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
13 static char *saved_boot_config;
14
boot_config_proc_show(struct seq_file * m,void * v)15 static int boot_config_proc_show(struct seq_file *m, void *v)
16 {
17 if (saved_boot_config)
18 seq_puts(m, 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 */
copy_xbc_key_value_list(char * dst,size_t size)26 static 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(leaf, key, XBC_KEYLEN_MAX);
40 if (ret < 0)
41 break;
42 ret = snprintf(dst, rest(dst, end), "%s = ", key);
43 if (ret < 0)
44 break;
45 dst += ret;
46 vnode = xbc_node_get_child(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(dst, rest(dst, end), "%c%s%c%s",
54 q, val, q, xbc_node_is_array(vnode) ? ", " : "\n");
55 if (ret < 0)
56 goto out;
57 dst += ret;
58 }
59 } else {
60 ret = snprintf(dst, rest(dst, end), "\"\"\n");
61 if (ret < 0)
62 break;
63 dst += ret;
64 }
65 }
66 out:
67 kfree(key);
68
69 return ret < 0 ? ret : dst - (end - size);
70 }
71
proc_boot_config_init(void)72 static int __init proc_boot_config_init(void)
73 {
74 int len;
75
76 len = copy_xbc_key_value_list(NULL, 0);
77 if (len < 0)
78 return len;
79
80 if (len > 0) {
81 saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
82 if (!saved_boot_config)
83 return -ENOMEM;
84
85 len = copy_xbc_key_value_list(saved_boot_config, len + 1);
86 if (len < 0) {
87 kfree(saved_boot_config);
88 return len;
89 }
90 }
91
92 proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
93
94 return 0;
95 }
96 fs_initcall(proc_boot_config_init);
97