/* SPDX-License-Identifier: GPL-2.0 */
/*
 * Copyright (c) 2024 Meta Platforms, Inc. and affiliates.
 * Copyright (c) 2024 David Vernet <dvernet@meta.com>
 */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

/* Returns read len on success, or -errno on failure. */
static ssize_t read_text(const char *path, char *buf, size_t max_len)
{
        ssize_t len;
        int fd;

        fd = open(path, O_RDONLY);
        if (fd < 0)
                return -errno;

        len = read(fd, buf, max_len - 1);

        if (len >= 0)
                buf[len] = 0;

        close(fd);
        return len < 0 ? -errno : len;
}

/* Returns written len on success, or -errno on failure. */
static ssize_t write_text(const char *path, char *buf, ssize_t len)
{
        int fd;
        ssize_t written;

        fd = open(path, O_WRONLY | O_APPEND);
        if (fd < 0)
                return -errno;

        written = write(fd, buf, len);
        close(fd);
        return written < 0 ? -errno : written;
}

long file_read_long(const char *path)
{
        char buf[128];


        if (read_text(path, buf, sizeof(buf)) <= 0)
                return -1;

        return atol(buf);
}

int file_write_long(const char *path, long val)
{
        char buf[64];
        int ret;

        ret = sprintf(buf, "%ld", val);
        if (ret < 0)
                return ret;

        if (write_text(path, buf, ret) <= 0)
                return -1;

        return 0;
}