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"""
btrfs-snap.py: source target newname
creates a exactly named snapshots and bails out if they exist
"""
import argparse
import fcntl
import os
import sys
import cffi
ffi = cffi.FFI()
ffi.cdef("""
#define BTRFS_IOC_SNAP_CREATE_V2 ...
struct btrfs_ioctl_vol_args_v2 {
int64_t fd;
char name[];
...;
};
""")
ffi.set_source("_btrfs_cffi", "#include <btrfs/ioctl.h>")
ffi.compile()
# ____________________________________________________________
from _btrfs_cffi import ffi, lib
parser = argparse.ArgumentParser(usage=__doc__.strip())
parser.add_argument('source', help='source subvolume')
parser.add_argument('target', help='target directory')
parser.add_argument('newname', help='name of the new snapshot')
opts = parser.parse_args()
source = os.open(opts.source, os.O_DIRECTORY)
target = os.open(opts.target, os.O_DIRECTORY)
args = ffi.new('struct btrfs_ioctl_vol_args_v2 *')
args.name = opts.newname
args.fd = source
args_buffer = ffi.buffer(args)
try:
fcntl.ioctl(target, lib.BTRFS_IOC_SNAP_CREATE_V2, args_buffer)
except IOError as e:
print e
sys.exit(1)
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