/*
 * 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 2008 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <thread.h>
#include <synch.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <dirent.h>
#include <regex.h>
#include <errno.h>
#include <stdarg.h>
#include <libdevinfo.h>
#include <zone.h>
#include <sys/modctl.h>
#include <syslog.h>
#include <sys/stat.h>
#include <assert.h>


struct finddevhdl {
        int     npaths;
        int     curpath;
        char    **paths;
};


#define GLOBAL_DEV_PATH(devpath)                        \
        ((getzoneid() == GLOBAL_ZONEID) &&              \
            ((strcmp(devpath, "/dev") == 0) ||          \
            (strncmp(devpath, "/dev/", strlen("/dev/")) == 0)))

/*
 * Return true if a device exists
 * If the path refers into the /dev filesystem, use a
 * private interface to query if the device exists but
 * without triggering an implicit reconfig if it does not.
 * Note: can only function properly with absolute pathnames
 * and only functions for persisted global /dev names, ie
 * those managed by devfsadm.  For paths other than
 * /dev, stat(2) is sufficient.
 */
int
device_exists(const char *devname)
{
        int     rv;
        struct stat st;

        if (GLOBAL_DEV_PATH(devname)) {
                rv = modctl(MODDEVEXISTS, devname, strlen(devname));
                return ((rv == 0) ? 1 : 0);
        }
        if (stat(devname, &st) == 0)
                return (1);
        return (0);
}


/*
 * Use the standard library readdir to read the contents of
 * directories on alternate root mounted filesystems.
 * Return results as per dev_readdir_devfs().
 *
 * The directory is traversed twice.  First, to calculate
 * the size of the buffer required; second, to copy the
 * directory contents into the buffer.  If the directory
 * contents grow in between passes, which should almost
 * never happen, start over again.
 */
static int
finddev_readdir_alt(const char *path, finddevhdl_t *handlep)
{
        struct finddevhdl *handle;
        DIR *dir;
        struct dirent *dp;
        size_t n;

        *handlep = NULL;
        if ((dir = opendir(path)) == NULL)
                return (ENOENT);

restart:
        handle = calloc(1, sizeof (struct finddevhdl));
        if (handle == NULL) {
                (void) closedir(dir);
                return (ENOMEM);
        }

        handle->npaths = 0;
        handle->curpath = 0;
        handle->paths = NULL;

        n = 0;
        rewinddir(dir);
        while ((dp = readdir(dir)) != NULL) {
                if ((strcmp(dp->d_name, ".") == 0) ||
                    (strcmp(dp->d_name, "..") == 0))
                        continue;
                n++;
        }

        handle->npaths = n;
        handle->paths = calloc(n, sizeof (char *));
        if (handle->paths == NULL) {
                free(handle);
                (void) closedir(dir);
                return (ENOMEM);
        }

        n = 0;
        rewinddir(dir);
        while ((dp = readdir(dir)) != NULL) {
                if ((strcmp(dp->d_name, ".") == 0) ||
                    (strcmp(dp->d_name, "..") == 0))
                        continue;
                if (n == handle->npaths) {
                        /*
                         * restart if directory contents have out-grown
                         * buffer allocated in the first pass.
                         */
                        finddev_close((finddevhdl_t)handle);
                        goto restart;
                }
                handle->paths[n] = strdup(dp->d_name);
                if (handle->paths[n] == NULL) {
                        (void) closedir(dir);
                        finddev_close((finddevhdl_t)handle);
                        return (ENOMEM);
                }
                n++;
        }
        (void) closedir(dir);
        *handlep = (finddevhdl_t)handle;
        return (0);
}

/*
 * Use of the dev filesystem's private readdir does not trigger
 * the implicit device reconfiguration.
 *
 * Note: only useable with paths mounted on an instance of the
 * dev filesystem.
 *
 * Does not return the . and .. entries.
 * Empty directories are returned as an zero-length list.
 * ENOENT is returned as a NULL list pointer.
 */
static int
finddev_readdir_devfs(const char *path, finddevhdl_t *handlep)
{
        struct finddevhdl       *handle;
        int                     n;
        int                     rv;
        int64_t                 bufsiz;
        char                    *pathlist;
        char                    *p;
        int                     len;

