Text file src/runtime/cgo/gcc_darwin_arm.c
1 // Copyright 2014 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 #include <limits.h>
6 #include <pthread.h>
7 #include <signal.h>
8 #include <string.h> /* for strerror */
9 #include <sys/param.h>
10 #include <unistd.h>
11
12 #include <CoreFoundation/CFBundle.h>
13 #include <CoreFoundation/CFString.h>
14
15 #include "libcgo.h"
16 #include "libcgo_unix.h"
17
18 #define magic (0xe696c4f4U)
19
20 // inittls allocates a thread-local storage slot for g.
21 //
22 // It finds the first available slot using pthread_key_create and uses
23 // it as the offset value for runtime.tlsg.
24 static void
25 inittls(void **tlsg, void **tlsbase)
26 {
27 pthread_key_t k;
28 int i, err;
29
30 err = pthread_key_create(&k, nil);
31 if(err != 0) {
32 fprintf(stderr, "runtime/cgo: pthread_key_create failed: %d\n", err);
33 abort();
34 }
35 //fprintf(stderr, "runtime/cgo: k = %d, tlsbase = %p\n", (int)k, tlsbase); // debug
36 pthread_setspecific(k, (void*)magic);
37 // The first key should be at 258.
38 for (i=0; i<PTHREAD_KEYS_MAX; i++) {
39 if (*(tlsbase+i) == (void*)magic) {
40 *tlsg = (void*)(i*sizeof(void *));
41 pthread_setspecific(k, 0);
42 return;
43 }
44 }
45 fprintf(stderr, "runtime/cgo: could not find pthread key.\n");
46 abort();
47 }
48
49 static void *threadentry(void*);
50 static void (*setg_gcc)(void*);
51
52 void
53 _cgo_sys_thread_start(ThreadStart *ts)
54 {
55 pthread_attr_t attr;
56 sigset_t ign, oset;
57 pthread_t p;
58 size_t size;
59 int err;
60
61 sigfillset(&ign);
62 pthread_sigmask(SIG_SETMASK, &ign, &oset);
63
64 pthread_attr_init(&attr);
65 size = 0;
66 pthread_attr_getstacksize(&attr, &size);
67 // Leave stacklo=0 and set stackhi=size; mstart will do the rest.
68 ts->g->stackhi = size;
69 err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
70
71 pthread_sigmask(SIG_SETMASK, &oset, nil);
72
73 if (err != 0) {
74 fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
75 abort();
76 }
77 }
78
79 extern void crosscall_arm1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
80 static void*
81 threadentry(void *v)
82 {
83 ThreadStart ts;
84
85 ts = *(ThreadStart*)v;
86 free(v);
87
88 darwin_arm_init_thread_exception_port();
89
90 crosscall_arm1(ts.fn, setg_gcc, (void*)ts.g);
91 return nil;
92 }
93
94 // init_working_dir sets the current working directory to the app root.
95 // By default darwin/arm processes start in "/".
96 static void
97 init_working_dir()
98 {
99 CFBundleRef bundle = CFBundleGetMainBundle();
100 if (bundle == NULL) {
101 fprintf(stderr, "runtime/cgo: no main bundle\n");
102 return;
103 }
104 CFURLRef url_ref = CFBundleCopyResourceURL(bundle, CFSTR("Info"), CFSTR("plist"), NULL);
105 if (url_ref == NULL) {
106 // No Info.plist found. It can happen on Corellium virtual devices.
107 return;
108 }
109 CFStringRef url_str_ref = CFURLGetString(url_ref);
110 char buf[MAXPATHLEN];
111 Boolean res = CFStringGetCString(url_str_ref, buf, sizeof(buf), kCFStringEncodingUTF8);
112 CFRelease(url_ref);
113 if (!res) {
114 fprintf(stderr, "runtime/cgo: cannot get URL string\n");
115 return;
116 }
117
118 // url is of the form "file:///path/to/Info.plist".
119 // strip it down to the working directory "/path/to".
120 int url_len = strlen(buf);
121 if (url_len < sizeof("file://")+sizeof("/Info.plist")) {
122 fprintf(stderr, "runtime/cgo: bad URL: %s\n", buf);
123 return;
124 }
125 buf[url_len-sizeof("/Info.plist")+1] = 0;
126 char *dir = &buf[0] + sizeof("file://")-1;
127
128 if (chdir(dir) != 0) {
129 fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", dir);
130 }
131
132 // The test harness in go_darwin_arm_exec passes the relative working directory
133 // in the GoExecWrapperWorkingDirectory property of the app bundle.
134 CFStringRef wd_ref = CFBundleGetValueForInfoDictionaryKey(bundle, CFSTR("GoExecWrapperWorkingDirectory"));
135 if (wd_ref != NULL) {
136 if (!CFStringGetCString(wd_ref, buf, sizeof(buf), kCFStringEncodingUTF8)) {
137 fprintf(stderr, "runtime/cgo: cannot get GoExecWrapperWorkingDirectory string\n");
138 return;
139 }
140 if (chdir(buf) != 0) {
141 fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", buf);
142 }
143 }
144 }
145
146 void
147 x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
148 {
149 pthread_attr_t attr;
150 size_t size;
151
152 setg_gcc = setg;
153 pthread_attr_init(&attr);
154 pthread_attr_getstacksize(&attr, &size);
155 g->stacklo = (uintptr)&attr - size + 4096;
156 pthread_attr_destroy(&attr);
157
158 // yes, tlsbase from mrc might not be correctly aligned.
159 inittls(tlsg, (void**)((uintptr)tlsbase & ~3));
160
161 darwin_arm_init_mach_exception_handler();
162 darwin_arm_init_thread_exception_port();
163 init_working_dir();
164 }
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