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Make stdin pollable on Windows

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You can now play Super Mario Bros in CMD.EXE using Cosmopolitan! This is
thanks to a new worker thread that's spawned on Windows whenever any one
of poll(), select(), or ioctl(FIONREAD) is linked.
This commit is contained in:
Justine Tunney 2023-08-13 22:42:25 -07:00
parent ef6387ee5e
commit 9c0821def7
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
15 changed files with 280 additions and 58 deletions
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49
libc/runtime/winmain.greg.c
View file

@ -17,6 +17,7 @@
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/internal.h"
#include "libc/calls/state.internal.h"
#include "libc/calls/syscall_support-nt.internal.h"
#include "libc/dce.h"
@ -37,6 +38,7 @@
#include "libc/nt/enum/filesharemode.h"
#include "libc/nt/enum/pageflags.h"
#include "libc/nt/files.h"
#include "libc/nt/ipc.h"
#include "libc/nt/memory.h"
#include "libc/nt/pedef.internal.h"
#include "libc/nt/process.h"
@ -44,6 +46,8 @@
#include "libc/nt/signals.h"
#include "libc/nt/struct/ntexceptionpointers.h"
#include "libc/nt/struct/teb.h"
#include "libc/nt/synchronization.h"
#include "libc/nt/thread.h"
#include "libc/nt/thunk/msabi.h"
#include "libc/runtime/internal.h"
#include "libc/runtime/memtrack.internal.h"
@ -54,6 +58,26 @@
#ifdef __x86_64__
/**
* @fileoverview makes windows stdin handle capable of being poll'd
*
* 1. On Windows, there's no way to check how many bytes of input are
* available from the cmd.exe console. The only thing you can do is a
* blocking read that can't be interrupted.
*
* 2. On Windows, it's up to the parent process whether or not the
* handles it passes us are capable of non-blocking overlapped i/o
* reads (which we need for busy polling to check for interrupts).
*
* So we solve this by creating a thread which just does naive reads on
* standard input, and then relays the data to the process via a named
* pipe, which we explicitly creaete with overlapped i/o enabled.
*
* This code runs very early during process initialization, at the
* beginning of WinMain(). This module is only activated if the app
* links any one of: poll(), select(), or ioctl(FIONREAD).
*/
// clang-format off
__msabi extern typeof(AddVectoredExceptionHandler) *const __imp_AddVectoredExceptionHandler;
__msabi extern typeof(CloseHandle) *const __imp_CloseHandle;
@ -68,6 +92,7 @@ __msabi extern typeof(GetCurrentProcessId) *const __imp_GetCurrentProcessId;
__msabi extern typeof(GetEnvironmentStrings) *const __imp_GetEnvironmentStringsW;
__msabi extern typeof(GetStdHandle) *const __imp_GetStdHandle;
__msabi extern typeof(MapViewOfFileEx) *const __imp_MapViewOfFileEx;
__msabi extern typeof(ReadFile) *const __imp_ReadFile;
__msabi extern typeof(SetConsoleCP) *const __imp_SetConsoleCP;
__msabi extern typeof(SetConsoleMode) *const __imp_SetConsoleMode;
__msabi extern typeof(SetConsoleOutputCP) *const __imp_SetConsoleOutputCP;
@ -147,22 +172,8 @@ __msabi static textwindows int OnEarlyWinCrash(struct NtExceptionPointers *ep) {
__builtin_unreachable();
}
// this makes it possible for our read() implementation to periodically
// poll for signals while performing a blocking overlapped io operation
__msabi static textwindows void ReopenConsoleForOverlappedIo(void) {
uint32_t mode;
int64_t hOld, hNew;
hOld = __imp_GetStdHandle(kNtStdInputHandle);
if (__imp_GetConsoleMode(hOld, &mode)) {
hNew = __imp_CreateFileW(u"CONIN$", kNtGenericRead | kNtGenericWrite,
kNtFileShareRead | kNtFileShareWrite,
&kNtIsInheritable, kNtOpenExisting,
kNtFileFlagOverlapped, 0);
if (hNew != kNtInvalidHandleValue) {
__imp_SetStdHandle(kNtStdInputHandle, hNew);
__imp_CloseHandle(hOld);
}
}
__msabi static textwindows bool ProxyStdin(void) {
return true;
}
// this ensures close(1) won't accidentally close(2) for example
@ -196,8 +207,6 @@ __msabi static textwindows wontreturn void WinMainNew(const char16_t *cmdline) {
intptr_t stackaddr, allocaddr;
version = NtGetPeb()->OSMajorVersion;
__oldstack = (intptr_t)__builtin_frame_address(0);
ReopenConsoleForOverlappedIo();
DeduplicateStdioHandles();
if ((intptr_t)v_ntsubsystem == kNtImageSubsystemWindowsCui && version >= 10) {
rc = __imp_SetConsoleCP(kNtCpUtf8);
NTTRACE("SetConsoleCP(kNtCpUtf8) → %hhhd", rc);
@ -268,6 +277,10 @@ __msabi textwindows int64_t WinMain(int64_t hInstance, int64_t hPrevInstance,
os = _HOSTWINDOWS; /* madness https://news.ycombinator.com/item?id=21019722 */
kStartTsc = rdtsc();
__pid = __imp_GetCurrentProcessId();
DeduplicateStdioHandles();
if (_weaken(WinMainStdin)) {
_weaken(WinMainStdin)();
}
#if !IsTiny()
__wincrashearly =
__imp_AddVectoredExceptionHandler(1, (void *)OnEarlyWinCrash);