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Text file src/runtime/cgo/gcc_darwin_arm64.c

Documentation: runtime/cgo

     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; mstart 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	}

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