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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
103
104
105int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, unsigned flags)
106{
107 char dev[LOOP_NAMESIZE];
108 char *try;
109 bb_loop_info loopinfo;
110 struct stat statbuf;
111 int i, dfd, ffd, mode, rc;
112
113 rc = dfd = -1;
114
115
116 mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
117 open_ffd:
118 ffd = open(file, mode);
119 if (ffd < 0) {
120 if (mode != O_RDONLY) {
121 mode = O_RDONLY;
122 goto open_ffd;
123 }
124 return -errno;
125 }
126
127 try = *device;
128 if (!try) {
129 i = get_free_loop();
130 if (i == -2) {
131 i = 0;
132 try = dev;
133 goto old_style;
134 }
135 if (i == -1) {
136 close(ffd);
137 return -1;
138 }
139 try = *device = xasprintf(LOOP_FORMAT, i);
140 goto try_to_open;
141 }
142
143 old_style:
144
145
146 for (i = 0; rc && i < 1048576; i++) {
147 sprintf(dev, LOOP_FORMAT, i);
148
149 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
150 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
151 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
152 && errno == ENOENT
153 && try == dev
154 ) {
155
156 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
157 goto try_to_open;
158 }
159
160 rc = -1;
161 break;
162 }
163 try_to_open:
164
165 dfd = open(try, mode);
166 if (dfd < 0 && errno == EROFS) {
167 mode = O_RDONLY;
168 dfd = open(try, mode);
169 }
170 if (dfd < 0) {
171 if (errno == ENXIO) {
172
173 rc = -1;
174 break;
175 }
176 goto try_again;
177 }
178
179 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
180
181
182 if (rc && errno == ENXIO) {
183
184 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
185 memset(&loopinfo, 0, sizeof(loopinfo));
186 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
187 loopinfo.lo_offset = offset;
188
189
190
191
192
193
194 loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
195 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
196 if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
197
198
199 loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
200 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
201 }
202 if (rc != 0) {
203 ioctl(dfd, LOOP_CLR_FD, 0);
204 }
205 }
206 } else {
207 rc = -1;
208 }
209 if (rc != 0) {
210 close(dfd);
211 }
212 try_again:
213 if (*device) break;
214 }
215 close(ffd);
216 if (rc == 0) {
217 if (!*device)
218 *device = xstrdup(dev);
219 return dfd;
220 }
221 return rc;
222}
223