1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
11 #include <linux/version.h>
13 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
15 /* For 2.6, use the cleaned up header to get the 64 bit API. */
16 // Commented out per Rob's request
17 //# include "fix_u32.h" /* some old toolchains need __u64 for linux/loop.h */
18 # include <linux/loop.h>
19 typedef struct loop_info64 bb_loop_info;
20 # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
21 # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
25 /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
26 /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
27 # include <linux/posix_types.h>
28 # define LO_NAME_SIZE 64
29 # define LO_KEY_SIZE 32
30 # define LOOP_SET_FD 0x4C00
31 # define LOOP_CLR_FD 0x4C01
32 # define BB_LOOP_SET_STATUS 0x4C02
33 # define BB_LOOP_GET_STATUS 0x4C03
36 __kernel_dev_t lo_device;
37 unsigned long lo_inode;
38 __kernel_dev_t lo_rdevice;
41 int lo_encrypt_key_size;
43 char lo_file_name[LO_NAME_SIZE];
44 unsigned char lo_encrypt_key[LO_KEY_SIZE];
45 unsigned long lo_init[2];
50 char* FAST_FUNC query_loop(const char *device)
53 bb_loop_info loopinfo;
56 fd = open(device, O_RDONLY);
58 if (ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo) == 0) {
59 dev = xasprintf("%"OFF_FMT"u %s", (off_t) loopinfo.lo_offset,
60 (char *)loopinfo.lo_file_name);
68 int FAST_FUNC del_loop(const char *device)
72 fd = open(device, O_RDONLY);
75 rc = ioctl(fd, LOOP_CLR_FD, 0);
81 /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
82 *device is loop device to use, or if *device==NULL finds a loop device to
83 mount it on and sets *device to a strdup of that loop device name. This
84 search will re-use an existing loop device already bound to that
85 file/offset if it finds one.
87 int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, int ro)
89 char dev[LOOP_NAMESIZE];
91 bb_loop_info loopinfo;
93 int i, dfd, ffd, mode, rc = -1;
95 /* Open the file. Barf if this doesn't work. */
96 mode = ro ? O_RDONLY : O_RDWR;
97 ffd = open(file, mode);
99 if (mode != O_RDONLY) {
101 ffd = open(file, mode);
107 /* Find a loop device. */
108 try = *device ? *device : dev;
109 /* 1048575 is a max possible minor number in Linux circa 2010 */
110 for (i = 0; rc && i < 1048576; i++) {
111 sprintf(dev, LOOP_FORMAT, i);
113 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
114 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
115 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
119 /* Node doesn't exist, try to create it. */
120 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
123 /* Ran out of block devices, return failure. */
128 /* Open the sucker and check its loopiness. */
129 dfd = open(try, mode);
130 if (dfd < 0 && errno == EROFS) {
132 dfd = open(try, mode);
137 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
139 /* If device is free, claim it. */
140 if (rc && errno == ENXIO) {
141 memset(&loopinfo, 0, sizeof(loopinfo));
142 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
143 loopinfo.lo_offset = offset;
144 /* Associate free loop device with file. */
145 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
146 if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
149 ioctl(dfd, LOOP_CLR_FD, 0);
152 /* If this block device already set up right, re-use it.
153 (Yes this is racy, but associating two loop devices with the same
154 file isn't pretty either. In general, mounting the same file twice
155 without using losetup manually is problematic.)
158 if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
159 || offset != loopinfo.lo_offset
170 *device = xstrdup(dev);
171 return (mode == O_RDONLY); /* 1:ro, 0:rw */