gcc_libinit_windows.c

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build cgo
     6  
     7  #define WIN32_LEAN_AND_MEAN
     8  #include <windows.h>
     9  #include <process.h>
    10  
    11  #include <stdio.h>
    12  #include <stdlib.h>
    13  #include <errno.h>
    14  
    15  #include "libcgo.h"
    16  
    17  static volatile LONG runtime_init_once_gate = 0;
    18  static volatile LONG runtime_init_once_done = 0;
    19  
    20  static CRITICAL_SECTION runtime_init_cs;
    21  
    22  static HANDLE runtime_init_wait;
    23  static int runtime_init_done;
    24  
    25  // Pre-initialize the runtime synchronization objects
    26  void
    27  _cgo_preinit_init() {
    28  	 runtime_init_wait = CreateEvent(NULL, TRUE, FALSE, NULL);
    29  	 if (runtime_init_wait == NULL) {
    30  		fprintf(stderr, "runtime: failed to create runtime initialization wait event.\n");
    31  		abort();
    32  	 }
    33  
    34  	 InitializeCriticalSection(&runtime_init_cs);
    35  }
    36  
    37  // Make sure that the preinit sequence has run.
    38  void
    39  _cgo_maybe_run_preinit() {
    40  	 if (!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
    41  			if (InterlockedIncrement(&runtime_init_once_gate) == 1) {
    42  				 _cgo_preinit_init();
    43  				 InterlockedIncrement(&runtime_init_once_done);
    44  			} else {
    45  				 // Decrement to avoid overflow.
    46  				 InterlockedDecrement(&runtime_init_once_gate);
    47  				 while(!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
    48  						Sleep(0);
    49  				 }
    50  			}
    51  	 }
    52  }
    53  
    54  void
    55  x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
    56  	uintptr_t thandle;
    57  
    58  	thandle = _beginthread(func, 0, arg);
    59  	if(thandle == -1) {
    60  		fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
    61  		abort();
    62  	}
    63  }
    64  
    65  int
    66  _cgo_is_runtime_initialized() {
    67  	 EnterCriticalSection(&runtime_init_cs);
    68  	 int status = runtime_init_done;
    69  	 LeaveCriticalSection(&runtime_init_cs);
    70  	 return status;
    71  }
    72  
    73  uintptr_t
    74  _cgo_wait_runtime_init_done(void) {
    75  	void (*pfn)(struct context_arg*);
    76  
    77  	 _cgo_maybe_run_preinit();
    78  	while (!_cgo_is_runtime_initialized()) {
    79  			WaitForSingleObject(runtime_init_wait, INFINITE);
    80  	}
    81  	pfn = _cgo_get_context_function();
    82  	if (pfn != nil) {
    83  		struct context_arg arg;
    84  
    85  		arg.Context = 0;
    86  		(*pfn)(&arg);
    87  		return arg.Context;
    88  	}
    89  	return 0;
    90  }
    91  
    92  void
    93  x_cgo_notify_runtime_init_done(void* dummy) {
    94  	 _cgo_maybe_run_preinit();
    95  
    96  	 EnterCriticalSection(&runtime_init_cs);
    97  	runtime_init_done = 1;
    98  	 LeaveCriticalSection(&runtime_init_cs);
    99  
   100  	 if (!SetEvent(runtime_init_wait)) {
   101  		fprintf(stderr, "runtime: failed to signal runtime initialization complete.\n");
   102  		abort();
   103  	}
   104  }
   105  
   106  // The context function, used when tracing back C calls into Go.
   107  static void (*cgo_context_function)(struct context_arg*);
   108  
   109  // Sets the context function to call to record the traceback context
   110  // when calling a Go function from C code. Called from runtime.SetCgoTraceback.
   111  void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
   112  	EnterCriticalSection(&runtime_init_cs);
   113  	cgo_context_function = context;
   114  	LeaveCriticalSection(&runtime_init_cs);
   115  }
   116  
   117  // Gets the context function.
   118  void (*(_cgo_get_context_function(void)))(struct context_arg*) {
   119  	void (*ret)(struct context_arg*);
   120  
   121  	EnterCriticalSection(&runtime_init_cs);
   122  	ret = cgo_context_function;
   123  	LeaveCriticalSection(&runtime_init_cs);
   124  	return ret;
   125  }
   126
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