runtime: change read and write to return negative errno value

The internal read and write functions used to return -1 on error;
change them to return a negative errno value instead.
This will be used by later CLs in this series.

For most targets this is a simplification, although for ones that call
into libc it is a complication.

Updates #27707

Change-Id: Id02bf9487f03e7e88e4f2b85e899e986738697ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/171823
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

1 files changed, 0 insertions, 26 deletions

diff --git a/src/runtime/runtime_test.go b/src/runtime/runtime_test.go
index ab7a03b2d1..26ae77456a 100644
--- a/src/runtime/runtime_test.go
+++ b/src/runtime/runtime_test.go
@@ -290,32 +290,6 @@ func TestTrailingZero(t *testing.T) {
 	}
 }
 
-func TestBadOpen(t *testing.T) {
-	if GOOS == "windows" || GOOS == "js" {
-		t.Skip("skipping OS that doesn't have open/read/write/close")
-	}
-	// make sure we get the correct error code if open fails. Same for
-	// read/write/close on the resulting -1 fd. See issue 10052.
-	nonfile := []byte("/notreallyafile")
-	fd := Open(&nonfile[0], 0, 0)
-	if fd != -1 {
-		t.Errorf("open(\"%s\")=%d, want -1", string(nonfile), fd)
-	}
-	var buf [32]byte
-	r := Read(-1, unsafe.Pointer(&buf[0]), int32(len(buf)))
-	if r != -1 {
-		t.Errorf("read()=%d, want -1", r)
-	}
-	w := Write(^uintptr(0), unsafe.Pointer(&buf[0]), int32(len(buf)))
-	if w != -1 {
-		t.Errorf("write()=%d, want -1", w)
-	}
-	c := Close(-1)
-	if c != -1 {
-		t.Errorf("close()=%d, want -1", c)
-	}
-}
-
 func TestAppendGrowth(t *testing.T) {
 	var x []int64
 	check := func(want int) {