Contents of /tags/mkinitrd-6_2_3/busybox/libbb/loop.c
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Mon May 31 20:54:44 2010 UTC (14 years, 3 months ago) by niro
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Mon May 31 20:54:44 2010 UTC (14 years, 3 months ago) by niro
File MIME type: text/plain
File size: 4428 byte(s)
tagged 'mkinitrd-6_2_3'
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 the GPL v2 or later, see the file LICENSE in this tarball. |
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 | /* linux/loop.h relies on __u64. Make sure we have that as a proper type |
17 | * until userspace is widely fixed. */ |
18 | # if (defined __INTEL_COMPILER && !defined __GNUC__) \ |
19 | || (defined __GNUC__ && defined __STRICT_ANSI__) |
20 | __extension__ typedef long long __s64; |
21 | __extension__ typedef unsigned long long __u64; |
22 | # endif |
23 | # include <linux/loop.h> |
24 | typedef struct loop_info64 bb_loop_info; |
25 | # define BB_LOOP_SET_STATUS LOOP_SET_STATUS64 |
26 | # define BB_LOOP_GET_STATUS LOOP_GET_STATUS64 |
27 | |
28 | #else |
29 | |
30 | /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */ |
31 | /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */ |
32 | # include <linux/posix_types.h> |
33 | # define LO_NAME_SIZE 64 |
34 | # define LO_KEY_SIZE 32 |
35 | # define LOOP_SET_FD 0x4C00 |
36 | # define LOOP_CLR_FD 0x4C01 |
37 | # define BB_LOOP_SET_STATUS 0x4C02 |
38 | # define BB_LOOP_GET_STATUS 0x4C03 |
39 | typedef struct { |
40 | int lo_number; |
41 | __kernel_dev_t lo_device; |
42 | unsigned long lo_inode; |
43 | __kernel_dev_t lo_rdevice; |
44 | int lo_offset; |
45 | int lo_encrypt_type; |
46 | int lo_encrypt_key_size; |
47 | int lo_flags; |
48 | char lo_file_name[LO_NAME_SIZE]; |
49 | unsigned char lo_encrypt_key[LO_KEY_SIZE]; |
50 | unsigned long lo_init[2]; |
51 | char reserved[4]; |
52 | } bb_loop_info; |
53 | #endif |
54 | |
55 | char* FAST_FUNC query_loop(const char *device) |
56 | { |
57 | int fd; |
58 | bb_loop_info loopinfo; |
59 | char *dev = 0; |
60 | |
61 | fd = open(device, O_RDONLY); |
62 | if (fd < 0) return 0; |
63 | if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo)) |
64 | dev = xasprintf("%ld %s", (long) loopinfo.lo_offset, |
65 | (char *)loopinfo.lo_file_name); |
66 | close(fd); |
67 | |
68 | return dev; |
69 | } |
70 | |
71 | int FAST_FUNC del_loop(const char *device) |
72 | { |
73 | int fd, rc; |
74 | |
75 | fd = open(device, O_RDONLY); |
76 | if (fd < 0) return 1; |
77 | rc = ioctl(fd, LOOP_CLR_FD, 0); |
78 | close(fd); |
79 | |
80 | return rc; |
81 | } |
82 | |
83 | /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error. |
84 | *device is loop device to use, or if *device==NULL finds a loop device to |
85 | mount it on and sets *device to a strdup of that loop device name. This |
86 | search will re-use an existing loop device already bound to that |
87 | file/offset if it finds one. |
88 | */ |
89 | int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset) |
90 | { |
91 | char dev[LOOP_NAMESIZE]; |
92 | char *try; |
93 | bb_loop_info loopinfo; |
94 | struct stat statbuf; |
95 | int i, dfd, ffd, mode, rc = -1; |
96 | |
97 | /* Open the file. Barf if this doesn't work. */ |
98 | mode = O_RDWR; |
99 | ffd = open(file, mode); |
100 | if (ffd < 0) { |
101 | mode = O_RDONLY; |
102 | ffd = open(file, mode); |
103 | if (ffd < 0) |
104 | return -errno; |
105 | } |
106 | |
107 | /* Find a loop device. */ |
108 | try = *device ? *device : dev; |
109 | for (i = 0; rc; i++) { |
110 | sprintf(dev, LOOP_FORMAT, i); |
111 | |
112 | /* Ran out of block devices, return failure. */ |
113 | if (stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) { |
114 | rc = -ENOENT; |
115 | break; |
116 | } |
117 | /* Open the sucker and check its loopiness. */ |
118 | dfd = open(try, mode); |
119 | if (dfd < 0 && errno == EROFS) { |
120 | mode = O_RDONLY; |
121 | dfd = open(try, mode); |
122 | } |
123 | if (dfd < 0) |
124 | goto try_again; |
125 | |
126 | rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo); |
127 | |
128 | /* If device is free, claim it. */ |
129 | if (rc && errno == ENXIO) { |
130 | memset(&loopinfo, 0, sizeof(loopinfo)); |
131 | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE); |
132 | loopinfo.lo_offset = offset; |
133 | /* Associate free loop device with file. */ |
134 | if (!ioctl(dfd, LOOP_SET_FD, ffd)) { |
135 | if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) |
136 | rc = 0; |
137 | else |
138 | ioctl(dfd, LOOP_CLR_FD, 0); |
139 | } |
140 | |
141 | /* If this block device already set up right, re-use it. |
142 | (Yes this is racy, but associating two loop devices with the same |
143 | file isn't pretty either. In general, mounting the same file twice |
144 | without using losetup manually is problematic.) |
145 | */ |
146 | } else if (strcmp(file, (char *)loopinfo.lo_file_name) != 0 |
147 | || offset != loopinfo.lo_offset) { |
148 | rc = -1; |
149 | } |
150 | close(dfd); |
151 | try_again: |
152 | if (*device) break; |
153 | } |
154 | close(ffd); |
155 | if (!rc) { |
156 | if (!*device) |
157 | *device = xstrdup(dev); |
158 | return (mode == O_RDONLY); /* 1:ro, 0:rw */ |
159 | } |
160 | return rc; |
161 | } |