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