fix ptsname_r to conform to the upcoming posix requirements

it should return the error code rather than 0/-1 and setting errno.

src/misc/ptsname.c

@@ -1,9 +1,15 @@
 #include <stdlib.h>
+#include <errno.h>
 
 int __ptsname_r(int, char *, size_t);
 
 char *ptsname(int fd)
 {
 	static char buf[9 + sizeof(int)*3 + 1];
-	return __ptsname_r(fd, buf, sizeof buf) < 0 ? 0 : buf;
+	int err = __ptsname_r(fd, buf, sizeof buf);
+	if (err) {
+		errno = err;
+		return 0;
+	}
+	return buf;
 }

src/misc/pty.c

@@ -2,7 +2,9 @@
 #include <sys/ioctl.h>
 #include <stdio.h>
 #include <fcntl.h>
+#include <errno.h>
 #include "libc.h"
+#include "syscall.h"
 
 int posix_openpt(int flags)
 {
@@ -22,10 +24,11 @@ int unlockpt(int fd)
 
 int __ptsname_r(int fd, char *buf, size_t len)
 {
-	int pty;
+	int pty, err;
 	if (!buf) len = 0;
-	return -( ioctl (fd, TIOCGPTN, &pty) < 0
-		|| snprintf(buf, len, "/dev/pts/%d", pty) >= len );
+	if ((err = __syscall(SYS_ioctl, fd, TIOCGPTN, &pty))) return err;
+	if (snprintf(buf, len, "/dev/pts/%d", pty) >= len) return ERANGE;
+	return 0;
 }
 
 weak_alias(__ptsname_r, ptsname_r);