/* Initial program startup for running under the GNU Hurd.

   Copyright (C) 1991-2018 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or

   modify it under the terms of the GNU Lesser General Public

   License as published by the Free Software Foundation; either

   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public

   License along with the GNU C Library; if not, see

   <http://www.gnu.org/licenses/>.  */

#include <errno.h>

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <hurd.h>

#include <hurd/exec_startup.h>

#include <sysdep.h>

#include <unistd.h>

#include <elf.h>

#include <set-hooks.h>

#include "hurdstartup.h"

#include <argz.h>

mach_port_t *_hurd_init_dtable;

mach_msg_type_number_t _hurd_init_dtablesize;

extern void __mach_init (void);

/* Entry point.  This is the first thing in the text segment.

   The exec server started the initial thread in our task with this spot the

   PC, and a stack that is presumably big enough.  We do basic Mach

   initialization so mig-generated stubs work, and then do an exec_startup

   RPC on our bootstrap port, to which the exec server responds with the

   information passed in the exec call, as well as our original bootstrap

   port, and the base address and size of the preallocated stack.

   If using cthreads, we are given a new stack by cthreads initialization and

   deallocate the stack set up by the exec server.  On the new stack we call

   `start1' (above) to do the rest of the startup work.  Since the stack may

   disappear out from under us in a machine-dependent way, we use a pile of

   static variables to communicate the information from exec_startup to start1.

   This is unfortunate but preferable to machine-dependent frobnication to copy

   the state from the old stack to the new one.  */

void

_hurd_startup (void **argptr, void (*main) (intptr_t *data))

{

  error_t err;

  mach_port_t in_bootstrap;

  char *args, *env;

  mach_msg_type_number_t argslen, envlen;

  struct hurd_startup_data data;

  char **argv, **envp;

  int argc, envc;

  intptr_t *argcptr;

  vm_address_t addr;

  /* Attempt to map page zero redzoned before we receive any RPC

     data that might get allocated there.  We can ignore errors.  */

  addr = 0;

  __vm_map (__mach_task_self (),

	    &addr, __vm_page_size, 0, 0, MACH_PORT_NULL, 0, 1,

	    VM_PROT_NONE, VM_PROT_NONE, VM_INHERIT_COPY);

  if (err = __task_get_special_port (__mach_task_self (), TASK_BOOTSTRAP_PORT,

				     &in_bootstrap))

    LOSE;

  if (in_bootstrap != MACH_PORT_NULL)

    {

      /* Call the exec server on our bootstrap port and

	 get all our standard information from it.  */

      argslen = envlen = 0;

      data.dtablesize = data.portarraysize = data.intarraysize = 0;

      err = __exec_startup_get_info (in_bootstrap,

				     &data.user_entry,

				     &data.phdr, &data.phdrsz,

				     &data.stack_base, &data.stack_size,

				     &data.flags,

				     &args, &argslen,

				     &env, &envlen,

				     &data.dtable, &data.dtablesize,

				     &data.portarray, &data.portarraysize,

				     &data.intarray, &data.intarraysize);

      __mach_port_deallocate (__mach_task_self (), in_bootstrap);

    }

  if (err || in_bootstrap == MACH_PORT_NULL || (data.flags & EXEC_STACK_ARGS))

    {

      /* Either we have no bootstrap port, or the RPC to the exec server

	 failed, or whoever started us up passed the flag saying args are

	 on the stack.  Try to snarf the args in the canonical Mach way.

	 Hopefully either they will be on the stack as expected, or the

	 stack will be zeros so we don't crash.  */

      argcptr = (intptr_t *) argptr;

      argc = argcptr[0];

      argv = (char **) &argcptr[1];

      envp = &argv[argc + 1];

      envc = 0;

      while (envp[envc])

	++envc;

    }

  else

    {

      /* Turn the block of null-separated strings we were passed for the

	 arguments and environment into vectors of pointers to strings.  */

      /* Count up the arguments so we can allocate ARGV.  */

      argc = __argz_count (args, argslen);

      /* Count up the environment variables so we can allocate ENVP.  */

      envc = __argz_count (env, envlen);

      /* There were some arguments.  Allocate space for the vectors of

	 pointers and fill them in.  We allocate the space for the

	 environment pointers immediately after the argv pointers because

	 the ELF ABI will expect it.  */

      argcptr = __alloca (sizeof (intptr_t) +

			  (argc + 1 + envc + 1) * sizeof (char *) +

			  sizeof (struct hurd_startup_data));

      *argcptr = argc;

      argv = (void *) (argcptr + 1);

      __argz_extract (args, argslen, argv);

      /* There was some environment.  */

      envp = &argv[argc + 1];

      __argz_extract (env, envlen, envp);

    }

  if (err || in_bootstrap == MACH_PORT_NULL)

    {

      /* Either we have no bootstrap port, or the RPC to the exec server

	 failed.  Set all our other variables to have empty information.  */

      data.flags = 0;

      args = env = NULL;

      argslen = envlen = 0;

      data.dtable = NULL;

      data.dtablesize = 0;

      data.portarray = NULL;

      data.portarraysize = 0;

      data.intarray = NULL;

      data.intarraysize = 0;

    }

  else if ((void *) &envp[envc + 1] == argv[0])

    {

      /* The arguments arrived on the stack from the kernel, but our

	 protocol requires some space after them for a `struct

	 hurd_startup_data'.  Move them.  */

      struct

	{

	  intptr_t count;

	  char *argv[argc + 1];

	  char *envp[envc + 1];

	  struct hurd_startup_data data;

	} *args = alloca (sizeof *args);

      if ((void *) &args[1] == (void *) argcptr)

	args = alloca (-((char *) &args->data - (char *) args));

      memmove (args, argcptr, (char *) &args->data - (char *) args);

      argcptr = (void *) args;

      argv = args->argv;

      envp = args->envp;

    }

  {

    struct hurd_startup_data *d = (void *) &envp[envc + 1];

    if ((void *) d != argv[0])

      {

	*d = data;

	_hurd_init_dtable = d->dtable;

	_hurd_init_dtablesize = d->dtablesize;

      }

    (*main) (argcptr);

  }

  /* Should never get here.  */

  LOSE;

  abort ();

}