ff567f7943
appended to an executable that's being run (yes, I'm doing this) you get EPERM, but mounting readonly fixes it. Doing the fallback all the time shouldn't hurt, and is one less test.
141 lines
4.2 KiB
C
141 lines
4.2 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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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extern int del_loop(const char *device)
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{
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int fd,rc=0;
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if ((fd = open(device, O_RDONLY)) < 0) rc=1;
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else {
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if (ioctl(fd, LOOP_CLR_FD, 0) < 0) rc=1;
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close(fd);
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}
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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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extern int set_loop(char **device, const char *file, int offset)
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{
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char dev[20];
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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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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(*device ? : dev, &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(dev, mode))<0 && errno==EROFS)
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dfd=open(dev,mode=O_RDONLY);
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if(dfd<0) continue;
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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(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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} else if(strcmp(file,loopinfo.lo_file_name)
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|| offset!=loopinfo.lo_offset) rc=1;
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close(dfd);
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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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/* END CODE */
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/*
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Local Variables:
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c-file-style: "linux"
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c-basic-offset: 4
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tab-width: 4
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End:
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*/
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