blob: d30b378d7541d5ab4bff00a0b12082f317b57486
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 | |
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 | |
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 | */ |
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 |