Make improvements

- Fix build flakes
- Polyfill SIGWINCH on Windows
- Fix an execve issue on Windows
- Make strerror show more information
- Improve cmd.exe setup/teardown on Windows
- Support bracketed paste mode in Blinkenlights
- Show keyboard shortcuts in Blinkenlights status bar
- Fixed copy_file_range() and copyfile() w/ zip filesystem
- Size optimize GetDosArgv() to keep life.com 12kb in size
- Improve Blinkenlights ability to load weird ELF executables
- Fix program_executable_name and add GetInterpreterExecutableName
- Make Python in tiny mode fail better if docstrings are requested
- Update Python test exclusions in tiny* modes such as tinylinux
- Add bulletproof unbreakable kprintf() troubleshooting function
- Remove "oldskool" keyword from ape.S for virus scanners
- Fix issue that caused backtraces to not print sometimes
- Improve Blinkenlights serial uart character i/o
- Make clock_gettime() not clobber errno on xnu
- Improve sha256 cpuid check for old computers
- Integrate some bestline linenoise fixes
- Show runit process names better in htop
- Remove SIGPIPE from ShowCrashReports()
- Make realpath() not clobber errno
- Avoid attaching GDB on non-Linux
- Improve img.com example

libc/runtime/fork.c

@@ -17,9 +17,14 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/bits/bits.h"
+#include "libc/bits/weaken.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/internal.h"
+#include "libc/calls/sysdebug.internal.h"
 #include "libc/dce.h"
+#include "libc/nt/process.h"
+
+extern int __pid;
 
 /**
  * Creates new process.
@@ -29,7 +34,7 @@
  */
 int fork(void) {
   axdx_t ad;
-  int ax, dx;
+  int ax, dx, parent;
   if (!IsWindows()) {
     ad = sys_fork();
     ax = ad.ax;
@@ -43,7 +48,19 @@ int fork(void) {
     ax = sys_fork_nt();
   }
   if (!ax) {
-    __onfork();
+    if (!IsWindows()) {
+      dx = sys_getpid().ax;
+    } else {
+      dx = GetCurrentProcessId();
+    }
+    parent = __pid;
+    __pid = dx;
+    SYSDEBUG("fork() → 0 (child of %d)", parent);
+    if (weaken(__onfork)) {
+      weaken(__onfork)();
+    }
+  } else {
+    SYSDEBUG("fork() → %d% m", ax);
   }
   return ax;
 }