6 files changed, 60 insertions, 32 deletions

diff --git a/pkg/sentry/syscalls/linux/linux64.go b/pkg/sentry/syscalls/linux/linux64.go
index 18d24ab61..61acd0abd 100644
--- a/pkg/sentry/syscalls/linux/linux64.go
+++ b/pkg/sentry/syscalls/linux/linux64.go
@@ -232,7 +232,7 @@ var AMD64 = &kernel.SyscallTable{
 		184: syscalls.Error("tuxcall", syserror.ENOSYS, "Not implemented in Linux.", nil),
 		185: syscalls.Error("security", syserror.ENOSYS, "Not implemented in Linux.", nil),
 		186: syscalls.Supported("gettid", Gettid),
-		187: syscalls.ErrorWithEvent("readahead", syserror.ENOSYS, "", []string{"gvisor.dev/issue/261"}), // TODO(b/29351341)
+		187: syscalls.Supported("readahead", Readahead),
 		188: syscalls.Error("setxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
 		189: syscalls.Error("lsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
 		190: syscalls.Error("fsetxattr", syserror.ENOTSUP, "Requires filesystem support.", nil),
diff --git a/pkg/sentry/syscalls/linux/sys_read.go b/pkg/sentry/syscalls/linux/sys_read.go
index 3ab54271c..cd31e0649 100644
--- a/pkg/sentry/syscalls/linux/sys_read.go
+++ b/pkg/sentry/syscalls/linux/sys_read.go
@@ -72,6 +72,39 @@ func Read(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallC
 	return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "read", file)
 }
 
+// Readahead implements readahead(2).
+func Readahead(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+	fd := args[0].Int()
+	offset := args[1].Int64()
+	size := args[2].SizeT()
+
+	file := t.GetFile(fd)
+	if file == nil {
+		return 0, nil, syserror.EBADF
+	}
+	defer file.DecRef()
+
+	// Check that the file is readable.
+	if !file.Flags().Read {
+		return 0, nil, syserror.EBADF
+	}
+
+	// Check that the size is valid.
+	if int(size) < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Check that the offset is legitimate.
+	if offset < 0 {
+		return 0, nil, syserror.EINVAL
+	}
+
+	// Return EINVAL; if the underlying file type does not support readahead,
+	// then Linux will return EINVAL to indicate as much. In the future, we
+	// may extend this function to actually support readahead hints.
+	return 0, nil, syserror.EINVAL
+}
+
 // Pread64 implements linux syscall pread64(2).
 func Pread64(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
 	fd := args[0].Int()
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index 3bac4d90d..b5a72ce63 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -531,7 +531,7 @@ func SetSockOpt(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sy
 		return 0, nil, syserror.ENOTSOCK
 	}
 
-	if optLen <= 0 {
+	if optLen < 0 {
 		return 0, nil, syserror.EINVAL
 	}
 	if optLen > maxOptLen {
diff --git a/pkg/sentry/syscalls/linux/sys_splice.go b/pkg/sentry/syscalls/linux/sys_splice.go
index f0a292f2f..9f705ebca 100644
--- a/pkg/sentry/syscalls/linux/sys_splice.go
+++ b/pkg/sentry/syscalls/linux/sys_splice.go
@@ -245,12 +245,12 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
 		if inOffset != 0 || outOffset != 0 {
 			return 0, nil, syserror.ESPIPE
 		}
-	default:
-		return 0, nil, syserror.EINVAL
-	}
 
-	// We may not refer to the same pipe; otherwise it's a continuous loop.
-	if inFile.Dirent.Inode.StableAttr.InodeID == outFile.Dirent.Inode.StableAttr.InodeID {
+		// We may not refer to the same pipe; otherwise it's a continuous loop.
+		if inFile.Dirent.Inode.StableAttr.InodeID == outFile.Dirent.Inode.StableAttr.InodeID {
+			return 0, nil, syserror.EINVAL
+		}
+	default:
 		return 0, nil, syserror.EINVAL
 	}
 
diff --git a/pkg/sentry/syscalls/linux/sys_time.go b/pkg/sentry/syscalls/linux/sys_time.go
index 4b3f043a2..b887fa9d7 100644
--- a/pkg/sentry/syscalls/linux/sys_time.go
+++ b/pkg/sentry/syscalls/linux/sys_time.go
@@ -15,6 +15,7 @@
 package linux
 
 import (
+	"fmt"
 	"time"
 
 	"gvisor.dev/gvisor/pkg/abi/linux"
@@ -228,41 +229,35 @@ func clockNanosleepFor(t *kernel.Task, c ktime.Clock, dur time.Duration, rem use
 
 	timer.Destroy()
 
-	var remaining time.Duration
-	// Did we just block for the entire duration?
-	if err == syserror.ETIMEDOUT {
-		remaining = 0
-	} else {
-		remaining = dur - after.Sub(start)
+	switch err {
+	case syserror.ETIMEDOUT:
+		// Slept for entire timeout.
+		return nil
+	case syserror.ErrInterrupted:
+		// Interrupted.
+		remaining := dur - after.Sub(start)
 		if remaining < 0 {
 			remaining = time.Duration(0)
 		}
-	}
 
-	// Copy out remaining time.
-	if err != nil && rem != usermem.Addr(0) {
-		timeleft := linux.NsecToTimespec(remaining.Nanoseconds())
-		if err := copyTimespecOut(t, rem, &timeleft); err != nil {
-			return err
+		// Copy out remaining time.
+		if rem != 0 {
+			timeleft := linux.NsecToTimespec(remaining.Nanoseconds())
+			if err := copyTimespecOut(t, rem, &timeleft); err != nil {
+				return err
+			}
 		}
-	}
-
-	// Did we just block for the entire duration?
-	if err == syserror.ETIMEDOUT {
-		return nil
-	}
 
-	// If interrupted, arrange for a restart with the remaining duration.
-	if err == syserror.ErrInterrupted {
+		// Arrange for a restart with the remaining duration.
 		t.SetSyscallRestartBlock(&clockNanosleepRestartBlock{
 			c:        c,
 			duration: remaining,
 			rem:      rem,
 		})
 		return kernel.ERESTART_RESTARTBLOCK
+	default:
+		panic(fmt.Sprintf("Impossible BlockWithTimer error %v", err))
 	}
-
-	return err
 }
 
 // Nanosleep implements linux syscall Nanosleep(2).
diff --git a/pkg/sentry/syscalls/linux/sys_utsname.go b/pkg/sentry/syscalls/linux/sys_utsname.go
index 271ace08e..748e8dd8d 100644
--- a/pkg/sentry/syscalls/linux/sys_utsname.go
+++ b/pkg/sentry/syscalls/linux/sys_utsname.go
@@ -79,11 +79,11 @@ func Sethostname(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.S
 		return 0, nil, syserror.EINVAL
 	}
 
-	name, err := t.CopyInString(nameAddr, int(size))
-	if err != nil {
+	name := make([]byte, size)
+	if _, err := t.CopyInBytes(nameAddr, name); err != nil {
 		return 0, nil, err
 	}
 
-	utsns.SetHostName(name)
+	utsns.SetHostName(string(name))
 	return 0, nil, nil
 }