internal/syscall/windows: increase internal Windows O_ flags values

The lowercase o_ flags are invented values. These conflict with
constants that will soon be allowed by os.OpenFile, which values will
be mandated by the Windows API. To avoid this overlap, the internal
values have been increased to the 33-63 bit range, as the Windows ones
are in the 0-32 bit range.

Updates #73676

Change-Id: I0f657f3ed3403de150f1730a5a65ae887a18a4e9
Reviewed-on: https://go-review.googlesource.com/c/go/+/697363
Reviewed-by: Damien Neil <dneil@google.com>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>

3 files changed, 13 insertions, 12 deletions

diff --git a/src/internal/syscall/windows/at_windows.go b/src/internal/syscall/windows/at_windows.go
index d48fce1c99..8b19a03e7e 100644
--- a/src/internal/syscall/windows/at_windows.go
+++ b/src/internal/syscall/windows/at_windows.go
@@ -13,16 +13,17 @@ import (
 
 // Openat flags not supported by syscall.Open.
 //
-// These are invented values.
+// These are invented values, use values in the 33-63 bit range
+// to avoid overlap with flags and attributes supported by [syscall.Open].
 //
 // When adding a new flag here, add an unexported version to
 // the set of invented O_ values in syscall/types_windows.go
 // to avoid overlap.
 const (
-	O_DIRECTORY    = 0x100000   // target must be a directory
-	O_NOFOLLOW_ANY = 0x20000000 // disallow symlinks anywhere in the path
-	O_OPEN_REPARSE = 0x40000000 // FILE_OPEN_REPARSE_POINT, used by Lstat
-	O_WRITE_ATTRS  = 0x80000000 // FILE_WRITE_ATTRIBUTES, used by Chmod
+	O_DIRECTORY    = 0x100000000 // target must be a directory
+	O_NOFOLLOW_ANY = 0x200000000 // disallow symlinks anywhere in the path
+	O_OPEN_REPARSE = 0x400000000 // FILE_OPEN_REPARSE_POINT, used by Lstat
+	O_WRITE_ATTRS  = 0x800000000 // FILE_WRITE_ATTRIBUTES, used by Chmod
 )
 
 func Openat(dirfd syscall.Handle, name string, flag uint64, perm uint32) (_ syscall.Handle, e1 error) {
diff --git a/src/os/root_windows.go b/src/os/root_windows.go
index 523ee48d13..afc645d8f8 100644
--- a/src/os/root_windows.go
+++ b/src/os/root_windows.go
@@ -129,7 +129,7 @@ func openRootInRoot(r *Root, name string) (*Root, error) {
 // rootOpenFileNolog is Root.OpenFile.
 func rootOpenFileNolog(root *Root, name string, flag int, perm FileMode) (*File, error) {
 	fd, err := doInRoot(root, name, nil, func(parent syscall.Handle, name string) (syscall.Handle, error) {
-		return openat(parent, name, flag, perm)
+		return openat(parent, name, uint64(flag), perm)
 	})
 	if err != nil {
 		return nil, &PathError{Op: "openat", Path: name, Err: err}
@@ -138,8 +138,8 @@ func rootOpenFileNolog(root *Root, name string, flag int, perm FileMode) (*File,
 	return newFile(fd, joinPath(root.Name(), name), "file", false), nil
 }
 
-func openat(dirfd syscall.Handle, name string, flag int, perm FileMode) (syscall.Handle, error) {
-	h, err := windows.Openat(dirfd, name, uint64(flag)|syscall.O_CLOEXEC|windows.O_NOFOLLOW_ANY, syscallMode(perm))
+func openat(dirfd syscall.Handle, name string, flag uint64, perm FileMode) (syscall.Handle, error) {
+	h, err := windows.Openat(dirfd, name, flag|syscall.O_CLOEXEC|windows.O_NOFOLLOW_ANY, syscallMode(perm))
 	if err == syscall.ELOOP || err == syscall.ENOTDIR {
 		if link, err := readReparseLinkAt(dirfd, name); err == nil {
 			return syscall.InvalidHandle, errSymlink(link)
diff --git a/src/syscall/types_windows.go b/src/syscall/types_windows.go
index 92fa796a80..dd21fc8329 100644
--- a/src/syscall/types_windows.go
+++ b/src/syscall/types_windows.go
@@ -48,10 +48,10 @@ const (
 	O_SYNC         = 0x01000
 	O_ASYNC        = 0x02000
 	O_CLOEXEC      = 0x80000
-	o_DIRECTORY    = 0x100000   // used by internal/syscall/windows
-	o_NOFOLLOW_ANY = 0x20000000 // used by internal/syscall/windows
-	o_OPEN_REPARSE = 0x40000000 // used by internal/syscall/windows
-	o_WRITE_ATTRS  = 0x80000000 // used by internal/syscall/windows
+	o_DIRECTORY    = 0x100000000 // used by internal/syscall/windows
+	o_NOFOLLOW_ANY = 0x200000000 // used by internal/syscall/windows
+	o_OPEN_REPARSE = 0x400000000 // used by internal/syscall/windows
+	o_WRITE_ATTRS  = 0x800000000 // used by internal/syscall/windows
 )
 
 const (