/* vi: set sw=4 ts=4: *//* * devno.c - find a particular device by its device number (major/minor) * * Copyright (C) 2000, 2001, 2003 Theodore Ts'o * Copyright (C) 2001 Andreas Dilger * * %Begin-Header% * This file may be redistributed under the terms of the * GNU Lesser General 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#include <sys/stat.h>#include <dirent.h>#ifdef HAVE_ERRNO_H#include <errno.h>#endif#ifdef HAVE_SYS_MKDEV_H#include <sys/mkdev.h>#endif#include "blkidP.h"struct dir_list {	char	*name;	struct dir_list *next;};char *blkid_strndup(const char *s, int length){	char *ret;	if (!s)		return NULL;	if (!length)		length = strlen(s);	ret = xmalloc(length + 1);	strncpy(ret, s, length);	ret[length] = '\0';	return ret;}char *blkid_strdup(const char *s){	return blkid_strndup(s, 0);}/* * 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 = blkid_strdup(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 = NULL;}static void scan_dir(char *dir_name, dev_t devno, struct dir_list **list,			    char **devname){	DIR	*dir;	struct dirent *dp;	char	path[1024];	int	dirlen;	struct stat st;	if ((dir = opendir(dir_name)) == NULL)		return;	dirlen = strlen(dir_name) + 2;	while ((dp = readdir(dir)) != 0) {		if (dirlen + strlen(dp->d_name) >= sizeof(path))			continue;		if (dp->d_name[0] == '.' &&		    ((dp->d_name[1] == 0) ||		     ((dp->d_name[1] == '.') && (dp->d_name[2] == 0))))			continue;		sprintf(path, "%s/%s", dir_name, dp->d_name);		if (stat(path, &st) < 0)			continue;		if (S_ISDIR(st.st_mode))			add_to_dirlist(path, list);		else if (S_ISBLK(st.st_mode) && st.st_rdev == devno) {			*devname = blkid_strdup(path);			DBG(DEBUG_DEVNO,			    printf("found 0x%llx at %s (%p)\n", devno,				   path, *devname));			break;		}	}	closedir(dir);}/* Directories where we will try to search for device numbers */const char *blkid_devdirs[] = { "/devices", "/devfs", "/dev", NULL };/* * 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 *blkid_devno_to_devname(dev_t devno){	struct dir_list *list = NULL, *new_list = NULL;	char *devname = NULL;	const char **dir;	/*	 * Add the starting directories to search in reverse order of	 * importance, since we are using a stack...	 */	for (dir = blkid_devdirs; *dir; dir++)		add_to_dirlist(*dir, &list);	while (list) {		struct dir_list *current = list;		list = list->next;		DBG(DEBUG_DEVNO, printf("directory %s\n", current->name));		scan_dir(current->name, devno, &new_list, &devname);		free(current->name);		free(current);		if (devname)			break;		/*		 * If we're done checking at this level, descend to		 * the next level of subdirectories. (breadth-first)		 */		if (list == NULL) {			list = new_list;			new_list = NULL;		}	}	free_dirlist(&list);	free_dirlist(&new_list);	if (!devname) {		DBG(DEBUG_DEVNO,		    printf("blkid: cannot find devno 0x%04lx\n",			   (unsigned long) devno));	} else {		DBG(DEBUG_DEVNO,		    printf("found devno 0x%04llx as %s\n", devno, devname));	}	return devname;}#ifdef TEST_PROGRAMint main(int argc, char** argv){	char	*devname, *tmp;	int	major, minor;	dev_t	devno;	const char *errmsg = "Cannot parse %s: %s\n";	blkid_debug_mask = DEBUG_ALL;	if ((argc != 2) && (argc != 3)) {		fprintf(stderr, "Usage:\t%s device_number\n\t%s major minor\n"			"Resolve a device number to a device name\n",			argv[0], argv[0]);		exit(1);	}	if (argc == 2) {		devno = 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);		}		devno = makedev(major, minor);	}	printf("Looking for device 0x%04Lx\n", devno);	devname = blkid_devno_to_devname(devno);	free(devname);	return 0;}#endif