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-rw-r--r--pkg/sentry/syscalls/BUILD3
-rw-r--r--pkg/sentry/syscalls/linux/BUILD10
-rw-r--r--pkg/sentry/syscalls/linux/error.go72
-rw-r--r--pkg/sentry/syscalls/linux/linux64_amd64.go2
-rw-r--r--pkg/sentry/syscalls/linux/linux64_arm64.go2
-rw-r--r--pkg/sentry/syscalls/linux/sigset.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_aio.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_epoll.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_file.go6
-rw-r--r--pkg/sentry/syscalls/linux/sys_futex.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_getdents.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_mempolicy.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_mmap.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_mount.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_pipe.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_poll.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_random.go4
-rw-r--r--pkg/sentry/syscalls/linux/sys_read.go4
-rw-r--r--pkg/sentry/syscalls/linux/sys_rlimit.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_seccomp.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_sem.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_signal.go7
-rw-r--r--pkg/sentry/syscalls/linux/sys_socket.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_splice.go35
-rw-r--r--pkg/sentry/syscalls/linux/sys_stat.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_stat_amd64.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_stat_arm64.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_thread.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_time.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_timer.go4
-rw-r--r--pkg/sentry/syscalls/linux/sys_write.go2
-rw-r--r--pkg/sentry/syscalls/linux/sys_xattr.go3
-rw-r--r--pkg/sentry/syscalls/linux/timespec.go2
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/BUILD24
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/linux64.go16
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go25
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/linux64_override_arm64.go25
-rw-r--r--pkg/sentry/syscalls/linux/vfs2/sys_read.go95
38 files changed, 306 insertions, 73 deletions
diff --git a/pkg/sentry/syscalls/BUILD b/pkg/sentry/syscalls/BUILD
index 79d972202..b8d1bd415 100644
--- a/pkg/sentry/syscalls/BUILD
+++ b/pkg/sentry/syscalls/BUILD
@@ -1,4 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
package(licenses = ["notice"])
@@ -8,7 +8,6 @@ go_library(
"epoll.go",
"syscalls.go",
],
- importpath = "gvisor.dev/gvisor/pkg/sentry/syscalls",
visibility = ["//:sandbox"],
deps = [
"//pkg/abi/linux",
diff --git a/pkg/sentry/syscalls/linux/BUILD b/pkg/sentry/syscalls/linux/BUILD
index 917f74e07..be16ee686 100644
--- a/pkg/sentry/syscalls/linux/BUILD
+++ b/pkg/sentry/syscalls/linux/BUILD
@@ -1,4 +1,4 @@
-load("//tools/go_stateify:defs.bzl", "go_library")
+load("//tools:defs.bzl", "go_library")
package(licenses = ["notice"])
@@ -57,18 +57,18 @@ go_library(
"sys_xattr.go",
"timespec.go",
],
- importpath = "gvisor.dev/gvisor/pkg/sentry/syscalls/linux",
visibility = ["//:sandbox"],
deps = [
"//pkg/abi",
"//pkg/abi/linux",
"//pkg/binary",
"//pkg/bpf",
+ "//pkg/context",
"//pkg/log",
"//pkg/metric",
"//pkg/rand",
+ "//pkg/safemem",
"//pkg/sentry/arch",
- "//pkg/sentry/context",
"//pkg/sentry/fs",
"//pkg/sentry/fs/anon",
"//pkg/sentry/fs/lock",
@@ -88,16 +88,16 @@ go_library(
"//pkg/sentry/loader",
"//pkg/sentry/memmap",
"//pkg/sentry/mm",
- "//pkg/sentry/safemem",
"//pkg/sentry/socket",
"//pkg/sentry/socket/control",
"//pkg/sentry/socket/unix/transport",
"//pkg/sentry/syscalls",
"//pkg/sentry/usage",
- "//pkg/sentry/usermem",
+ "//pkg/sentry/vfs",
"//pkg/sync",
"//pkg/syserr",
"//pkg/syserror",
+ "//pkg/usermem",
"//pkg/waiter",
],
)
diff --git a/pkg/sentry/syscalls/linux/error.go b/pkg/sentry/syscalls/linux/error.go
index 60469549d..64de56ac5 100644
--- a/pkg/sentry/syscalls/linux/error.go
+++ b/pkg/sentry/syscalls/linux/error.go
@@ -22,6 +22,7 @@ import (
"gvisor.dev/gvisor/pkg/metric"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/syserror"
)
@@ -31,20 +32,58 @@ var (
partialResultOnce sync.Once
)
+// HandleIOErrorVFS2 handles special error cases for partial results. For some
+// errors, we may consume the error and return only the partial read/write.
