934da82913
device at the same time. We should only CLR_FD if the set status fails, not if the SET_FD fails.
143 lines
3.9 KiB
C
143 lines
3.9 KiB
C
/* vi: set sw=4 ts=4: */
|
|
/*
|
|
* Utility routines.
|
|
*
|
|
* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
|
|
*
|
|
* Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
|
|
*/
|
|
|
|
|
|
#include <features.h>
|
|
#include <stdio.h>
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <string.h>
|
|
#include <unistd.h>
|
|
#include <sys/ioctl.h>
|
|
#include "libbb.h"
|
|
|
|
/* For 2.6, use the cleaned up header to get the 64 bit API. */
|
|
#include <linux/version.h>
|
|
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
|
|
#include <linux/loop.h>
|
|
typedef struct loop_info64 bb_loop_info;
|
|
#define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
|
|
#define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
|
|
|
|
/* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
|
|
#else
|
|
/* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/
|
|
#include <linux/posix_types.h>
|
|
#define LO_NAME_SIZE 64
|
|
#define LO_KEY_SIZE 32
|
|
#define LOOP_SET_FD 0x4C00
|
|
#define LOOP_CLR_FD 0x4C01
|
|
#define BB_LOOP_SET_STATUS 0x4C02
|
|
#define BB_LOOP_GET_STATUS 0x4C03
|
|
typedef struct {
|
|
int lo_number;
|
|
__kernel_dev_t lo_device;
|
|
unsigned long lo_inode;
|
|
__kernel_dev_t lo_rdevice;
|
|
int lo_offset;
|
|
int lo_encrypt_type;
|
|
int lo_encrypt_key_size;
|
|
int lo_flags;
|
|
char lo_file_name[LO_NAME_SIZE];
|
|
unsigned char lo_encrypt_key[LO_KEY_SIZE];
|
|
unsigned long lo_init[2];
|
|
char reserved[4];
|
|
} bb_loop_info;
|
|
#endif
|
|
|
|
char *query_loop(const char *device)
|
|
{
|
|
int fd;
|
|
bb_loop_info loopinfo;
|
|
char *dev=0;
|
|
|
|
if ((fd = open(device, O_RDONLY)) < 0) return 0;
|
|
if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
|
|
dev=bb_xasprintf("%ld %s", (long) loopinfo.lo_offset,
|
|
(char *)loopinfo.lo_file_name);
|
|
close(fd);
|
|
|
|
return dev;
|
|
}
|
|
|
|
|
|
int del_loop(const char *device)
|
|
{
|
|
int fd, rc;
|
|
|
|
if ((fd = open(device, O_RDONLY)) < 0) return 1;
|
|
rc=ioctl(fd, LOOP_CLR_FD, 0);
|
|
close(fd);
|
|
|
|
return rc;
|
|
}
|
|
|
|
/* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
|
|
*device is loop device to use, or if *device==NULL finds a loop device to
|
|
mount it on and sets *device to a strdup of that loop device name. This
|
|
search will re-use an existing loop device already bound to that
|
|
file/offset if it finds one.
|
|
*/
|
|
int set_loop(char **device, const char *file, int offset)
|
|
{
|
|
char dev[20], *try;
|
|
bb_loop_info loopinfo;
|
|
struct stat statbuf;
|
|
int i, dfd, ffd, mode, rc=-1;
|
|
|
|
/* Open the file. Barf if this doesn't work. */
|
|
if((ffd = open(file, mode=O_RDWR))<0 && (ffd = open(file,mode=O_RDONLY))<0)
|
|
return -errno;
|
|
|
|
/* Find a loop device. */
|
|
try=*device ? : dev;
|
|
for(i=0;rc;i++) {
|
|
sprintf(dev, LOOP_FORMAT, i);
|
|
|
|
/* Ran out of block devices, return failure. */
|
|
if(stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
|
|
rc=-ENOENT;
|
|
break;
|
|
}
|
|
/* Open the sucker and check its loopiness. */
|
|
if((dfd=open(try, mode))<0 && errno==EROFS)
|
|
dfd=open(try, mode = O_RDONLY);
|
|
if(dfd<0) goto try_again;
|
|
|
|
rc=ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
|
|
|
|
/* If device free, claim it. */
|
|
if(rc && errno==ENXIO) {
|
|
memset(&loopinfo, 0, sizeof(loopinfo));
|
|
safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
|
|
loopinfo.lo_offset = offset;
|
|
/* Associate free loop device with file. */
|
|
if(!ioctl(dfd, LOOP_SET_FD, ffd)) {
|
|
if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) rc=0;
|
|
else ioctl(dfd, LOOP_CLR_FD, 0);
|
|
}
|
|
|
|
/* If this block device already set up right, re-use it.
|
|
(Yes this is racy, but associating two loop devices with the same
|
|
file isn't pretty either. In general, mounting the same file twice
|
|
without using losetup manually is problematic.)
|
|
*/
|
|
} else if(strcmp(file,(char *)loopinfo.lo_file_name)
|
|
|| offset!=loopinfo.lo_offset) rc=-1;
|
|
close(dfd);
|
|
try_again:
|
|
if(*device) break;
|
|
}
|
|
close(ffd);
|
|
if(!rc) {
|
|
if(!*device) *device=strdup(dev);
|
|
return mode==O_RDONLY ? 1 : 0;
|
|
} else return rc;
|
|
}
|