cosmopolitan/libc/calls/winexec.c
Justine Tunney 29eb7e67bb
Fix fork() regression on Windows
Recent optimizations to fork() introduced a regression, that could cause
the subprocess to fail unexpectedly, when TlsAlloc() returns a different
index. This is because we were burning the indexes into the displacement
of x86 opcodes. So when fork() happened and the executable memory copied
it would use the old index. Right now the way this is being solved is to
not copy the executable on fork() and then re-apply code changes. If you
need to be able to preserve self-modified code on fork, reach out and we
can implement a better solution for you. This gets us unblocked quickly.
2025-01-05 09:25:23 -08:00

94 lines
3.9 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2023 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/internal.h"
#include "libc/calls/struct/sigset.internal.h"
#include "libc/nt/errors.h"
#include "libc/nt/events.h"
#include "libc/nt/files.h"
#include "libc/nt/runtime.h"
#include "libc/nt/struct/overlapped.h"
#include "libc/str/str.h"
#include "libc/str/tab.h"
#include "third_party/linenoise/linenoise.h"
#define Read32(s) (s[3] << 24 | s[2] << 16 | s[1] << 8 | s[0])
#define EXT(s) Read32(s "\0\0")
static inline bool IsGraph(wint_t c) {
return 0x21 <= c && c <= 0x7E;
}
static uint32_t GetFileExtension(const char16_t *s) {
uint32_t w;
size_t i, n;
n = s ? strlen16(s) : 0;
for (i = w = 0; n--;) {
wint_t c = s[n];
if (!IsGraph(c))
return 0;
if (c == '.')
break;
if (++i > 4)
return 0;
w <<= 8;
w |= kToLower[c];
}
return w;
}
// checks if file should be considered an executable on windows
textwindows int IsWindowsExecutable(int64_t handle, const char16_t *path) {
// fast path known file extensions
// shaves away 100ms of gnu make latency in cosmo monorepo
uint32_t ext;
if (!IsTiny() && (ext = GetFileExtension(path))) {
if (ext == EXT("c") || // c code
ext == EXT("cc") || // c++ code
ext == EXT("h") || // c/c++ header
ext == EXT("s") || // assembly code
ext == EXT("o")) { // object file
return false;
}
if (ext == EXT("com") || // mz executable
ext == EXT("exe") || // mz executable
ext == EXT("sh")) { // bourne shells
return true;
}
}
// read first two bytes of file
// access() and stat() aren't cancelation points
bool ok;
char buf[2];
uint32_t got;
BLOCK_SIGNALS;
struct NtOverlapped overlap = {.hEvent = CreateEvent(0, 0, 0, 0)};
ok = overlap.hEvent &&
(ReadFile(handle, buf, 2, 0, &overlap) ||
GetLastError() == kNtErrorIoPending) &&
GetOverlappedResult(handle, &overlap, &got, true);
CloseHandle(overlap.hEvent);
ALLOW_SIGNALS;
// it's an executable if it starts with `MZ` or `#!`
return ok && got == 2 && //
((buf[0] == 'M' && buf[1] == 'Z') || //
(buf[0] == '#' && buf[1] == '!'));
}