cmd/rmvolmgr/vold.c

	vold.c revision f48205be61a214698b763ff550ab9e657525104c
/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

/*
 * Vold compatibility for rmvolmgr: emulate old commands as well as
 * action_filemgr.so to notify legacy apps via /tmp/.removable pipes.
 * A lot of this code is copied verbatim from vold sources.
 *
 * Here's the original description of action_filemgr.so:
 *
 * action_filemgr.so - filemgr interface routines for rmmount
 *
 * This shared object allows rmmount to communicate with filemgr.
 * This is done by communicating over a named pipe that filemgr
 * creates in directory NOTIFY_DIR.  The name of the pipe must
 * begin with NOTIFY_NAME.  This source file contains #define
 * compiler directives set the values of NOTIFY_DIR and NOTIFY_NAME.
 *
 * After a partition on a medium has been mounted as a result of
 * either insertion or remounting of the medium, the action()
 * method creates a file named with the symbolic name of the
 * device in which the medium is inserted and the partition name
 * (e.g. "jaz0-s2") in NOTIFY_DIR.  The file consists of one text
 * line containing a string naming the mount point of the partition,
 * a string giving the raw device path to the partition, and a
 * string naming the file system type on the partition.  The action()
 * method then sends a single character ('i' for insertion, 'r' for
 * remounting) through the named pipe NOTIFY_NAME to tell filemgr to
 * look for new files in NOTIFY_DIR.
 *
 * If a medium containing no mountable partitions is inserted
 * or remounted in a device, the action() method creates a file
 * named with the symbolic name of the device in NOTIFY_DIR.
 * The file consists of one text line containing a string
 * giving the symbolic name of the device and a string naming
 * the reason that the medium couldn't be mounted.  The action
 * method then sends either an 'i' or an 'r' through the named
 * pipe to tell filemgr to look for new files in NOTIFY_DIR.
 *
 * When a medium is ejected or unmounted, the action() method
 * removes the files that were created in NOTIFY_DIR when the medium
 * was inserted or remounted and sends a single character ('e' for
 * ejection, 'u' for unmounting) through the named pipe.
 *
 * The following environment variables must be set before calling action():
 *
 *  VOLUME_ACTION       action that occurred (e.g. "insert", "eject")
 *  VOLUME_SYMDEV       symbolic name (e.g. "cdrom0", "floppy1")
 *  VOLUME_NAME     volume name (e.g. "unnamed_cdrom", "s2")
 */


#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <strings.h>
#include <dirent.h>
#include <signal.h>
#include <errno.h>
#include <libintl.h>
#include <zone.h>
#include <pwd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/dkio.h>
#include <sys/cdio.h>
#include <sys/vtoc.h>
#include <sys/param.h>
#include <sys/wait.h>
#include <libcontract.h>
#include <sys/contract/process.h>
#include <sys/ctfs.h>
#include <tsol/label.h>

#include "vold.h"
#include "rmm_common.h"

int     rmm_debug = 0;
boolean_t   rmm_vold_actions_enabled = B_FALSE;
boolean_t   rmm_vold_mountpoints_enabled = B_FALSE;

static char *prog_name = NULL;
static pid_t    prog_pid = 0;
static int  system_labeled = 0;
static uid_t    mnt_uid = (uid_t)-1;
static gid_t    mnt_gid = (gid_t)-1;
static zoneid_t mnt_zoneid = -1;
static char mnt_zoneroot[MAXPATHLEN];
static char mnt_userdir[MAXPATHLEN];

/*
 * Private attribute types and attributes.
 */
static const char notify_characters[] = {
    'e',
    'i',
    'r',
    'u'
};

static const char *result_strings[] = {
    "FALSE",
    "TRUE"
};

#define NOTIFY_DIR  "/tmp/.removable"   /* dir where filemgr looks */
#define NOTIFY_NAME "notify"        /* named pipe to talk over */

static void volrmmount_usage();
static void volcheck_usage();
static int  vold_action(struct action_arg *aap);
static void vold_update_mountpoints(struct action_arg *aap);
static char *not_mountable(struct action_arg *aa);
static int  create_one_notify_file(char *fstype,
                char *mount_point,
                char *notify_file,
                char *raw_partitionp,
                char *reason,
                char *symdev);
static int  create_notify_files(struct action_arg **aa);
static boolean_t notify_clients(action_t action, int do_notify);
static void popdir(int fd);
static int  pushdir(const char *dir);
static boolean_t remove_notify_files(struct action_arg **aa);

