/* vi: set sw=4 ts=4: */
/*
 * 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>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <stdlib.h>
#include <string.h>
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <dirent.h>
#ifdef HAVE_ERRNO_H
#include <errno.h>
#endif
#ifdef 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 = NULL, *new_list = NULL;
        struct dir_list *current;
        char    *ret_path = NULL;

        /*
         * 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 = "Cannot 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("Cannot find device.\n");
        }
        return 0;
}

#endif