+//
+// op and f are used only for panics.
+func HandleIOErrorVFS2(t *kernel.Task, partialResult bool, err, intr error, op string, f *vfs.FileDescription) error {
+ known, err := handleIOErrorImpl(t, partialResult, err, intr, op)
+ if err != nil {
+ return err
+ }
+ if !known {
+ // An unknown error is encountered with a partial read/write.
+ fs := f.Mount().Filesystem().VirtualFilesystem()
+ root := vfs.RootFromContext(t)
+ name, _ := fs.PathnameWithDeleted(t, root, f.VirtualDentry())
+ log.Traceback("Invalid request partialResult %v and err (type %T) %v for %s operation on %q", partialResult, err, err, op, name)
+ partialResultOnce.Do(partialResultMetric.Increment)
+ }
+ return nil
+}
+
// handleIOError handles special error cases for partial results. For some
// errors, we may consume the error and return only the partial read/write.
//
// op and f are used only for panics.
func handleIOError(t *kernel.Task, partialResult bool, err, intr error, op string, f *fs.File) error {
+ known, err := handleIOErrorImpl(t, partialResult, err, intr, op)
+ if err != nil {
+ return err
+ }
+ if !known {
+ // An unknown error is encountered with a partial read/write.
+ name, _ := f.Dirent.FullName(nil /* ignore chroot */)
+ log.Traceback("Invalid request partialResult %v and err (type %T) %v for %s operation on %q, %T", partialResult, err, err, op, name, f.FileOperations)
+ partialResultOnce.Do(partialResultMetric.Increment)
+ }
+ return nil
+}
+
+// handleIOError handles special error cases for partial results. For some
+// errors, we may consume the error and return only the partial read/write.
+//
+// Returns false if error is unknown.
+func handleIOErrorImpl(t *kernel.Task, partialResult bool, err, intr error, op string) (bool, error) {
switch err {
case nil:
// Typical successful syscall.
- return nil
+ return true, nil
case io.EOF:
// EOF is always consumed. If this is a partial read/write
// (result != 0), the application will see that, otherwise
// they will see 0.
- return nil
+ return true, nil
case syserror.ErrExceedsFileSizeLimit:
// Ignore partialResult because this error only applies to
// normal files, and for those files we cannot accumulate
@@ -53,20 +92,20 @@ func handleIOError(t *kernel.Task, partialResult bool, err, intr error, op strin
// Do not consume the error and return it as EFBIG.
// Simultaneously send a SIGXFSZ per setrlimit(2).
t.SendSignal(kernel.SignalInfoNoInfo(linux.SIGXFSZ, t, t))
- return syserror.EFBIG
+ return true, syserror.EFBIG
case syserror.ErrInterrupted:
// The syscall was interrupted. Return nil if it completed
// partially, otherwise return the error code that the syscall
// needs (to indicate to the kernel what it should do).
if partialResult {
- return nil
+ return true, nil
}
- return intr
+ return true, intr
}
if !partialResult {
// Typical syscall error.
- return err
+ return true, err
}
switch err {
@@ -75,14 +114,14 @@ func handleIOError(t *kernel.Task, partialResult bool, err, intr error, op strin
// read/write. Like ErrWouldBlock, since we have a
// partial read/write, we consume the error and return
// the partial result.
- return nil
+ return true, nil
case syserror.EFAULT:
// EFAULT is only shown the user if nothing was
// read/written. If we read something (this case), they see
// a partial read/write. They will then presumably try again
// with an incremented buffer, which will EFAULT with
// result == 0.
- return nil
+ return true, nil
case syserror.EPIPE:
// Writes to a pipe or socket will return EPIPE if the other
// side is gone. The partial write is returned. EPIPE will be
@@ -90,32 +129,29 @@ func handleIOError(t *kernel.Task, partialResult bool, err, intr error, op strin
//
// TODO(gvisor.dev/issue/161): In some cases SIGPIPE should
// also be sent to the application.