/*
 * should be called once from main()
 */
/* ARGSUSED */
void
vold_init(int argc, char **argv)
{
    system_labeled = is_system_labeled();
}

/*
 * Old version of rmmount(1M)
 */
/* ARGSUSED */
int
vold_rmmount(int argc, char **argv)
{
    char        *volume_action;
    char        *volume_mediatype;
    char        *volume_mount_mode;
    char        *volume_name;
    char        *volume_path;
    char        *volume_pcfs_id;
    char        *volume_symdev;
    char        *volume_zonename;
    char        *volume_user;
    action_t    action;
    char        mountpoint[MAXPATHLEN];
    char        *zonemountpoint;
    char        *arg_mountpoint = NULL;
    LibHalContext   *hal_ctx;
    DBusError   error;
    rmm_error_t rmm_error;
    int     ret;

    prog_name = argv[0];
    prog_pid = getpid();

    mnt_zoneroot[0] = '\0';
    mnt_userdir[0] = '\0';

    volume_action = getenv("VOLUME_ACTION");
    volume_mediatype = getenv("VOLUME_MEDIATYPE");
    volume_mount_mode = getenv("VOLUME_MOUNT_MODE");
    volume_name = getenv("VOLUME_NAME");
    volume_path = getenv("VOLUME_PATH");
    volume_pcfs_id = getenv("VOLUME_PCFS_ID");
    volume_symdev = getenv("VOLUME_SYMDEV");

    if (system_labeled) {
        volume_zonename = getenv("VOLUME_ZONE_NAME");
        volume_user = getenv("VOLUME_USER");
    }
    if (volume_action == NULL) {
        dprintf("%s(%ld): VOLUME_ACTION was null!!\n",
            prog_name, prog_pid);
        return (-1);
    }
    if (volume_mediatype == NULL) {
        dprintf("%s(%ld): VOLUME_MEDIATYPE was null!!\n",
            prog_name, prog_pid);
        return (-1);
    }
    if (volume_mount_mode == NULL) {
        volume_mount_mode = "rw";
    }
    if (volume_name == NULL) {
        dprintf("%s(%ld): VOLUME_NAME was null!!\n",
            prog_name, prog_pid);
        return (-1);
    }
    if (volume_path == NULL) {
        dprintf("%s(%ld): VOLUME_PATH was null!!\n",
            prog_name, prog_pid);
        return (-1);
    }
    if (volume_pcfs_id == NULL) {
        volume_pcfs_id = "";
    }
    if (volume_symdev == NULL) {
        dprintf("%s(%ld): VOLUME_SYMDEV was null!!\n",
            prog_name, prog_pid);
        return (-1);
    }

    if (system_labeled) {
        if (volume_zonename != NULL &&
            strcmp(volume_zonename, GLOBAL_ZONENAME) != 0) {
            if ((mnt_zoneid =
                getzoneidbyname(volume_zonename)) != -1) {
                if (zone_getattr(mnt_zoneid, ZONE_ATTR_ROOT,
                    mnt_zoneroot, MAXPATHLEN) == -1) {
                    dprintf("%s(%ld): NO ZONEPATH!!\n",
                        prog_name, prog_pid);
                    return (-1);
                }
            }
        } else {
            mnt_zoneid = GLOBAL_ZONEID;
            mnt_zoneroot[0] = '\0';
        }
        if (volume_user != NULL) {
            struct passwd    *pw;

            if ((pw = getpwnam(volume_user)) == NULL) {
                dprintf("%s(%ld) %s\n", prog_name, prog_pid,
                    ": VOLUME_USER was not a valid user!");
                return (-1);
            }
            mnt_uid = pw->pw_uid;
            mnt_gid = pw->pw_gid;

            if (snprintf(mnt_userdir, sizeof (mnt_userdir),
                "/%s-%s", volume_user, volume_symdev) >=
                sizeof (mnt_userdir))
                return (-1);
        } else {
            mnt_uid = 0;
            mnt_userdir[0] = '\0';
        }

        rmm_vold_mountpoints_enabled = B_FALSE;
        rmm_vold_actions_enabled = B_TRUE;
    } else {
        rmm_vold_mountpoints_enabled = B_TRUE;
        rmm_vold_actions_enabled = B_TRUE;
    }

    if ((hal_ctx = rmm_hal_init(0, 0, 0, &error, &rmm_error)) == NULL) {
        rmm_dbus_error_free(&error);

