1 /* vi: set sw=4 ts=4: */
2 /*
3 * Utility routines.
4 *
5 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
6 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
7 *
8 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
9 */
10 #include "libbb.h"
11 #include <linux/version.h>
12
13 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
14
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
22
23 #else
24
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
34 typedef struct {
35 int lo_number;
36 __kernel_dev_t lo_device;
37 unsigned long lo_inode;
38 __kernel_dev_t lo_rdevice;
39 int lo_offset;
40 int lo_encrypt_type;
41 int lo_encrypt_key_size;
42 int lo_flags;
43 char lo_file_name[LO_NAME_SIZE];
44 unsigned char lo_encrypt_key[LO_KEY_SIZE];
45 unsigned long lo_init[2];
46 char reserved[4];
47 } bb_loop_info;
48 #endif
49
query_loop(const char * device)50 char* FAST_FUNC query_loop(const char *device)
51 {
52 int fd;
53 bb_loop_info loopinfo;
54 char *dev = NULL;
55
56 fd = open(device, O_RDONLY);
57 if (fd >= 0) {
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);
61 }
62 close(fd);
63 }
64
65 return dev;
66 }
67
del_loop(const char * device)68 int FAST_FUNC del_loop(const char *device)
69 {
70 int fd, rc;
71
72 fd = open(device, O_RDONLY);
73 if (fd < 0)
74 return 1;
75 rc = ioctl(fd, LOOP_CLR_FD, 0);
76 close(fd);
77
78 return rc;
79 }
80
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.
86 */
set_loop(char ** device,const char * file,unsigned long long offset,int ro)87 int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, int ro)
88 {
89 char dev[LOOP_NAMESIZE];
90 char *try;
91 bb_loop_info loopinfo;
92 struct stat statbuf;
93 int i, dfd, ffd, mode, rc = -1;
94
95 /* Open the file. Barf if this doesn't work. */
96 mode = ro ? O_RDONLY : O_RDWR;
97 open_ffd:
98 ffd = open(file, mode);
99 if (ffd < 0) {
100 if (mode != O_RDONLY) {
101 mode = O_RDONLY;
102 goto open_ffd;
103 }
104 return -errno;
105 }
106
107 /* Find a loop device. */
108 try = *device ? *device : dev;
109 /* 1048575 (0xfffff) is a max possible minor number in Linux circa 2010 */
110 for (i = 0; rc && i < 1048576; i++) {
111 sprintf(dev, LOOP_FORMAT, i);
112
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
116 && errno == ENOENT
117 && try == dev
118 ) {
119 /* Node doesn't exist, try to create it. */
120 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
121 goto try_to_open;
122 }
123 /* Ran out of block devices, return failure. */
124 rc = -1;
125 break;
126 }
127 try_to_open:
128 /* Open the sucker and check its loopiness. */
129 dfd = open(try, mode);
130 if (dfd < 0 && errno == EROFS) {
131 mode = O_RDONLY;
132 dfd = open(try, mode);
133 }
134 if (dfd < 0) {
135 if (errno == ENXIO) {
136 /* Happens if loop module is not loaded */
137 rc = -1;
138 break;
139 }
140 goto try_again;
141 }
142
143 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
144
145 /* If device is free, claim it. */
146 if (rc && errno == ENXIO) {
147 memset(&loopinfo, 0, sizeof(loopinfo));
148 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
149 loopinfo.lo_offset = offset;
150 /* Associate free loop device with file. */
151 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
152 if (ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo) == 0)
153 rc = 0;
154 else
155 ioctl(dfd, LOOP_CLR_FD, 0);
156 }
157 } else {
158 rc = -1;
159 }
160 close(dfd);
161 try_again:
162 if (*device) break;
163 }
164 close(ffd);
165 if (rc == 0) {
166 if (!*device)
167 *device = xstrdup(dev);
168 return (mode == O_RDONLY); /* 1:ro, 0:rw */
169 }
170 return rc;
171 }
172