libguestfs/df/domains.c

/* virt-df
 * Copyright (C) 2010 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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <config.h>

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

#ifdef HAVE_LIBVIRT
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
#endif

#include "progname.h"

#define GUESTFS_PRIVATE_FOR_EACH_DISK 1

#include "guestfs.h"
#include "options.h"
#include "virt-df.h"

#ifdef HAVE_LIBVIRT

/* Limit the number of devices we will ever add to the appliance.  The
 * overall limit in current libguestfs is 25: 26 = number of letters
 * in the English alphabet since we are only confident that
 * /dev/sd[a-z] will work because of various limits, minus 1 because
 * that may be used by the ext2 initial filesystem.  (RHBZ#635373).
 */
#define MAX_DISKS 25

/* The list of domains and disks that we build up in
 * get_domains_from_libvirt.
 */
struct disk {
  struct disk *next;
  char *filename;
  char *format; /* could be NULL */
};

struct domain {
  char *name;
  char *uuid;
  struct disk *disks;
  size_t nr_disks;
};

struct domain *domains = NULL;
size_t nr_domains;

static int
compare_domain_names (const void *p1, const void *p2)
{
  const struct domain *d1 = p1;
  const struct domain *d2 = p2;

  return strcmp (d1->name, d2->name);
}

static void
free_domain (struct domain *domain)
{
  struct disk *disk, *next;

  for (disk = domain->disks; disk; disk = next) {
    next = disk->next;
    free (disk->filename);
    free (disk->format);
    free (disk);
  }

  free (domain->name);
  free (domain->uuid);
}

static void add_domains_by_id (virConnectPtr conn, int *ids, size_t n);
static void add_domains_by_name (virConnectPtr conn, char **names, size_t n);
static void add_domain (virDomainPtr dom);
static int add_disk (guestfs_h *g, const char *filename, const char *format, int readonly, void *domain_vp);
static void multi_df (struct domain *, size_t n);

void
get_domains_from_libvirt (void)
{
  virErrorPtr err;
  virConnectPtr conn;
  int n;
  size_t i, j, nr_disks_added;

  nr_domains = 0;
  domains = NULL;

  /* Get the list of all domains. */
  conn = virConnectOpenReadOnly (libvirt_uri);
  if (!conn) {
    err = virGetLastError ();
    fprintf (stderr,
             _("%s: could not connect to libvirt (code %d, domain %d): %s"),
             program_name, err->code, err->domain, err->message);
    exit (EXIT_FAILURE);
  }

  n = virConnectNumOfDomains (conn);
  if (n == -1) {
    err = virGetLastError ();
    fprintf (stderr,
             _("%s: could not get number of running domains (code %d, domain %d): %s"),
             program_name, err->code, err->domain, err->message);
    exit (EXIT_FAILURE);
  }

  int ids[n];
  n = virConnectListDomains (conn, ids, n);
  if (n == -1) {
    err = virGetLastError ();
    fprintf (stderr,
             _("%s: could not list running domains (code %d, domain %d): %s"),
             program_name, err->code, err->domain, err->message);
    exit (EXIT_FAILURE);
  }

  add_domains_by_id (conn, ids, n);

  n = virConnectNumOfDefinedDomains (conn);
  if (n == -1) {
    err = virGetLastError ();
    fprintf (stderr,
             _("%s: could not get number of inactive domains (code %d, domain %d): %s"),
             program_name, err->code, err->domain, err->message);
    exit (EXIT_FAILURE);
  }

  char *names[n];
  n = virConnectListDefinedDomains (conn, names, n);
  if (n == -1) {
    err = virGetLastError ();
    fprintf (stderr,
             _("%s: could not list inactive domains (code %d, domain %d): %s"),
             program_name, err->code, err->domain, err->message);
    exit (EXIT_FAILURE);
  }

  add_domains_by_name (conn, names, n);

  /* You must free these even though the libvirt documentation doesn't
   * mention it.
   */
  for (i = 0; i < (size_t) n; ++i)
    free (names[i]);

  virConnectClose (conn);

  /* No domains? */
  if (nr_domains == 0)
    return;

  /* Sort the domains alphabetically by name for display. */
  qsort (domains, nr_domains, sizeof (struct domain), compare_domain_names);

  print_title ();

  /* To minimize the number of times we have to launch the appliance,
   * shuffle as many domains together as we can, but not exceeding
   * MAX_DISKS per request.  If --one-per-guest was requested then only
   * request disks from a single guest each time.
   * Interesting application for NP-complete knapsack problem here.
   */
  if (one_per_guest) {
    for (i = 0; i < nr_domains; ++i)
      multi_df (&domains[i], 1);
  } else {
    for (i = 0; i < nr_domains; /**/) {
      nr_disks_added = 0;

      /* Make a request with domains [i..j-1]. */
      for (j = i; j < nr_domains; ++j) {
        if (nr_disks_added + domains[j].nr_disks > MAX_DISKS)
          break;
        nr_disks_added += domains[j].nr_disks;
      }
      multi_df (&domains[i], j-i);

      i = j;
    }
  }

  /* Free up domains structure. */
  for (i = 0; i < nr_domains; ++i)
    free_domain (&domains[i]);
  free (domains);
}

static void
add_domains_by_id (virConnectPtr conn, int *ids, size_t n)
{
  size_t i;
  virDomainPtr dom;

  for (i = 0; i < n; ++i) {
    if (ids[i] != 0) {          /* RHBZ#538041 */
      dom = virDomainLookupByID (conn, ids[i]);
      if (dom) { /* transient errors are possible here, ignore them */
        add_domain (dom);
        virDomainFree (dom);
      }
    }
  }
}

