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// +build selinux,linux
package selinux
import (
"syscall"
"unsafe"
)
var _zero uintptr
// Returns a []byte slice if the xattr is set and nil otherwise
// Requires path and its attribute as arguments
func lgetxattr(path string, attr string) ([]byte, error) {
var sz int
pathBytes, err := syscall.BytePtrFromString(path)
if err != nil {
return nil, err
}
attrBytes, err := syscall.BytePtrFromString(attr)
if err != nil {
return nil, err
}
// Start with a 128 length byte array
sz = 128
dest := make([]byte, sz)
destBytes := unsafe.Pointer(&dest[0])
_sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
switch {
case errno == syscall.ENODATA:
return nil, errno
case errno == syscall.ENOTSUP:
return nil, errno
case errno == syscall.ERANGE:
// 128 byte array might just not be good enough,
// A dummy buffer is used ``uintptr(0)`` to get real size
// of the xattrs on disk
_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(unsafe.Pointer(nil)), uintptr(0), 0, 0)
sz = int(_sz)
if sz < 0 {
return nil, errno
}
dest = make([]byte, sz)
destBytes := unsafe.Pointer(&dest[0])
_sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
if errno != 0 {
return nil, errno
}
case errno != 0:
return nil, errno
}
sz = int(_sz)
return dest[:sz], nil
}
func lsetxattr(path string, attr string, data []byte, flags int) error {
pathBytes, err := syscall.BytePtrFromString(path)
if err != nil {
return err
}
attrBytes, err := syscall.BytePtrFromString(attr)
if err != nil {
return err
}
var dataBytes unsafe.Pointer
if len(data) > 0 {
dataBytes = unsafe.Pointer(&data[0])
} else {
dataBytes = unsafe.Pointer(&_zero)
}
_, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
if errno != 0 {
return errno
}
return nil
}
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