os: if descriptor is non-blocking, retain that in Fd method

For #58408
Fixes #60211

Change-Id: I30f5678b46e15121865b19d1c0f82698493fad4e
Reviewed-on: https://go-review.googlesource.com/c/go/+/495079
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Bryan Mills <bcmills@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

diff --git a/src/internal/syscall/unix/nonblocking.go b/src/internal/syscall/unix/nonblocking.go
index a0becd1e01e04d3db393f8562f5e17114c684d06..6c6f0674d66702f58a70021602c5cb9f265309eb 100644 (file)
--- a/src/internal/syscall/unix/nonblocking.go
+++ b/src/internal/syscall/unix/nonblocking.go
@@ -19,3 +19,7 @@ func IsNonblock(fd int) (nonblocking bool, err error) {
        }
        return flag&syscall.O_NONBLOCK != 0, nil
 }
+
+func HasNonblockFlag(flag int) bool {
+       return flag&syscall.O_NONBLOCK != 0
+}

diff --git a/src/internal/syscall/unix/nonblocking_js.go b/src/internal/syscall/unix/nonblocking_js.go
index 8ed40f3f9104adcd09159a2e73e949d763a5259c..cfe78c58d8de2c2bac2f173e98a6908aac051b95 100644 (file)
--- a/src/internal/syscall/unix/nonblocking_js.go
+++ b/src/internal/syscall/unix/nonblocking_js.go
@@ -9,3 +9,7 @@ package unix
 func IsNonblock(fd int) (nonblocking bool, err error) {
        return false, nil
 }
+
+func HasNonblockFlag(flag int) bool {
+       return false
+}

diff --git a/src/internal/syscall/unix/nonblocking_libc.go b/src/internal/syscall/unix/nonblocking_libc.go
index bff668496236e680aa21772299db9369abc402a5..1310dbf8ce5478f82ace66958a541d50249d555d 100644 (file)
--- a/src/internal/syscall/unix/nonblocking_libc.go
+++ b/src/internal/syscall/unix/nonblocking_libc.go
@@ -19,6 +19,10 @@ func IsNonblock(fd int) (nonblocking bool, err error) {
        return flag&syscall.O_NONBLOCK != 0, nil
 }
 
+func HasNonblockFlag(flag int) bool {
+       return flag&syscall.O_NONBLOCK != 0
+}
+
 // Implemented in the syscall package.
 //
 //go:linkname fcntl syscall.fcntl

diff --git a/src/internal/syscall/unix/nonblocking_wasip1.go b/src/internal/syscall/unix/nonblocking_wasip1.go
index 208db28c3efdb119dae82774ed206878445eb817..5b2b53bf5c3c6860e413229c43ad52e86574f5d4 100644 (file)
--- a/src/internal/syscall/unix/nonblocking_wasip1.go
+++ b/src/internal/syscall/unix/nonblocking_wasip1.go
@@ -19,6 +19,10 @@ func IsNonblock(fd int) (nonblocking bool, err error) {
        return flags&syscall.FDFLAG_NONBLOCK != 0, nil
 }
 
+func HasNonblockFlag(flag int) bool {
+       return flag&syscall.FDFLAG_NONBLOCK != 0
+}
+
 // This helper is implemented in the syscall package. It means we don't have
 // to redefine the fd_fdstat_get host import or the fdstat struct it
 // populates.

diff --git a/src/os/fifo_test.go b/src/os/fifo_test.go
index 867c294f5ecbbacb7b30517300a242ab58217724..df4b2ee757c6a58ef6f146b0ae37ee9bacf944a1 100644 (file)
--- a/src/os/fifo_test.go
+++ b/src/os/fifo_test.go
@@ -8,6 +8,7 @@ package os_test
 
 import (
        "errors"
+       "internal/syscall/unix"
        "internal/testenv"
        "io/fs"
        "os"
@@ -155,3 +156,52 @@ func TestNonPollable(t *testing.T) {
                }
        }
 }
+
+// Issue 60211.
+func TestOpenFileNonBlocking(t *testing.T) {
+       exe, err := os.Executable()
+       if err != nil {
+               t.Skipf("can't find executable: %v", err)
+       }
+       f, err := os.OpenFile(exe, os.O_RDONLY|syscall.O_NONBLOCK, 0666)
+       if err != nil {
+               t.Fatal(err)
+       }
+       defer f.Close()
+       nonblock, err := unix.IsNonblock(int(f.Fd()))
+       if err != nil {
+               t.Fatal(err)
+       }
+       if !nonblock {
+               t.Errorf("file opened with O_NONBLOCK but in blocking mode")
+       }
+}
+
+func TestNewFileNonBlocking(t *testing.T) {
+       var p [2]int
+       if err := syscall.Pipe(p[:]); err != nil {
+               t.Fatal(err)
+       }
+       if err := syscall.SetNonblock(p[0], true); err != nil {
+               t.Fatal(err)
+       }
+       f := os.NewFile(uintptr(p[0]), "pipe")
+       nonblock, err := unix.IsNonblock(p[0])
+       if err != nil {
+               t.Fatal(err)
+       }
+       if !nonblock {
+               t.Error("pipe blocking after NewFile")
+       }
+       fd := f.Fd()
+       if fd != uintptr(p[0]) {
+               t.Errorf("Fd returned %d, want %d", fd, p[0])
+       }
+       nonblock, err = unix.IsNonblock(p[0])
+       if err != nil {
+               t.Fatal(err)
+       }
+       if !nonblock {
+               t.Error("pipe blocking after Fd")
+       }
+}

diff --git a/src/os/file_unix.go b/src/os/file_unix.go
index f7f942f5f528e45ea98a75c423ee2014529a3bf3..3d3a8b2056b793bd7ddf3e1d9cbf3eb0ca584693 100644 (file)
--- a/src/os/file_unix.go
+++ b/src/os/file_unix.go
@@ -116,12 +116,12 @@ const (
        // kindNewFile means that the descriptor was passed to us via NewFile.
        kindNewFile newFileKind = iota
        // kindOpenFile means that the descriptor was opened using
-       // Open, Create, or OpenFile.
+       // Open, Create, or OpenFile (without O_NONBLOCK).
        kindOpenFile
        // kindPipe means that the descriptor was opened using Pipe.
        kindPipe
-       // kindNonBlock means that the descriptor was passed to us via NewFile,
-       // and the descriptor is already in non-blocking mode.
+       // kindNonBlock means that the descriptor is already in
+       // non-blocking mode.
        kindNonBlock
        // kindNoPoll means that we should not put the descriptor into
        // non-blocking mode, because we know it is not a pipe or FIFO.
@@ -184,7 +184,9 @@ func newFile(fd uintptr, name string, kind newFileKind) *File {
        clearNonBlock := false
        if pollable {
                if kind == kindNonBlock {
-                       f.nonblock = true
+                       // The descriptor is already in non-blocking mode.
+                       // We only set f.nonblock if we put the file into
+                       // non-blocking mode.
                } else if err := syscall.SetNonblock(fdi, true); err == nil {
                        f.nonblock = true
                        clearNonBlock = true
@@ -263,7 +265,12 @@ func openFileNolog(name string, flag int, perm FileMode) (*File, error) {
                syscall.CloseOnExec(r)
        }
 
-       f := newFile(uintptr(r), name, kindOpenFile)
+       kind := kindOpenFile
+       if unix.HasNonblockFlag(flag) {
+               kind = kindNonBlock
+       }
+
+       f := newFile(uintptr(r), name, kind)
        f.pfd.SysFile = s
        return f, nil
 }