- return nil
+ return true, nil
case syserror.ENOSPC:
// Similar to EPIPE. Return what we wrote this time, and let
// ENOSPC be returned on the next call.
- return nil
+ return true, nil
case syserror.ECONNRESET:
// For TCP sendfile connections, we may have a reset. But we
// should just return n as the result.
- return nil
+ return true, nil
case syserror.ErrWouldBlock:
// Syscall would block, but completed a partial read/write.
// This case should only be returned by IssueIO for nonblocking
// files. Since we have a partial read/write, we consume
// ErrWouldBlock, returning the partial result.
- return nil
+ return true, nil
}
switch err.(type) {
case kernel.SyscallRestartErrno:
// Identical to the EINTR case.
- return nil
+ return true, nil
}
- // An unknown error is encountered with a partial read/write.
- name, _ := f.Dirent.FullName(nil /* ignore chroot */)
- log.Traceback("Invalid request partialResult %v and err (type %T) %v for %s operation on %q, %T", partialResult, err, err, op, name, f.FileOperations)
- partialResultOnce.Do(partialResultMetric.Increment)
- return nil
+ // Error is unknown and cannot be properly handled.
+ return false, nil
}
diff --git a/pkg/sentry/syscalls/linux/linux64_amd64.go b/pkg/sentry/syscalls/linux/linux64_amd64.go
index c76771a54..7435b50bf 100644
--- a/pkg/sentry/syscalls/linux/linux64_amd64.go
+++ b/pkg/sentry/syscalls/linux/linux64_amd64.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/syscalls"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// AMD64 is a table of Linux amd64 syscall API with the corresponding syscall
diff --git a/pkg/sentry/syscalls/linux/linux64_arm64.go b/pkg/sentry/syscalls/linux/linux64_arm64.go
index d3587fda6..03a39fe65 100644
--- a/pkg/sentry/syscalls/linux/linux64_arm64.go
+++ b/pkg/sentry/syscalls/linux/linux64_arm64.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/syscalls"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// ARM64 is a table of Linux arm64 syscall API with the corresponding syscall
diff --git a/pkg/sentry/syscalls/linux/sigset.go b/pkg/sentry/syscalls/linux/sigset.go
index 333013d8c..2ddb2b146 100644
--- a/pkg/sentry/syscalls/linux/sigset.go
+++ b/pkg/sentry/syscalls/linux/sigset.go
@@ -17,8 +17,8 @@ package linux
import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// copyInSigSet copies in a sigset_t, checks its size, and ensures that KILL and
diff --git a/pkg/sentry/syscalls/linux/sys_aio.go b/pkg/sentry/syscalls/linux/sys_aio.go
index f56411bfe..b401978db 100644
--- a/pkg/sentry/syscalls/linux/sys_aio.go
+++ b/pkg/sentry/syscalls/linux/sys_aio.go
@@ -23,8 +23,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel/eventfd"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/mm"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// I/O commands.
diff --git a/pkg/sentry/syscalls/linux/sys_epoll.go b/pkg/sentry/syscalls/linux/sys_epoll.go
index 65b4a227b..5f11b496c 100644
--- a/pkg/sentry/syscalls/linux/sys_epoll.go
+++ b/pkg/sentry/syscalls/linux/sys_epoll.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/epoll"
"gvisor.dev/gvisor/pkg/sentry/syscalls"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
diff --git a/pkg/sentry/syscalls/linux/sys_file.go b/pkg/sentry/syscalls/linux/sys_file.go
index 9bc2445a5..421845ebb 100644
--- a/pkg/sentry/syscalls/linux/sys_file.go
+++ b/pkg/sentry/syscalls/linux/sys_file.go
@@ -18,8 +18,8 @@ import (
"syscall"
"gvisor.dev/gvisor/pkg/abi/linux"
+ "gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/arch"
- "gvisor.dev/gvisor/pkg/sentry/context"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/fs/lock"
"gvisor.dev/gvisor/pkg/sentry/fs/tmpfs"
@@ -28,8 +28,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel/fasync"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/limits"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// fileOpAt performs an operation on the second last component in the path.
@@ -767,7 +767,7 @@ func Close(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscall
// Note that Remove provides a reference on the file that we may use to
// flush. It is still active until we drop the final reference below
// (and other reference-holding operations complete).