        /* if HAL's not running, must be root */
        if (geteuid() != 0) {
            (void) fprintf(stderr,
                gettext("%s(%ld) error: must be root to execute\n"),
                prog_name, prog_pid);
            return (-1);
        }
    }

    if (strcmp(volume_action, "eject") == 0) {
        action = EJECT;
    } else if (strcmp(volume_action, "insert") == 0) {
        action = INSERT;

        if (system_labeled) {
            /*
             * create mount point
             */
            if (strlen(mnt_userdir) > 0) {
                if (snprintf(mountpoint, MAXPATHLEN,
                    "%s/%s%s", mnt_zoneroot, volume_mediatype,
                    mnt_userdir) > MAXPATHLEN) {
                    return (-1);

                }
                (void) makepath(mountpoint, 0700);
                (void) chown(mountpoint, mnt_uid, mnt_gid);
                /*
                 * set the top level directory bits to 0755
                 * so user can access it.
                 */
                if (snprintf(mountpoint, MAXPATHLEN,
                    "%s/%s", mnt_zoneroot,
                    volume_mediatype) <= MAXPATHLEN) {
                    (void) chmod(mountpoint, 0755);
                }
            }
            if (snprintf(mountpoint, MAXPATHLEN,
                "%s/%s%s/%s", mnt_zoneroot, volume_mediatype,
                mnt_userdir, volume_name) > MAXPATHLEN) {
                (void) fprintf(stderr,
                    gettext("%s(%ld) error: path too long\n"),
                    prog_name, prog_pid);
                return (-1);
            }

            /* make our mountpoint */
            (void) makepath(mountpoint, 0755);

            arg_mountpoint = mountpoint;
        }
    } else if (strcmp(volume_action, "remount") == 0) {
        action = REMOUNT;
    } else if (strcmp(volume_action, "unmount") == 0) {
        action = UNMOUNT;
    }

    ret = rmm_action(hal_ctx, volume_symdev, action, 0, 0, 0,
        arg_mountpoint) ? 0 : 1;

    if (hal_ctx != NULL) {
        rmm_hal_fini(hal_ctx);
    }

    return (ret);
}


/*
 * this should be called after rmm_hal_{mount,unmount,eject}
 */
int
vold_postprocess(LibHalContext *hal_ctx, const char *udi,
    struct action_arg *aap)
{
    int ret = 0;

    /* valid mountpoint required */
    if ((aap->aa_action == INSERT) || (aap->aa_action == REMOUNT)) {
        rmm_volume_aa_update_mountpoint(hal_ctx, udi, aap);
        if ((aap->aa_mountpoint == NULL) ||
            (strlen(aap->aa_mountpoint) == 0)) {
            return (1);
        }
    }

    if (rmm_vold_mountpoints_enabled) {
        vold_update_mountpoints(aap);
    }
    if (rmm_vold_actions_enabled) {
        ret = vold_action(aap);
    }

    return (ret);
}

/*
 * update legacy symlinks
 *
 * For cdrom:
 *
 *  /cdrom/<name> -> original mountpoint
 *  /cdrom/cdrom0 -> ./<name>
 *  /cdrom/cdrom -> cdrom0  (only for cdrom0)
 *
 * If it's a slice or partition, /cdrom/<name> becomes a directory:
 *
 *  /cdrom/<name>/s0
 *
 * Same for rmdisk and floppy.
 *
 * On labeled system (Trusted Solaris), links are in a user directory.
 */
static void
vold_update_mountpoints(struct action_arg *aap)
{
    boolean_t   is_partition;
    char        part_dir[2 * MAXNAMELEN];
    char        symname_mp[2 * MAXNAMELEN];
    char        symcontents_mp[MAXNAMELEN];
    char        symname[2 * MAXNAMELEN];
    char        symcontents[MAXNAMELEN];

    is_partition = (aap->aa_partname != NULL);

    if (!system_labeled) {
        if (!is_partition) {
            /* /cdrom/<name> -> original mountpoint */
            (void) snprintf(symcontents_mp, sizeof (symcontents_mp),
                "%s", aap->aa_mountpoint);
            (void) snprintf(symname_mp, sizeof (symname_mp),
                "/%s/%s", aap->aa_media, aap->aa_name);
        } else {
            /* /cdrom/<name>/slice -> original mountpoint */
            (void) snprintf(part_dir, sizeof (part_dir),
                "/%s/%s", aap->aa_media, aap->aa_name);
            (void) snprintf(symcontents_mp, sizeof (symcontents_mp),
                "%s", aap->aa_mountpoint);
            (void) snprintf(symname_mp, sizeof (symname_mp),
                "/%s/%s/%s", aap->aa_media, aap->aa_name,
                aap->aa_partname);

