busybox/libbb/find_root_device.c

/* vi: set sw=4 ts=4: */
/*
 * Utility routines.
 *
 * Copyright (C) tons of folks.  Tracking down who wrote what
 * isn't something I'm going to worry about...  If you wrote something
 * here, please feel free to acknowledge your work.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * Based in part on code from sash, Copyright (c) 1999 by David I. Bell 
 * Permission has been granted to redistribute this code under the GPL.
 *
 */

#include <stdio.h>
#include <string.h>
#include <dirent.h>
#include <stdlib.h>
#include "libbb.h"



extern char *find_real_root_device_name(const char* name)
{
	DIR *dir;
	struct dirent *entry;
	struct stat statBuf, rootStat;
	char *fileName;
	dev_t dev;

	if (stat("/", &rootStat) != 0) {
		perror_msg("could not stat '/'");
		return NULL;
	}
	if ((dev = rootStat.st_rdev)==0) dev=rootStat.st_dev;

	dir = opendir("/dev");
	if (!dir) {
		perror_msg("could not open '/dev'");
		goto fallback;
	}

	while((entry = readdir(dir)) != NULL) {

		/* Must skip ".." since that is "/", and so we 
		 * would get a false positive on ".."  */
		if (strcmp(entry->d_name, "..") == 0)
			continue;

		fileName = concat_path_file("/dev/", entry->d_name);

		/* Some char devices have the same dev_t as block
		 * devices, so make sure this is a block device */
		if (stat(fileName, &statBuf) == 0 && 
				S_ISBLK(statBuf.st_mode)!=0 &&
				statBuf.st_rdev == dev) {
			return fileName; 
		}
		free(fileName);
	}
	closedir(dir);

fallback:
	/* don't use stack space, caller expects to free() result */
	fileName=xmalloc(20);
	sprintf(fileName,"(rdev %u)",(unsigned int) rootStat.st_rdev);
	return fileName;
}


/* END CODE */
/*
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*/