- file := t.FDTable().Remove(fd)
+ file, _ := t.FDTable().Remove(fd)
if file == nil {
return 0, nil, syserror.EBADF
}
diff --git a/pkg/sentry/syscalls/linux/sys_futex.go b/pkg/sentry/syscalls/linux/sys_futex.go
index bde17a767..b68261f72 100644
--- a/pkg/sentry/syscalls/linux/sys_futex.go
+++ b/pkg/sentry/syscalls/linux/sys_futex.go
@@ -21,8 +21,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// futexWaitRestartBlock encapsulates the state required to restart futex(2)
diff --git a/pkg/sentry/syscalls/linux/sys_getdents.go b/pkg/sentry/syscalls/linux/sys_getdents.go
index 912cbe4ff..f66f4ffde 100644
--- a/pkg/sentry/syscalls/linux/sys_getdents.go
+++ b/pkg/sentry/syscalls/linux/sys_getdents.go
@@ -23,8 +23,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// Getdents implements linux syscall getdents(2) for 64bit systems.
diff --git a/pkg/sentry/syscalls/linux/sys_mempolicy.go b/pkg/sentry/syscalls/linux/sys_mempolicy.go
index f5a519d8a..ac934dc6f 100644
--- a/pkg/sentry/syscalls/linux/sys_mempolicy.go
+++ b/pkg/sentry/syscalls/linux/sys_mempolicy.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// We unconditionally report a single NUMA node. This also means that our
diff --git a/pkg/sentry/syscalls/linux/sys_mmap.go b/pkg/sentry/syscalls/linux/sys_mmap.go
index 58a05b5bb..9959f6e61 100644
--- a/pkg/sentry/syscalls/linux/sys_mmap.go
+++ b/pkg/sentry/syscalls/linux/sys_mmap.go
@@ -22,8 +22,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/memmap"
"gvisor.dev/gvisor/pkg/sentry/mm"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// Brk implements linux syscall brk(2).
diff --git a/pkg/sentry/syscalls/linux/sys_mount.go b/pkg/sentry/syscalls/linux/sys_mount.go
index 8c13e2d82..eb5ff48f5 100644
--- a/pkg/sentry/syscalls/linux/sys_mount.go
+++ b/pkg/sentry/syscalls/linux/sys_mount.go
@@ -19,8 +19,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// Mount implements Linux syscall mount(2).
diff --git a/pkg/sentry/syscalls/linux/sys_pipe.go b/pkg/sentry/syscalls/linux/sys_pipe.go
index 418d7fa5f..798344042 100644
--- a/pkg/sentry/syscalls/linux/sys_pipe.go
+++ b/pkg/sentry/syscalls/linux/sys_pipe.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/pipe"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// pipe2 implements the actual system call with flags.
diff --git a/pkg/sentry/syscalls/linux/sys_poll.go b/pkg/sentry/syscalls/linux/sys_poll.go
index 2b2df989a..4f8762d7d 100644
--- a/pkg/sentry/syscalls/linux/sys_poll.go
+++ b/pkg/sentry/syscalls/linux/sys_poll.go
@@ -23,8 +23,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/limits"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
diff --git a/pkg/sentry/syscalls/linux/sys_random.go b/pkg/sentry/syscalls/linux/sys_random.go
index bc4c588bf..c0aa0fd60 100644
--- a/pkg/sentry/syscalls/linux/sys_random.go
+++ b/pkg/sentry/syscalls/linux/sys_random.go
@@ -19,11 +19,11 @@ import (
"math"
"gvisor.dev/gvisor/pkg/rand"
+ "gvisor.dev/gvisor/pkg/safemem"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/safemem"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
const (
diff --git a/pkg/sentry/syscalls/linux/sys_read.go b/pkg/sentry/syscalls/linux/sys_read.go
index cd31e0649..227692f06 100644
--- a/pkg/sentry/syscalls/linux/sys_read.go
+++ b/pkg/sentry/syscalls/linux/sys_read.go
@@ -23,13 +23,13 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/socket"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
const (
- // EventMaskRead contains events that can be triggerd on reads.
+ // EventMaskRead contains events that can be triggered on reads.
