make tmpfile fail after exceeding max tries.

src/stdio/tmpfile.c

@@ -3,14 +3,17 @@
 #include <unistd.h>
 #include "stdio_impl.h"
 
+#define MAXTRIES 100
+
 FILE *tmpfile(void)
 {
 	char buf[L_tmpnam], *s;
 	int fd;
 	FILE *f;
-	for (;;) {
+	int try;
+	for (try=0; try<MAXTRIES; try++) {
 		s = tmpnam(buf);
-		if (!s) return NULL;
+		if (!s) return 0;
 		fd = syscall(SYS_open, s, O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0600);
 		if (fd >= 0) {
 			f = __fdopen(fd, "w+");
@@ -18,6 +21,7 @@ FILE *tmpfile(void)
 			return f;
 		}
 	}
+	return 0;
 }
 
 LFS64(tmpfile);