        }
        /* /cdrom/cdrom0 -> ./<name> */
        (void) snprintf(symcontents, sizeof (symcontents),
            "./%s", aap->aa_name);
        (void) snprintf(symname, sizeof (symname),
            "/%s/%s", aap->aa_media, aap->aa_symdev);
    } else {
        if (!is_partition) {
            /* /cdrom/<user>/<name> -> original mountpoint */
            (void) snprintf(symcontents_mp, sizeof (symcontents_mp),
                "%s", aap->aa_mountpoint);
            (void) snprintf(symname_mp, sizeof (symname_mp),
                "%s/%s/%s", mnt_zoneroot, aap->aa_media,
                aap->aa_symdev);
        } else {
            /* /cdrom/<user>/<name>/slice -> original mountpoint */
            (void) snprintf(symcontents_mp, sizeof (symcontents_mp),
                "%s", aap->aa_mountpoint);
            (void) snprintf(symname_mp, sizeof (symname_mp),
                "%s/%s/%s", mnt_zoneroot, aap->aa_media,
                aap->aa_symdev, aap->aa_partname);
        }

        /* /cdrom/<user>/cdrom0 -> ./<user>/<name> */
        (void) snprintf(symcontents, sizeof (symcontents),
            ".%s/%s", mnt_userdir, aap->aa_name);
        (void) snprintf(symname, sizeof (symname), "%s/%s/%s",
            mnt_zoneroot, aap->aa_media, aap->aa_symdev);
    }

    (void) unlink(symname);
    (void) unlink(symname_mp);
    if (is_partition) {
        (void) rmdir(part_dir);
    }

    if ((aap->aa_action == INSERT) || (aap->aa_action == REMOUNT)) {
        (void) mkdir(aap->aa_media, 0755);
        if (is_partition) {
            (void) mkdir(part_dir, 0755);
        }
        (void) symlink(symcontents_mp, symname_mp);
        (void) symlink(symcontents, symname);
    }
}


static int
vold_action(struct action_arg *aap)
{
    action_t    action;
    int     result;
    int     do_notify = FALSE;
    action_t    notify_act = EJECT;
    struct action_arg *aa[2];
    struct action_arg a1;

    dprintf("%s[%d]: entering action()\n", __FILE__, __LINE__);

    /*
     * on Trusted Extensions, actions are executed in the user's zone
     */
    if (mnt_zoneid > GLOBAL_ZONEID) {
        pid_t   pid;
        int status;
        int ifx;
        int tmpl_fd;
        int err = 0;

        tmpl_fd = open64(CTFS_ROOT "/process/template",
            O_RDWR);
        if (tmpl_fd == -1)
            return (1);

        /*
         * Deliver no events, don't inherit,
         * and allow it to be orphaned.
         */
        err |= ct_tmpl_set_critical(tmpl_fd, 0);
        err |= ct_tmpl_set_informative(tmpl_fd, 0);
        err |= ct_pr_tmpl_set_fatal(tmpl_fd,
            CT_PR_EV_HWERR);
        err |= ct_pr_tmpl_set_param(tmpl_fd,
            CT_PR_PGRPONLY |
            CT_PR_REGENT);
        if (err || ct_tmpl_activate(tmpl_fd)) {
            (void) close(tmpl_fd);
            return (1);
        }
        switch (pid = fork1()) {
        case 0:
            (void) ct_tmpl_clear(tmpl_fd);
            for (ifx = 0; ifx < _NFILE; ifx++)
                (void) close(ifx);

            if (zone_enter(mnt_zoneid) == -1)
                _exit(0);

