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 /* linux/loop.h relies on __u64. Make sure we have that as a proper type
17 * until userspace is widely fixed. */
18 # if (defined __INTEL_COMPILER && !defined __GNUC__) \
19 || (defined __GNUC__ && defined __STRICT_ANSI__)
20 __extension__ typedef long long __s64;
21 __extension__ typedef unsigned long long __u64;
23 # include <linux/loop.h>
24 typedef struct loop_info64 bb_loop_info;
25 # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
26 # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
30 /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
31 /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
32 # include <linux/posix_types.h>
33 # define LO_NAME_SIZE 64
34 # define LO_KEY_SIZE 32
35 # define LOOP_SET_FD 0x4C00
36 # define LOOP_CLR_FD 0x4C01
37 # define BB_LOOP_SET_STATUS 0x4C02
38 # define BB_LOOP_GET_STATUS 0x4C03
41 __kernel_dev_t lo_device;
42 unsigned long lo_inode;
43 __kernel_dev_t lo_rdevice;
46 int lo_encrypt_key_size;
48 char lo_file_name[LO_NAME_SIZE];
49 unsigned char lo_encrypt_key[LO_KEY_SIZE];
50 unsigned long lo_init[2];
55 char* FAST_FUNC query_loop(const char *device)
58 bb_loop_info loopinfo;
61 fd = open(device, O_RDONLY);
63 if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
64 dev = xasprintf("%ld %s", (long) loopinfo.lo_offset,
65 (char *)loopinfo.lo_file_name);
71 int FAST_FUNC del_loop(const char *device)
75 fd = open(device, O_RDONLY);
77 rc = ioctl(fd, LOOP_CLR_FD, 0);
83 /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
84 *device is loop device to use, or if *device==NULL finds a loop device to
85 mount it on and sets *device to a strdup of that loop device name. This
86 search will re-use an existing loop device already bound to that
87 file/offset if it finds one.
89 int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset)
91 char dev[LOOP_NAMESIZE];
93 bb_loop_info loopinfo;
95 int i, dfd, ffd, mode, rc = -1;
97 /* Open the file. Barf if this doesn't work. */
99 ffd = open(file, mode);
102 ffd = open(file, mode);
107 /* Find a loop device. */
108 try = *device ? : dev;
109 for (i = 0; rc; i++) {
110 sprintf(dev, LOOP_FORMAT, i);
112 /* Ran out of block devices, return failure. */
113 if (stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
117 /* Open the sucker and check its loopiness. */
118 dfd = open(try, mode);
119 if (dfd < 0 && errno == EROFS) {
121 dfd = open(try, mode);
126 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
128 /* If device is free, claim it. */
129 if (rc && errno == ENXIO) {
130 memset(&loopinfo, 0, sizeof(loopinfo));
131 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
132 loopinfo.lo_offset = offset;
133 /* Associate free loop device with file. */
134 if (!ioctl(dfd, LOOP_SET_FD, ffd)) {
135 if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo))
138 ioctl(dfd, LOOP_CLR_FD, 0);
141 /* If this block device already set up right, re-use it.
142 (Yes this is racy, but associating two loop devices with the same
143 file isn't pretty either. In general, mounting the same file twice
144 without using losetup manually is problematic.)
146 } else if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
147 || offset != loopinfo.lo_offset) {
157 *device = xstrdup(dev);
158 return (mode == O_RDONLY); /* 1:ro, 0:rw */