| 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 | } |