            /* entered zone, proceed to action */
            break;
        case -1:
            dprintf("fork1 failed \n ");
            return (1);
        default :
            (void) ct_tmpl_clear(tmpl_fd);
            (void) close(tmpl_fd);
            if (waitpid(pid, &status, 0) < 0) {
                dprintf("%s(%ld): waitpid() "
                    "failed (errno %d) \n",
                    prog_name, prog_pid, errno);
                return (1);
            }
            }

    }

    /* only support one action at a time XXX */
    a1.aa_path = NULL;
    aa[0] = aap;
    aa[1] = &a1;

    action = aa[0]->aa_action;

    if (action == CLEAR_MOUNTS) {
        /*
         * Remove the notifications files, but don't
         * notify the client.  The "clear_mounts" action
         * simply clears all existing mounts of a medium's
         * partitions after a medium has been repartitioned.
         * Then vold builds a new file system that reflects
         * the medium's new partition structure and mounts
         * the new partitions by calling rmmount, and therefore
         * action(), with the VOLUME_ACTION environment variable
         * set to "remount".
         */
        result = remove_notify_files(aa);
        result = TRUE;
    } else if (action == EJECT) {
        result = remove_notify_files(aa);
        if (result == TRUE) {
            do_notify = TRUE;
            notify_act = EJECT;
        }
    } else if (action = INSERT) {
        result = create_notify_files(aa);
        if (result == TRUE) {
            do_notify = TRUE;
            notify_act = INSERT;
        }
    } else if (action == REMOUNT) {
        result = create_notify_files(aa);
        if (result == TRUE) {
            do_notify = TRUE;
            notify_act = REMOUNT;
        }
    } else if (action == UNMOUNT) {
        result = remove_notify_files(aa);
        if (result == TRUE) {
            do_notify = TRUE;
            notify_act = UNMOUNT;
        }
    } else {
        dprintf("%s[%d]: action(): invalid action: %s\n",
            __FILE__, __LINE__, action);
        result = FALSE;
    }

    if (result == TRUE) {
        result = notify_clients(notify_act, do_notify);
    }

    dprintf("%s[%d]: leaving action(), result = %s\n",
        __FILE__, __LINE__, result_strings[result]);

    if (mnt_zoneid > GLOBAL_ZONEID) {
        /* exit forked local zone process */
        _exit(0);
    }

    if (result == TRUE) {
        /*
         * File Manager is running. return 0.
         * see man page rmmount.conf(4).
         */
        return (0);
    } else {
        return (1);
    }
}


/*
 * Returns NULL if a medium or partition is mountable
 * and a string stating the reason the medium or partition
 * can't be mounted if the medium or partition isn't mountable.
 *
 * If the volume_name of the medium or partition is one of the
 * following, the medium or partition isn't mountable.
 *
 * unlabeled_<media_type>
 * unknown_format
 * password_protected
 */
/* ARGSUSED */
static char *
not_mountable(struct action_arg *aa)
{
    return (NULL);
}

static int
create_notify_files(struct action_arg **aa)
{
    int ai;
    char    *fstype;
    char    *mount_point;
    char    notify_file[64];
    char    *raw_partitionp;
    char    *reason; /* Why the medium wasn't mounted */
    int result;
    char    *symdev;

    dprintf("%s[%d]: entering create_notify_files()\n", __FILE__, __LINE__);