EventMaskRead = waiter.EventIn | waiter.EventHUp | waiter.EventErr
)
diff --git a/pkg/sentry/syscalls/linux/sys_rlimit.go b/pkg/sentry/syscalls/linux/sys_rlimit.go
index 51e3f836b..e08c333d6 100644
--- a/pkg/sentry/syscalls/linux/sys_rlimit.go
+++ b/pkg/sentry/syscalls/linux/sys_rlimit.go
@@ -19,8 +19,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/limits"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// rlimit describes an implementation of 'struct rlimit', which may vary from
diff --git a/pkg/sentry/syscalls/linux/sys_seccomp.go b/pkg/sentry/syscalls/linux/sys_seccomp.go
index 18510ead8..5b7a66f4d 100644
--- a/pkg/sentry/syscalls/linux/sys_seccomp.go
+++ b/pkg/sentry/syscalls/linux/sys_seccomp.go
@@ -19,8 +19,8 @@ import (
"gvisor.dev/gvisor/pkg/bpf"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// userSockFprog is equivalent to Linux's struct sock_fprog on amd64.
diff --git a/pkg/sentry/syscalls/linux/sys_sem.go b/pkg/sentry/syscalls/linux/sys_sem.go
index cde3b54e7..5f54f2456 100644
--- a/pkg/sentry/syscalls/linux/sys_sem.go
+++ b/pkg/sentry/syscalls/linux/sys_sem.go
@@ -22,8 +22,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
const opsMax = 500 // SEMOPM
diff --git a/pkg/sentry/syscalls/linux/sys_signal.go b/pkg/sentry/syscalls/linux/sys_signal.go
index fb6efd5d8..7e1747a0c 100644
--- a/pkg/sentry/syscalls/linux/sys_signal.go
+++ b/pkg/sentry/syscalls/linux/sys_signal.go
@@ -23,8 +23,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/signalfd"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// "For a process to have permission to send a signal it must
@@ -245,6 +245,11 @@ func RtSigaction(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.S
sig := linux.Signal(args[0].Int())
newactarg := args[1].Pointer()
oldactarg := args[2].Pointer()
+ sigsetsize := args[3].SizeT()
+
+ if sigsetsize != linux.SignalSetSize {
+ return 0, nil, syserror.EINVAL
+ }
var newactptr *arch.SignalAct
if newactarg != 0 {
diff --git a/pkg/sentry/syscalls/linux/sys_socket.go b/pkg/sentry/syscalls/linux/sys_socket.go
index cda517a81..2919228d0 100644
--- a/pkg/sentry/syscalls/linux/sys_socket.go
+++ b/pkg/sentry/syscalls/linux/sys_socket.go
@@ -26,9 +26,9 @@ import (
"gvisor.dev/gvisor/pkg/sentry/socket"
"gvisor.dev/gvisor/pkg/sentry/socket/control"
"gvisor.dev/gvisor/pkg/sentry/socket/unix/transport"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserr"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// minListenBacklog is the minimum reasonable backlog for listening sockets.
diff --git a/pkg/sentry/syscalls/linux/sys_splice.go b/pkg/sentry/syscalls/linux/sys_splice.go
index dd3a5807f..fd642834b 100644
--- a/pkg/sentry/syscalls/linux/sys_splice.go
+++ b/pkg/sentry/syscalls/linux/sys_splice.go
@@ -25,6 +25,10 @@ import (
// doSplice implements a blocking splice operation.
func doSplice(t *kernel.Task, outFile, inFile *fs.File, opts fs.SpliceOpts, nonBlocking bool) (int64, error) {
+ if opts.Length < 0 || opts.SrcStart < 0 || opts.DstStart < 0 {
+ return 0, syserror.EINVAL
+ }
+
var (
total int64
n int64
@@ -82,11 +86,6 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
offsetAddr := args[2].Pointer()
count := int64(args[3].SizeT())
- // Don't send a negative number of bytes.
- if count < 0 {
- return 0, nil, syserror.EINVAL
- }
-
// Get files.
inFile := t.GetFile(inFD)
if inFile == nil {
@@ -136,11 +135,6 @@ func Sendfile(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Sysc
return 0, nil, err
}
- // The offset must be valid.
