syscall: rename SysProcAttr.Unshare to Unshareflags

For symmetry with Cloneflags and it looks slightly weird because there
is syscall.Unshare method.

Change-Id: I3d710177ca8f27c05b344407f212cbbe3435094b
Reviewed-on: https://go-review.googlesource.com/23612Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

src/syscall/exec_linux.go

@@ -20,21 +20,21 @@ type SysProcIDMap struct {
 }
 
 type SysProcAttr struct {
-	Chroot      string         // Chroot.
-	Credential  *Credential    // Credential.
-	Ptrace      bool           // Enable tracing.
-	Setsid      bool           // Create session.
-	Setpgid     bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
-	Setctty     bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
-	Noctty      bool           // Detach fd 0 from controlling terminal
-	Ctty        int            // Controlling TTY fd
-	Foreground  bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
-	Pgid        int            // Child's process group ID if Setpgid.
-	Pdeathsig   Signal         // Signal that the process will get when its parent dies (Linux only)
-	Cloneflags  uintptr        // Flags for clone calls (Linux only)
-	Unshare     uintptr        // Flags for unshare calls (Linux only)
-	UidMappings []SysProcIDMap // User ID mappings for user namespaces.
-	GidMappings []SysProcIDMap // Group ID mappings for user namespaces.
+	Chroot       string         // Chroot.
+	Credential   *Credential    // Credential.
+	Ptrace       bool           // Enable tracing.
+	Setsid       bool           // Create session.
+	Setpgid      bool           // Set process group ID to Pgid, or, if Pgid == 0, to new pid.
+	Setctty      bool           // Set controlling terminal to fd Ctty (only meaningful if Setsid is set)
+	Noctty       bool           // Detach fd 0 from controlling terminal
+	Ctty         int            // Controlling TTY fd
+	Foreground   bool           // Place child's process group in foreground. (Implies Setpgid. Uses Ctty as fd of controlling TTY)
+	Pgid         int            // Child's process group ID if Setpgid.
+	Pdeathsig    Signal         // Signal that the process will get when its parent dies (Linux only)
+	Cloneflags   uintptr        // Flags for clone calls (Linux only)
+	Unshareflags uintptr        // Flags for unshare calls (Linux only)
+	UidMappings  []SysProcIDMap // User ID mappings for user namespaces.
+	GidMappings  []SysProcIDMap // Group ID mappings for user namespaces.
 	// GidMappingsEnableSetgroups enabling setgroups syscall.
 	// If false, then setgroups syscall will be disabled for the child process.
 	// This parameter is no-op if GidMappings == nil. Otherwise for unprivileged
@@ -196,8 +196,8 @@ func forkAndExecInChild(argv0 *byte, argv, envv []*byte, chroot, dir *byte, attr
 	}
 
 	// Unshare
-	if sys.Unshare != 0 {
-		_, _, err1 = RawSyscall(SYS_UNSHARE, sys.Unshare, 0, 0)
+	if sys.Unshareflags != 0 {
+		_, _, err1 = RawSyscall(SYS_UNSHARE, sys.Unshareflags, 0, 0)
 		if err1 != 0 {
 			goto childerror
 		}

src/syscall/exec_linux_test.go

@@ -143,7 +143,7 @@ func TestUnshare(t *testing.T) {
 
 	cmd := exec.Command("cat", "/proc/net/dev")
 	cmd.SysProcAttr = &syscall.SysProcAttr{
-		Unshare: syscall.CLONE_NEWNET,
+		Unshareflags: syscall.CLONE_NEWNET,
 	}
 	out, err := cmd.CombinedOutput()
 	if err != nil {