    ai = 0;
    result = FALSE;
    symdev = aa[ai]->aa_symdev;
    while ((aa[ai] != NULL) && (aa[ai]->aa_path != NULL)) {
        if (aa[ai]->aa_mountpoint != NULL) {
            if (aa[ai]->aa_type) {
                fstype = aa[ai]->aa_type;
            } else {
                fstype = "unknown";
            }
            mount_point = aa[ai]->aa_mountpoint;
            if (aa[ai]->aa_partname != NULL) {
                /*
                 * Is aa_partname ever NULL?
                 * When time permits, check.
                 * If it is, the action taken
                 * in the else clause could produce
                 * file name conflicts.
                 */
                sprintf(notify_file, "%s-%s", symdev,
                        aa[ai]->aa_partname);
            } else {
                sprintf(notify_file, "%s-0", symdev);
            }
            reason = NULL;
        } else {
            /*
             * The partition isn't mounted.
             */
            fstype = "none";
            mount_point = "none";
            reason = not_mountable(aa[ai]);
            if (reason != NULL) {
                sprintf(notify_file, "%s-0", symdev);
            } else {
                /*
                 * Either the partition is a backup slice, or
                 * rmmount tried to mount the partition, but
                 * idenf_fs couldn't identify the file system
                 * type; that can occur when rmmount is
                 * trying to mount all the slices in a Solaris
                 * VTOC, and one or more partitions don't have
                 * file systems in them.
                 */
                if (aa[0]->aa_partname != NULL) {
                    /*
                     * Is aa_partname ever NULL?
                     * When time permits, check.
                     * If it is, the action taken
                     * in the else clause could produce
                     * file name conflicts.
                     */
                    sprintf(notify_file, "%s-%s", symdev,
                            aa[0]->aa_partname);
                } else {
                    sprintf(notify_file, "%s-0", symdev);
                }
                if ((aa[0]->aa_type != NULL) &&
                    (strcmp(aa[0]->aa_type, "backup_slice")
                        == 0)) {
                    reason = "backup_slice";
                } else {
                    reason = "unformatted_media";
                }
                /*
                 * "unformatted_media" should be
                 * changed to "unformmated_medium" for
                 * grammatical correctness, but
                 * "unformatted_media" is now specified
                 * in the interface to filemgr, so the
                 * change can't be made without the
                 * approval of the CDE group.
                 */
            }
        }
        raw_partitionp = aa[0]->aa_rawpath;
        result = create_one_notify_file(fstype,
                mount_point,
                notify_file,
                raw_partitionp,
                reason,
                symdev);
        ai++;
    }
    dprintf("%s[%d]: leaving create_notify_files(), result = %s\n",
        __FILE__, __LINE__, result_strings[result]);
    return (result);
}

static int
create_one_notify_file(char *fstype,
    char *mount_point,
    char *notify_file,
    char *raw_partitionp,
    char *reason,
    char *symdev)
{
    /*
     * For a mounted partition, create a notification file
     * indicating the mount point,  the raw device pathname
     * of the partition, and the partition's file system
     * type.  For an unmounted partition, create a
     * notification file containing the reason that the
     * partition wasn't mounted and the raw device pathname
     * of the partition.
     *
     * Create the file as root in a world-writable
     * directory that resides in a world-writable directory.
     *
     * Handle two possible race conditions that could
     * allow security breaches.
     */

    int current_working_dir_fd;
    int file_descriptor;
    FILE    *filep;
    int result;

    dprintf("%s[%d]:Entering create_one_notify_file()\n",
        __FILE__, __LINE__);
    dprintf("\tcreate_one_notify_file(): fstype = %s\n", fstype);
    dprintf("\tcreate_one_notify_file(): mount_point = %s\n", mount_point);
    dprintf("\tcreate_one_notify_file(): notify_file = %s\n", notify_file);
    dprintf("\tcreate_one_notify_file(): raw_partitionp = %s\n",
        raw_partitionp);
    if (reason != NULL) {
        dprintf("\tcreate_one_notify_file(): reason = %s\n", reason);
    } else {
        dprintf("\tcreate_one_notify_file(): reason = NULL\n");
    }
    dprintf("\tcreate_one_notify_file(): symdev = %s\n", symdev);