static void
add_domains_by_name (virConnectPtr conn, char **names, size_t n)
{
  size_t i;
  virDomainPtr dom;

  for (i = 0; i < n; ++i) {
    dom = virDomainLookupByName (conn, names[i]);
    if (dom) { /* transient errors are possible here, ignore them */
      add_domain (dom);
      virDomainFree (dom);
    }
  }
}

static void
add_domain (virDomainPtr dom)
{
  struct domain *domain;

  domains = realloc (domains, (nr_domains + 1) * sizeof (struct domain));
  if (domains == NULL) {
    perror ("realloc");
    exit (EXIT_FAILURE);
  }

  domain = &domains[nr_domains];
  nr_domains++;

  domain->name = strdup (virDomainGetName (dom));
  if (domain->name == NULL) {
    perror ("strdup");
    exit (EXIT_FAILURE);
  }

  char uuid[VIR_UUID_STRING_BUFLEN];
  if (virDomainGetUUIDString (dom, uuid) == 0) {
    domain->uuid = strdup (uuid);
    if (domain->uuid == NULL) {
      perror ("strdup");
      exit (EXIT_FAILURE);
    }
  }
  else
    domain->uuid = NULL;

  domain->disks = NULL;
  int n = guestfs___for_each_disk (g, dom, add_disk, domain);
  if (n == -1)
    exit (EXIT_FAILURE);
  domain->nr_disks = n;

  if (domain->nr_disks > MAX_DISKS) {
    fprintf (stderr,
             _("%s: ignoring %s, it has too many disks (%zu > %d)"),
             program_name, domain->name, domain->nr_disks, MAX_DISKS);
    free_domain (domain);
    nr_domains--;
    return;
  }
}

static int
add_disk (guestfs_h *g,
          const char *filename, const char *format, int readonly,
          void *domain_vp)
{
  struct domain *domain = domain_vp;
  struct disk *disk;

  disk = malloc (sizeof *disk);
  if (disk == NULL) {
    perror ("malloc");
    return -1;
  }

  disk->next = domain->disks;
  domain->disks = disk;

  disk->filename = strdup (filename);
  if (disk->filename == NULL) {
    perror ("malloc");
    return -1;
  }
  if (format) {
    disk->format = strdup (format);
    if (disk->format == NULL) {
      perror ("malloc");
      return -1;
    }
  }
  else
    disk->format = NULL;

  return 0;
}

static size_t
count_strings (char **argv)
{
  size_t i;

  for (i = 0; argv[i] != NULL; ++i)
    ;
  return i;
}

static void reset_guestfs_handle (void);
static void add_disks_to_handle_reverse (struct disk *disk);

/* Perform 'df' operation on the domain(s) given in the list. */
static void
multi_df (struct domain *domains, size_t n)
{
  size_t i;
  size_t nd;
  int r;
  char **devices;

  /* Add all the disks to the handle (since they were added in reverse
   * order, we must add them here in reverse too).
   */
  for (i = 0; i < n; ++i)
    add_disks_to_handle_reverse (domains[i].disks);

  /* Launch the handle. */
  if (guestfs_launch (g) == -1)
    exit (EXIT_FAILURE);

  devices = guestfs_list_devices (g);
  if (devices == NULL)
    exit (EXIT_FAILURE);

  /* Check the number of disks we think we added is the same as the
   * number of devices returned by libguestfs.
   */
  nd = 0;
  for (i = 0; i < n; ++i)
    nd += domains[i].nr_disks;
  assert (nd == count_strings (devices));

  nd = 0;
  for (i = 0; i < n; ++i) {
    /* So that &devices[nd] is a NULL-terminated list of strings. */
    char *p = devices[nd + domains[i].nr_disks];
    devices[nd + domains[i].nr_disks] = NULL;

    r = df_on_handle (domains[i].name, domains[i].uuid, &devices[nd], nd);

    /* Restore devices to original. */
    devices[nd + domains[i].nr_disks] = p;
    nd += domains[i].nr_disks;

    /* Something broke in df_on_handle.  Give up on the remaining
     * devices for this handle, but keep going on the next handle.
     */
    if (r == -1)
      break;
  }

  for (i = 0; devices[i] != NULL; ++i)
    free (devices[i]);
  free (devices);

  /* Reset the handle. */
  reset_guestfs_handle ();
}

static void
add_disks_to_handle_reverse (struct disk *disk)
{
  if (disk == NULL)
    return;

  add_disks_to_handle_reverse (disk->next);

  struct guestfs_add_drive_opts_argv optargs = { .bitmask = 0 };

  optargs.bitmask |= GUESTFS_ADD_DRIVE_OPTS_READONLY_BITMASK;
  optargs.readonly = 1;

  if (disk->format) {
    optargs.bitmask |= GUESTFS_ADD_DRIVE_OPTS_FORMAT_BITMASK;
    optargs.format = disk->format;
  }

  if (guestfs_add_drive_opts_argv (g, disk->filename, &optargs) == -1)
    exit (EXIT_FAILURE);
}

/* Close and reopen the libguestfs handle. */
static void
reset_guestfs_handle (void)
{
  /* Copy the settings from the old handle. */
  int verbose = guestfs_get_verbose (g);
  int trace = guestfs_get_trace (g);

  guestfs_close (g);

  g = guestfs_create ();
  if (g == NULL) {
    fprintf (stderr, _("guestfs_create: failed to create handle\n"));
    exit (EXIT_FAILURE);
  }

  guestfs_set_verbose (g, verbose);
  guestfs_set_trace (g, trace);
}

#endif