- if offset < 0 {
- return 0, nil, syserror.EINVAL
- }
-
// Do the splice.
n, err = doSplice(t, outFile, inFile, fs.SpliceOpts{
Length: count,
@@ -211,8 +205,10 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
opts := fs.SpliceOpts{
Length: count,
}
+ inFileAttr := inFile.Dirent.Inode.StableAttr
+ outFileAttr := outFile.Dirent.Inode.StableAttr
switch {
- case fs.IsPipe(inFile.Dirent.Inode.StableAttr) && !fs.IsPipe(outFile.Dirent.Inode.StableAttr):
+ case fs.IsPipe(inFileAttr) && !fs.IsPipe(outFileAttr):
if inOffset != 0 {
return 0, nil, syserror.ESPIPE
}
@@ -225,11 +221,12 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
if _, err := t.CopyIn(outOffset, &offset); err != nil {
return 0, nil, err
}
+
// Use the destination offset.
opts.DstOffset = true
opts.DstStart = offset
}
- case !fs.IsPipe(inFile.Dirent.Inode.StableAttr) && fs.IsPipe(outFile.Dirent.Inode.StableAttr):
+ case !fs.IsPipe(inFileAttr) && fs.IsPipe(outFileAttr):
if outOffset != 0 {
return 0, nil, syserror.ESPIPE
}
@@ -242,17 +239,18 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
if _, err := t.CopyIn(inOffset, &offset); err != nil {
return 0, nil, err
}
+
// Use the source offset.
opts.SrcOffset = true
opts.SrcStart = offset
}
- case fs.IsPipe(inFile.Dirent.Inode.StableAttr) && fs.IsPipe(outFile.Dirent.Inode.StableAttr):
+ case fs.IsPipe(inFileAttr) && fs.IsPipe(outFileAttr):
if inOffset != 0 || outOffset != 0 {
return 0, nil, syserror.ESPIPE
}
// 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 {
+ if inFileAttr.InodeID == outFileAttr.InodeID {
return 0, nil, syserror.EINVAL
}
default:
@@ -262,6 +260,15 @@ func Splice(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.Syscal
// Splice data.
n, err := doSplice(t, outFile, inFile, opts, nonBlock)
+ // Special files can have additional requirements for granularity. For
+ // example, read from eventfd returns EINVAL if a size is less 8 bytes.
+ // Inotify is another example. read will return EINVAL is a buffer is
+ // too small to return the next event, but a size of an event isn't
+ // fixed, it is sizeof(struct inotify_event) + {NAME_LEN} + 1.
+ if n != 0 && err != nil && (fs.IsAnonymous(inFileAttr) || fs.IsAnonymous(outFileAttr)) {
+ err = nil
+ }
+
// See above; inFile is chosen arbitrarily here.
return uintptr(n), nil, handleIOError(t, n != 0, err, kernel.ERESTARTSYS, "splice", inFile)
}
diff --git a/pkg/sentry/syscalls/linux/sys_stat.go b/pkg/sentry/syscalls/linux/sys_stat.go
index 69b17b799..c841abccb 100644
--- a/pkg/sentry/syscalls/linux/sys_stat.go
+++ b/pkg/sentry/syscalls/linux/sys_stat.go
@@ -19,8 +19,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// Stat implements linux syscall stat(2).
diff --git a/pkg/sentry/syscalls/linux/sys_stat_amd64.go b/pkg/sentry/syscalls/linux/sys_stat_amd64.go
index 58afb4a9a..75a567bd4 100644
--- a/pkg/sentry/syscalls/linux/sys_stat_amd64.go
+++ b/pkg/sentry/syscalls/linux/sys_stat_amd64.go
@@ -21,7 +21,7 @@ import (
"gvisor.dev/gvisor/pkg/binary"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// copyOutStat copies the attributes (sattr, uattr) to the struct stat at
diff --git a/pkg/sentry/syscalls/linux/sys_stat_arm64.go b/pkg/sentry/syscalls/linux/sys_stat_arm64.go
index 3e1251e0b..80c98d05c 100644
--- a/pkg/sentry/syscalls/linux/sys_stat_arm64.go
+++ b/pkg/sentry/syscalls/linux/sys_stat_arm64.go
@@ -21,7 +21,7 @@ import (
"gvisor.dev/gvisor/pkg/binary"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// copyOutStat copies the attributes (sattr, uattr) to the struct stat at
diff --git a/pkg/sentry/syscalls/linux/sys_thread.go b/pkg/sentry/syscalls/linux/sys_thread.go
index b47c3b5c4..0c9e2255d 100644
--- a/pkg/sentry/syscalls/linux/sys_thread.go
+++ b/pkg/sentry/syscalls/linux/sys_thread.go
@@ -24,8 +24,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
"gvisor.dev/gvisor/pkg/sentry/kernel/sched"
"gvisor.dev/gvisor/pkg/sentry/loader"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
const (
diff --git a/pkg/sentry/syscalls/linux/sys_time.go b/pkg/sentry/syscalls/linux/sys_time.go
index b887fa9d7..2d2aa0819 100644
--- a/pkg/sentry/syscalls/linux/sys_time.go
+++ b/pkg/sentry/syscalls/linux/sys_time.go
@@ -22,8 +22,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// The most significant 29 bits hold either a pid or a file descriptor.
