Make fixes and improvements

- Invent iso8601us() for faster timestamps
- Improve --strace descriptions of sigset_t
- Rebuild the Landlock Make bootstrap binary
- Introduce MODE=sysv for non-Windows builds
- Permit OFD fcntl() locks under pledge(flock)
- redbean can now protect your kernel from ddos
- Have vfork() fallback to sys_fork() not fork()
- Change kmalloc() to not die when out of memory
- Improve documentation for some termios functions
- Rewrite putenv() and friends to conform to POSIX
- Fix linenoise + strace verbosity issue on Windows
- Fix regressions in our ability to show backtraces
- Change redbean SetHeader() to no-op if value is nil
- Improve fcntl() so SQLite locks work in non-WAL mode
- Remove some unnecessary work during fork() on Windows
- Create redbean-based SSL reverse proxy for IPv4 TurfWar
- Fix ape/apeinstall.sh warning when using non-bash shells
- Add ProgramTrustedIp(), and IsTrustedIp() APIs to redbean
- Support $PWD, $UID, $GID, and $EUID in command interpreter
- Introduce experimental JTqFpD APE prefix for non-Windows builds
- Invent blackhole daemon for firewalling IP addresses via UNIX named socket
- Add ProgramTokenBucket(), AcquireToken(), and CountTokens() APIs to redbean

libc/calls/tcsendbreak.c

@@ -17,18 +17,53 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/calls/internal.h"
 #include "libc/calls/syscall-sysv.internal.h"
+#include "libc/calls/syscall_support-nt.internal.h"
 #include "libc/calls/termios.h"
 #include "libc/dce.h"
+#include "libc/intrin/strace.internal.h"
+#include "libc/nt/comms.h"
 #include "libc/sysv/consts/termios.h"
+#include "libc/sysv/errfuns.h"
 
-int tcsendbreak(int fd, int len) {
-  if (!IsBsd()) {
-    return sys_ioctl(fd, TCSBRK, 0);
-  } else {
-    if (sys_ioctl(fd, TIOCSBRK, 0) == -1) return -1;
-    usleep(400000);
-    if (sys_ioctl(fd, TIOCCBRK, 0) == -1) return -1;
-    return 0;
-  }
+static int sys_tcsendbreak_bsd(int fd) {
+  if (sys_ioctl(fd, TIOCSBRK, 0) == -1) return -1;
+  usleep(400000);
+  if (sys_ioctl(fd, TIOCCBRK, 0) == -1) return -1;
+  return 0;
+}
+
+static textwindows int sys_tcsendbreak_nt(int fd) {
+  if (!__isfdopen(fd)) return ebadf();
+  if (!TransmitCommChar(g_fds.p[fd].handle, '\0')) return __winerr();
+  return 0;
+}
+
+/**
+ * Sends break.
+ *
+ * @param fd is file descriptor of tty
+ * @param duration of 0 sends a break for 0.25-0.5 seconds, and other
+ *     durations are treated the same by this implementation
+ * @raise EBADF if `fd` isn't an open file descriptor
+ * @raise ENOTTY if `fd` is open but not a teletypewriter
+ * @raise EIO if process group of writer is orphoned, calling thread is
+ *     not blocking `SIGTTOU`, and process isn't ignoring `SIGTTOU`
+ * @raise ENOSYS on bare metal
+ * @asyncsignalsafe
+ */
+int tcsendbreak(int fd, int duration) {
+  int rc;
+  if (IsMetal()) {
+    rc = enosys();
+  } else if (IsBsd()) {
+    rc = sys_tcsendbreak_bsd(fd);
+  } else if (!IsWindows()) {
+    rc = sys_ioctl(fd, TCSBRK, 0);
+  } else {
+    rc = sys_tcsendbreak_nt(fd);
+  }
+  STRACE("tcsendbreak(%d, %u) → %d% m", fd, duration, rc);
+  return rc;
 }