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/time/iso8601.c

@@ -16,37 +16,78 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/time/struct/tm.h"
 #include "libc/time/time.h"
 
 /**
  * Converts timestamp to ISO-8601 formatted string.
+ *
+ * For example:
+ *
+ *     char *GetZuluTime(void) {
+ *       char *p;
+ *       struct tm tm;
+ *       struct timespec ts;
+ *       static _Thread_local int64_t last;
+ *       static _Thread_local char str[21];
+ *       clock_gettime(0, &ts);
+ *       if (ts.tv_sec != last) {
+ *         gmtime_r(&ts.tv_sec, &tm);
+ *         last = ts.tv_sec;
+ *         stpcpy(iso8601(str, &tm), "Z");
+ *       }
+ *       return str;
+ *     }
+ *
+ * Will return timestamps that look like:
+ *
+ *     2020-01-01T13:14:15Z
+ *
+ * The generated timestamp is always exactly 19 characters long. It is
+ * also always nul terminated too.
+ *
+ * This function defines no failure conditions. The results of passing
+ * timestamp values outside of the appropriate intervals is undefined.
+ *
+ * @param p is buffer with at least 20 bytes
+ * @param tm has valid gmtime_r() or localtime_r() output
+ * @return pointer to nul terminator within `p`, cf. stpcpy()
+ * @see iso8601us() for microsecond timestamps
+ * @asyncsignalsafe
+ * @threadsafe
  */
 char *iso8601(char p[hasatleast 20], struct tm *tm) {
   int x;
   x = tm->tm_year + 1900;
+  _unassert(0 <= x && x <= 9999);
   *p++ = '0' + x / 1000;
   *p++ = '0' + x / 100 % 10;
   *p++ = '0' + x / 10 % 10;
   *p++ = '0' + x % 10;
   *p++ = '-';
   x = tm->tm_mon + 1;
+  _unassert(1 <= x && x <= 12);
   *p++ = '0' + x / 10;
   *p++ = '0' + x % 10;
   *p++ = '-';
   x = tm->tm_mday;
+  _unassert(1 <= x && x <= 31);
   *p++ = '0' + x / 10;
   *p++ = '0' + x % 10;
   *p++ = 'T';
   x = tm->tm_hour;
+  _unassert(0 <= x && x <= 23);
   *p++ = '0' + x / 10;
   *p++ = '0' + x % 10;
   *p++ = ':';
   x = tm->tm_min;
+  _unassert(0 <= x && x <= 59);
   *p++ = '0' + x / 10;
   *p++ = '0' + x % 10;
   *p++ = ':';
   x = tm->tm_sec;
+  _unassert(0 <= x && x <= 60);
   *p++ = '0' + x / 10;
   *p++ = '0' + x % 10;
   *p = 0;