Contents of /tags/mkinitrd-6_1_3/busybox/libbb/loop.c
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Mon May 4 18:51:23 2009 UTC (15 years, 4 months ago) by niro
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File size: 4096 byte(s)
Mon May 4 18:51:23 2009 UTC (15 years, 4 months ago) by niro
File MIME type: text/plain
File size: 4096 byte(s)
tagged 'mkinitrd-6_1_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 | |
11 | #include "libbb.h" |
12 | |
13 | /* For 2.6, use the cleaned up header to get the 64 bit API. */ |
14 | #include <linux/version.h> |
15 | #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0) |
16 | #include <linux/loop.h> |
17 | typedef struct loop_info64 bb_loop_info; |
18 | #define BB_LOOP_SET_STATUS LOOP_SET_STATUS64 |
19 | #define BB_LOOP_GET_STATUS LOOP_GET_STATUS64 |
20 | |
21 | /* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */ |
22 | #else |
23 | /* Stuff stolen from linux/loop.h for 2.4 and earlier kernels*/ |
24 | #include <linux/posix_types.h> |
25 | #define LO_NAME_SIZE 64 |
26 | #define LO_KEY_SIZE 32 |
27 | #define LOOP_SET_FD 0x4C00 |
28 | #define LOOP_CLR_FD 0x4C01 |
29 | #define BB_LOOP_SET_STATUS 0x4C02 |
30 | #define BB_LOOP_GET_STATUS 0x4C03 |
31 | typedef struct { |
32 | int lo_number; |
33 | __kernel_dev_t lo_device; |
34 | unsigned long lo_inode; |
35 | __kernel_dev_t lo_rdevice; |
36 | int lo_offset; |
37 | int lo_encrypt_type; |
38 | int lo_encrypt_key_size; |
39 | int lo_flags; |
40 | char lo_file_name[LO_NAME_SIZE]; |
41 | unsigned char lo_encrypt_key[LO_KEY_SIZE]; |
42 | unsigned long lo_init[2]; |
43 | char reserved[4]; |
44 | } bb_loop_info; |
45 | #endif |
46 | |
47 | char* FAST_FUNC query_loop(const char *device) |
48 | { |
49 | int fd; |
50 | bb_loop_info loopinfo; |
51 | char *dev = 0; |
52 | |
53 | fd = open(device, O_RDONLY); |
54 | if (fd < 0) return 0; |
55 | if (!ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo)) |
56 | dev = xasprintf("%ld %s", (long) loopinfo.lo_offset, |
57 | (char *)loopinfo.lo_file_name); |
58 | close(fd); |
59 | |
60 | return dev; |
61 | } |
62 | |
63 | |
64 | int FAST_FUNC del_loop(const char *device) |
65 | { |
66 | int fd, rc; |
67 | |
68 | fd = open(device, O_RDONLY); |
69 | if (fd < 0) return 1; |
70 | rc = ioctl(fd, LOOP_CLR_FD, 0); |
71 | close(fd); |
72 | |
73 | return rc; |
74 | } |
75 | |
76 | /* Returns 0 if mounted RW, 1 if mounted read-only, <0 for error. |
77 | *device is loop device to use, or if *device==NULL finds a loop device to |
78 | mount it on and sets *device to a strdup of that loop device name. This |
79 | search will re-use an existing loop device already bound to that |
80 | file/offset if it finds one. |
81 | */ |
82 | int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset) |
83 | { |
84 | char dev[LOOP_NAMESIZE]; |
85 | char *try; |
86 | bb_loop_info loopinfo; |
87 | struct stat statbuf; |
88 | int i, dfd, ffd, mode, rc = -1; |
89 | |
90 | /* Open the file. Barf if this doesn't work. */ |
91 | mode = O_RDWR; |
92 | ffd = open(file, mode); |
93 | if (ffd < 0) { |
94 | mode = O_RDONLY; |
95 | ffd = open(file, mode); |
96 | if (ffd < 0) |
97 | return -errno; |
98 | } |
99 | |
100 | /* Find a loop device. */ |
101 | try = *device ? : dev; |
102 | for (i = 0; rc; i++) { |
103 | sprintf(dev, LOOP_FORMAT, i); |
104 | |
105 | /* Ran out of block devices, return failure. */ |
106 | if (stat(try, &statbuf) || !S_ISBLK(statbuf.st_mode)) { |
107 | rc = -ENOENT; |
108 | break; |
109 | } |
110 | /* Open the sucker and check its loopiness. */ |
111 | dfd = open(try, mode); |
112 | if (dfd < 0 && errno == EROFS) { |
113 | mode = O_RDONLY; |
114 | dfd = open(try, mode); |
115 | } |
116 | if (dfd < 0) |
117 | goto try_again; |
118 | |
119 | rc = ioctl(dfd, BB_LOOP_GET_STATUS, &loopinfo); |
120 | |
121 | /* If device is free, claim it. */ |
122 | if (rc && errno == ENXIO) { |
123 | memset(&loopinfo, 0, sizeof(loopinfo)); |
124 | safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE); |
125 | loopinfo.lo_offset = offset; |
126 | /* Associate free loop device with file. */ |
127 | if (!ioctl(dfd, LOOP_SET_FD, ffd)) { |
128 | if (!ioctl(dfd, BB_LOOP_SET_STATUS, &loopinfo)) |
129 | rc = 0; |
130 | else |
131 | ioctl(dfd, LOOP_CLR_FD, 0); |
132 | } |
133 | |
134 | /* If this block device already set up right, re-use it. |
135 | (Yes this is racy, but associating two loop devices with the same |
136 | file isn't pretty either. In general, mounting the same file twice |
137 | without using losetup manually is problematic.) |
138 | */ |
139 | } else if (strcmp(file, (char *)loopinfo.lo_file_name) != 0 |
140 | || offset != loopinfo.lo_offset) { |
141 | rc = -1; |
142 | } |
143 | close(dfd); |
144 | try_again: |
145 | if (*device) break; |
146 | } |
147 | close(ffd); |
148 | if (!rc) { |
149 | if (!*device) |
150 | *device = xstrdup(dev); |
151 | return (mode == O_RDONLY); /* 1:ro, 0:rw */ |
152 | } |
153 | return rc; |
154 | } |