github.com/likebike/go--@v0.0.0-20190911215757-0bd925d16e96/go/src/runtime/cgo/gcc_darwin_arm.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  
    12  #include "libcgo.h"
    13  #include "libcgo_unix.h"
    14  
    15  #include <CoreFoundation/CFBundle.h>
    16  #include <CoreFoundation/CFString.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  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  		fprintf(stderr, "runtime/cgo: no Info.plist URL\n");
   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  		// Notify the test harness that we're correctly set up
   144  		raise(SIGINT);
   145  	}
   146  }
   147  
   148  void
   149  x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
   150  {
   151  	pthread_attr_t attr;
   152  	size_t size;
   153  
   154  	setg_gcc = setg;
   155  	pthread_attr_init(&attr);
   156  	pthread_attr_getstacksize(&attr, &size);
   157  	g->stacklo = (uintptr)&attr - size + 4096;
   158  	pthread_attr_destroy(&attr);
   159  
   160  	// yes, tlsbase from mrc might not be correctly aligned.
   161  	inittls(tlsg, (void**)((uintptr)tlsbase & ~3));
   162  
   163  	darwin_arm_init_mach_exception_handler();
   164  	darwin_arm_init_thread_exception_port();
   165  	init_working_dir();
   166  }