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 } 82