1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* 3 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates. 4 * Copyright (c) 2024 David Vernet <dvernet@meta.com> 5 */ 6 #include <errno.h> 7 #include <fcntl.h> 8 #include <stdio.h> 9 #include <stdlib.h> 10 #include <string.h> 11 #include <unistd.h> 12 13 /* Returns read len on success, or -errno on failure. */ 14 static ssize_t read_text(const char *path, char *buf, size_t max_len) 15 { 16 ssize_t len; 17 int fd; 18 19 fd = open(path, O_RDONLY); 20 if (fd < 0) 21 return -errno; 22 23 len = read(fd, buf, max_len - 1); 24 25 if (len >= 0) 26 buf[len] = 0; 27 28 close(fd); 29 return len < 0 ? -errno : len; 30 } 31 32 /* Returns written len on success, or -errno on failure. */ 33 static ssize_t write_text(const char *path, char *buf, ssize_t len) 34 { 35 int fd; 36 ssize_t written; 37 38 fd = open(path, O_WRONLY | O_APPEND); 39 if (fd < 0) 40 return -errno; 41 42 written = write(fd, buf, len); 43 close(fd); 44 return written < 0 ? -errno : written; 45 } 46 47 long file_read_long(const char *path) 48 { 49 char buf[128]; 50 51 52 if (read_text(path, buf, sizeof(buf)) <= 0) 53 return -1; 54 55 return atol(buf); 56 } 57 58 int file_write_long(const char *path, long val) 59 { 60 char buf[64]; 61 int ret; 62 63 ret = sprintf(buf, "%lu", val); 64 if (ret < 0) 65 return ret; 66 67 if (write_text(path, buf, sizeof(buf)) <= 0) 68 return -1; 69 70 return 0; 71 } 72