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

1 files changed, 37 insertions, 0 deletions

diff --git a/libgo/runtime/go-strerror.c b/libgo/runtime/go-strerror.c
new file mode 100644
index 0000000..13d1d91
--- /dev/null
+++ b/libgo/runtime/go-strerror.c
@@ -0,0 +1,37 @@
+/* go-strerror.c -- wrapper around XSI-compliant strerror_r.
+
+   Copyright 2022 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.  */
+
+/* There are two version of strerror_r on GNU/Linux: a GNU-specific
+   and an XSI-compliant version.  The former version is only available
+   on glibc.  Since glibc 2.13, the XSI-compliant version is also
+   provided by glibc if _GNU_SOURCE is not defined.  Since the
+   entirety of gofrontend is compiled with _GNU_SOURCE, this file
+   exists to selectively undefine it and provides an alias to the
+   XSI-compliant version of strerror_r(3).  */
+
+#ifdef __linux__
+
+/* Force selection of XSI-compliant strerror_r by glibc.  */
+#undef XOPEN_SOURCE
+#define XOPEN_SOURCE 600
+#undef _POSIX_C_SOURCE
+#define _POSIX_C_SOURCE 200112L
+#undef _GNU_SOURCE
+
+#endif /* __linux__ */
+
+#include <string.h>
+
+#ifndef HAVE_STRERROR_R
+// Provided by go-nosys.c if not provided by libc itself.
+extern int strerror_r (int, char *, size_t);
+#endif
+
+int
+go_strerror (int errnum, char *buf, size_t buflen)
+{
+  return strerror_r (errnum, buf, buflen);
+}