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1 | /* |
2 | * Copyright (c) 2019, Mellanox Technologies. All rights reserved. | |
3 | * Copyright (C) 2023 Intel Corporation. | |
4 | * | |
5 | * This software is available to you under a choice of one of two | |
6 | * licenses. You may choose to be licensed under the terms of the GNU | |
7 | * General Public License (GPL) Version 2, available from the file | |
8 | * COPYING in the main directory of this source tree, or the | |
9 | * OpenIB.org BSD license below: | |
10 | * | |
11 | * Redistribution and use in source and binary forms, with or | |
12 | * without modification, are permitted provided that the following | |
13 | * conditions are met: | |
14 | * | |
15 | * - Redistributions of source code must retain the above | |
16 | * copyright notice, this list of conditions and the following | |
17 | * disclaimer. | |
18 | * | |
19 | * - Redistributions in binary form must reproduce the above | |
20 | * copyright notice, this list of conditions and the following | |
21 | * disclaimer in the documentation and/or other materials | |
22 | * provided with the distribution. | |
23 | * | |
24 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
25 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
26 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
27 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
28 | * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
29 | * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
30 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
31 | * SOFTWARE. | |
32 | * | |
33 | * Authors: Yi Liu <yi.l.liu@intel.com> | |
34 | * | |
35 | * Copied from | |
36 | * https://github.com/linux-rdma/rdma-core/blob/master/util/open_cdev.c | |
37 | * | |
38 | */ | |
39 | ||
40 | #include "qemu/osdep.h" | |
41 | #include "qemu/chardev_open.h" | |
42 | ||
43 | static int open_cdev_internal(const char *path, dev_t cdev) | |
44 | { | |
45 | struct stat st; | |
46 | int fd; | |
47 | ||
48 | fd = qemu_open_old(path, O_RDWR); | |
49 | if (fd == -1) { | |
50 | return -1; | |
51 | } | |
52 | if (fstat(fd, &st) || !S_ISCHR(st.st_mode) || | |
53 | (cdev != 0 && st.st_rdev != cdev)) { | |
54 | close(fd); | |
55 | return -1; | |
56 | } | |
57 | return fd; | |
58 | } | |
59 | ||
60 | static int open_cdev_robust(dev_t cdev) | |
61 | { | |
62 | g_autofree char *devpath = NULL; | |
63 | ||
64 | /* | |
65 | * This assumes that udev is being used and is creating the /dev/char/ | |
66 | * symlinks. | |
67 | */ | |
68 | devpath = g_strdup_printf("/dev/char/%u:%u", major(cdev), minor(cdev)); | |
69 | return open_cdev_internal(devpath, cdev); | |
70 | } | |
71 | ||
72 | int open_cdev(const char *devpath, dev_t cdev) | |
73 | { | |
74 | int fd; | |
75 | ||
76 | fd = open_cdev_internal(devpath, cdev); | |
77 | if (fd == -1 && cdev != 0) { | |
78 | return open_cdev_robust(cdev); | |
79 | } | |
80 | return fd; | |
81 | } |