hurd/hurdstartup.c

   1 /* Initial program startup for running under the GNU Hurd.
   2    Copyright (C) 1991,92,93,94,95,96,97,98,2002 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <stdlib.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <hurd.h>
  25 #include <hurd/exec_startup.h>
  26 #include <sysdep.h>
  27 #include <hurd/threadvar.h>
  28 #include <unistd.h>
  29 #include <elf.h>
  30 #include <set-hooks.h>
  31 #include "hurdstartup.h"
  32 #include <argz.h>
  33
  34 mach_port_t *_hurd_init_dtable;
  35 mach_msg_type_number_t _hurd_init_dtablesize;
  36
  37 extern void __mach_init (void);
  38
  39 /* Entry point.  This is the first thing in the text segment.
  40
  41    The exec server started the initial thread in our task with this spot the
  42    PC, and a stack that is presumably big enough.  We do basic Mach
  43    initialization so mig-generated stubs work, and then do an exec_startup
  44    RPC on our bootstrap port, to which the exec server responds with the
  45    information passed in the exec call, as well as our original bootstrap
  46    port, and the base address and size of the preallocated stack.
  47
  48    If using cthreads, we are given a new stack by cthreads initialization and
  49    deallocate the stack set up by the exec server.  On the new stack we call
  50    `start1' (above) to do the rest of the startup work.  Since the stack may
  51    disappear out from under us in a machine-dependent way, we use a pile of
  52    static variables to communicate the information from exec_startup to start1.
  53    This is unfortunate but preferable to machine-dependent frobnication to copy
  54    the state from the old stack to the new one.  */
  55
  56
  57 void
  58 _hurd_startup (void **argptr, void (*main) (intptr_t *data))
  59 {
  60   error_t err;
  61   mach_port_t in_bootstrap;
  62   char *args, *env;
  63   mach_msg_type_number_t argslen, envlen;
  64   struct hurd_startup_data data;
  65   char **argv, **envp;
  66   int argc, envc;
  67   intptr_t *argcptr;
  68   vm_address_t addr;
  69
  70   /* Attempt to map page zero redzoned before we receive any RPC
  71      data that might get allocated there.  We can ignore errors.  */
  72   addr = 0;
  73   __vm_map (__mach_task_self (),
  74             &addr, __vm_page_size, 0, 0, MACH_PORT_NULL, 0, 1,
  75             VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);
  76
  77   if (err = __task_get_special_port (__mach_task_self (), TASK_BOOTSTRAP_PORT,
  78                                      &in_bootstrap))
  79     LOSE;
  80
  81   if (in_bootstrap != MACH_PORT_NULL)
  82     {
  83       /* Call the exec server on our bootstrap port and
  84          get all our standard information from it.  */
  85
  86       argslen = envlen = 0;
  87       data.dtablesize = data.portarraysize = data.intarraysize = 0;
  88
  89       err = __exec_startup_get_info (in_bootstrap,
  90                                      &data.user_entry,
  91                                      &data.phdr, &data.phdrsz,
  92                                      &data.stack_base, &data.stack_size,
  93                                      &data.flags,
  94                                      &args, &argslen,
  95                                      &env, &envlen,
  96                                      &data.dtable, &data.dtablesize,
  97                                      &data.portarray, &data.portarraysize,
  98                                      &data.intarray, &data.intarraysize);
  99       __mach_port_deallocate (__mach_task_self (), in_bootstrap);
 100     }
 101
 102   if (err || in_bootstrap == MACH_PORT_NULL || (data.flags & EXEC_STACK_ARGS))
 103     {
 104       /* Either we have no bootstrap port, or the RPC to the exec server
 105          failed, or whoever started us up passed the flag saying args are
 106          on the stack.  Try to snarf the args in the canonical Mach way.
 107          Hopefully either they will be on the stack as expected, or the
 108          stack will be zeros so we don't crash.  */
 109
 110       argcptr = (intptr_t *) argptr;
 111       argc = argcptr[0];
 112       argv = (char **) &argcptr[1];
 113       envp = &argv[argc + 1];
 114       envc = 0;
 115       while (envp[envc])
 116         ++envc;
 117     }
 118   else
 119     {
 120       /* Turn the block of null-separated strings we were passed for the
 121          arguments and environment into vectors of pointers to strings.  */
 122
 123       /* Count up the arguments so we can allocate ARGV.  */
 124       argc = __argz_count (args, argslen);
 125       /* Count up the environment variables so we can allocate ENVP.  */
 126       envc = __argz_count (env, envlen);
 127
 128       /* There were some arguments.  Allocate space for the vectors of
 129          pointers and fill them in.  We allocate the space for the
 130          environment pointers immediately after the argv pointers because
 131          the ELF ABI will expect it.  */
 132       argcptr = __alloca (sizeof (intptr_t) +
 133                           (argc + 1 + envc + 1) * sizeof (char *) +
 134                           sizeof (struct hurd_startup_data));
 135       *argcptr = argc;
 136       argv = (void *) (argcptr + 1);
 137       __argz_extract (args, argslen, argv);
 138
 139       /* There was some environment.  */
 140       envp = &argv[argc + 1];
 141       __argz_extract (env, envlen, envp);
 142     }
 143
 144   if (err || in_bootstrap == MACH_PORT_NULL)
 145     {
 146       /* Either we have no bootstrap port, or the RPC to the exec server
 147          failed.  Set all our other variables to have empty information.  */
 148
 149       data.flags = 0;
 150       args = env = NULL;
 151       argslen = envlen = 0;
 152       data.dtable = NULL;
 153       data.dtablesize = 0;
 154       data.portarray = NULL;
 155       data.portarraysize = 0;
 156       data.intarray = NULL;
 157       data.intarraysize = 0;
 158     }
 159   else if ((void *) &envp[envc + 1] == argv[0])
 160     {
 161       /* The arguments arrived on the stack from the kernel, but our
 162          protocol requires some space after them for a `struct
 163          hurd_startup_data'.  Move them.  */
 164       struct
 165         {
 166           intptr_t count;
 167           char *argv[argc + 1];
 168           char *envp[envc + 1];
 169           struct hurd_startup_data data;
 170         } *args = alloca (sizeof *args);
 171       if ((void *) &args[1] == (void *) argcptr)
 172         args = alloca (-((char *) &args->data - (char *) args));
 173       memmove (args, argcptr, (char *) &args->data - (char *) args);
 174       argcptr = (void *) args;
 175       argv = args->argv;
 176       envp = args->envp;
 177     }
 178
 179   {
 180     struct hurd_startup_data *d = (void *) &envp[envc + 1];
 181
 182     if ((void *) d != argv[0])
 183       {
 184         *d = data;
 185         _hurd_init_dtable = d->dtable;
 186         _hurd_init_dtablesize = d->dtablesize;
 187       }
 188
 189     (*main) (argcptr);
 190   }
 191
 192   /* Should never get here.  */
 193   LOSE;
 194   abort ();
 195 }