Improve general quality of libcontainer

Docker-DCO-1.1-Signed-off-by: Guillaume J. Charmes <guillaume.charmes@docker.com> (github: creack)

system/calls_linux.go

@@ -0,0 +1,121 @@
+package system
+
+import (
+	"syscall"
+)
+
+func Chroot(dir string) error {
+	return syscall.Chroot(dir)
+}
+
+func Chdir(dir string) error {
+	return syscall.Chdir(dir)
+}
+
+func Exec(cmd string, args []string, env []string) error {
+	return syscall.Exec(cmd, args, env)
+}
+
+func Fork() (int, error) {
+	syscall.ForkLock.Lock()
+	pid, _, err := syscall.Syscall(syscall.SYS_FORK, 0, 0, 0)
+	syscall.ForkLock.Unlock()
+	if err != 0 {
+		return -1, err
+	}
+	return int(pid), nil
+}
+
+func Mount(source, target, fstype string, flags uintptr, data string) error {
+	return syscall.Mount(source, target, fstype, flags, data)
+}
+
+func Unmount(target string, flags int) error {
+	return syscall.Unmount(target, flags)
+}
+
+func Pivotroot(newroot, putold string) error {
+	return syscall.PivotRoot(newroot, putold)
+}
+
+func Unshare(flags int) error {
+	return syscall.Unshare(flags)
+}
+
+func Clone(flags uintptr) (int, error) {
+	syscall.ForkLock.Lock()
+	pid, _, err := syscall.RawSyscall(syscall.SYS_CLONE, flags, 0, 0)
+	syscall.ForkLock.Unlock()
+	if err != 0 {
+		return -1, err
+	}
+	return int(pid), nil
+}
+
+func UsetCloseOnExec(fd uintptr) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_FCNTL, fd, syscall.F_SETFD, 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func Setgroups(gids []int) error {
+	return syscall.Setgroups(gids)
+}
+
+func Setresgid(rgid, egid, sgid int) error {
+	return syscall.Setresgid(rgid, egid, sgid)
+}
+
+func Setresuid(ruid, euid, suid int) error {
+	return syscall.Setresuid(ruid, euid, suid)
+}
+
+func Sethostname(name string) error {
+	return syscall.Sethostname([]byte(name))
+}
+
+func Setsid() (int, error) {
+	return syscall.Setsid()
+}
+
+func Ioctl(fd uintptr, flag, data uintptr) error {
+	if _, _, err := syscall.Syscall(syscall.SYS_IOCTL, fd, flag, data); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func Closefd(fd uintptr) error {
+	return syscall.Close(int(fd))
+}
+
+func Dup2(fd1, fd2 uintptr) error {
+	return syscall.Dup2(int(fd1), int(fd2))
+}
+
+func Mknod(path string, mode uint32, dev int) error {
+	return syscall.Mknod(path, mode, dev)
+}
+
+func ParentDeathSignal() error {
+	if _, _, err := syscall.RawSyscall(syscall.SYS_PRCTL, syscall.PR_SET_PDEATHSIG, uintptr(syscall.SIGKILL), 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func Setctty() error {
+	if _, _, err := syscall.RawSyscall(syscall.SYS_IOCTL, 0, uintptr(syscall.TIOCSCTTY), 0); err != 0 {
+		return err
+	}
+	return nil
+}
+
+func Mkfifo(name string, mode uint32) error {
+	return syscall.Mkfifo(name, mode)
+}
+
+func Umask(mask int) int {
+	return syscall.Umask(mask)
+}

system/pty_linux.go

@@ -0,0 +1,31 @@
+package system
+
+import (
+	"fmt"
+	"os"
+	"syscall"
+	"unsafe"
+)
+
+// Unlockpt unlocks the slave pseudoterminal device corresponding to the master pseudoterminal referred to by f.
+// Unlockpt should be called before opening the slave side of a pseudoterminal.
+func Unlockpt(f *os.File) error {
+	var u int
+	return Ioctl(f.Fd(), syscall.TIOCSPTLCK, uintptr(unsafe.Pointer(&u)))
+}
+
+// Ptsname retrieves the name of the first available pts for the given master.
+func Ptsname(f *os.File) (string, error) {
+	var n int
+
+	if err := Ioctl(f.Fd(), syscall.TIOCGPTN, uintptr(unsafe.Pointer(&n))); err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("/dev/pts/%d", n), nil
+}
+
+// OpenPtmx opens /dev/ptmx, i.e. the PTY master.
+func OpenPtmx() (*os.File, error) {
+	// O_NOCTTY and O_CLOEXEC are not present in os package so we use the syscall's one for all.
+	return os.OpenFile("/dev/ptmx", syscall.O_RDONLY|syscall.O_NOCTTY|syscall.O_CLOEXEC, 0)
+}

system/setns_linux.go

@@ -0,0 +1,13 @@
+package system
+
+import (
+	"syscall"
+)
+
+func Setns(fd uintptr, flags uintptr) error {
+	_, _, err := syscall.RawSyscall(SYS_SETNS, fd, flags, 0)
+	if err != 0 {
+		return err
+	}
+	return nil
+}

system/setns_linux_amd64.go

@@ -0,0 +1,8 @@
+// +build linux,amd64
+
+package system
+
+// Via http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7b21fddd087678a70ad64afc0f632e0f1071b092
+const (
+	SYS_SETNS = 308
+)