        *handlep = NULL;
        handle = calloc(1, sizeof (struct finddevhdl));
        if (handle == NULL)
                return (ENOMEM);

        handle->npaths = 0;
        handle->curpath = 0;
        handle->paths = NULL;

        rv = modctl(MODDEVREADDIR, path, strlen(path), NULL, &bufsiz);
        if (rv != 0) {
                free(handle);
                return (rv);
        }

        for (;;) {
                assert(bufsiz != 0);
                if ((pathlist = malloc(bufsiz)) == NULL) {
                        free(handle);
                        return (ENOMEM);
                }

                rv = modctl(MODDEVREADDIR, path, strlen(path),
                    pathlist, &bufsiz);
                if (rv == 0) {
                        for (n = 0, p = pathlist;
                            (len = strlen(p)) > 0; p += len+1) {
                                n++;
                        }
                        handle->npaths = n;
                        handle->paths = calloc(n, sizeof (char *));
                        if (handle->paths == NULL) {
                                free(handle);
                                free(pathlist);
                                return (ENOMEM);
                        }
                        for (n = 0, p = pathlist;
                            (len = strlen(p)) > 0; p += len+1, n++) {
                                handle->paths[n] = strdup(p);
                                if (handle->paths[n] == NULL) {
                                        finddev_close((finddevhdl_t)handle);
                                        free(pathlist);
                                        return (ENOMEM);
                                }
                        }
                        *handlep = (finddevhdl_t)handle;
                        free(pathlist);
                        return (0);
                }
                free(pathlist);
                switch (errno) {
                case EAGAIN:
                        break;
                case ENOENT:
                default:
                        free(handle);
                        return (errno);
                }
        }
        /*NOTREACHED*/
}

int
finddev_readdir(const char *path, finddevhdl_t *handlep)
{
        if (GLOBAL_DEV_PATH(path)) {
                return (finddev_readdir_devfs(path, handlep));
        }
        return (finddev_readdir_alt(path, handlep));
}

/*
 * Return true if a directory is empty
 * Use the standard library readdir to determine if a directory is
 * empty.
 */
static int
finddev_emptydir_alt(const char *path)
{
        DIR             *dir;
        struct dirent   *dp;

        if ((dir = opendir(path)) == NULL)
                return (ENOENT);

        while ((dp = readdir(dir)) != NULL) {
                if ((strcmp(dp->d_name, ".") == 0) ||
                    (strcmp(dp->d_name, "..") == 0))
                        continue;
                (void) closedir(dir);
                return (0);             /* not empty */
        }
        (void) closedir(dir);
        return (1);                     /* empty */
}

/*
 * Use of the dev filesystem's private readdir does (not trigger
 * the implicit device reconfiguration) to determine if a directory
 * is empty.
 *
 * Note: only useable with paths mounted on an instance of the
 * dev filesystem.
 *
 * Does not return the . and .. entries.
 * Empty directories are returned as an zero-length list.
 * ENOENT is returned as a NULL list pointer.
 */
static int
finddev_emptydir_devfs(const char *path)
{
        int     rv;
        int     empty;

        rv = modctl(MODDEVEMPTYDIR, path, strlen(path), &empty);
        if (rv == 0) {
                return (empty);
        }
        return (0);
}

int
finddev_emptydir(const char *path)
{
        if (GLOBAL_DEV_PATH(path)) {
                return (finddev_emptydir_devfs(path));
        }
        return (finddev_emptydir_alt(path));
}

void
finddev_close(finddevhdl_t arg)
{
        struct finddevhdl *handle = (struct finddevhdl *)arg;
        int i;

        for (i = 0; i < handle->npaths; i++) {
                if (handle->paths[i])
                        free(handle->paths[i]);
        }
        free(handle->paths);
        free(handle);
}

const char *
finddev_next(finddevhdl_t arg)
{
        struct finddevhdl *handle = (struct finddevhdl *)arg;
        const char *path = NULL;

        if (handle->curpath < handle->npaths) {
                path = handle->paths[handle->curpath];
                handle->curpath++;
        }
        return (path);
}