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 | * Copyright (C) 2005 by Rob Landley <rob@landley.net>
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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9 | */
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10 | #include "libbb.h"
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11 | #include <linux/version.h>
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12 |
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13 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
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14 |
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15 | /* For 2.6, use the cleaned up header to get the 64 bit API. */
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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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19 | typedef struct loop_info64 bb_loop_info;
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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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22 |
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23 | #else
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24 |
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25 | /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
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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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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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50 | char* FAST_FUNC query_loop(const char *device)
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51 | {
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52 | int fd;
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53 | bb_loop_info loopinfo;
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54 | char *dev = NULL;
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55 |
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56 | fd = open(device, O_RDONLY);
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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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64 |
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65 | return dev;
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66 | }
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67 |
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68 | int FAST_FUNC del_loop(const char *device)
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69 | {
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70 | int fd, rc;
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71 |
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72 | fd = open(device, O_RDONLY);
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73 | if (fd < 0)
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74 | 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 FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, int ro)
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88 | {
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89 | char dev[LOOP_NAMESIZE];
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90 | char *try;
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91 | bb_loop_info loopinfo;
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92 | struct stat statbuf;
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93 | int i, dfd, ffd, mode, rc = -1;
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94 |
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95 | /* Open the file. Barf if this doesn't work. */
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96 | mode = ro ? O_RDONLY : O_RDWR;
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97 | open_ffd:
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98 | ffd = open(file, mode);
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99 | if (ffd < 0) {
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100 | if (mode != O_RDONLY) {
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101 | mode = O_RDONLY;
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102 | goto open_ffd;
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103 | }
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104 | return -errno;
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105 | }
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106 |
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107 | /* Find a loop device. */
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108 | try = *device ? *device : dev;
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109 | /* 1048575 (0xfffff) is a max possible minor number in Linux circa 2010 */
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110 | for (i = 0; rc && i < 1048576; i++) {
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111 | sprintf(dev, LOOP_FORMAT, i);
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112 |
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113 | IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
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114 | if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
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115 | if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
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116 | && errno == ENOENT
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117 | && try == dev
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118 | ) {
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119 | /* Node doesn't exist, try to create it. */
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120 | if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
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121 | goto try_to_open;
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122 | }
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123 | /* Ran out of block devices, return failure. */
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124 | rc = -1;
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125 | break;
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126 | }
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127 | try_to_open:
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128 | /* Open the sucker and check its loopiness. */
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129 | dfd = open(try, mode);
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130 | if (dfd < 0 && errno == EROFS) {
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131 | mode = O_RDONLY;
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132 | dfd = open(try, mode);
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133 | }
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134 | if (dfd < 0) {
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135 | if (errno == ENXIO) {
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136 | /* Happens if loop module is not loaded */
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137 | rc = -1;
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138 | break;
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139 | }
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140 | goto try_again;
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141 | }
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142 |
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143 | rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
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144 |
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145 | /* If device is free, claim it. */
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146 | if (rc && errno == ENXIO) {
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147 | memset(&loopinfo, 0, sizeof(loopinfo));
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148 | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
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149 | loopinfo.lo_offset = offset;
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150 | /* Associate free loop device with file. */
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151 | if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
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152 | if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
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153 | rc = 0;
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154 | else
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155 | ioctl(dfd, LOOP_CLR_FD, 0);
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156 | }
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157 | } else {
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158 | rc = -1;
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159 | }
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160 | close(dfd);
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161 | try_again:
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162 | if (*device) break;
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163 | }
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164 | close(ffd);
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165 | if (rc == 0) {
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166 | if (!*device)
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167 | *device = xstrdup(dev);
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168 | return (mode == O_RDONLY); /* 1:ro, 0:rw */
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169 | }
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170 | return rc;
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171 | }
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