syscall, runtime: always call XSI strerror_r

This does the right thing for either glibc or musl on GNU/Linux.

Based on patch by Sören Tempel.

Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/454176

2 files changed, 9 insertions, 47 deletions

diff --git a/libgo/go/syscall/errstr.go b/libgo/go/syscall/errstr.go
index 59f7a82..9f688e2 100644
--- a/libgo/go/syscall/errstr.go
+++ b/libgo/go/syscall/errstr.go
@@ -4,23 +4,19 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !hurd && !linux
-// +build !hurd,!linux
-
 package syscall
 
-//sysnb	strerror_r(errnum int, buf []byte) (err Errno)
-//strerror_r(errnum _C_int, buf *byte, buflen Size_t) _C_int
+import "internal/bytealg"
+
+//extern go_strerror
+func go_strerror(_C_int, *byte, Size_t) _C_int
 
 func Errstr(errnum int) string {
-	for len := 128; ; len *= 2 {
-		b := make([]byte, len)
-		errno := strerror_r(errnum, b)
+	for size := 128; ; size *= 2 {
+		b := make([]byte, size)
+		errno := go_strerror(_C_int(errnum), &b[0], Size_t(len(b)))
 		if errno == 0 {
-			i := 0
-			for b[i] != 0 {
-				i++
-			}
+			i := bytealg.IndexByte(b, 0)
 			// Lowercase first letter: Bad -> bad, but
 			// STREAM -> STREAM.
 			if i > 1 && 'A' <= b[0] && b[0] <= 'Z' && 'a' <= b[1] && b[1] <= 'z' {
@@ -29,7 +25,7 @@ func Errstr(errnum int) string {
 			return string(b[:i])
 		}
 		if errno != ERANGE {
-			return "errstr failure"
+			return "strerror_r failure"
 		}
 	}
 }
diff --git a/libgo/go/syscall/errstr_glibc.go b/libgo/go/syscall/errstr_glibc.go
deleted file mode 100644
index 03a327d..0000000
--- a/libgo/go/syscall/errstr_glibc.go
+++ /dev/null
@@ -1,34 +0,0 @@
-// errstr_glibc.go -- GNU/Linux and GNU/Hurd specific error strings.
-
-// Copyright 2010 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// We use this rather than errstr.go because on GNU/Linux sterror_r
-// returns a pointer to the error message, and may not use buf at all.
-
-//go:build hurd || linux
-// +build hurd linux
-
-package syscall
-
-import "unsafe"
-
-//sysnb	strerror_r(errnum int, b []byte) (errstr *byte)
-//strerror_r(errnum _C_int, b *byte, len Size_t) *byte
-
-func Errstr(errnum int) string {
-	a := make([]byte, 128)
-	p := strerror_r(errnum, a)
-	b := (*[1000]byte)(unsafe.Pointer(p))
-	i := 0
-	for b[i] != 0 {
-		i++
-	}
-	// Lowercase first letter: Bad -> bad, but STREAM -> STREAM.
-	if i > 1 && 'A' <= b[0] && b[0] <= 'Z' && 'a' <= b[1] && b[1] <= 'z' {
-		c := b[0] + 'a' - 'A'
-		return string(c) + string(b[1:i])
-	}
-	return string(b[:i])
-}