Fix bugs and make improvements

- Get clone() working on FreeBSD
- Increase some Python build quotas
- Add more atomic builtins to chibicc
- Fix ASAN poisoning of alloca() memory
- Make MODE= mandatory link path tinier
- Improve the examples folder a little bit
- Start working on some more resource limits
- Make the linenoise auto-complete UI as good as GNU readline
- Update compile.com, avoiding AVX codegen on non-AVX systems
- Make sure empty path to syscalls like opendir raises ENOENT
- Correctly polyfill ENOENT vs. ENOTDIR on the New Technology
- Port bestline's paredit features to //third_party/linenoise
- Remove workarounds for RHEL 5.0 bugs that were fixed in 5.1

examples/rlimit.c

@@ -0,0 +1,72 @@
+#if 0
+/*─────────────────────────────────────────────────────────────────╗
+│ To the extent possible under law, Justine Tunney has waived      │
+│ all copyright and related or neighboring rights to this file,    │
+│ as it is written in the following disclaimers:                   │
+│   • http://unlicense.org/                                        │
+│   • http://creativecommons.org/publicdomain/zero/1.0/            │
+╚─────────────────────────────────────────────────────────────────*/
+#endif
+#include "libc/calls/calls.h"
+#include "libc/calls/strace.internal.h"
+#include "libc/calls/struct/rlimit.h"
+#include "libc/errno.h"
+#include "libc/intrin/kprintf.h"
+#include "libc/log/color.internal.h"
+#include "libc/macros.internal.h"
+#include "libc/stdio/stdio.h"
+#include "libc/str/str.h"
+#include "libc/sysv/consts/rlim.h"
+#include "libc/sysv/consts/rlimit.h"
+
+/**
+ * @fileoverview tool for printing and changing system resource limits
+ *
+ * This is what you do if you want to not accidentally bomb your system
+ * with runaway code. If you haven't accidentally bombed your UNIX
+ * system before then you're not pushing it hard enough.
+ */
+
+static void SetLimit(int resource, uint64_t soft, uint64_t hard) {
+  struct rlimit old;
+  struct rlimit lim = {soft, hard};
+  if (resource == 127) return;
+  if (setrlimit(resource, &lim) == -1) {
+    if (!getrlimit(resource, &old)) {
+      lim.rlim_max = MIN(hard, old.rlim_max);
+      lim.rlim_cur = MIN(soft, lim.rlim_max);
+      if (!setrlimit(resource, &lim)) {
+        fprintf(stderr, "%snote: setrlimit(%s) downgraded to {%,ld, %,ld}\n",
+                __strace_rlimit_name(resource), lim.rlim_cur, lim.rlim_max);
+        return;
+      }
+    }
+    fprintf(stderr, "error: setrlimit(%s, %,ld, %,ld) failed %m%n",
+            __strace_rlimit_name(resource), soft, hard);
+    exit(1);
+  }
+}
+
+int main(int argc, char *argv[]) {
+  int i, rc;
+  struct rlimit rlim;
+
+  // // example of how you might change the limits
+  // SetLimit(RLIMIT_CPU, 3, 33);
+  // SetLimit(RLIMIT_NPROC, 4, 128);
+  // SetLimit(RLIMIT_NOFILE, 32, 128);
+  // SetLimit(RLIMIT_SIGPENDING, 16, 1024);
+  // SetLimit(RLIMIT_AS, 8 * 1024 * 1024, 1l * 1024 * 1024 * 1024);
+  // SetLimit(RLIMIT_RSS, 8 * 1024 * 1024, 1l * 1024 * 1024 * 1024);
+  // SetLimit(RLIMIT_DATA, 8 * 1024 * 1024, 1l * 1024 * 1024 * 1024);
+  // SetLimit(RLIMIT_FSIZE, 8 * 1000 * 1000, 1l * 1000 * 1000 * 1000);
+
+  for (i = 0; i < RLIM_NLIMITS; ++i) {
+    rc = getrlimit(i, &rlim);
+    printf("setrlimit(%-20s, %,16ld, %,16ld) → %d %s\n",
+           __strace_rlimit_name(i), rlim.rlim_cur, rlim.rlim_max, rc,
+           !rc ? "" : strerror(errno));
+  }
+
+  return 0;
+}