source: MondoRescue/trunk/mindi-busybox/e2fsprogs/ext2fs/finddev.c@ 904

/*
 * finddev.c -- this routine attempts to find a particular device in
 *  /dev
 *
 * Copyright (C) 2000 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>
#include <string.h>
#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#if HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <dirent.h>
#if HAVE_ERRNO_H
#include <errno.h>
#endif
#if HAVE_SYS_MKDEV_H
#include <sys/mkdev.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"

struct dir_list {
    char    *name;
    struct dir_list *next;
};

/*
 * This function adds an entry to the directory list
 */
static void add_to_dirlist(const char *name, struct dir_list **list)
{
    struct dir_list *dp;

    dp = xmalloc(sizeof(struct dir_list));
    dp->name = xmalloc(strlen(name)+1);
    strcpy(dp->name, name);
    dp->next = *list;
    *list = dp;
}

/*
 * This function frees a directory list
 */
static void free_dirlist(struct dir_list **list)
{
    struct dir_list *dp, *next;

    for (dp = *list; dp; dp = next) {
        next = dp->next;
        free(dp->name);
        free(dp);
    }
    *list = 0;
}

static int scan_dir(char *dir_name, dev_t device, struct dir_list **list,
            char **ret_path)
{
    DIR *dir;
    struct dirent *dp;
    char    path[1024], *cp;
    int dirlen;
    struct stat st;

    dirlen = strlen(dir_name);
    if ((dir = opendir(dir_name)) == NULL)
        return errno;
    dp = readdir(dir);
    while (dp) {
        if (dirlen + strlen(dp->d_name) + 2 >= sizeof(path))
            goto skip_to_next;
        if (dp->d_name[0] == '.' &&
            ((dp->d_name[1] == 0) ||
             ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))
            goto skip_to_next;
        sprintf(path, "%s/%s", dir_name, dp->d_name);
        if (stat(path, &st) < 0)
            goto skip_to_next;
        if (S_ISDIR(st.st_mode))
            add_to_dirlist(path, list);
        if (S_ISBLK(st.st_mode) && st.st_rdev == device) {
            cp = xmalloc(strlen(path)+1);
            strcpy(cp, path);
            *ret_path = cp;
            goto success;
        }
    skip_to_next:
        dp = readdir(dir);
    }
success:
    closedir(dir);
    return 0;
}

/*
 * This function finds the pathname to a block device with a given
 * device number.  It returns a pointer to allocated memory to the
 * pathname on success, and NULL on failure.
 */
char *ext2fs_find_block_device(dev_t device)
{
    struct dir_list *list = 0, *new_list = 0;
    struct dir_list *current;
    char    *ret_path = 0;

    /*
     * Add the starting directories to search...
     */
    add_to_dirlist("/devices", &list);
    add_to_dirlist("/devfs", &list);
    add_to_dirlist("/dev", &list);

    while (list) {
        current = list;
        list = list->next;
#ifdef DEBUG
        printf("Scanning directory %s\n", current->name);
#endif
        scan_dir(current->name, device, &new_list, &ret_path);
        free(current->name);
        free(current);
        if (ret_path)
            break;
        /*
         * If we're done checking at this level, descend to
         * the next level of subdirectories. (breadth-first)
         */
        if (list == 0) {
            list = new_list;
            new_list = 0;
        }
    }
    free_dirlist(&list);
    free_dirlist(&new_list);
    return ret_path;
}


#ifdef DEBUG
int main(int argc, char** argv)
{
    char    *devname, *tmp;
    int major, minor;
    dev_t   device;
    const char *errmsg = "Couldn't parse %s: %s\n";

    if ((argc != 2) && (argc != 3)) {
        fprintf(stderr, "Usage: %s device_number\n", argv[0]);
        fprintf(stderr, "\t: %s major minor\n", argv[0]);
        exit(1);
    }
    if (argc == 2) {
        device = strtoul(argv[1], &tmp, 0);
        if (*tmp) {
            fprintf(stderr, errmsg, "device number", argv[1]);
            exit(1);
        }
    } else {
        major = strtoul(argv[1], &tmp, 0);
        if (*tmp) {
            fprintf(stderr, errmsg, "major number", argv[1]);
            exit(1);
        }
        minor = strtoul(argv[2], &tmp, 0);
        if (*tmp) {
            fprintf(stderr, errmsg, "minor number", argv[2]);
            exit(1);
        }
        device = makedev(major, minor);
        printf("Looking for device 0x%04x (%d:%d)\n", device,
               major, minor);
    }
    devname = ext2fs_find_block_device(device);
    if (devname) {
        printf("Found device!  %s\n", devname);
        free(devname);
    } else {
        printf("Couldn't find device.\n");
    }
    return 0;
}

#endif