vendor: update syscalls dependency

vendor/golang.org/x/sys/unix/openbsd_pledge.go

@@ -8,31 +8,159 @@
 package unix
 
 import (
+	"errors"
+	"fmt"
+	"strconv"
 	"syscall"
 	"unsafe"
 )
 
-const (
-	SYS_PLEDGE = 108
-)
-
-// Pledge implements the pledge syscall. For more information see pledge(2).
-func Pledge(promises string, paths []string) error {
-	promisesPtr, err := syscall.BytePtrFromString(promises)
+// Pledge implements the pledge syscall.
+//
+// The pledge syscall does not accept execpromises on OpenBSD releases
+// before 6.3.
+//
+// execpromises must be empty when Pledge is called on OpenBSD
+// releases predating 6.3, otherwise an error will be returned.
+//
+// For more information see pledge(2).
+func Pledge(promises, execpromises string) error {
+	maj, min, err := majmin()
 	if err != nil {
 		return err
 	}
-	promisesUnsafe, pathsUnsafe := unsafe.Pointer(promisesPtr), unsafe.Pointer(nil)
-	if paths != nil {
-		var pathsPtr []*byte
-		if pathsPtr, err = syscall.SlicePtrFromStrings(paths); err != nil {
+
+	err = pledgeAvailable(maj, min, execpromises)
+	if err != nil {
+		return err
+	}
+
+	pptr, err := syscall.BytePtrFromString(promises)
+	if err != nil {
+		return err
+	}
+
+	// This variable will hold either a nil unsafe.Pointer or
+	// an unsafe.Pointer to a string (execpromises).
+	var expr unsafe.Pointer
+
+	// If we're running on OpenBSD > 6.2, pass execpromises to the syscall.
+	if maj > 6 || (maj == 6 && min > 2) {
+		exptr, err := syscall.BytePtrFromString(execpromises)
+		if err != nil {
 			return err
 		}
-		pathsUnsafe = unsafe.Pointer(&pathsPtr[0])
+		expr = unsafe.Pointer(exptr)
 	}
-	_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(promisesUnsafe), uintptr(pathsUnsafe), 0)
+
+	_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)), uintptr(expr), 0)
 	if e != 0 {
 		return e
 	}
+
+	return nil
+}
+
+// PledgePromises implements the pledge syscall.
+//
+// This changes the promises and leaves the execpromises untouched.
+//
+// For more information see pledge(2).
+func PledgePromises(promises string) error {
+	maj, min, err := majmin()
+	if err != nil {
+		return err
+	}
+
+	err = pledgeAvailable(maj, min, "")
+	if err != nil {
+		return err
+	}
+
+	// This variable holds the execpromises and is always nil.
+	var expr unsafe.Pointer
+
+	pptr, err := syscall.BytePtrFromString(promises)
+	if err != nil {
+		return err
+	}
+
+	_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(unsafe.Pointer(pptr)), uintptr(expr), 0)
+	if e != 0 {
+		return e
+	}
+
+	return nil
+}
+
+// PledgeExecpromises implements the pledge syscall.
+//
+// This changes the execpromises and leaves the promises untouched.
+//
+// For more information see pledge(2).
+func PledgeExecpromises(execpromises string) error {
+	maj, min, err := majmin()
+	if err != nil {
+		return err
+	}
+
+	err = pledgeAvailable(maj, min, execpromises)
+	if err != nil {
+		return err
+	}
+
+	// This variable holds the promises and is always nil.
+	var pptr unsafe.Pointer
+
+	exptr, err := syscall.BytePtrFromString(execpromises)
+	if err != nil {
+		return err
+	}
+
+	_, _, e := syscall.Syscall(SYS_PLEDGE, uintptr(pptr), uintptr(unsafe.Pointer(exptr)), 0)
+	if e != 0 {
+		return e
+	}
+
+	return nil
+}
+
+// majmin returns major and minor version number for an OpenBSD system.
+func majmin() (major int, minor int, err error) {
+	var v Utsname
+	err = Uname(&v)
+	if err != nil {
+		return
+	}
+
+	major, err = strconv.Atoi(string(v.Release[0]))
+	if err != nil {
+		err = errors.New("cannot parse major version number returned by uname")
+		return
+	}
+
+	minor, err = strconv.Atoi(string(v.Release[2]))
+	if err != nil {
+		err = errors.New("cannot parse minor version number returned by uname")
+		return
+	}
+
+	return
+}
+
+// pledgeAvailable checks for availability of the pledge(2) syscall
+// based on the running OpenBSD version.
+func pledgeAvailable(maj, min int, execpromises string) error {
+	// If OpenBSD <= 5.9, pledge is not available.
+	if (maj == 5 && min != 9) || maj < 5 {
+		return fmt.Errorf("pledge syscall is not available on OpenBSD %d.%d", maj, min)
+	}
+
+	// If OpenBSD <= 6.2 and execpromises is not empty,
+	// return an error - execpromises is not available before 6.3
+	if (maj < 6 || (maj == 6 && min <= 2)) && execpromises != "" {
+		return fmt.Errorf("cannot use execpromises on OpenBSD %d.%d", maj, min)
+	}
+
 	return nil
 }