github.com/aloncn/graphics-go@v0.0.1/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  // +build cgo
     6  
     7  #include <limits.h>
     8  #include <pthread.h>
     9  #include <signal.h>
    10  #include <string.h> /* for strerror */
    11  #include <sys/param.h>
    12  #include <unistd.h>
    13  
    14  #include "libcgo.h"
    15  
    16  #include <CoreFoundation/CFBundle.h>
    17  #include <CoreFoundation/CFString.h>
    18  
    19  #define magic (0xe696c4f4U)
    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 258.
    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  	sigfillset(&ign);
    63  	pthread_sigmask(SIG_SETMASK, &ign, &oset);
    64  
    65  	pthread_attr_init(&attr);
    66  	size = 0;
    67  	pthread_attr_getstacksize(&attr, &size);
    68  	// Leave stacklo=0 and set stackhi=size; mstack will do the rest.
    69  	ts->g->stackhi = size;
    70  	err = pthread_create(&p, &attr, threadentry, ts);
    71  
    72  	pthread_sigmask(SIG_SETMASK, &oset, nil);
    73  
    74  	if (err != 0) {
    75  		fprintf(stderr, "runtime/cgo: pthread_create failed: %s\n", strerror(err));
    76  		abort();
    77  	}
    78  }
    79  
    80  extern void crosscall_arm1(void (*fn)(void), void (*setg_gcc)(void*), void *g);
    81  static void*
    82  threadentry(void *v)
    83  {
    84  	ThreadStart ts;
    85  
    86  	ts = *(ThreadStart*)v;
    87  	free(v);
    88  
    89  	darwin_arm_init_thread_exception_port();
    90  
    91  	crosscall_arm1(ts.fn, setg_gcc, (void*)ts.g);
    92  	return nil;
    93  }
    94  
    95  // init_working_dir sets the current working directory to the app root.
    96  // By default darwin/arm processes start in "/".
    97  static void
    98  init_working_dir()
    99  {
   100  	CFBundleRef bundle = CFBundleGetMainBundle();
   101  	if (bundle == NULL) {
   102  		fprintf(stderr, "runtime/cgo: no main bundle\n");
   103  		return;
   104  	}
   105  	CFURLRef url_ref = CFBundleCopyResourceURL(bundle, CFSTR("Info"), CFSTR("plist"), NULL);
   106  	if (url_ref == NULL) {
   107  		fprintf(stderr, "runtime/cgo: no Info.plist URL\n");
   108  		return;
   109  	}
   110  	CFStringRef url_str_ref = CFURLGetString(url_ref);
   111  	char url[MAXPATHLEN];
   112          if (!CFStringGetCString(url_str_ref, url, sizeof(url), kCFStringEncodingUTF8)) {
   113  		fprintf(stderr, "runtime/cgo: cannot get URL string\n");
   114  		return;
   115  	}
   116  
   117  	// url is of the form "file:///path/to/Info.plist".
   118  	// strip it down to the working directory "/path/to".
   119  	int url_len = strlen(url);
   120  	if (url_len < sizeof("file://")+sizeof("/Info.plist")) {
   121  		fprintf(stderr, "runtime/cgo: bad URL: %s\n", url);
   122  		return;
   123  	}
   124  	url[url_len-sizeof("/Info.plist")+1] = 0;
   125  	char *dir = &url[0] + sizeof("file://")-1;
   126  
   127  	if (chdir(dir) != 0) {
   128  		fprintf(stderr, "runtime/cgo: chdir(%s) failed\n", dir);
   129  	}
   130  
   131  	// No-op to set a breakpoint on, immediately after the real chdir.
   132  	// Gives the test harness in go_darwin_arm_exec (which uses lldb) a
   133  	// chance to move the working directory.
   134  	getwd(dir);
   135  }
   136  
   137  void
   138  x_cgo_init(G *g, void (*setg)(void*), void **tlsg, void **tlsbase)
   139  {
   140  	pthread_attr_t attr;
   141  	size_t size;
   142  
   143  	setg_gcc = setg;
   144  	pthread_attr_init(&attr);
   145  	pthread_attr_getstacksize(&attr, &size);
   146  	g->stacklo = (uintptr)&attr - size + 4096;
   147  	pthread_attr_destroy(&attr);
   148  
   149  	// yes, tlsbase from mrc might not be correctly aligned.
   150  	inittls(tlsg, (void**)((uintptr)tlsbase & ~3));
   151  
   152  	darwin_arm_init_mach_exception_handler();
   153  	darwin_arm_init_thread_exception_port();
   154  	init_working_dir();
   155  }