Fix bugs and make code tinier

- Fixed bug where stdio eof wasn't being sticky
- Fixed bug where fseeko() wasn't clearing eof state
- Removed assert() usage from libc favoring _unassert() / _npassert()

test/libc/runtime/exit_test.c

@@ -0,0 +1,62 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2022 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/runtime/runtime.h"
+#include "libc/testlib/subprocess.h"
+#include "libc/testlib/testlib.h"
+
+int i, *p;
+
+void SetUp(void) {
+  p = _mapshared(FRAMESIZE);
+}
+
+void TearDown(void) {
+  munmap(p, FRAMESIZE);
+}
+
+void AtExit3(void) {
+  p[i++] = 3;
+}
+
+void AtExit2(void) {
+  p[i++] = 2;
+  exit(2);
+}
+
+void AtExit1(void) {
+  p[i++] = 1;
+  atexit(AtExit2);
+  exit(1);
+}
+
+// consistent with glibc, musl, freebsd, openbsd & netbsd
+// please note posix says recursion is undefined behavior
+// however, fifo ordering of atexit handlers is specified
+TEST(exit, test) {
+  SPAWN(fork);
+  atexit(AtExit3);
+  atexit(AtExit3);
+  atexit(AtExit1);
+  exit(0);
+  EXITS(2);
+  ASSERT_EQ(1, p[0]);
+  ASSERT_EQ(2, p[1]);
+  ASSERT_EQ(3, p[2]);
+  ASSERT_EQ(3, p[3]);
+}