/*
   Copyright (C) 2017 Free Software Foundation, Inc.

   Written by Miles Bader <miles@gnu.org>

   This file is part of the GNU Hurd.

   The GNU Hurd is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   The GNU Hurd 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
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with the GNU Hurd.  If not, see <http://www.gnu.org/licenses/>.
*/

/* Fsysopts and command line option parsing */

#include "options.h"

#include <stdlib.h>
#include <argp.h>
#include <argz.h>
#include <error.h>
#include <regex.h>

#include "pcifs.h"

#define PCI_SLOT_REGEX "^(([0-9a-fA-F]{4}):)?([0-9a-fA-F]{2}):([0-9a-fA-F]{2})\\.([0-7])$"
#define PCI_SLOT_REGEX_GROUPS 6	// 2: Domain, 3: Bus, 4: Dev, 5: Func

/* Fsysopts and command line option parsing */

/* Adds an empty interface slot to H, and sets H's current interface to it, or
   returns an error. */
static error_t
parse_hook_add_set (struct parse_hook *h)
{
  struct pcifs_perm *new = realloc (h->permsets,
				    (h->num_permsets +
				     1) * sizeof (struct pcifs_perm));
  if (!new)
    return ENOMEM;

  h->permsets = new;
  h->num_permsets++;
  h->curset = new + h->num_permsets - 1;
  h->curset->domain = -1;
  h->curset->bus = -1;
  h->curset->dev = -1;
  h->curset->func = -1;
  h->curset->d_class = -1;
  h->curset->d_subclass = -1;
  h->curset->uid = -1;
  h->curset->gid = -1;

  return 0;
}

/*
 * Some options depend on other options to be valid. Check whether all
 * dependences are met.
 */
static error_t
check_options_validity (struct parse_hook *h)
{
  int i;
  struct pcifs_perm *p;

  for (p = h->permsets, i = 0; i < h->num_permsets; i++, p++)
    {
      if ((p->func >= 0 && p->dev < 0)
	  || (p->dev >= 0 && p->bus < 0)
	  || (p->bus >= 0 && p->domain < 0)
	  || (p->d_subclass >= 0 && p->d_class < 0)
	  || ((p->uid >= 0 || p->gid >= 0)
	      && (p->d_class < 0 && p->domain < 0)) || ((p->d_class >= 0
							 || p->domain >= 0)
							&& !(p->uid >= 0
							     || p->gid >= 0)))
	return EINVAL;
    }

  return 0;
}

/* Option parser */
static error_t
parse_opt (int opt, char *arg, struct argp_state *state)
{
  error_t err = 0;
  struct parse_hook *h = state->hook;
  regex_t slot_regex;
  regmatch_t slot_regex_groups[PCI_SLOT_REGEX_GROUPS];
  char regex_group_val[5];

  /* Return _ERR from this routine */
#define RETURN(_err)                          \
  do { return _err; } while (0)

  /* Print a parsing error message and (if exiting is turned off) return the
     error code ERR.  */
#define PERR(err, fmt, args...)               \
  do { argp_error (state, fmt , ##args); RETURN (err); } while (0)

  /* Like PERR but for non-parsing errors.  */
#define FAIL(rerr, status, perr, fmt, args...)  \
  do{ argp_failure (state, status, perr, fmt , ##args); RETURN (rerr); } while(0)

  if (!arg && state->next < state->argc && (*state->argv[state->next] != '-'))
    {
      arg = state->argv[state->next];
      state->next++;
    }

  /* Compile regular expression to check --slot option */
  err = regcomp (&slot_regex, PCI_SLOT_REGEX, REG_EXTENDED);
  if (err)
    FAIL (err, 1, err, "option parsing");

  switch (opt)
    {
    case 'C':
      h->curset->d_class = strtol (arg, 0, 16);
      break;
    case 'c':
      h->curset->d_subclass = strtol (arg, 0, 16);
      break;
    case 'd':
      h->curset->domain = strtol (arg, 0, 16);
      break;
    case 'b':
      if (h->curset->domain < 0)
	h->curset->domain = 0;

      h->curset->bus = strtol (arg, 0, 16);
      break;
    case 's':
      h->curset->dev = strtol (arg, 0, 16);
      break;
    case 'f':
      h->curset->func = strtol (arg, 0, 16);
      break;
    case 'D':
      err =
	regexec (&slot_regex, arg, PCI_SLOT_REGEX_GROUPS, slot_regex_groups,
		 0);
      if (!err)
	{
	  // Domain, 0000 by default
	  if (slot_regex_groups[2].rm_so >= 0)
	    {
	      strncpy (regex_group_val, arg + slot_regex_groups[2].rm_so, 4);
	      regex_group_val[4] = 0;
	    }
	  else
	    {
	      strncpy (regex_group_val, "0000", 5);
	    }

	  h->curset->domain = strtol (regex_group_val, 0, 16);

