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// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <process.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include "libcgo.h"
#include "libcgo_windows.h"
// Ensure there's one symbol marked __declspec(dllexport).
// If there are no exported symbols, the unfortunate behavior of
// the binutils linker is to also strip the relocations table,
// resulting in non-PIE binary. The other option is the
// --export-all-symbols flag, but we don't need to export all symbols
// and this may overflow the export table (#40795).
// See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
__declspec(dllexport) int _cgo_dummy_export;
static volatile LONG runtime_init_once_gate = 0;
static volatile LONG runtime_init_once_done = 0;
static CRITICAL_SECTION runtime_init_cs;
static HANDLE runtime_init_wait;
static int runtime_init_done;
uintptr_t x_cgo_pthread_key_created;
void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
// Pre-initialize the runtime synchronization objects
void
_cgo_preinit_init() {
runtime_init_wait = CreateEvent(NULL, TRUE, FALSE, NULL);
if (runtime_init_wait == NULL) {
fprintf(stderr, "runtime: failed to create runtime initialization wait event.\n");
abort();
}
InitializeCriticalSection(&runtime_init_cs);
}
// Make sure that the preinit sequence has run.
void
_cgo_maybe_run_preinit() {
if (!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
if (InterlockedIncrement(&runtime_init_once_gate) == 1) {
_cgo_preinit_init();
InterlockedIncrement(&runtime_init_once_done);
} else {
// Decrement to avoid overflow.
InterlockedDecrement(&runtime_init_once_gate);
while(!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
Sleep(0);
}
}
}
}
void
x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
_cgo_beginthread(func, arg);
}
int
_cgo_is_runtime_initialized() {
EnterCriticalSection(&runtime_init_cs);
int status = runtime_init_done;
LeaveCriticalSection(&runtime_init_cs);
return status;
}
uintptr_t
_cgo_wait_runtime_init_done(void) {
void (*pfn)(struct context_arg*);
_cgo_maybe_run_preinit();
while (!_cgo_is_runtime_initialized()) {
WaitForSingleObject(runtime_init_wait, INFINITE);
}
pfn = _cgo_get_context_function();
if (pfn != nil) {
struct context_arg arg;
arg.Context = 0;
(*pfn)(&arg);
return arg.Context;
}
return 0;
}
// Should not be used since x_cgo_pthread_key_created will always be zero.
void x_cgo_bindm(void* dummy) {
fprintf(stderr, "unexpected cgo_bindm on Windows\n");
abort();
}
void
x_cgo_notify_runtime_init_done(void* dummy) {
_cgo_maybe_run_preinit();
EnterCriticalSection(&runtime_init_cs);
runtime_init_done = 1;
LeaveCriticalSection(&runtime_init_cs);
if (!SetEvent(runtime_init_wait)) {
fprintf(stderr, "runtime: failed to signal runtime initialization complete.\n");
abort();
}
}
// The context function, used when tracing back C calls into Go.
static void (*cgo_context_function)(struct context_arg*);
// Sets the context function to call to record the traceback context
// when calling a Go function from C code. Called from runtime.SetCgoTraceback.
void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
EnterCriticalSection(&runtime_init_cs);
cgo_context_function = context;
LeaveCriticalSection(&runtime_init_cs);
}
// Gets the context function.
void (*(_cgo_get_context_function(void)))(struct context_arg*) {
void (*ret)(struct context_arg*);
EnterCriticalSection(&runtime_init_cs);
ret = cgo_context_function;
LeaveCriticalSection(&runtime_init_cs);
return ret;
}
void _cgo_beginthread(void (*func)(void*), void* arg) {
int tries;
uintptr_t thandle;
for (tries = 0; tries < 20; tries++) {
thandle = _beginthread(func, 0, arg);
if (thandle == -1 && errno == EACCES) {
// "Insufficient resources", try again in a bit.
//
// Note that the first Sleep(0) is a yield.
Sleep(tries); // milliseconds
continue;
} else if (thandle == -1) {
break;
}
return; // Success!
}
fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
abort();
}
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