1// SPDX-License-Identifier: GPL-2.0
2/*
3 * /proc/bootconfig - Extra boot configuration
4 */
5#include <linux/fs.h>
6#include <linux/init.h>
7#include <linux/printk.h>
8#include <linux/proc_fs.h>
9#include <linux/seq_file.h>
10#include <linux/bootconfig.h>
11#include <linux/slab.h>
12
13static char *saved_boot_config;
14
15static int boot_config_proc_show(struct seq_file *m, void *v)
16{
17 if (saved_boot_config)
18 seq_puts(m, s: saved_boot_config);
19 return 0;
20}
21
22/* Rest size of buffer */
23#define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
24
25/* Return the needed total length if @size is 0 */
26static int __init copy_xbc_key_value_list(char *dst, size_t size)
27{
28 struct xbc_node *leaf, *vnode;
29 char *key, *end = dst + size;
30 const char *val;
31 char q;
32 int ret = 0;
33
34 key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
35 if (!key)
36 return -ENOMEM;
37
38 xbc_for_each_key_value(leaf, val) {
39 ret = xbc_node_compose_key(node: leaf, buf: key, XBC_KEYLEN_MAX);
40 if (ret < 0)
41 break;
42 ret = snprintf(buf: dst, rest(dst, end), fmt: "%s = ", key);
43 if (ret < 0)
44 break;
45 dst += ret;
46 vnode = xbc_node_get_child(node: leaf);
47 if (vnode) {
48 xbc_array_for_each_value(vnode, val) {
49 if (strchr(val, '"'))
50 q = '\'';
51 else
52 q = '"';
53 ret = snprintf(buf: dst, rest(dst, end), fmt: "%c%s%c%s",
54 q, val, q, xbc_node_is_array(node: vnode) ? ", " : "\n");
55 if (ret < 0)
56 goto out;
57 dst += ret;
58 }
59 } else {
60 ret = snprintf(buf: dst, rest(dst, end), fmt: "\"\"\n");
61 if (ret < 0)
62 break;
63 dst += ret;
64 }
65 }
66 if (cmdline_has_extra_options() && ret >= 0 && boot_command_line[0]) {
67 ret = snprintf(buf: dst, rest(dst, end), fmt: "# Parameters from bootloader:\n# %s\n",
68 boot_command_line);
69 if (ret > 0)
70 dst += ret;
71 }
72out:
73 kfree(objp: key);
74
75 return ret < 0 ? ret : dst - (end - size);
76}
77
78static int __init proc_boot_config_init(void)
79{
80 int len;
81
82 len = copy_xbc_key_value_list(NULL, size: 0);
83 if (len < 0)
84 return len;
85
86 if (len > 0) {
87 saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
88 if (!saved_boot_config)
89 return -ENOMEM;
90
91 len = copy_xbc_key_value_list(dst: saved_boot_config, size: len + 1);
92 if (len < 0) {
93 kfree(objp: saved_boot_config);
94 return len;
95 }
96 }
97
98 proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
99
100 return 0;
101}
102fs_initcall(proc_boot_config_init);
103

source code of linux/fs/proc/bootconfig.c