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/runtime/vfork.S

@@ -20,7 +20,6 @@
 #include "libc/intrin/strace.internal.h"
 #include "libc/thread/tls.h"
 #include "libc/macros.internal.h"
-.privileged
 
 //	Forks process without copying page tables.
 //
@@ -32,37 +31,55 @@
 //	do anything in a vfork()'d child process. TLS memory must not
 //	be disabled (it's enabled by default) since vfork() needs it.
 //
+//	What makes vfork() dangerous is that any changes to memory in
+//	the child process can happen in the parent too. The exception
+//	to this rule is `errno` which is saved/restored in a register
+//	by this implementation. However, despite its dangers, vfork's
+//	performance is irresistible and wonderous to behold. If safer
+//	code is desired, consider posix_spawn() which uses vfork().
+//
 //	Do not make the assumption that the parent is suspended until
-//	the child terminates since this impl calls fork() on Windows,
-//	OpenBSD, and MacOS.
+//	the child terminates since this uses the raw fork system call
+//	on Windows, OpenBSD, and MacOS. In that case the process will
+//	proceed without blocking the parent; however, the `__vforked`
+//	variable is still set to true in the child, so lock functions
+//	won't do anything, and other functions shall change behavior.
+//	This ensures that, even if the operating system does not give
+//	us the performance of vfork(), we'll still be able to cut out
+//	the libc overhead, e.g. pthread_atfork().
 //
 //	@return	pid of child process or 0 if forked process
 //	@returnstwice
 //	@threadsafe
 //	@vforksafe
-vfork:	call	__require_tls
-	xor	%edi,%edi		# dwCreationFlags
-#ifdef __SANITIZE_ADDRESS__
-	jmp	fork			# TODO: asan and vfork don't mix?
-	.endfn	vfork,globl
-#else
-#if SupportsWindows()
-	testb	IsWindows()
-	jnz	sys_fork_nt		# and we're lucky to have that
-#endif
-#if SupportsXnu()
-	testb	IsXnu()
-	jnz	fork
-#endif
-#if SupportsOpenbsd()
-	testb	IsOpenbsd()
-	jnz	fork			# fake vfork plus msyscall issues
-#endif
+vfork:
+#if !IsTiny()
+	push	%rbp
+	mov	%rsp,%rbp
+	.profilable
+	call	__require_tls
 #ifdef SYSDEBUG
 	ezlea	.Llog,di
 	call	__stracef
-#endif /* SYSDEBUG */
+#endif
+	pop	%rbp
+#endif
 	mov	%fs:0,%r9		# get thread information block
+#if SupportsWindows()
+	testb	IsWindows()
+	jnz	6f			# and we're lucky to have that
+#endif
+#ifdef __SANITIZE_ADDRESS__
+	jmp	5f			# TODO: asan and vfork don't mix?
+#endif
+#if SupportsXnu()
+	testb	IsXnu()
+	jnz	5f
+#endif
+#if SupportsOpenbsd()
+	testb	IsOpenbsd()
+	jnz	5f			# fake vfork plus msyscall issues
+#endif
 	mov	0x3c(%r9),%r8d		# avoid question of @vforksafe errno
 	pop	%rsi			# saves return address in a register
 	mov	__NR_vfork(%rip),%eax
@@ -79,12 +96,35 @@ vfork:	call	__require_tls
 	cmp	$-4095,%eax
 	jae	systemfive_error
 	mov	%r8d,0x3c(%r9)		# restore errno
-	test	%eax,%eax
-	jnz	.Lprnt
-.Lchld:	orb	$TIB_FLAG_VFORKED,0x40(%r9)
+1:	test	%eax,%eax
+	jnz	.Lpar
+.Lchi:	orb	$TIB_FLAG_VFORKED,0x40(%r9)
 	ret
-.Lprnt:	andb	$~TIB_FLAG_VFORKED,0x40(%r9)
+.Lpar:	andb	$~TIB_FLAG_VFORKED,0x40(%r9)
 	ret
+#if SupportsXnu() || SupportsOpenbsd() || defined(__SANITIZE_ADDRESS__)
+5:	push	%rbp
+	mov	%rsp,%rbp
+	push	%r9
+	push	%r9
+	call	sys_fork
+	pop	%r9
+	pop	%r9
+	pop	%rbp
+	jmp	1b
+#endif
+#if SupportsWindows()
+6:	push	%rbp
+	mov	%rsp,%rbp
+	push	%r9
+	push	%r9
+	xor	%edi,%edi		# dwCreationFlags
+	call	sys_fork_nt
+	pop	%r9
+	pop	%r9
+	pop	%rbp
+	jmp	1b
+#endif
 	.endfn	vfork,globl
 
 #ifdef SYSDEBUG
@@ -93,5 +133,3 @@ vfork:	call	__require_tls
 	.asciz	"vfork()\n"
 	.previous
 #endif /* DEBUGSYS */
-
-#endif /* __SANITIZE_ADDRESS__ */