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 #define WIN32_LEAN_AND_MEAN
6 #include <windows.h>
7 #include <process.h>
8
9 #include <stdio.h>
10 #include <stdlib.h>
11 #include <errno.h>
12
13 #include "libcgo.h"
14 #include "libcgo_windows.h"
15
16 // Ensure there's one symbol marked __declspec(dllexport).
17 // If there are no exported symbols, the unfortunate behavior of
18 // the binutils linker is to also strip the relocations table,
19 // resulting in non-PIE binary. The other option is the
20 // --export-all-symbols flag, but we don't need to export all symbols
21 // and this may overflow the export table (#40795).
22 // See https://sourceware.org/bugzilla/show_bug.cgi?id=19011
23 __declspec(dllexport) int _cgo_dummy_export;
24
25 static volatile LONG runtime_init_once_gate = 0;
26 static volatile LONG runtime_init_once_done = 0;
27
28 static CRITICAL_SECTION runtime_init_cs;
29
30 static HANDLE runtime_init_wait;
31 static int runtime_init_done;
32
33 uintptr_t x_cgo_pthread_key_created;
34 void (*x_crosscall2_ptr)(void (*fn)(void *), void *, int, size_t);
35
36 // Pre-initialize the runtime synchronization objects
37 void
_cgo_preinit_init()38 _cgo_preinit_init() {
39 runtime_init_wait = CreateEvent(NULL, TRUE, FALSE, NULL);
40 if (runtime_init_wait == NULL) {
41 fprintf(stderr, "runtime: failed to create runtime initialization wait event.\n");
42 abort();
43 }
44
45 InitializeCriticalSection(&runtime_init_cs);
46 }
47
48 // Make sure that the preinit sequence has run.
49 void
_cgo_maybe_run_preinit()50 _cgo_maybe_run_preinit() {
51 if (!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
52 if (InterlockedIncrement(&runtime_init_once_gate) == 1) {
53 _cgo_preinit_init();
54 InterlockedIncrement(&runtime_init_once_done);
55 } else {
56 // Decrement to avoid overflow.
57 InterlockedDecrement(&runtime_init_once_gate);
58 while(!InterlockedExchangeAdd(&runtime_init_once_done, 0)) {
59 Sleep(0);
60 }
61 }
62 }
63 }
64
65 void
x_cgo_sys_thread_create(void (* func)(void *),void * arg)66 x_cgo_sys_thread_create(void (*func)(void*), void* arg) {
67 _cgo_beginthread(func, arg);
68 }
69
70 int
_cgo_is_runtime_initialized()71 _cgo_is_runtime_initialized() {
72 EnterCriticalSection(&runtime_init_cs);
73 int status = runtime_init_done;
74 LeaveCriticalSection(&runtime_init_cs);
75 return status;
76 }
77
78 uintptr_t
_cgo_wait_runtime_init_done(void)79 _cgo_wait_runtime_init_done(void) {
80 void (*pfn)(struct context_arg*);
81
82 _cgo_maybe_run_preinit();
83 while (!_cgo_is_runtime_initialized()) {
84 WaitForSingleObject(runtime_init_wait, INFINITE);
85 }
86 pfn = _cgo_get_context_function();
87 if (pfn != nil) {
88 struct context_arg arg;
89
90 arg.Context = 0;
91 (*pfn)(&arg);
92 return arg.Context;
93 }
94 return 0;
95 }
96
97 // Should not be used since x_cgo_pthread_key_created will always be zero.
x_cgo_bindm(void * dummy)98 void x_cgo_bindm(void* dummy) {
99 fprintf(stderr, "unexpected cgo_bindm on Windows\n");
100 abort();
101 }
102
103 void
x_cgo_notify_runtime_init_done(void * dummy)104 x_cgo_notify_runtime_init_done(void* dummy) {
105 _cgo_maybe_run_preinit();
106
107 EnterCriticalSection(&runtime_init_cs);
108 runtime_init_done = 1;
109 LeaveCriticalSection(&runtime_init_cs);
110
111 if (!SetEvent(runtime_init_wait)) {
112 fprintf(stderr, "runtime: failed to signal runtime initialization complete.\n");
113 abort();
114 }
115 }
116
117 // The context function, used when tracing back C calls into Go.
118 static void (*cgo_context_function)(struct context_arg*);
119
120 // Sets the context function to call to record the traceback context
121 // when calling a Go function from C code. Called from runtime.SetCgoTraceback.
x_cgo_set_context_function(void (* context)(struct context_arg *))122 void x_cgo_set_context_function(void (*context)(struct context_arg*)) {
123 EnterCriticalSection(&runtime_init_cs);
124 cgo_context_function = context;
125 LeaveCriticalSection(&runtime_init_cs);
126 }
127
128 // Gets the context function.
_cgo_get_context_function(void)129 void (*(_cgo_get_context_function(void)))(struct context_arg*) {
130 void (*ret)(struct context_arg*);
131
132 EnterCriticalSection(&runtime_init_cs);
133 ret = cgo_context_function;
134 LeaveCriticalSection(&runtime_init_cs);
135 return ret;
136 }
137
_cgo_beginthread(void (* func)(void *),void * arg)138 void _cgo_beginthread(void (*func)(void*), void* arg) {
139 int tries;
140 uintptr_t thandle;
141
142 for (tries = 0; tries < 20; tries++) {
143 thandle = _beginthread(func, 0, arg);
144 if (thandle == -1 && errno == EACCES) {
145 // "Insufficient resources", try again in a bit.
146 //
147 // Note that the first Sleep(0) is a yield.
148 Sleep(tries); // milliseconds
149 continue;
150 } else if (thandle == -1) {
151 break;
152 }
153 return; // Success!
154 }
155
156 fprintf(stderr, "runtime: failed to create new OS thread (%d)\n", errno);
157 abort();
158 }
159