libgo/runtime/go-libmain.c

   1 /* go-libmain.c -- the startup function for a Go library.
   2
   3    Copyright 2015 The Go Authors. All rights reserved.
   4    Use of this source code is governed by a BSD-style
   5    license that can be found in the LICENSE file.  */
   6
   7 #include "config.h"
   8
   9 #include <errno.h>
  10 #include <pthread.h>
  11 #include <stdlib.h>
  12 #include <time.h>
  13 #include <unistd.h>
  14
  15 #include "runtime.h"
  16 #include "array.h"
  17 #include "arch.h"
  18 #include "malloc.h"
  19
  20 /* This is used when building a standalone Go library using the Go
  21    command's -buildmode=c-archive or -buildmode=c-shared option.  It
  22    starts up the Go code as a global constructor but does not take any
  23    other action.  The main program is written in some other language
  24    and calls exported Go functions as needed.  */
  25
  26 static void die (const char *, int);
  27 static void initfn (int, char **, char **);
  28 static void *gostart (void *);
  29
  30 /* Used to pass arguments to the thread that runs the Go startup.  */
  31
  32 struct args {
  33   int argc;
  34   char **argv;
  35 };
  36
  37 /* We use .init_array so that we can get the command line arguments.
  38    This obviously assumes .init_array support; different systems may
  39    require other approaches.  */
  40
  41 typedef void (*initarrayfn) (int, char **, char **);
  42
  43 static initarrayfn initarray[1]
  44 __attribute__ ((section (".init_array"), used)) =
  45   { initfn };
  46
  47 /* This function is called at program startup time.  It starts a new
  48    thread to do the actual Go startup, so that program startup is not
  49    paused waiting for the Go initialization functions.  Exported cgo
  50    functions will wait for initialization to complete if
  51    necessary.  */
  52
  53 static void
  54 initfn (int argc, char **argv, char** env __attribute__ ((unused)))
  55 {
  56   int err;
  57   pthread_attr_t attr;
  58   struct args *a;
  59   pthread_t tid;
  60
  61   runtime_isarchive = true;
  62
  63   setIsCgo ();
  64   runtime_cpuinit ();
  65   runtime_initsig(true);
  66
  67   a = (struct args *) malloc (sizeof *a);
  68   if (a == NULL)
  69     die ("malloc", errno);
  70   a->argc = argc;
  71   a->argv = argv;
  72
  73   err = pthread_attr_init (&attr);
  74   if (err != 0)
  75     die ("pthread_attr_init", err);
  76   err = pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
  77   if (err != 0)
  78     die ("pthread_attr_setdetachstate", err);
  79
  80   err = pthread_create (&tid, &attr, gostart, (void *) a);
  81   if (err != 0)
  82     die ("pthread_create", err);
  83
  84   err = pthread_attr_destroy (&attr);
  85   if (err != 0)
  86     die ("pthread_attr_destroy", err);
  87 }
  88
  89 /* Start up the Go runtime.  */
  90
  91 static void *
  92 gostart (void *arg)
  93 {
  94   struct args *a = (struct args *) arg;
  95
  96   if (runtime_isstarted)
  97     return NULL;
  98   runtime_isstarted = true;
  99
 100   runtime_check ();
 101   runtime_args (a->argc, (byte **) a->argv);
 102   runtime_osinit ();
 103   runtime_schedinit ();
 104   __go_go (runtime_main, NULL);
 105   runtime_mstart (runtime_m ());
 106   abort ();
 107 }
 108
 109 /* If something goes wrong during program startup, crash.  There is no
 110    way to report failure and nobody to whom to report it.  */
 111
 112 static void
 113 die (const char *fn, int err)
 114 {
 115   fprintf (stderr, "%s: %d\n", fn, err);
 116   exit (EXIT_FAILURE);
 117 }