func Open(name string, flag int, perm os.FileMode) (o Object, err error) {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
fd, err := C.shm_open(cname, C.int(flag), C.mode_t(perm))
if err != nil {
return o, err
}
return Object{File: os.NewFile(uintptr(fd), name), name: name}, nil
}
func shm_open(name string, flag int) (uintptr, error) {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
fd, err := C.shm_open(cname, C.int(flag), 0666)
if err != nil {
return 0, err
}
return uintptr(fd), nil
}
// Creates a new region of shared memory by creating and mapping in a new
// shm object. The returned region "owns" the shm object, and will mark it for
// unlinking when the region is closed.
func NewRegion(name string, length int) (result region, err error) {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
fd, err := C.shm_open(
cname,
C.int(os.O_CREATE|os.O_EXCL|os.O_RDWR),
0600)
if err != nil {
return
}
file := os.NewFile(uintptr(fd), name)
defer func() {
if err != nil {
file.Close()
}
}()
err = syscall.Ftruncate(int(fd), int64(length))
if err != nil {
return
}
buf, err := syscall.Mmap(int(fd), 0, length,
syscall.PROT_READ|syscall.PROT_WRITE,
syscall.MAP_SHARED)
if err != nil {
return
}
result = region{
bytes: buf,
fd: file,
name: name,
unlink: true}
return
}
// Creates a new region instance by attaching to an existing shm object
// and mapping it into the process address space. This region does not "own"
// the underlying shm object, and will not call shm_unlink on it when the
// region is closed.
func OpenRegion(name string) (result region, err error) {
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
fd, err := C.shm_open(cname, C.int(os.O_RDWR), 0)
if err != nil {
return
}
file := os.NewFile(uintptr(fd), name)
defer func() {
if err != nil {
file.Close()
}
}()
shmInfo, err := file.Stat()
if err != nil {
rpcLog.Error("Failed to stat the shared memory block: %s", err.Error())
return
}
buf, err := syscall.Mmap(int(fd), 0, int(shmInfo.Size()),
syscall.PROT_READ|syscall.PROT_WRITE,
syscall.MAP_SHARED)
if err != nil {
return
}
result = region{
bytes: buf,
fd: file,
name: name,
unlink: false,
}
return
}
