libguestfs/daemon/available.c

/* libguestfs - the guestfsd daemon
 * Copyright (C) 2009 Red Hat Inc.
 *
 * This program 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 of the License, or
 * (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "c-ctype.h"
#include "ignore-value.h"

#include "guestfs_protocol.h"
#include "daemon.h"
#include "actions.h"
#include "optgroups.h"

GUESTFSD_EXT_CMD(str_grep, grep);
GUESTFSD_EXT_CMD(str_modprobe, modprobe);

static int
available (char *const *groups, int error_on_unavailable)
{
  int av;
  size_t i, j;

  for (i = 0; groups[i] != NULL; ++i) {
    for (j = 0; optgroups[j].group != NULL; ++j) {
      if (STREQ (groups[i], optgroups[j].group)) {
        av = optgroups[j].available ();
        if (!av) {
          if (error_on_unavailable) {
            reply_with_error ("%s: group not available", optgroups[j].group);
            return -1;
          }
          else
            return 0;
        }
        break; /* out of for (j) loop */
      }
    }

    /* Unknown group? */
    if (optgroups[j].group == NULL) {
      reply_with_error ("%s: unknown group", groups[i]);
      return -1;
    }
  }

  /* All specified groups available. */
  return 1;
}

int
do_feature_available (char *const *groups)
{
  return available (groups, 0);
}

int
do_available (char *const *groups)
{
  if (available (groups, 1) == -1)
    return -1;

  /* No error, so all groups available, just returns no error. */
  return 0;
}

char **
do_available_all_groups (void)
{
  size_t i;
  DECLARE_STRINGSBUF (groups);

  for (i = 0; optgroups[i].group != NULL; ++i) {
    if (add_string (&groups, optgroups[i].group) == -1)
      return NULL;
  }

  if (end_stringsbuf (&groups) == -1)
    return NULL;

  return groups.argv;           /* caller frees */
}

/* Search for filesystem in /proc/filesystems, ignoring "nodev". */
static int
test_proc_filesystems (const char *filesystem)
{
  size_t len = strlen (filesystem) + 32;
  char regex[len];
  CLEANUP_FREE char *err = NULL;
  int r;

  snprintf (regex, len, "^[[:space:]]*%s$", filesystem);

  r = commandr (NULL, &err, str_grep, regex, "/proc/filesystems", NULL);
  if (r == -1 || r >= 2) {
    fprintf (stderr, "grep /proc/filesystems: %s", err);
    return -1;
  }

  return r == 0;
}

/* Do modprobe, ignore any errors. */
static void
modprobe (const char *module)
{
  ignore_value (command (NULL, NULL, str_modprobe, module, NULL));
}

/* Internal function for testing if a filesystem is available.  Note
 * this must not call reply_with_error functions.
 */
int
filesystem_available (const char *filesystem)
{
  int r;

  r = test_proc_filesystems (filesystem);
  if (r == -1 || r > 0)
    return r;

  /* Not found: try to modprobe the module, then test again. */
  if (optgroup_linuxmodules_available ()) {
    modprobe (filesystem);

    r = test_proc_filesystems (filesystem);
    if (r == -1)
      return -1;
  }

  return r;
}

int
do_filesystem_available (const char *filesystem)
{
  size_t i, len = strlen (filesystem);
  int r;

  for (i = 0; i < len; ++i) {
    if (!c_isalnum (filesystem[i]) && filesystem[i] != '_') {
      reply_with_error ("filesystem name contains non-alphanumeric characters");
      return -1;
    }
  }

  r = filesystem_available (filesystem);
  if (r == -1) {
    reply_with_error ("error testing for filesystem availability; "
                      "enable verbose mode and look at preceding output");
    return -1;
  }

  return r;
}