Fix bugs and add security features to redbean

- Fix a regression with the previous change that broke redbean
- Add chroot(), resource limit, seccomp, and other stuff to redbean
- Write lots and lots of documentation
- Iron out more system call issues

libc/calls/fixenotdir.c

@@ -0,0 +1,63 @@
+/*-*- 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/calls/internal.h"
+#include "libc/errno.h"
+#include "libc/nt/enum/fileflagandattributes.h"
+#include "libc/nt/errors.h"
+#include "libc/nt/files.h"
+
+static textwindows bool SubpathExistsThatsNotDirectory(char16_t *path) {
+  int e;
+  char16_t *p;
+  uint32_t attrs;
+  e = errno;
+  while ((p = strrchr16(path, '\\'))) {
+    *p = u'\0';
+    if ((attrs = GetFileAttributes(path)) != -1u) {
+      if (attrs & kNtFileAttributeDirectory) {
+        return false;
+      } else {
+        return true;
+      }
+    } else {
+      errno = e;
+    }
+  }
+  return false;
+}
+
+// WIN32 doesn't distinguish between ENOTDIR and ENOENT. UNIX strictly
+// requires that a directory component *exists* but is not a directory
+// whereas WIN32 will return ENOTDIR if a dir label simply isn't found
+//
+// - ENOTDIR: A component used as a directory in pathname is not, in
+//   fact, a directory. -or- pathname is relative and dirfd is a file
+//   descriptor referring to a file other than a directory.
+//
+// - ENOENT: A directory component in pathname does not exist or is a
+//   dangling symbolic link.
+//
+textwindows int64_t __fix_enotdir(int64_t rc, char16_t *path) {
+  if (rc == -1 && errno == kNtErrorPathNotFound) {
+    if (!SubpathExistsThatsNotDirectory(path)) {
+      errno = kNtErrorFileNotFound;
+    }
+  }
+  return rc;
+}