[PATCH 3/3] src: switch to using strerror_l() instead of strerror_r()

[git at andred.net]

From: André Draszik <adraszik at tycoint.com>

glibc provides two versions of strerror_r(), which
can be chosen between using feature test macros
_GNU_SOURCE and _POSIX_C_SOURCE. libnl is built using
the former, hence we get the glibc special version,
and all code so far has been written for this.

Other C libraries like musl on the other hand only try
to be posix compliant, and only ever provide the posix
version of strerror_r(), which has a different signature.

Uses in libnl hence generally cause printf() of an *int*
with a *string format* specifier for that reason.

Additionally, strerror_r() has been deprecated:
  http://austingroupbugs.net/view.php?id=655

Switch to using strerror_l().

Signed-off-by: André Draszik <adraszik at tycoint.com>
Reviewed-by: Stephane Ayotte <sayotte at tycoint.com>
---
 src/lib/utils.c | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/src/lib/utils.c b/src/lib/utils.c
index 467aaed..5878f27 100644
--- a/src/lib/utils.c
+++ b/src/lib/utils.c
@@ -22,6 +22,7 @@
  */
 
 #include <netlink/cli/utils.h>
+#include <locale.h>
 
 /**
  * Parse a text based 32 bit unsigned integer argument
@@ -70,7 +71,6 @@ void nl_cli_print_version(void)
 void nl_cli_fatal(int err, const char *fmt, ...)
 {
 	va_list ap;
-	char buf[256];
 
 	fprintf(stderr, "Error: ");
 
@@ -79,8 +79,22 @@ void nl_cli_fatal(int err, const char *fmt, ...)
 		vfprintf(stderr, fmt, ap);
 		va_end(ap);
 		fprintf(stderr, "\n");
-	} else
-		fprintf(stderr, "%s\n", strerror_r(err, buf, sizeof(buf)));
+	} else {
+		char *buf;
+		locale_t loc = newlocale(LC_MESSAGES_MASK, "", (locale_t)0);
+		if (loc == (locale_t)0) {
+			if (errno == ENOENT)
+				loc = newlocale(LC_MESSAGES_MASK,
+						"POSIX", (locale_t)0);
+			if (loc == (locale_t)0)
+				buf = "newlocale() failed";
+		}
+		if (loc != (locale_t)0)
+			buf = strerror_l(err, loc);
+		fprintf(stderr, "%s\n", buf);
+		if (loc != (locale_t)0)
+			freelocale(loc);
+	}
 
 	exit(abs(err));
 }
-- 
2.9.3