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Eric Andersenaad1a882001-03-16 22:47:14 +00001/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
Bernhard Reutner-Fischer7547a6e2005-10-15 20:56:31 +00005 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
Rob Landley53437472006-07-16 08:14:35 +00006 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
Eric Andersenaad1a882001-03-16 22:47:14 +00007 *
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +00008 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
Eric Andersenaad1a882001-03-16 22:47:14 +00009 */
10
Eric Andersenaad1a882001-03-16 22:47:14 +000011#include "libbb.h"
Eric Andersenef8cd3b2004-02-06 07:16:36 +000012
Rob Landley6a6798b2005-08-10 20:35:54 +000013/* For 2.6, use the cleaned up header to get the 64 bit API. */
Eric Andersenef8cd3b2004-02-06 07:16:36 +000014#include <linux/version.h>
Eric Andersencf6ef052004-08-16 08:29:44 +000015#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
Rob Landley6a6798b2005-08-10 20:35:54 +000016#include <linux/loop.h>
17typedef struct loop_info64 bb_loop_info;
18#define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
19#define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
Eric Andersenef8cd3b2004-02-06 07:16:36 +000020
Rob Landley6a6798b2005-08-10 20:35:54 +000021/* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
22#else
23/* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/
24#include <linux/posix_types.h>
Eric Andersenef8cd3b2004-02-06 07:16:36 +000025#define LO_NAME_SIZE 64
26#define LO_KEY_SIZE 32
27#define LOOP_SET_FD 0x4C00
28#define LOOP_CLR_FD 0x4C01
Rob Landley6a6798b2005-08-10 20:35:54 +000029#define BB_LOOP_SET_STATUS 0x4C02
30#define BB_LOOP_GET_STATUS 0x4C03
31typedef struct {
Eric Andersenef8cd3b2004-02-06 07:16:36 +000032 int lo_number;
Rob Landley6a6798b2005-08-10 20:35:54 +000033 __kernel_dev_t lo_device;
Eric Andersenef8cd3b2004-02-06 07:16:36 +000034 unsigned long lo_inode;
Rob Landley6a6798b2005-08-10 20:35:54 +000035 __kernel_dev_t lo_rdevice;
Eric Andersenef8cd3b2004-02-06 07:16:36 +000036 int lo_offset;
37 int lo_encrypt_type;
38 int lo_encrypt_key_size;
39 int lo_flags;
Rob Landley6a6798b2005-08-10 20:35:54 +000040 char lo_file_name[LO_NAME_SIZE];
Eric Andersenef8cd3b2004-02-06 07:16:36 +000041 unsigned char lo_encrypt_key[LO_KEY_SIZE];
42 unsigned long lo_init[2];
43 char reserved[4];
Rob Landley6a6798b2005-08-10 20:35:54 +000044} bb_loop_info;
45#endif
Eric Andersenaad1a882001-03-16 22:47:14 +000046
Rob Landley1d589b22005-11-29 23:47:10 +000047char *query_loop(const char *device)
Eric Andersenaad1a882001-03-16 22:47:14 +000048{
Rob Landley1d589b22005-11-29 23:47:10 +000049 int fd;
50 bb_loop_info loopinfo;
Denis Vlasenko13858992006-10-08 12:49:22 +000051 char *dev = 0;
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000052
Denis Vlasenko13858992006-10-08 12:49:22 +000053 fd = open(device, O_RDONLY);
54 if (fd < 0) return 0;
Rob Landley1d589b22005-11-29 23:47:10 +000055 if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo))
Denis Vlasenko13858992006-10-08 12:49:22 +000056 dev = xasprintf("%ld %s", (long) loopinfo.lo_offset,
Eric Andersen76b24272006-01-30 17:30:22 +000057 (char *)loopinfo.lo_file_name);
Rob Landley1d589b22005-11-29 23:47:10 +000058 close(fd);
Eric Andersenaad1a882001-03-16 22:47:14 +000059
Rob Landley1d589b22005-11-29 23:47:10 +000060 return dev;
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000061}
Rob Landley1d589b22005-11-29 23:47:10 +000062
63
64int del_loop(const char *device)
65{
66 int fd, rc;
67
Denis Vlasenko13858992006-10-08 12:49:22 +000068 fd = open(device, O_RDONLY);
69 if (fd < 0) return 1;
70 rc = ioctl(fd, LOOP_CLR_FD, 0);
Rob Landley1d589b22005-11-29 23:47:10 +000071 close(fd);
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000072
Rob Landley6a6798b2005-08-10 20:35:54 +000073 return rc;
Eric Andersenaad1a882001-03-16 22:47:14 +000074}
75
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +000076/* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error.
