| 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * Utility routines.
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| 4 | *
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| 5 | * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
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| 6 | *
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| 7 | * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
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| 8 | */
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| 9 |
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| 10 |
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| 11 | #include <features.h>
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| 12 | #include <stdio.h>
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| 13 | #include <errno.h>
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| 14 | #include <fcntl.h>
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| 15 | #include <string.h>
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| 16 | #include <unistd.h>
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| 17 | #include <sys/ioctl.h>
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| 18 | #include "libbb.h"
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| 19 |
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| 20 | /* For 2.6, use the cleaned up header to get the 64 bit API. */
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| 21 | #include <linux/version.h>
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| 22 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
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| 23 | #include <linux/loop.h>
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| 24 | typedef struct loop_info64 bb_loop_info;
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| 25 | #define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
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| 26 | #define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
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| 27 |
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| 28 | /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
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| 29 | #else
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| 30 | /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/
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| 31 | #include <linux/posix_types.h>
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| 32 | #define LO_NAME_SIZE 64
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| 33 | #define LO_KEY_SIZE 32
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| 34 | #define LOOP_SET_FD 0x4C00
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| 35 | #define LOOP_CLR_FD 0x4C01
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| 36 | #define BB_LOOP_SET_STATUS 0x4C02
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| 37 | #define BB_LOOP_GET_STATUS 0x4C03
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| 38 | typedef struct {
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| 39 | int lo_number;
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| 40 | __kernel_dev_t lo_device;
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| 41 | unsigned long lo_inode;
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| 42 | __kernel_dev_t lo_rdevice;
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| 43 | int lo_offset;
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| 44 | int lo_encrypt_type;
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| 45 | int lo_encrypt_key_size;
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| 46 | int lo_flags;
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| 47 | char lo_file_name[LO_NAME_SIZE];
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| 48 | unsigned char lo_encrypt_key[LO_KEY_SIZE];
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| 49 | unsigned long lo_init[2];
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| 50 | char reserved[4];
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| 51 | } bb_loop_info;
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| 52 | #endif
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| 53 |
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| 54 | char *query_loop(const char *device)
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| 55 | {
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| 56 | int fd;
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| 57 | bb_loop_info loopinfo;
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| 58 | char *dev=0;
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| 59 |
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| 60 | if ((fd = open(device, O_RDONLY)) < 0) return 0;
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| 61 | if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
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| 62 | dev=bb_xasprintf("%ld %s", (long) loopinfo.lo_offset,
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| 63 | (char *)loopinfo.lo_file_name);
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| 64 | close(fd);
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| 65 |
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| 66 | return dev;
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| 67 | }
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| 68 |
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| 69 |
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| 70 | int del_loop(const char *device)
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| 71 | {
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| 72 | int fd, rc;
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| 73 |
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| 74 | if ((fd = open(device, O_RDONLY)) < 0) return 1;
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| 75 | rc=ioctl(fd, LOOP_CLR_FD, 0);
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| 76 | close(fd);
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| 77 |
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| 78 | return rc;
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| 79 | }
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| 80 |
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| 81 | /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
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| 82 | *device is loop device to use, or if *device==NULL finds a loop device to
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| 83 | mount it on and sets *device to a strdup of that loop device name. This
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| 84 | search will re-use an existing loop device already bound to that
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| 85 | file/offset if it finds one.
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| 86 | */
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| 87 | int set_loop(char **device, const char *file, int offset)
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| 88 | {
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| 89 | char dev[20], *try;
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| 90 | bb_loop_info loopinfo;
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| 91 | struct stat statbuf;
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| 92 | int i, dfd, ffd, mode, rc=-1;
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| 93 |
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| 94 | /* Open the file. Barf if this doesn't work. */
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| 95 | if((ffd = open(file, mode=O_RDWR))<0 && (ffd = open(file,mode=O_RDONLY))<0)
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| 96 | return -errno;
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| 97 |
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| 98 | /* Find a loop device. */
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| 99 | try=*device ? : dev;
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| 100 | for(i=0;rc;i++) {
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| 101 | sprintf(dev, LOOP_FORMAT, i);
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| 102 |
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| 103 | /* Ran out of block devices, return failure. */
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| 104 | if(stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
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| 105 | rc=-ENOENT;
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| 106 | break;
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| 107 | }
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| 108 | /* Open the sucker and check its loopiness. */
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| 109 | if((dfd=open(try, mode))<0 && errno==EROFS)
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| 110 | dfd=open(try, mode = O_RDONLY);
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| 111 | if(dfd<0) goto try_again;
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| 112 |
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| 113 | rc=ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
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| 114 |
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| 115 | /* If device free, claim it. */
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| 116 | if(rc && errno==ENXIO) {
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| 117 | memset(&loopinfo, 0, sizeof(loopinfo));
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| 118 | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
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| 119 | loopinfo.lo_offset = offset;
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| 120 | /* Associate free loop device with file. */
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| 121 | if(!ioctl(dfd, LOOP_SET_FD, ffd)) {
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| 122 | if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) rc=0;
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| 123 | else ioctl(dfd, LOOP_CLR_FD, 0);
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| 124 | }
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| 125 |
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| 126 | /* If this block device already set up right, re-use it.
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| 127 | (Yes this is racy, but associating two loop devices with the same
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| 128 | file isn't pretty either. In general, mounting the same file twice
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| 129 | without using losetup manually is problematic.)
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| 130 | */
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| 131 | } else if(strcmp(file,(char *)loopinfo.lo_file_name)
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| 132 | || offset!=loopinfo.lo_offset) rc=-1;
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| 133 | close(dfd);
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| 134 | try_again:
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| 135 | if(*device) break;
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| 136 | }
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| 137 | close(ffd);
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| 138 | if(!rc) {
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| 139 | if(!*device) *device=strdup(dev);
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| 140 | return mode==O_RDONLY ? 1 : 0;
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| 141 | } else return rc;
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| 142 | }
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