    result = TRUE;
    /*
     * Handle Race Condition One:
     *
     *   If NOTIFY_DIR exists, make sure it is not a symlink.
     *   if it is, remove it and try to create it.  Check
     *   again to make sure NOTIFY_DIR isn't a symlink.
     *   If it is, remove it and return without creating
     *   a notification file.  The condition can only occur if
     *   someone is trying to break into the system by running
     *   a program that repeatedly creates NOTIFY_DIR as a
     *   symlink.  If NOTIFY_DIR exists and isn't a symlink,
     *   change the working directory to NOTIFY_DIR.
     */
    current_working_dir_fd = pushdir(NOTIFY_DIR);
    if (current_working_dir_fd < 0) {
        (void) makepath(NOTIFY_DIR, 0777);
        current_working_dir_fd = pushdir(NOTIFY_DIR);
        if (current_working_dir_fd < 0) {
            result = FALSE;
        }
    }
    /*
     * Handle Race Condition Two:
     *
     * Create the notification file in NOTIFY_DIR.
     * Remove any files with the same name that may already be
     * there, using remove(), as it safely removes directories.
     * Then open the file O_CREAT|O_EXCL, which doesn't follow
     * symlinks and requires that the file not exist already,
     * so the new file actually resides in the current working
     * directory.  Create the file with access mode 644, which
     * renders it unusable by anyone trying to break into the
     * system.
     */
    if (result == TRUE) {
        /*
         * The current working directory is now NOTIFY_DIR.
         */
        (void) remove(notify_file);
        file_descriptor =
            open(notify_file, O_CREAT|O_EXCL|O_WRONLY, 0644);
        if (file_descriptor < 0) {
            dprintf("%s[%d]: can't create %s/%s; %m\n",
                __FILE__, __LINE__, NOTIFY_DIR, notify_file);
            result = FALSE;
        } else {
            filep = fdopen(file_descriptor, "w");
            if (filep != NULL) {
                if (reason == NULL) {
                    (void) fprintf(filep, "%s %s %s",
                        mount_point,
                        raw_partitionp,
                        fstype);
                    (void) fclose(filep);
                dprintf("%s[%d]: Just wrote %s %s %s to %s\n",
                        __FILE__,
                        __LINE__,
                        mount_point,
                        raw_partitionp,
                        fstype,
                        notify_file);
                } else {
                    (void) fprintf(filep, "%s %s",
                        reason, raw_partitionp);
                    (void) fclose(filep);
                dprintf("%s[%d]: Just wrote %s %s to %s\n",
                        __FILE__,
                        __LINE__,
                        reason,
                        raw_partitionp,
                        notify_file);
                }
            } else {
                dprintf("%s[%d]: can't write %s/%s; %m\n",
                    __FILE__, __LINE__,
                    NOTIFY_DIR, notify_file);
                (void) close(file_descriptor);
                result = FALSE;
            }
        }
        popdir(current_working_dir_fd);
    }
    dprintf("%s[%d]: leaving create_one_notify_file, result = %s\n",
        __FILE__, __LINE__, result_strings[result]);
    return (result);
}

static boolean_t
notify_clients(action_t action, int do_notify)
{
    /*
     * Notify interested applications of changes in the state
     * of removable media.  Interested applications are those
     * that create a named pipe in NOTIFY_DIR with a name that
     * begins with "notify".  Open the pipe and write a
     * character through it that indicates the type of state
     * change = 'e' for ejections, 'i' for insertions, 'r'
     * for remounts of the file systems on repartitioned media,
     * and 'u' for unmounts of file systems.
     */

    int     current_working_dir_fd;
    DIR     *dirp;
    struct dirent   *dir_entryp;
    size_t      len;
    int     fd;
    char        namebuf[MAXPATHLEN];
    char        notify_character;
    void        (*old_signal_handler)();
    int     result;
    struct stat sb;

    dprintf("%s[%d]: entering notify_clients()\n", __FILE__, __LINE__);

    result = TRUE;
    /*
     * Use relative pathnames after changing the
     * working directory to the notification directory.
     * Check to make sure that each "notify" file is a
     * named pipe to make sure that it hasn't changed
     * its file type, which could mean that someone is
     * trying to use "notify" files to break into the
     * system.
     */
    if ((current_working_dir_fd = pushdir(NOTIFY_DIR)) < 0) {
        result = FALSE;
    }
    if (result == TRUE) {
        dirp = opendir(".");
        if (dirp == NULL) {
            dprintf("%s[%d]:opendir failed on '.'; %m\n",
                __FILE__, __LINE__);
            popdir(current_working_dir_fd);
            result = FALSE;
        }
    }
    if (result == TRUE) {
        /*
         * Read through the directory and write a notify
         * character to all files whose names start with "notify".
         */
        result = FALSE;
        old_signal_handler = signal(SIGPIPE, SIG_IGN);
        len = strlen(NOTIFY_NAME);
        while (dir_entryp = readdir(dirp)) {
            if (strncmp(dir_entryp->d_name, NOTIFY_NAME, len)
                != 0) {
                continue;
            }
            result = TRUE;
            if (do_notify != TRUE) {
                continue;
            }
            (void) sprintf(namebuf, "%s/%s",
                NOTIFY_DIR, dir_entryp->d_name);
            if ((fd = open(namebuf, O_WRONLY|O_NDELAY)) < 0) {
                dprintf("%s[%d]: open failed for %s; %m\n",
                    __FILE__, __LINE__, namebuf);
                continue;
            }
            /*
             * Check to be sure that the entry is a named pipe.
             * That closes a small security hole that could
             * enable unauthorized access to the system root.
             */
            if ((fstat(fd, &sb) < 0) || (!S_ISFIFO(sb.st_mode))) {
                dprintf("%s[%d]: %s isn't a named pipe\n",
                    __FILE__, __LINE__, namebuf);

