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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
8c1be37e LP |
2 | /*** |
3 | This file is part of systemd. | |
4 | ||
5 | Copyright 2016 Lennart Poettering | |
6 | ||
7 | systemd is free software; you can redistribute it and/or modify it | |
8 | under the terms of the GNU Lesser General Public License as published by | |
9 | the Free Software Foundation; either version 2.1 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | systemd is distributed in the hope that it will be useful, but | |
13 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | Lesser General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU Lesser General Public License | |
18 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
19 | ***/ | |
20 | ||
21 | #include <fcntl.h> | |
22 | #include <linux/loop.h> | |
23 | #include <sys/ioctl.h> | |
24 | #include <sys/stat.h> | |
25 | ||
26 | #include "alloc-util.h" | |
27 | #include "fd-util.h" | |
28 | #include "loop-util.h" | |
29 | ||
30 | int loop_device_make(int fd, int open_flags, LoopDevice **ret) { | |
31 | const struct loop_info64 info = { | |
32 | .lo_flags = LO_FLAGS_AUTOCLEAR|LO_FLAGS_PARTSCAN|(open_flags == O_RDONLY ? LO_FLAGS_READ_ONLY : 0), | |
33 | }; | |
34 | ||
35 | _cleanup_close_ int control = -1, loop = -1; | |
36 | _cleanup_free_ char *loopdev = NULL; | |
37 | struct stat st; | |
38 | LoopDevice *d; | |
39 | int nr; | |
40 | ||
41 | assert(fd >= 0); | |
42 | assert(ret); | |
43 | assert(IN_SET(open_flags, O_RDWR, O_RDONLY)); | |
44 | ||
45 | if (fstat(fd, &st) < 0) | |
46 | return -errno; | |
47 | ||
48 | if (S_ISBLK(st.st_mode)) { | |
49 | int copy; | |
50 | ||
51 | /* If this is already a block device, store a copy of the fd as it is */ | |
52 | ||
53 | copy = fcntl(fd, F_DUPFD_CLOEXEC, 3); | |
54 | if (copy < 0) | |
55 | return -errno; | |
56 | ||
57 | d = new0(LoopDevice, 1); | |
58 | if (!d) | |
59 | return -ENOMEM; | |
60 | ||
61 | *d = (LoopDevice) { | |
62 | .fd = copy, | |
63 | .nr = -1, | |
64 | }; | |
65 | ||
66 | *ret = d; | |
67 | ||
68 | return 0; | |
69 | } | |
70 | ||
71 | if (!S_ISREG(st.st_mode)) | |
72 | return -EINVAL; | |
73 | ||
74 | control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK); | |
75 | if (control < 0) | |
76 | return -errno; | |
77 | ||
78 | nr = ioctl(control, LOOP_CTL_GET_FREE); | |
79 | if (nr < 0) | |
80 | return -errno; | |
81 | ||
82 | if (asprintf(&loopdev, "/dev/loop%i", nr) < 0) | |
83 | return -ENOMEM; | |
84 | ||
85 | loop = open(loopdev, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags); | |
86 | if (loop < 0) | |
87 | return -errno; | |
88 | ||
89 | if (ioctl(loop, LOOP_SET_FD, fd) < 0) | |
90 | return -errno; | |
91 | ||
92 | if (ioctl(loop, LOOP_SET_STATUS64, &info) < 0) | |
93 | return -errno; | |
94 | ||
95 | d = new(LoopDevice, 1); | |
96 | if (!d) | |
97 | return -ENOMEM; | |
98 | ||
99 | *d = (LoopDevice) { | |
100 | .fd = loop, | |
101 | .node = loopdev, | |
102 | .nr = nr, | |
103 | }; | |
104 | ||
105 | loop = -1; | |
106 | loopdev = NULL; | |
107 | ||
108 | *ret = d; | |
109 | ||
110 | return (*ret)->fd; | |
111 | } | |
112 | ||
113 | int loop_device_make_by_path(const char *path, int open_flags, LoopDevice **ret) { | |
114 | _cleanup_close_ int fd = -1; | |
115 | ||
116 | assert(path); | |
117 | assert(ret); | |
118 | assert(IN_SET(open_flags, O_RDWR, O_RDONLY)); | |
119 | ||
120 | fd = open(path, O_CLOEXEC|O_NONBLOCK|O_NOCTTY|open_flags); | |
121 | if (fd < 0) | |
122 | return -errno; | |
123 | ||
124 | return loop_device_make(fd, open_flags, ret); | |
125 | } | |
126 | ||
127 | LoopDevice* loop_device_unref(LoopDevice *d) { | |
128 | if (!d) | |
129 | return NULL; | |
130 | ||
131 | if (d->fd >= 0) { | |
132 | ||
a2ea3b2f | 133 | if (d->nr >= 0 && !d->relinquished) { |
8c1be37e LP |
134 | if (ioctl(d->fd, LOOP_CLR_FD) < 0) |
135 | log_debug_errno(errno, "Failed to clear loop device: %m"); | |
136 | ||
137 | } | |
138 | ||
139 | safe_close(d->fd); | |
140 | } | |
141 | ||
a2ea3b2f | 142 | if (d->nr >= 0 && !d->relinquished) { |
8c1be37e LP |
143 | _cleanup_close_ int control = -1; |
144 | ||
145 | control = open("/dev/loop-control", O_RDWR|O_CLOEXEC|O_NOCTTY|O_NONBLOCK); | |
146 | if (control < 0) | |
147 | log_debug_errno(errno, "Failed to open loop control device: %m"); | |
148 | else { | |
149 | if (ioctl(control, LOOP_CTL_REMOVE, d->nr) < 0) | |
150 | log_debug_errno(errno, "Failed to remove loop device: %m"); | |
151 | } | |
152 | } | |
153 | ||
154 | free(d->node); | |
155 | free(d); | |
156 | ||
157 | return NULL; | |
158 | } | |
a2ea3b2f LP |
159 | |
160 | void loop_device_relinquish(LoopDevice *d) { | |
161 | assert(d); | |
162 | ||
163 | /* Don't attempt to clean up the loop device anymore from this point on. Leave the clean-ing up to the kernel | |
164 | * itself, using the loop device "auto-clear" logic we already turned on when creating the device. */ | |
165 | ||
166 | d->relinquished = true; | |
167 | } |