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 the GPL v2 or later, see the file LICENSE in this tarball.
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)
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. */
97 ffd = open(file, mode);
100 ffd = open(file, mode);
105 /* Find a loop device. */
106 try = *device ? *device : dev;
107 /* 1048575 is a max possible minor number in Linux circa 2010 */
108 for (i = 0; rc && i < 1048576; i++) {
109 sprintf(dev, LOOP_FORMAT, i);
111 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
112 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
113 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
117 /* Node doesn't exist, try to create it. */
118 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
121 /* Ran out of block devices, return failure. */
126 /* Open the sucker and check its loopiness. */
127 dfd = open(try, mode);
128 if (dfd < 0 && errno == EROFS) {
130 dfd = open(try, mode);
135 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
137 /* If device is free, claim it. */
138 if (rc && errno == ENXIO) {
139 memset(&loopinfo, 0, sizeof(loopinfo));
140 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
141 loopinfo.lo_offset = offset;
142 /* Associate free loop device with file. */
143 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
144 if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
147 ioctl(dfd, LOOP_CLR_FD, 0);
150 /* If this block device already set up right, re-use it.
151 (Yes this is racy, but associating two loop devices with the same
152 file isn't pretty either. In general, mounting the same file twice
153 without using losetup manually is problematic.)
156 if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
157 || offset != loopinfo.lo_offset
168 *device = xstrdup(dev);
169 return (mode == O_RDONLY); /* 1:ro, 0:rw */