diff --git a/pkg/sentry/syscalls/linux/sys_timer.go b/pkg/sentry/syscalls/linux/sys_timer.go
index d4134207b..a4c400f87 100644
--- a/pkg/sentry/syscalls/linux/sys_timer.go
+++ b/pkg/sentry/syscalls/linux/sys_timer.go
@@ -20,8 +20,8 @@ import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
const nsecPerSec = int64(time.Second)
@@ -146,7 +146,7 @@ func TimerCreate(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.S
return 0, nil, err
}
- return uintptr(id), nil, nil
+ return 0, nil, nil
}
// TimerSettime implements linux syscall timer_settime(2).
diff --git a/pkg/sentry/syscalls/linux/sys_write.go b/pkg/sentry/syscalls/linux/sys_write.go
index ad4b67806..aba892939 100644
--- a/pkg/sentry/syscalls/linux/sys_write.go
+++ b/pkg/sentry/syscalls/linux/sys_write.go
@@ -23,8 +23,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/kernel"
ktime "gvisor.dev/gvisor/pkg/sentry/kernel/time"
"gvisor.dev/gvisor/pkg/sentry/socket"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
"gvisor.dev/gvisor/pkg/waiter"
)
diff --git a/pkg/sentry/syscalls/linux/sys_xattr.go b/pkg/sentry/syscalls/linux/sys_xattr.go
index e35c077d6..efb95555c 100644
--- a/pkg/sentry/syscalls/linux/sys_xattr.go
+++ b/pkg/sentry/syscalls/linux/sys_xattr.go
@@ -21,8 +21,8 @@ import (
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/fs"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// GetXattr implements linux syscall getxattr(2).
@@ -103,6 +103,7 @@ func getXattr(t *kernel.Task, d *fs.Dirent, nameAddr usermem.Addr, size uint64)
return 0, "", err
}
+ // TODO(b/148380782): Support xattrs in namespaces other than "user".
if !strings.HasPrefix(name, linux.XATTR_USER_PREFIX) {
return 0, "", syserror.EOPNOTSUPP
}
diff --git a/pkg/sentry/syscalls/linux/timespec.go b/pkg/sentry/syscalls/linux/timespec.go
index 4ff8f9234..ddc3ee26e 100644
--- a/pkg/sentry/syscalls/linux/timespec.go
+++ b/pkg/sentry/syscalls/linux/timespec.go
@@ -19,8 +19,8 @@ import (
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/sentry/kernel"
- "gvisor.dev/gvisor/pkg/sentry/usermem"
"gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
)
// copyTimespecIn copies a Timespec from the untrusted app range to the kernel.
diff --git a/pkg/sentry/syscalls/linux/vfs2/BUILD b/pkg/sentry/syscalls/linux/vfs2/BUILD
new file mode 100644
index 000000000..6b8a00b6e
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/BUILD
@@ -0,0 +1,24 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+ name = "vfs2",
+ srcs = [
+ "linux64.go",
+ "linux64_override_amd64.go",
+ "linux64_override_arm64.go",
+ "sys_read.go",
+ ],
+ visibility = ["//:sandbox"],
+ deps = [
+ "//pkg/sentry/arch",
+ "//pkg/sentry/kernel",
+ "//pkg/sentry/syscalls",
+ "//pkg/sentry/syscalls/linux",
+ "//pkg/sentry/vfs",
+ "//pkg/syserror",
+ "//pkg/usermem",
+ "//pkg/waiter",
+ ],
+)
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64.go b/pkg/sentry/syscalls/linux/vfs2/linux64.go
new file mode 100644
index 000000000..19ee36081
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64.go
@@ -0,0 +1,16 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package vfs2 provides syscall implementations that use VFS2.
