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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. */14static 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. */33static 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 47long 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 58int 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