Re: [libgo] Provide strerror_r replacement (PR go/47515)

[Ian Lance Taylor <iant at google dot com>]

Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE> writes:

> Apart from the lack of wait4, libgo on IRIX 6.5 contained an undefined
> reference to strerror_r.  This patch provides a replacement, based on
> gnulib/lib/strerror_r.c, but massively simplified.

I addressed this in a different way, with a new variant of
syscall.Errstr written in Go.  Bootstrapped and ran Go testsuite on
x86_64-unknown-linux-gnu.  Committed to mainline.

Ian

diff -r ad3d14acbce1 libgo/Makefile.am
--- a/libgo/Makefile.am	Wed Mar 30 14:45:29 2011 -0700
+++ b/libgo/Makefile.am	Wed Mar 30 15:31:01 2011 -0700
@@ -1264,7 +1264,11 @@
 if LIBGO_IS_RTEMS
 syscall_errstr_file = syscalls/errstr_rtems.go
 else
+if HAVE_STRERROR_R
 syscall_errstr_file = syscalls/errstr.go
+else
+syscall_errstr_file = syscalls/errstr_nor.go
+endif
 endif
 
 # Declare libc_strerror_r which is the Go name for strerror_r.
@@ -1273,7 +1277,7 @@
 syscall_errstr_decl_file = syscalls/errstr_decl_rtems.go
 else
 if LIBGO_IS_LINUX
-# In Linux the POSIX strerror_r is called __xpg_strerror_r.
+# On GNU/Linux the POSIX strerror_r is called __xpg_strerror_r.
 syscall_errstr_decl_file = syscalls/errstr_decl_linux.go
 else
 # On other systems we hope strerror_r is just strerror_r.
diff -r ad3d14acbce1 libgo/configure.ac
--- a/libgo/configure.ac	Wed Mar 30 14:45:29 2011 -0700
+++ b/libgo/configure.ac	Wed Mar 30 15:31:01 2011 -0700
@@ -380,7 +380,9 @@
 
 AC_CHECK_HEADERS(sys/mman.h syscall.h sys/epoll.h sys/ptrace.h sys/syscall.h sys/user.h sys/utsname.h)
 AM_CONDITIONAL(HAVE_SYS_MMAN_H, test "$ac_cv_header_sys_mman_h" = yes)
-AC_CHECK_FUNCS(srandom random strsignal)
+
+AC_CHECK_FUNCS(srandom random strerror_r strsignal)
+AM_CONDITIONAL(HAVE_STRERROR_R, test "$ac_cv_func_strerror_r" = yes)
 
 AC_CACHE_CHECK([for __sync_bool_compare_and_swap_4],
 [libgo_cv_func___sync_bool_compare_and_swap_4],
diff -r ad3d14acbce1 libgo/syscalls/errstr_nor.go
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgo/syscalls/errstr_nor.go	Wed Mar 30 15:31:01 2011 -0700
@@ -0,0 +1,32 @@
+// errstr.go -- Error strings when there is no strerror_r.
+
+// Copyright 2011 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.
+
+package syscall
+
+import (
+	"sync"
+	"unsafe"
+)
+
+func libc_strerror(int) *byte __asm__ ("strerror")
+
+var errstr_lock sync.Mutex
+
+func Errstr(errno int) string {
+	errstr_lock.Lock()
+
+	bp := libc_strerror(errno)
+	b := (*[1000]byte)(unsafe.Pointer(bp))
+	i := 0
+	for b[i] != 0 {
+		i++
+	}
+	s := string(b[:i])
+
+	errstr_lock.Unlock()
+
+	return s
+}