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Commit | Line | Data |
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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
8c1be37e | 2 | /*** |
8c1be37e | 3 | Copyright 2016 Lennart Poettering |
8c1be37e LP |
4 | ***/ |
5 | ||
dccca82b | 6 | #include <errno.h> |
8c1be37e LP |
7 | #include <fcntl.h> |
8 | #include <linux/loop.h> | |
9 | #include <sys/ioctl.h> | |
10 | #include <sys/stat.h> | |
11 | ||
12 | #include "alloc-util.h" | |
13 | #include "fd-util.h" | |
14 | #include "loop-util.h" | |
3cc44114 | 15 | #include "stat-util.h" |
8c1be37e LP |
16 | |
17 | int loop_device_make(int fd, int open_flags, LoopDevice **ret) { | |
18 | const struct loop_info64 info = { | |
19 | .lo_flags = LO_FLAGS_AUTOCLEAR|LO_FLAGS_PARTSCAN|(open_flags == O_RDONLY ? LO_FLAGS_READ_ONLY : 0), | |
20 | }; | |
21 | ||
22 | _cleanup_close_ int control = -1, loop = -1; | |
23 | _cleanup_free_ char *loopdev = NULL; | |
24 | struct stat st; | |
25 | LoopDevice *d; | |
3cc44114 | 26 | int nr, r; |
8c1be37e LP |
27 | |
28 | assert(fd >= 0); | |
29 | assert(ret); | |
30 | assert(IN_SET(open_flags, O_RDWR, O_RDONLY)); | |
31 | ||
32 | if (fstat(fd, &st) < 0) | |
33 | return -errno; | |
34 | ||
35 | if (S_ISBLK(st.st_mode)) { | |
36 | int copy; | |
37 | ||
38 | /* If this is already a block device, store a copy of the fd as it is */ | |
39 | ||
40 | copy = fcntl(fd, F_DUPFD_CLOEXEC, 3); | |
41 | if (copy < 0) | |
42 | return -errno; | |
43 | ||
44 | d = new0(LoopDevice, 1); | |
45 | if (!d) | |
46 | return -ENOMEM; | |
47 | ||
48 | *d = (LoopDevice) { | |
49 | .fd = copy, | |
50 | .nr = -1, | |
51 | }; | |
52 | ||
53 | *ret = d; | |
54 | ||
55 | return 0; | |
56 | } | |
57 | ||
3cc44114 LP |
58 | r = stat_verify_regular(&st); |
59 | if (r < 0) | |
60 | return r; | |
8c1be37e LP |
61 | |
62 | control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK); | |
63 | if (control < 0) | |
64 | return -errno; | |
65 | ||
66 | nr = ioctl(control, LOOP_CTL_GET_FREE); | |
67 | if (nr < 0) | |
68 | return -errno; | |
69 | ||
70 | if (asprintf(&loopdev, "/dev/loop%i", nr) < 0) | |
71 | return -ENOMEM; | |
72 | ||
73 | loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags); | |
74 | if (loop < 0) | |
75 | return -errno; | |
76 | ||
77 | if (ioctl(loop, LOOP_SET_FD, fd) < 0) | |
78 | return -errno; | |
79 | ||
80 | if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) | |
81 | return -errno; | |
82 | ||
83 | d = new(LoopDevice, 1); | |
84 | if (!d) | |
85 | return -ENOMEM; | |
86 | ||
87 | *d = (LoopDevice) { | |
1cc6c93a YW |
88 | .fd = TAKE_FD(loop), |
89 | .node = TAKE_PTR(loopdev), | |
8c1be37e LP |
90 | .nr = nr, |
91 | }; | |
92 | ||
8c1be37e LP |
93 | *ret = d; |
94 | ||
95 | return (*ret)->fd; | |
96 | } | |
97 | ||
98 | int loop_device_make_by_path(const char *path, int open_flags, LoopDevice **ret) { | |
99 | _cleanup_close_ int fd = -1; | |
100 | ||
101 | assert(path); | |
102 | assert(ret); | |
103 | assert(IN_SET(open_flags, O_RDWR, O_RDONLY)); | |
104 | ||
105 | fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags); | |
106 | if (fd < 0) | |
107 | return -errno; | |
108 | ||
109 | return loop_device_make(fd, open_flags, ret); | |
110 | } | |
111 | ||
112 | LoopDevice* loop_device_unref(LoopDevice *d) { | |
113 | if (!d) | |
114 | return NULL; | |
115 | ||
116 | if (d->fd >= 0) { | |
117 | ||
a2ea3b2f | 118 | if (d->nr >= 0 && !d->relinquished) { |
8c1be37e LP |
119 | if (ioctl(d->fd, LOOP_CLR_FD) < 0) |
120 | log_debug_errno(errno, "Failed to clear loop device: %m"); | |
121 | ||
122 | } | |
123 | ||
124 | safe_close(d->fd); | |
125 | } | |
126 | ||
a2ea3b2f | 127 | if (d->nr >= 0 && !d->relinquished) { |
8c1be37e LP |
128 | _cleanup_close_ int control = -1; |
129 | ||
130 | control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK); | |
131 | if (control < 0) | |
132 | log_debug_errno(errno, "Failed to open loop control device: %m"); | |
133 | else { | |
134 | if (ioctl(control, LOOP_CTL_REMOVE, d->nr) < 0) | |
135 | log_debug_errno(errno, "Failed to remove loop device: %m"); | |
136 | } | |
137 | } | |
138 | ||
139 | free(d->node); | |
5fecf46d | 140 | return mfree(d); |
8c1be37e | 141 | } |
a2ea3b2f LP |
142 | |
143 | void loop_device_relinquish(LoopDevice *d) { | |
144 | assert(d); | |
145 | ||
146 | /* Don't attempt to clean up the loop device anymore from this point on. Leave the clean-ing up to the kernel | |
147 | * itself, using the loop device "auto-clear" logic we already turned on when creating the device. */ | |
148 | ||
149 | d->relinquished = true; | |
150 | } |