From d8fffd212303ec82ffdaa213a70328083cec14f7 Mon Sep 17 00:00:00 2001
From: Justine Tunney <jtunney@gmail.com>
Date: Thu, 28 Jan 2021 00:25:52 -0800
Subject: [PATCH] Change stack address on Windows

I rebooted Windows 7 and noticed that KERNEL32.DLL got relocated.
Microsoft needs to change and embrace the dream that was MULTICS.
Until then we'll need a better way to work around their dominion.
---
 libc/calls/ntspawn.c        |  3 +--
 libc/runtime/winmain.greg.c | 19 ++++++++++---------
 2 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/libc/calls/ntspawn.c b/libc/calls/ntspawn.c
index ae6a51abd8d..cbb2a7995ed 100644
--- a/libc/calls/ntspawn.c
+++ b/libc/calls/ntspawn.c
@@ -84,8 +84,7 @@ textwindows int ntspawn(
         mkntenvblock(block->envvars, envp) != -1) {
       if (CreateProcess(NULL, block->cmdline, opt_lpProcessAttributes,
                         opt_lpThreadAttributes, bInheritHandles,
-                        dwCreationFlags | kNtCreateNewProcessGroup |
-                            kNtCreateUnicodeEnvironment,
+                        dwCreationFlags | kNtCreateUnicodeEnvironment,
                         block->envvars, opt_lpCurrentDirectory, lpStartupInfo,
                         opt_out_lpProcessInformation)) {
         rc = 0;
diff --git a/libc/runtime/winmain.greg.c b/libc/runtime/winmain.greg.c
index 23ea5df92ca..577ae19bb59 100644
--- a/libc/runtime/winmain.greg.c
+++ b/libc/runtime/winmain.greg.c
@@ -46,9 +46,8 @@
 
 /*
  * TODO: Why can't we allocate addresses above 4GB on Windows 7 x64?
- * https://github.com/jart/cosmopolitan/issues/19
+ * TODO: How can we ensure we never overlap with KERNEL32.DLL?
  */
-#define ADDRESS 0x77700000 /*0000*/
 
 struct WinArgs {
   char *argv[4096];
@@ -101,21 +100,23 @@ static textwindows wontreturn void WinMainNew(void) {
   int64_t h;
   size_t size;
   int i, count;
+  uint64_t addr;
   long auxv[1][2];
   struct WinArgs *wa;
   const char16_t *env16;
   NormalizeCmdExe();
   *(/*unconst*/ int *)&__hostos = WINDOWS;
+  addr = NtGetVersion() < kNtVersionWindows10 ? 0xff00000 : 0x777000000000;
   size = ROUNDUP(STACKSIZE + sizeof(struct WinArgs), FRAMESIZE);
-  _mmi.p[0].h = __mmap$nt((char *)ADDRESS, size,
-                          PROT_READ | PROT_WRITE | PROT_EXEC, -1, 0)
-                    .maphandle;
-  _mmi.p[0].x = ADDRESS >> 16;
-  _mmi.p[0].y = (ADDRESS >> 16) + ((size >> 16) - 1);
+  _mmi.p[0].h =
+      __mmap$nt((char *)addr, size, PROT_READ | PROT_WRITE | PROT_EXEC, -1, 0)
+          .maphandle;
+  _mmi.p[0].x = addr >> 16;
+  _mmi.p[0].y = (addr >> 16) + ((size >> 16) - 1);
   _mmi.p[0].prot = PROT_READ | PROT_WRITE | PROT_EXEC;
   _mmi.p[0].flags = MAP_PRIVATE | MAP_ANONYMOUS;
   _mmi.i = pushpop(1L);
-  wa = (struct WinArgs *)(ADDRESS + size - sizeof(struct WinArgs));
+  wa = (struct WinArgs *)(addr + size - sizeof(struct WinArgs));
   count = GetDosArgv(GetCommandLine(), wa->argblock, ARG_MAX, wa->argv, 4096);
   for (i = 0; wa->argv[0][i]; ++i) {
     if (wa->argv[0][i] == '\\') {
@@ -127,7 +128,7 @@ static textwindows wontreturn void WinMainNew(void) {
   FreeEnvironmentStrings(env16);
   auxv[0][0] = pushpop(0L);
   auxv[0][1] = pushpop(0L);
-  _jmpstack((char *)ADDRESS + STACKSIZE, _executive, count, wa->argv, wa->envp,
+  _jmpstack((char *)addr + STACKSIZE, _executive, count, wa->argv, wa->envp,
             auxv);
 }