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
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