1
2
3
4
5
6
7
8
9
10#include "libbb.h"
11#include <linux/version.h>
12
13#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
14
15
16
17
18# include <linux/loop.h>
19typedef 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
26
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
34typedef 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
50char* 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
68int 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
82int FAST_FUNC get_free_loop(void)
83{
84 int fd;
85 int loopdevno;
86
87 fd = open("/dev/loop-control", O_RDWR | O_CLOEXEC);
88 if (fd == -1)
89 return fd - 1;
90
91#ifndef LOOP_CTL_GET_FREE
92# define LOOP_CTL_GET_FREE 0x4C82
93#endif
94 loopdevno = ioctl(fd, LOOP_CTL_GET_FREE);
95 close(fd);
96 return loopdevno;
97}
98
99
100
101
102
103int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset,
104 unsigned long long sizelimit, unsigned flags)
105{
106 char dev[LOOP_NAMESIZE];
107 char *try;
108 bb_loop_info loopinfo;
109 struct stat statbuf;
110 int i, lfd, ffd, mode, rc;
111
112
113 mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
114 open_ffd:
115 ffd = open(file, mode);
116 if (ffd < 0) {
117 if (mode != O_RDONLY) {
118 mode = O_RDONLY;
119 goto open_ffd;
120 }
121 return -errno;
122 }
123
124 try = *device;
125 if (!try) {
126 get_free_loopN:
127 i = get_free_loop();
128 if (i == -1) {
129 close(ffd);
130 return -1;
131 }
132 if (i >= 0) {
133 try = xasprintf(LOOP_FORMAT, i);
134 goto open_lfd;
135 }
136
137 try = dev;
138 }
139
140
141
142 for (i = 0; i <= 0xfffff; i++) {
143 sprintf(dev, LOOP_FORMAT, i);
144
145 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
146 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
147 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
148 && errno == ENOENT
149 && try == dev
150 ) {
151
152 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
153 goto open_lfd;
154 }
155
156 rc = -1;
157 break;
158 }
159 open_lfd:
160
161 lfd = rc = open(try, mode);
162 if (lfd < 0 && errno == EROFS) {
163 mode = O_RDONLY;
164 lfd = rc = open(try, mode);
165 }
166 if (lfd < 0) {
167 if (errno == ENXIO) {
168
169
170 break;
171 }
172 goto try_next_loopN;
173 }
174
175 rc = ioctl(lfd, BB_LOOP_GET_STATUS, &loopinfo);
176
177
178 if (rc && errno == ENXIO) {
179
180 if (ioctl(lfd, LOOP_SET_FD, ffd)) {
181
182 if (!*device
183 && try != dev
184 ) {
185 free(try);
186 close(lfd);
187
188 goto get_free_loopN;
189 }
190 goto close_and_try_next_loopN;
191 }
192 memset(&loopinfo, 0, sizeof(loopinfo));
193 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
194 loopinfo.lo_offset = offset;
195 loopinfo.lo_sizelimit = sizelimit;
196
197
198
199
200
201
202 loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
203 rc = ioctl(lfd, BB_LOOP_SET_STATUS, &loopinfo);
204 if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
205
206
207 loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
208 rc = ioctl(lfd, BB_LOOP_SET_STATUS, &loopinfo);
209 }
210 if (rc == 0) {
211
212 if (try != dev)
213 *device = try;
214 if (!*device)
215 *device = xstrdup(dev);
216 rc = lfd;
217 break;
218 }
219
220 ioctl(lfd, LOOP_CLR_FD, 0);
221 }
222
223 close_and_try_next_loopN:
224 close(lfd);
225 try_next_loopN:
226 rc = -1;
227 if (*device)
228 break;
229 }
230
231 close(ffd);
232 return rc;
233}
234