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/intrin/bt.c

@@ -17,10 +17,12 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/errno.h"
-#include "libc/intrin/intrin.h"
 #include "libc/intrin/kprintf.h"
 #include "libc/intrin/weaken.h"
 #include "libc/log/backtrace.internal.h"
+#include "libc/runtime/symbols.internal.h"
+
+static _Thread_local bool noreentry;
 
 /**
  * Shows backtrace if crash reporting facilities are linked.
@@ -28,12 +30,20 @@
 void _bt(const char *fmt, ...) {
   int e;
   va_list va;
+
+  if (!noreentry) {
+    noreentry = true;
+  } else {
+    return;
+  }
+
   if (fmt) {
     va_start(va, fmt);
     kvprintf(fmt, va);
     va_end(va);
   }
-  if (_weaken(ShowBacktrace)) {
+
+  if (_weaken(ShowBacktrace) && _weaken(GetSymbolTable)) {
     e = errno;
     _weaken(ShowBacktrace)(2, __builtin_frame_address(0));
     errno = e;
@@ -41,5 +51,18 @@ void _bt(const char *fmt, ...) {
     kprintf("_bt() can't show backtrace because you need:\n"
             "\tSTATIC_YOINK(\"ShowBacktrace\");\n"
             "to be linked.\n");
+    if (_weaken(PrintBacktraceUsingSymbols) && _weaken(GetSymbolTable)) {
+      e = errno;
+      _weaken(PrintBacktraceUsingSymbols)(2, __builtin_frame_address(0),
+                                          _weaken(GetSymbolTable)());
+      errno = e;
+    } else {
+      kprintf("_bt() can't show backtrace because you need:\n"
+              "\tSTATIC_YOINK(\"PrintBacktraceUsingSymbols\");\n"
+              "\tSTATIC_YOINK(\"GetSymbolTable\");\n"
+              "to be linked.\n");
+    }
   }
+
+  noreentry = false;
 }