+package vfs2
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
new file mode 100644
index 000000000..c134714ee
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64_override_amd64.go
@@ -0,0 +1,25 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs2
+
+import (
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/syscalls"
+)
+
+// Override syscall table to add syscalls implementations from this package.
+func Override(table map[uintptr]kernel.Syscall) {
+ table[0] = syscalls.Supported("read", Read)
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/linux64_override_arm64.go b/pkg/sentry/syscalls/linux/vfs2/linux64_override_arm64.go
new file mode 100644
index 000000000..6af5c400f
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/linux64_override_arm64.go
@@ -0,0 +1,25 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs2
+
+import (
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/syscalls"
+)
+
+// Override syscall table to add syscalls implementations from this package.
+func Override(table map[uintptr]kernel.Syscall) {
+ table[63] = syscalls.Supported("read", Read)
+}
diff --git a/pkg/sentry/syscalls/linux/vfs2/sys_read.go b/pkg/sentry/syscalls/linux/vfs2/sys_read.go
new file mode 100644
index 000000000..7667524c7
--- /dev/null
+++ b/pkg/sentry/syscalls/linux/vfs2/sys_read.go
@@ -0,0 +1,95 @@
+// Copyright 2020 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package vfs2
+
+import (
+ "gvisor.dev/gvisor/pkg/sentry/arch"
+ "gvisor.dev/gvisor/pkg/sentry/kernel"
+ "gvisor.dev/gvisor/pkg/sentry/syscalls/linux"
+ "gvisor.dev/gvisor/pkg/sentry/vfs"
+ "gvisor.dev/gvisor/pkg/syserror"
+ "gvisor.dev/gvisor/pkg/usermem"
+ "gvisor.dev/gvisor/pkg/waiter"
+)
+
+const (
+ // EventMaskRead contains events that can be triggered on reads.
+ EventMaskRead = waiter.EventIn | waiter.EventHUp | waiter.EventErr
+)
+
+// Read implements linux syscall read(2). Note that we try to get a buffer that
+// is exactly the size requested because some applications like qemu expect
+// they can do large reads all at once. Bug for bug. Same for other read
+// calls below.
+func Read(t *kernel.Task, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
+ fd := args[0].Int()
+ addr := args[1].Pointer()
+ size := args[2].SizeT()
+
+ file := t.GetFileVFS2(fd)
+ if file == nil {
+ return 0, nil, syserror.EBADF
+ }
+ defer file.DecRef()
+
+ // Check that the size is legitimate.
+ si := int(size)
+ if si < 0 {
+ return 0, nil, syserror.EINVAL
+ }
+
+ // Get the destination of the read.
+ dst, err := t.SingleIOSequence(addr, si, usermem.IOOpts{
+ AddressSpaceActive: true,
+ })
+ if err != nil {
+ return 0, nil, err
+ }
+
+ n, err := read(t, file, dst, vfs.ReadOptions{})
+ t.IOUsage().AccountReadSyscall(n)
+ return uintptr(n), nil, linux.HandleIOErrorVFS2(t, n != 0, err, kernel.ERESTARTSYS, "read", file)
+}
+
+func read(t *kernel.Task, file *vfs.FileDescription, dst usermem.IOSequence, opts vfs.ReadOptions) (int64, error) {
+ n, err := file.Read(t, dst, opts)
+ if err != syserror.ErrWouldBlock {
+ return n, err
+ }
+
+ // Register for notifications.
+ w, ch := waiter.NewChannelEntry(nil)
+ file.EventRegister(&w, EventMaskRead)
+
+ total := n
+ for {
+ // Shorten dst to reflect bytes previously read.
+ dst = dst.DropFirst(int(n))
+
+ // Issue the request and break out if it completes with anything other than
+ // "would block".
+ n, err := file.Read(t, dst, opts)
+ total += n
+ if err != syserror.ErrWouldBlock {
+ break
+ }
+ if err := t.Block(ch); err != nil {
+ break
+ }
+ }
+ file.EventUnregister(&w)
+
+ return total, err
+}