Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
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linux
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
8unsigned int page_size;
9
10static 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 */
36ssize_t readn(int fd, void *buf, size_t n)
37{
38 return ion(true, fd, buf, n);
39}
40
41/*
42 * Write exactly 'n' bytes or return an error.
43 */
44ssize_t writen(int fd, const void *buf, size_t n)
45{
46 /* ion does not modify buf. */
47 return ion(false, fd, (void *)buf, n);
48}