1 /* vi: set sw=4 ts=4: */
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
7 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
17 #include <sys/ioctl.h>
20 /* For 2.6, use the cleaned up header to get the 64 bit API. */
21 #include <linux/version.h>
22 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
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
28 /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
30 /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/
31 #include <linux/posix_types.h>
32 #define LO_NAME_SIZE 64
33 #define LO_KEY_SIZE 32
34 #define LOOP_SET_FD 0x4C00
35 #define LOOP_CLR_FD 0x4C01
36 #define BB_LOOP_SET_STATUS 0x4C02
37 #define BB_LOOP_GET_STATUS 0x4C03
40 __kernel_dev_t lo_device;
41 unsigned long lo_inode;
42 __kernel_dev_t lo_rdevice;
45 int lo_encrypt_key_size;
47 char lo_file_name[LO_NAME_SIZE];
48 unsigned char lo_encrypt_key[LO_KEY_SIZE];
49 unsigned long lo_init[2];
54 char *query_loop(const char *device)
57 bb_loop_info loopinfo;
60 if ((fd = open(device, O_RDONLY)) < 0) return 0;
61 if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
62 dev=bb_xasprintf("%ld %s", (long) loopinfo.lo_offset,
63 (char *)loopinfo.lo_file_name);
70 int del_loop(const char *device)
74 if ((fd = open(device, O_RDONLY)) < 0) return 1;
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 set_loop(char **device, const char *file, int offset)
90 bb_loop_info loopinfo;
92 int i, dfd, ffd, mode, rc=-1;
94 /* Open the file. Barf if this doesn't work. */
95 if((ffd = open(file, mode=O_RDWR))<0 && (ffd = open(file,mode=O_RDONLY))<0)
98 /* Find a loop device. */
101 sprintf(dev, LOOP_FORMAT, i);
103 /* Ran out of block devices, return failure. */
104 if(stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
108 /* Open the sucker and check its loopiness. */
109 if((dfd=open(try, mode))<0 && errno==EROFS)
110 dfd=open(try, mode = O_RDONLY);
111 if(dfd<0) goto try_again;
113 rc=ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
115 /* If device free, claim it. */
116 if(rc && errno==ENXIO) {
117 memset(&loopinfo, 0, sizeof(loopinfo));
118 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
119 loopinfo.lo_offset = offset;
120 /* Associate free loop device with file. */
121 if(!ioctl(dfd, LOOP_SET_FD, ffd)) {
122 if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) rc=0;
123 else ioctl(dfd, LOOP_CLR_FD, 0);
126 /* If this block device already set up right, re-use it.
127 (Yes this is racy, but associating two loop devices with the same
128 file isn't pretty either. In general, mounting the same file twice
129 without using losetup manually is problematic.)
131 } else if(strcmp(file,(char *)loopinfo.lo_file_name)
132 || offset!=loopinfo.lo_offset) rc=-1;
139 if(!*device) *device=strdup(dev);
140 return mode==O_RDONLY ? 1 : 0;