[821] | 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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[1765] | 6 | * Copyright (C) 2005 by Rob Landley <rob@landley.net>
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[821] | 7 | *
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[2725] | 8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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[821] | 9 | */
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| 10 | #include "libbb.h"
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[2725] | 11 | #include <linux/version.h>
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[821] | 12 |
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[2725] | 13 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
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| 14 |
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[821] | 15 | /* For 2.6, use the cleaned up header to get the 64 bit API. */
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[2725] | 16 | // Commented out per Rob's request
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| 17 | //# include "fix_u32.h" /* some old toolchains need __u64 for linux/loop.h */
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| 18 | # include <linux/loop.h>
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[821] | 19 | typedef struct loop_info64 bb_loop_info;
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[2725] | 20 | # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
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| 21 | # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
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[821] | 22 |
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[2725] | 23 | #else
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| 24 |
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[821] | 25 | /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
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[2725] | 26 | /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
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| 27 | # include <linux/posix_types.h>
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| 28 | # define LO_NAME_SIZE 64
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| 29 | # define LO_KEY_SIZE 32
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| 30 | # define LOOP_SET_FD 0x4C00
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| 31 | # define LOOP_CLR_FD 0x4C01
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| 32 | # define BB_LOOP_SET_STATUS 0x4C02
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| 33 | # define BB_LOOP_GET_STATUS 0x4C03
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[821] | 34 | typedef struct {
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| 35 | int lo_number;
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| 36 | __kernel_dev_t lo_device;
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| 37 | unsigned long lo_inode;
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| 38 | __kernel_dev_t lo_rdevice;
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| 39 | int lo_offset;
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| 40 | int lo_encrypt_type;
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| 41 | int lo_encrypt_key_size;
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| 42 | int lo_flags;
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| 43 | char lo_file_name[LO_NAME_SIZE];
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| 44 | unsigned char lo_encrypt_key[LO_KEY_SIZE];
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| 45 | unsigned long lo_init[2];
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| 46 | char reserved[4];
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| 47 | } bb_loop_info;
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| 48 | #endif
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| 49 |
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[2725] | 50 | char* FAST_FUNC query_loop(const char *device)
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[821] | 51 | {
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| 52 | int fd;
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| 53 | bb_loop_info loopinfo;
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[2725] | 54 | char *dev = NULL;
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[821] | 55 |
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[1765] | 56 | fd = open(device, O_RDONLY);
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[2725] | 57 | if (fd >= 0) {
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| 58 | if (ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo) == 0) {
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| 59 | dev = xasprintf("%"OFF_FMT"u %s", (off_t) loopinfo.lo_offset,
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| 60 | (char *)loopinfo.lo_file_name);
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| 61 | }
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| 62 | close(fd);
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| 63 | }
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[821] | 64 |
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| 65 | return dev;
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| 66 | }
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| 67 |
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[2725] | 68 | int FAST_FUNC del_loop(const char *device)
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[821] | 69 | {
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| 70 | int fd, rc;
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| 71 |
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[1765] | 72 | fd = open(device, O_RDONLY);
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[2725] | 73 | if (fd < 0)
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| 74 | return 1;
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[1765] | 75 | rc = ioctl(fd, LOOP_CLR_FD, 0);
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[821] | 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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[2725] | 87 | int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset)
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[821] | 88 | {
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[1765] | 89 | char dev[LOOP_NAMESIZE];
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| 90 | char *try;
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[821] | 91 | bb_loop_info loopinfo;
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| 92 | struct stat statbuf;
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[1765] | 93 | int i, dfd, ffd, mode, rc = -1;
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| 94 |
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[821] | 95 | /* Open the file. Barf if this doesn't work. */
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[1765] | 96 | mode = O_RDWR;
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| 97 | ffd = open(file, mode);
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| 98 | if (ffd < 0) {
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| 99 | mode = O_RDONLY;
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| 100 | ffd = open(file, mode);
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| 101 | if (ffd < 0)
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| 102 | return -errno;
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| 103 | }
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[821] | 104 |
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| 105 | /* Find a loop device. */
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[2725] | 106 | try = *device ? *device : dev;
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| 107 | /* 1048575 is a max possible minor number in Linux circa 2010 */
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| 108 | for (i = 0; rc && i < 1048576; i++) {
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[821] | 109 | sprintf(dev, LOOP_FORMAT, i);
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| 110 |
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[2725] | 111 | IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
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| 112 | if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
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| 113 | if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
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| 114 | && errno == ENOENT
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| 115 | && try == dev
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| 116 | ) {
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| 117 | /* Node doesn't exist, try to create it. */
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| 118 | if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
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| 119 | goto try_to_open;
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| 120 | }
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| 121 | /* Ran out of block devices, return failure. */
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[1765] | 122 | rc = -ENOENT;
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[821] | 123 | break;
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| 124 | }
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[2725] | 125 | try_to_open:
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[821] | 126 | /* Open the sucker and check its loopiness. */
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[1765] | 127 | dfd = open(try, mode);
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| 128 | if (dfd < 0 && errno == EROFS) {
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| 129 | mode = O_RDONLY;
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| 130 | dfd = open(try, mode);
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| 131 | }
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| 132 | if (dfd < 0)
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| 133 | goto try_again;
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[821] | 134 |
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[1765] | 135 | rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
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[821] | 136 |
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[1765] | 137 | /* If device is free, claim it. */
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| 138 | if (rc && errno == ENXIO) {
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[821] | 139 | memset(&loopinfo, 0, sizeof(loopinfo));
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| 140 | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
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| 141 | loopinfo.lo_offset = offset;
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| 142 | /* Associate free loop device with file. */
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[2725] | 143 | if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
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| 144 | if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
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[1765] | 145 | rc = 0;
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| 146 | else
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| 147 | ioctl(dfd, LOOP_CLR_FD, 0);
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[821] | 148 | }
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| 149 |
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| 150 | /* If this block device already set up right, re-use it.
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| 151 | (Yes this is racy, but associating two loop devices with the same
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| 152 | file isn't pretty either. In general, mounting the same file twice
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| 153 | without using losetup manually is problematic.)
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| 154 | */
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[2725] | 155 | } else
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| 156 | if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
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| 157 | || offset != loopinfo.lo_offset
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| 158 | ) {
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[1765] | 159 | rc = -1;
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| 160 | }
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[821] | 161 | close(dfd);
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[1765] | 162 | try_again:
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| 163 | if (*device) break;
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[821] | 164 | }
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| 165 | close(ffd);
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[2725] | 166 | if (rc == 0) {
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[1765] | 167 | if (!*device)
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| 168 | *device = xstrdup(dev);
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| 169 | return (mode == O_RDONLY); /* 1:ro, 0:rw */
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| 170 | }
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| 171 | return rc;
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[821] | 172 | }
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