1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <unistd.h> |
3 | #include <stdbool.h> |
4 | #include <errno.h> |
5 | #include <linux/kernel.h> |
6 | #include <internal/lib.h> |
7 | |
8 | unsigned int page_size; |
9 | |
10 | static ssize_t ion(bool is_read, int fd, void *buf, size_t n) |
11 | { |
12 | void *buf_start = buf; |
13 | size_t left = n; |
14 | |
15 | while (left) { |
16 | /* buf must be treated as const if !is_read. */ |
17 | ssize_t ret = is_read ? read(fd, buf, left) : |
18 | write(fd, buf, left); |
19 | |
20 | if (ret < 0 && errno == EINTR) |
21 | continue; |
22 | if (ret <= 0) |
23 | return ret; |
24 | |
25 | left -= ret; |
26 | buf += ret; |
27 | } |
28 | |
29 | BUG_ON((size_t)(buf - buf_start) != n); |
30 | return n; |
31 | } |
32 | |
33 | /* |
34 | * Read exactly 'n' bytes or return an error. |
35 | */ |
36 | ssize_t readn(int fd, void *buf, size_t n) |
37 | { |
38 | return ion(is_read: true, fd, buf, n); |
39 | } |
40 | |
41 | ssize_t preadn(int fd, void *buf, size_t n, off_t offs) |
42 | { |
43 | size_t left = n; |
44 | |
45 | while (left) { |
46 | ssize_t ret = pread(fd, buf, left, offs); |
47 | |
48 | if (ret < 0 && errno == EINTR) |
49 | continue; |
50 | if (ret <= 0) |
51 | return ret; |
52 | |
53 | left -= ret; |
54 | buf += ret; |
55 | offs += ret; |
56 | } |
57 | |
58 | return n; |
59 | } |
60 | |
61 | /* |
62 | * Write exactly 'n' bytes or return an error. |
63 | */ |
64 | ssize_t writen(int fd, const void *buf, size_t n) |
65 | { |
66 | /* ion does not modify buf. */ |
67 | return ion(is_read: false, fd, buf: (void *)buf, n); |
68 | } |
69 | |