github.com/tidwall/go@v0.0.0-20170415222209-6694a6888b7d/src/runtime/cgo/gcc_darwin_arm64.c (about)

     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  #include <stdlib.h>
    12  
    13  #include "libcgo.h"
    14  #include "libcgo_unix.h"
    15  
    16  #include <CoreFoundation/CFBundle.h>
    17  #include <CoreFoundation/CFString.h>
    18  
    19  #define magic (0xc476c475c47957UL)
    20  
    21  // inittls allocates a thread-local storage slot for g.
    22  //
    23  // It finds the first available slot using pthread_key_create and uses
    24  // it as the offset value for runtime.tlsg.
    25  static void
    26  inittls(void **tlsg, void **tlsbase)
    27  {
    28  	pthread_key_t k;
    29  	int i, err;
    30  
    31  	err = pthread_key_create(&k, nil);
    32  	if(err != 0) {
    33  		fprintf(stderr, "runtime/cgo: pthread_key_create failed: %d\n", err);
    34  		abort();
    35  	}
    36  	//fprintf(stderr, "runtime/cgo: k = %d, tlsbase = %p\n", (int)k, tlsbase); // debug
    37  	pthread_setspecific(k, (void*)magic);
    38  	// The first key should be at 257.
    39  	for (i=0; i<PTHREAD_KEYS_MAX; i++) {
    40  		if (*(tlsbase+i) == (void*)magic) {
    41  			*tlsg = (void*)(i*sizeof(void *));
    42  			pthread_setspecific(k, 0);
    43  			return;
    44  		}
    45  	}
    46  	fprintf(stderr, "runtime/cgo: could not find pthread key.\n");
    47  	abort();
    48  }
    49  
    50  static void *threadentry(void*);
    51  void (*setg_gcc)(void*);
    52  
    53  void
    54  _cgo_sys_thread_start(ThreadStart *ts)
    55  {
    56  	pthread_attr_t attr;
    57  	sigset_t ign, oset;
    58  	pthread_t p;
    59  	size_t size;
    60  	int err;
    61  
    62  	//fprintf(stderr, "runtime/cgo: _cgo_sys_thread_start: fn=%p, g=%p\n", ts->fn, ts->g); // debug
    63  	sigfillset(&ign);
    64  	pthread_sigmask(SIG_SETMASK, &ign, &oset);
    65  
    66  	pthread_attr_init(&attr);
    67  	size = 0;
    68  	pthread_attr_getstacksize(&attr, &size);
    69  	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
    70  	ts->g->stackhi = size;
    71  	err = _cgo_try_pthread_create(&p, &attr, threadentry, ts);
    72  
    73  	pthread_sigmask(SIG_SETMASK, &oset, nil);
    74  
    75  	if (err != 0) {
    76  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
    77  		abort();
    78  	}
    79  }
    80  
    81  extern void crosscall1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
    82  static void*
    83  threadentry(void *v)
    84  {
    85  	ThreadStart ts;
    86  
    87  	ts = *(ThreadStart*)v;
    88  	free(v);
    89  
    90  	darwin_arm_init_thread_exception_port();
    91  
    92  	crosscall1(ts.fn, setg_gcc, (void*)ts.g);
    93  	return nil;
    94  }
    95  
    96  // init_working_dir sets the current working directory to the app root.
    97  // By default darwin/arm processes start in "/".
    98  static void
    99  init_working_dir()
   100  {
   101  	CFBundleRef bundle = CFBundleGetMainBundle();
   102  	if (bundle == NULL) {
   103  		fprintf(stderr, "runtime/cgo: no main bundle\n");
   104  		return;
   105  	}
   106  	CFURLRef url_ref = CFBundleCopyResourceURL(bundle, CFSTR("Info"), CFSTR("plist"), NULL);
   107  	if (url_ref == NULL) {
   108  		fprintf(stderr, "runtime/cgo: no Info.plist URL\n");
   109  		return;
   110  	}
   111  	CFStringRef url_str_ref = CFURLGetString(url_ref);
   112  	char buf[MAXPATHLEN];
   113  	Boolean res = CFStringGetCString(url_str_ref, buf, sizeof(buf), kCFStringEncodingUTF8);
   114  	CFRelease(url_ref);
   115  	if (!res) {
   116  		fprintf(stderr, "runtime/cgo: cannot get URL string\n");
   117  		return;
   118  	}
   119  
   120  	// url is of the form "file:///path/to/Info.plist".
   121  	// strip it down to the working directory "/path/to".
   122  	int url_len = strlen(buf);
   123  	if (url_len < sizeof("file://")+sizeof("/Info.plist")) {
   124  		fprintf(stderr, "runtime/cgo: bad URL: %s\n", buf);
   125  		return;
   126  	}
   127  	buf[url_len-sizeof("/Info.plist")+1] = 0;
   128  	char *dir = &buf[0] + sizeof("file://")-1;
   129  
   130  	if (chdir(dir) != 0) {
   131  		fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", dir);
   132  	}
   133  
   134  	// The test harness in go_darwin_arm_exec passes the relative working directory
   135  	// in the GoExecWrapperWorkingDirectory property of the app bundle.
   136  	CFStringRef wd_ref = CFBundleGetValueForInfoDictionaryKey(bundle, CFSTR("GoExecWrapperWorkingDirectory"));
   137  	if (wd_ref != NULL) {
   138  		if (!CFStringGetCString(wd_ref, buf, sizeof(buf), kCFStringEncodingUTF8)) {
   139  			fprintf(stderr, "runtime/cgo: cannot get GoExecWrapperWorkingDirectory string\n");
   140  			return;
   141  		}
   142  		if (chdir(buf) != 0) {
   143  			fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", buf);
   144  		}
   145  		// Notify the test harness that we're correctly set up
   146  		raise(SIGINT);
   147  	}
   148  }
   149  
   150  void
   151  x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
   152  {
   153  	pthread_attr_t attr;
   154  	size_t size;
   155  
   156  	//fprintf(stderr, "x_cgo_init = %p\n", &x_cgo_init); // aid debugging in presence of ASLR
   157  	setg_gcc = setg;
   158  	pthread_attr_init(&attr);
   159  	pthread_attr_getstacksize(&attr, &size);
   160  	g->stacklo = (uintptr)&attr - size + 4096;
   161  	pthread_attr_destroy(&attr);
   162  
   163  	// yes, tlsbase from mrs might not be correctly aligned.
   164  	inittls(tlsg, (void**)((uintptr)tlsbase & ~7));
   165  
   166  	darwin_arm_init_mach_exception_handler();
   167  	darwin_arm_init_thread_exception_port();
   168  
   169  	init_working_dir();
   170  }