77 *device is loop device to use, or if *device==NULL finds a loop device to
78 mount it on and sets *device to a strdup of that loop device name. This
79 search will re-use an existing loop device already bound to that
80 file/offset if it finds one.
81 */
Denis Vlasenko13858992006-10-08 12:49:22 +000082int set_loop(char **device, const char *file, unsigned long long offset)
Eric Andersenaad1a882001-03-16 22:47:14 +000083{
Rob Landley1d589b22005-11-29 23:47:10 +000084 char dev[20], *try;
Rob Landley6a6798b2005-08-10 20:35:54 +000085 bb_loop_info loopinfo;
Eric Andersenaad1a882001-03-16 22:47:14 +000086 struct stat statbuf;
Denis Vlasenkoc34d3552007-04-19 00:09:34 +000087 int i, dfd, ffd, mode, rc = -1;
Denis Vlasenko9213a9e2006-09-17 16:28:10 +000088
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +000089 /* Open the file. Barf if this doesn't work. */
Denis Vlasenko13858992006-10-08 12:49:22 +000090 mode = O_RDWR;
91 ffd = open(file, mode);
92 if (ffd < 0) {
93 mode = O_RDONLY;
94 ffd = open(file, mode);
95 if (ffd < 0)
96 return -errno;
97 }
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +000098
99 /* Find a loop device. */
Denis Vlasenko13858992006-10-08 12:49:22 +0000100 try = *device ? : dev;
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000101 for (i = 0; rc; i++) {
Rob Landleyb70ccd92006-01-22 23:17:18 +0000102 sprintf(dev, LOOP_FORMAT, i);
Rob Landleyaae8b342006-03-18 02:38:10 +0000103
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000104 /* Ran out of block devices, return failure. */
Denis Vlasenko13858992006-10-08 12:49:22 +0000105 if (stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) {
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000106 rc = -ENOENT;
Rob Landley6a6798b2005-08-10 20:35:54 +0000107 break;
Eric Andersenaad1a882001-03-16 22:47:14 +0000108 }
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000109 /* Open the sucker and check its loopiness. */
Denis Vlasenko13858992006-10-08 12:49:22 +0000110 dfd = open(try, mode);
111 if (dfd < 0 && errno == EROFS) {
112 mode = O_RDONLY;
113 dfd = open(try, mode);
114 }
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000115 if (dfd < 0)
116 goto try_again;
Eric Andersenaad1a882001-03-16 22:47:14 +0000117
Denis Vlasenko13858992006-10-08 12:49:22 +0000118 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
Rob Landley1d589b22005-11-29 23:47:10 +0000119
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000120 /* If device is free, claim it. */
Denis Vlasenko13858992006-10-08 12:49:22 +0000121 if (rc && errno == ENXIO) {
Rob Landley6a6798b2005-08-10 20:35:54 +0000122 memset(&loopinfo, 0, sizeof(loopinfo));
Eric Andersen76b24272006-01-30 17:30:22 +0000123 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
Rob Landley6a6798b2005-08-10 20:35:54 +0000124 loopinfo.lo_offset = offset;
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000125 /* Associate free loop device with file. */
Denis Vlasenko13858992006-10-08 12:49:22 +0000126 if (!ioctl(dfd, LOOP_SET_FD, ffd)) {
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000127 if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo))
128 rc = 0;
129 else
130 ioctl(dfd, LOOP_CLR_FD, 0);
Rob Landley934da822006-06-25 15:29:12 +0000131 }
Rob Landleyaae8b342006-03-18 02:38:10 +0000132
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000133 /* If this block device already set up right, re-use it.
134 (Yes this is racy, but associating two loop devices with the same
135 file isn't pretty either. In general, mounting the same file twice
136 without using losetup manually is problematic.)
137 */
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000138 } else if (strcmp(file, (char *)loopinfo.lo_file_name) != 0
Denis Vlasenko7039a662006-10-08 17:54:47 +0000139 || offset != loopinfo.lo_offset) {
140 rc = -1;
141 }
Rob Landley6a6798b2005-08-10 20:35:54 +0000142 close(dfd);
Rob Landley90854672005-12-21 16:53:57 +0000143try_again:
Denis Vlasenko13858992006-10-08 12:49:22 +0000144 if (*device) break;
Rob Landley6a6798b2005-08-10 20:35:54 +0000145 }
146 close(ffd);
Denis Vlasenko13858992006-10-08 12:49:22 +0000147 if (!rc) {
Denis Vlasenkoc34d3552007-04-19 00:09:34 +0000148 if (!*device)
149 *device = xstrdup(dev);
150 return (mode == O_RDONLY) ? 1 : 0;
Denis Vlasenko13858992006-10-08 12:49:22 +0000151 }
152 return rc;
Rob Landley6a6798b2005-08-10 20:35:54 +0000153}