = ctypes.get_errno()
raise OSError(err, os.strerror(err))
return ret
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