Make more improvements

This change includes many bug fixes, for the NT polyfills, strings,
memory, boot, and math libraries which were discovered by adding more
tools for recreational programming, such as PC emulation. Lemon has also
been vendored because it works so well at parsing languages.

libc/runtime/winmain.greg.c

@@ -19,15 +19,32 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/bits/bits.h"
 #include "libc/bits/pushpop.h"
+#include "libc/bits/weaken.h"
 #include "libc/dce.h"
 #include "libc/nt/console.h"
+#include "libc/nt/enum/consolemodeflags.h"
+#include "libc/nt/enum/filetype.h"
 #include "libc/nt/enum/loadlibrarysearch.h"
+#include "libc/nt/files.h"
+#include "libc/nt/pedef.h"
+#include "libc/nt/process.h"
 #include "libc/nt/runtime.h"
+#include "libc/nt/struct/teb.h"
 #include "libc/runtime/getdosenviron.h"
 #include "libc/runtime/internal.h"
 #include "libc/runtime/missioncritical.h"
+#include "libc/runtime/runtime.h"
 
-static void LoadFasterAndPreventHijacking(void) {
+static struct CmdExe {
+  bool result;
+  struct OldNtConsole {
+    unsigned codepage;
+    unsigned mode;
+    int64_t handle;
+  } oldin, oldout;
+} g_cmdexe;
+
+static textwindows void MitigateDriveByDownloads(void) {
   unsigned wrote;
   if (!SetDefaultDllDirectories(kNtLoadLibrarySearchSearchSystem32)) {
     WriteFile(GetStdHandle(kNtStdErrorHandle), "nodll\n", 6, &wrote, NULL);
@@ -35,6 +52,78 @@ static void LoadFasterAndPreventHijacking(void) {
   }
 }
 
+static textwindows void RestoreCmdExe(void) {
+  if (g_cmdexe.oldin.handle) {
+    SetConsoleCP(g_cmdexe.oldin.codepage);
+    SetConsoleMode(g_cmdexe.oldin.handle, g_cmdexe.oldin.mode);
+  }
+  if (g_cmdexe.oldout.handle) {
+    SetConsoleOutputCP(g_cmdexe.oldout.codepage);
+    SetConsoleMode(g_cmdexe.oldout.handle, g_cmdexe.oldout.mode);
+  }
+}
+
+static textwindows void SetTrueColor(void) {
+  SetEnvironmentVariable(u"TERM", u"xterm-truecolor");
+}
+
+static textwindows void NormalizeCmdExe(void) {
+  int64_t handle, hstdin, hstdout, hstderr;
+  if ((int)weakaddr("v_ntsubsystem") == kNtImageSubsystemWindowsCui &&
+      NtGetVersion() >= kNtVersionWindows10) {
+    atexit(RestoreCmdExe);
+    hstdin = GetStdHandle(pushpop(kNtStdInputHandle));
+    hstdout = GetStdHandle(pushpop(kNtStdOutputHandle));
+    hstderr = GetStdHandle(pushpop(kNtStdErrorHandle));
+    if (GetFileType((handle = hstdin)) == kNtFileTypeChar) {
+      SetTrueColor();
+      g_cmdexe.oldin.handle = handle;
+      g_cmdexe.oldin.codepage = GetConsoleCP();
+      SetConsoleCP(kNtCpUtf8);
+      GetConsoleMode(handle, &g_cmdexe.oldin.mode);
+      SetConsoleMode(handle, g_cmdexe.oldin.mode | kNtEnableProcessedInput |
+                                 kNtEnableVirtualTerminalInput);
+    }
+    if (GetFileType((handle = hstdout)) == kNtFileTypeChar ||
+        GetFileType((handle = hstderr)) == kNtFileTypeChar) {
+      SetTrueColor();
+      g_cmdexe.oldout.handle = handle;
+      g_cmdexe.oldout.codepage = GetConsoleOutputCP();
+      SetConsoleOutputCP(kNtCpUtf8);
+      GetConsoleMode(handle, &g_cmdexe.oldout.mode);
+      SetConsoleMode(handle, g_cmdexe.oldout.mode | kNtEnableProcessedOutput |
+                                 kNtEnableVirtualTerminalProcessing);
+    }
+  }
+}
+
+/**
+ * Main function on Windows NT.
+ *
+ * The Cosmopolitan Runtime provides the following services, which aim
+ * to bring Windows NT behavior closer in harmony with System Five:
+ *
+ *   1. We configure CMD.EXE for UTF-8 and enable ANSI colors on Win10.
+ *
+ *   2. Command line arguments are passed as a blob of UTF-16 text. We
+ *      chop them up into an char *argv[] UTF-8 data structure, in
+ *      accordance with the DOS conventions for argument quoting.
+ *
+ *   3. Environment variables are passed to us as a sorted UTF-16 double
+ *      NUL terminated list. We translate this to char ** using UTF-8.
+ *
+ *   4. NT likes to choose a stack address that's beneath the program
+ *      image. We want to be able to assume that stack addresses are
+ *      located at higher addresses than heap and program memory. So the
+ *      _executive() function will switch stacks appropriately.
+ *
+ *   5. Windows users are afraid of "drive-by downloads" where someone
+ *      might accidentally an evil DLL to their Downloads folder which
+ *      then overrides the behavior of a legitimate EXE being run from
+ *      the downloads folder. Since we don't even use dynamic linking,
+ *      we've cargo culted some API calls, that may harden against it.
+ *
+ */
 textwindows int WinMain(void *hInstance, void *hPrevInstance,
                         const char *lpCmdLine, int nCmdShow) {
   int i, count;
@@ -42,7 +131,8 @@ textwindows int WinMain(void *hInstance, void *hPrevInstance,
   char *argarray[512], *envarray[512];
   char argblock[ARG_MAX], envblock[ENV_MAX];
   long auxarray[][2] = {{pushpop(0L), pushpop(0L)}};
-  LoadFasterAndPreventHijacking();
+  MitigateDriveByDownloads();
+  NormalizeCmdExe();
   *(/*unconst*/ int *)&hostos = WINDOWS;
   cmd16 = GetCommandLine();
   env16 = GetEnvironmentStrings();