	  // Bus
	  strncpy (regex_group_val, arg + slot_regex_groups[3].rm_so, 2);
	  regex_group_val[2] = 0;

	  h->curset->bus = strtol (regex_group_val, 0, 16);

	  // Dev
	  strncpy (regex_group_val, arg + slot_regex_groups[4].rm_so, 2);
	  regex_group_val[2] = 0;

	  h->curset->dev = strtol (regex_group_val, 0, 16);

	  // Func
	  regex_group_val[0] = arg[slot_regex_groups[5].rm_so];
	  regex_group_val[1] = 0;

	  h->curset->func = strtol (regex_group_val, 0, 16);
	}
      else
	{
	  PERR (err, "Wrong PCI slot. Format: [<domain>:]<bus>:<dev>.<func>");
	}
      break;
    case 'U':
      if (h->curset->uid >= 0)
	parse_hook_add_set (h);

      h->curset->uid = atoi (arg);
      break;
    case 'G':
      if (h->curset->gid >= 0)
	parse_hook_add_set (h);

      h->curset->gid = atoi (arg);
      break;
    case 'n':
      h->ncache_len = atoi (arg);
      break;
    case ARGP_KEY_INIT:
      /* Initialize our parsing state.  */
      h = malloc (sizeof (struct parse_hook));
      if (!h)
	FAIL (ENOMEM, 1, ENOMEM, "option parsing");

      h->permsets = 0;
      h->num_permsets = 0;
      h->ncache_len = NODE_CACHE_MAX;
      err = parse_hook_add_set (h);
      if (err)
	FAIL (err, 1, err, "option parsing");

      state->hook = h;
      break;

    case ARGP_KEY_SUCCESS:
      /* Check option dependencies */
      err = check_options_validity (h);
      if (err)
	{
	  if (fs->root)
	    {
	      /*
	       * If there's an option dependence error but the server is yet
	       * running, print the error and do nothing.
	       */
	      free (h->permsets);
	      free (h);
	      PERR (err, "Invalid options, no changes were applied");
	    }
	  else
	    /* Invalid options on a non-started server, exit() */
	    PERR (err, "Option dependence error");
	}

      /* Set permissions to FS */
      if (fs->params.perms)
	free (fs->params.perms);
      fs->params.perms = h->permsets;
      fs->params.num_perms = h->num_permsets;

      /* Set cache len */
      fs->params.node_cache_max = h->ncache_len;

      if (fs->root)
	{
	  /*
	   * FS is already initialized, that means we've been called by fsysopts.
	   * Update permissions.
	   */

	  /* Don't accept new RPCs during this process */
	  err = ports_inhibit_all_rpcs ();
	  if (err)
	    return err;

	  err = fs_set_permissions (fs);

	  /* Accept RPCs again */
	  ports_resume_all_rpcs ();
	}

      /* Free the hook */
      free (h);

      break;

    case ARGP_KEY_ERROR:
      /* Parsing error occurred, free the permissions. */
      free (h->permsets);
      free (h);
      break;

    default:
      return ARGP_ERR_UNKNOWN;
    }

  /* Free allocated regular expression for the --slot option */
  regfree (&slot_regex);

  return err;
}

/*
 * Print current permissions. Called by fsysopts.
 */
error_t
netfs_append_args (char **argz, size_t * argz_len)
{
  error_t err = 0;
  struct pcifs_perm *p;
  int i;

#define ADD_OPT(fmt, args...)           \
  do { char buf[100];                   \
       if (! err) {                     \
         snprintf (buf, sizeof buf, fmt , ##args);      \
         err = argz_add (argz, argz_len, buf); } } while (0)

  for (i = 0, p = fs->params.perms; i < fs->params.num_perms; i++, p++)
    {
      if (p->d_class >= 0)
	ADD_OPT ("--class=0x%02x", p->d_class);
      if (p->d_subclass >= 0)
	ADD_OPT ("--subclass=0x%02x", p->d_subclass);
      if (p->domain >= 0)
	ADD_OPT ("--domain=0x%04x", p->domain);
      if (p->bus >= 0)
	ADD_OPT ("--bus=0x%02x", p->bus);
      if (p->dev >= 0)
	ADD_OPT ("--slot=0x%02x", p->dev);
      if (p->func >= 0)
	ADD_OPT ("--func=%01u", p->func);
      if (p->uid >= 0)
	ADD_OPT ("--uid=%u", p->uid);
      if (p->gid >= 0)
	ADD_OPT ("--gid=%u", p->gid);
    }

  if (fs->params.node_cache_max != NODE_CACHE_MAX)
    ADD_OPT ("--ncache=%u", fs->params.node_cache_max);

#undef ADD_OPT
  return err;
}

struct argp pci_argp = { options, parse_opt, 0, doc };

struct argp *netfs_runtime_argp = &pci_argp;