1 files changed, 106 insertions, 0 deletions
diff --git a/sysv/sem.go b/sysv/sem.go
new file mode 100644
index 0000000..631a16b
--- /dev/null
+++ b/sysv/sem.go
@@ -0,0 +1,106 @@
+package sysv
+
+import (
+	"unsafe"
+
+	"golang.org/x/sys/unix"
+)
+
+const (
+	SYS_GETPID int = 0x0B + iota
+	SYS_GETVAL
+	SYS_SETVAL int = 0x010
+)
+
+const (
+	non = iota - one
+	one = 0x01
+	zro = 0x00
+)
+
+type oprations struct {
+	num uint16
+	opt int16
+	flg int16
+}
+
+type Semaphore struct {
+	nums int
+	smid int
+}
+
+func NewSemGet(key, nums, flags int) (*Semaphore, error) {
+	id, _, errno := unix.Syscall(
+		unix.SYS_SEMGET, uintptr(key),
+		uintptr(nums), uintptr(flags),
+	)
+	if errno != 0 {
+		return nil, error(errno)
+	}
+	return &Semaphore{nums: nums, smid: int(id)}, nil
+}
+
+func (sem *Semaphore) GetVal(semnum int) (int, error) {
+	vl, _, errno := unix.Syscall(
+		unix.SYS_SEMCTL, uintptr(sem.smid),
+		uintptr(semnum), uintptr(SYS_GETVAL),
+	)
+	if errno != 0 {
+		return int(vl), error(errno)
+	}
+	return int(vl), nil
+}
+
+func (sem *Semaphore) SetVal(semnum, v int) error {
+	_, _, errno := unix.Syscall6(
+		unix.SYS_SEMCTL, uintptr(sem.smid),
+		uintptr(semnum), uintptr(SYS_SETVAL), uintptr(v), 0, 0,
+	)
+	if errno != 0 {
+		return error(errno)
+	}
+	return nil
+}
+
+func (sem *Semaphore) GetPID(semnum int) (int, error) {
+	pid, _, errno := unix.Syscall(
+		unix.SYS_SEMCTL, uintptr(sem.smid),
+		uintptr(semnum), uintptr(SYS_GETPID),
+	)
+	if errno != 0 {
+		return int(pid), error(errno)
+	}
+	return int(pid), nil
+}
+
+func (sem *Semaphore) setops(n uint16, o, f int16) error {
+	opt := oprations{num: n, opt: o, flg: f}
+	_, _, errno := unix.Syscall(
+		unix.SYS_SEMOP, uintptr(sem.smid),
+		uintptr(unsafe.Pointer(&opt)), uintptr(sem.nums),
+	)
+
+	if errno != 0 {
+		return error(errno)
+	}
+	return nil
+}
+
+func (sem *Semaphore) Lock(semnum int) error {
+	return sem.setops(uint16(semnum), non, zro)
+}
+
+func (sem *Semaphore) Unlock(semnum int) error {
+	return sem.setops(uint16(semnum), one, zro)
+}
+
+func (sem *Semaphore) DelSem() error {
+	_, _, errno := unix.Syscall(
+		unix.SYS_SEMCTL, uintptr(sem.smid),
+		uintptr(0), uintptr(unix.IPC_RMID),
+	)
+	if errno != 0 {
+		return error(errno)
+	}
+	return nil
+}