                (void) close(fd);
                continue;
            }
            notify_character = notify_characters[action];
            if (write(fd, &notify_character, 1) < 0) {
                dprintf("%s[%d]: write failed for %s; %m\n",
                    __FILE__, __LINE__, namebuf);
                (void) close(fd);
                continue;
            }
            (void) close(fd);
        }
        (void) closedir(dirp);
        (void) signal(SIGPIPE, old_signal_handler);
        popdir(current_working_dir_fd);
    }
    dprintf("%s[%d]: leaving notify_clients(), result = %s\n",
        __FILE__, __LINE__, result_strings[result]);
    return (result);
}

static void
popdir(int fd)
{
    /*
     * Change the current working directory to the directory
     * specified by fd and close the fd.  Exit the program
     * on failure.
     */
    if (fchdir(fd) < 0) {
        dprintf("%s[%d]: popdir() failed\n", __FILE__, __LINE__);
        exit(1);
    }
    (void) close(fd);
}

static int
pushdir(const char *dir)
{
    /*
     * Change the current working directory to dir and
     * return a file descriptor for the old working
     * directory.
     *
     * Exception handling:
     *
     * If dir doesn't exist, leave the current working
     * directory the same and return -1.
     *
     * If dir isn't a directory, remove it, leave the
     * current working directory the same, and return -1.
     *
     * If open() fails on the current working directory
     * or the chdir operation fails on dir, leave the
     * current working directory the same and return -1.
     */

    int     current_working_dir_fd;
    struct stat stat_buf;

    if (lstat(dir, &stat_buf) < 0) {
        dprintf("%s[%d]: push_dir_and_check(): %s does not exist\n",
            __FILE__, __LINE__, dir);
        return (-1);
    }

    if (!(S_ISDIR(stat_buf.st_mode))) {
        dprintf("%s[%d]: push_dir_and_check(): %s not a directory.\n",
            __FILE__, __LINE__, dir);
        (void) remove(dir);
        return (-1);
    }
    if ((current_working_dir_fd = open(".", O_RDONLY)) < 0) {
        dprintf("%s[%d]: push_dir_and_check(): can't open %s.\n",
            __FILE__, __LINE__, dir);
        return (-1);
    }
    if (chdir(dir) < 0) {
        (void) close(current_working_dir_fd);
        dprintf("%s[%d]: push_dir_and_check(): can't chdir() to %s.\n",
            __FILE__, __LINE__, dir);
        return (-1);
    }
    return (current_working_dir_fd);
}

static boolean_t
remove_notify_files(struct action_arg **aa)
{
    int ai;
    int current_working_dir_fd;
    char    notify_file[64];
    int result;
    char    *symdev;

    dprintf("%s[%d]: entering remove_notify_files()\n", __FILE__, __LINE__);

    ai = 0;
    result = TRUE;
    symdev = aa[ai]->aa_symdev;
    while ((result == TRUE) &&
        (aa[ai] != NULL) &&
        (aa[ai]->aa_path != NULL)) {

        if (not_mountable(aa[ai])) {
            sprintf(notify_file, "%s-0", symdev);
        } else if (aa[ai]->aa_partname != NULL) {
            /*
             * Is aa_partname ever NULL?
             * When time permits, check.
             * If it is, the action taken
             * in the else clause could produce
             * file name conflicts.
             */
            sprintf(notify_file, "%s-%s",
                symdev, aa[0]->aa_partname);
        } else {
            sprintf(notify_file, "%s-0", symdev);
        }

        current_working_dir_fd = pushdir(NOTIFY_DIR);
        if (current_working_dir_fd < 0) {
            result = FALSE;
        }
        if ((result == TRUE) && (remove(notify_file) < 0)) {
            dprintf("%s[%d]: remove %s/%s; %m\n",
                __FILE__, __LINE__, NOTIFY_DIR, notify_file);
            result = FALSE;
        }
        if (current_working_dir_fd != -1) {
            popdir(current_working_dir_fd);
        }
        ai++;
    }
    dprintf("%s[%d]: leaving remove_notify_files(), result = %s\n",
        __FILE__, __LINE__, result_strings[result]);

    return (result);
}