lib/libdevinfo/devinfo_finddev.c

/*
 * 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.
 */

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

#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);
}