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