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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
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84
85
86
87int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset, unsigned flags)
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;
94
95 rc = dfd = -1;
96
97
98 mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
99 open_ffd:
100 ffd = open(file, mode);
101 if (ffd < 0) {
102 if (mode != O_RDONLY) {
103 mode = O_RDONLY;
104 goto open_ffd;
105 }
106 return -errno;
107 }
108
109
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111
112
113
114 try = *device ? *device : dev;
115
116 for (i = 0; rc && i < 1048576; i++) {
117 sprintf(dev, LOOP_FORMAT, i);
118
119 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
120 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
121 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
122 && errno == ENOENT
123 && try == dev
124 ) {
125
126 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
127 goto try_to_open;
128 }
129
130 rc = -1;
131 break;
132 }
133 try_to_open:
134
135 dfd = open(try, mode);
136 if (dfd < 0 && errno == EROFS) {
137 mode = O_RDONLY;
138 dfd = open(try, mode);
139 }
140 if (dfd < 0) {
141 if (errno == ENXIO) {
142
143 rc = -1;
144 break;
145 }
146 goto try_again;
147 }
148
149 rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo);
150
151
152 if (rc && errno == ENXIO) {
153
154 if (ioctl(dfd, LOOP_SET_FD, ffd) == 0) {
155 memset(&loopinfo, 0, sizeof(loopinfo));
156 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
157 loopinfo.lo_offset = offset;
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161
162
163
164 loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
165 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
166 if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
167
168
169 loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
170 rc = ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo);
171 }
172 if (rc != 0) {
173 ioctl(dfd, LOOP_CLR_FD, 0);
174 }
175 }
176 } else {
177 rc = -1;
178 }
179 if (rc != 0) {
180 close(dfd);
181 }
182 try_again:
183 if (*device) break;
184 }
185 close(ffd);
186 if (rc == 0) {
187 if (!*device)
188 *device = xstrdup(dev);
189 return dfd;
190 }
191 return rc;
192}
193