libguestfs/daemon/realpath.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., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <sys/types.h>
#include <dirent.h>

#include "ignore-value.h"

#include "daemon.h"
#include "actions.h"

char *
do_realpath (const char *path)
{
  char *ret;

  CHROOT_IN;
  ret = realpath (path, NULL);
  CHROOT_OUT;
  if (ret == NULL) {
    reply_with_perror ("realpath");
    return NULL;
  }

  return ret;			/* caller frees */
}

char *
do_case_sensitive_path (const char *path)
{
  char ret[PATH_MAX+1] = "/";
  size_t next = 1;

  /* MUST chdir ("/") before leaving this function. */
  if (chdir (sysroot) == -1) {
    reply_with_perror ("%s", sysroot);
    return NULL;
  }

  /* First character is a '/'.  Take each subsequent path element
   * and follow it.
   */
  while (*path) {
    size_t i = strcspn (path, "/");
    if (i == 0) {
      path++;
      continue;
    }

    if (verbose)
      fprintf (stderr, "case_sensitive_path: path = %s, next = %zu, i = %zu\n",
               path, next, i);

    if ((i == 1 && path[0] == '.') ||
        (i == 2 && path[0] == '.' && path[1] == '.')) {
      reply_with_error ("case_sensitive_path: path contained . or .. elements");
      goto error;
    }
    if (i > NAME_MAX) {
      reply_with_error ("case_sensitive_path: path element too long");
      goto error;
    }

    char name[NAME_MAX+1];
    memcpy (name, path, i);
    name[i] = '\0';

    /* Skip to next element in path (for the next loop iteration). */
    path += i;

    /* Read the current directory looking (case insensitively) for
     * this element of the path.
     */
    DIR *dir = opendir (".");
    if (dir == NULL) {
      reply_with_perror ("opendir");
      goto error;
    }

    struct dirent *d = NULL;

    errno = 0;
    while ((d = readdir (dir)) != NULL) {
      if (strcasecmp (d->d_name, name) == 0)
        break;
    }

    if (d == NULL && errno != 0) {
      reply_with_perror ("readdir");
      goto error;
    }

    if (closedir (dir) == -1) {
      reply_with_perror ("closedir");
      goto error;
    }

    if (d == NULL) {
      reply_with_error ("%s: no file or directory found with this name", name);
      goto error;
    }

    /* Add the real name of this path element to the return value. */
    if (next > 1)
      ret[next++] = '/';

    i = strlen (d->d_name);
    if (next + i >= PATH_MAX) {
      reply_with_error ("final path too long");
      goto error;
    }

    strcpy (&ret[next], d->d_name);
    next += i;

    /* Is it a directory?  Try going into it. */
    if (chdir (d->d_name) == -1) {
      /* ENOTDIR is OK provided we've reached the end of the path. */
      if (errno != ENOTDIR) {
        reply_with_perror ("chdir: %s", d->d_name);
        goto error;
      }

      if (*path) {
        reply_with_error ("%s: non-directory element in path", d->d_name);
        goto error;
      }
    }
  }

  ignore_value (chdir ("/"));

  ret[next] = '\0';
  char *retp = strdup (ret);
  if (retp == NULL) {
    reply_with_perror ("strdup");
    return NULL;
  }
  return retp;                  /* caller frees */

 error:
  ignore_value (chdir ("/"));
  return NULL;
}