fs/proc/bootconfig.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * /proc/bootconfig - Extra boot configuration
0004  */
0005 #include <linux/fs.h>
0006 #include <linux/init.h>
0007 #include <linux/printk.h>
0008 #include <linux/proc_fs.h>
0009 #include <linux/seq_file.h>
0010 #include <linux/bootconfig.h>
0011 #include <linux/slab.h>
0012
0013 static char *saved_boot_config;
0014
0015 static int boot_config_proc_show(struct seq_file *m, void *v)
0016 {
0017     if (saved_boot_config)
0018         seq_puts(m, saved_boot_config);
0019     return 0;
0020 }
0021
0022 /* Rest size of buffer */
0023 #define rest(dst, end) ((end) > (dst) ? (end) - (dst) : 0)
0024
0025 /* Return the needed total length if @size is 0 */
0026 static int __init copy_xbc_key_value_list(char *dst, size_t size)
0027 {
0028     struct xbc_node *leaf, *vnode;
0029     char *key, *end = dst + size;
0030     const char *val;
0031     char q;
0032     int ret = 0;
0033
0034     key = kzalloc(XBC_KEYLEN_MAX, GFP_KERNEL);
0035     if (!key)
0036         return -ENOMEM;
0037
0038     xbc_for_each_key_value(leaf, val) {
0039         ret = xbc_node_compose_key(leaf, key, XBC_KEYLEN_MAX);
0040         if (ret < 0)
0041             break;
0042         ret = snprintf(dst, rest(dst, end), "%s = ", key);
0043         if (ret < 0)
0044             break;
0045         dst += ret;
0046         vnode = xbc_node_get_child(leaf);
0047         if (vnode) {
0048             xbc_array_for_each_value(vnode, val) {
0049                 if (strchr(val, '"'))
0050                     q = '\'';
0051                 else
0052                     q = '"';
0053                 ret = snprintf(dst, rest(dst, end), "%c%s%c%s",
0054                     q, val, q, xbc_node_is_array(vnode) ? ", " : "\n");
0055                 if (ret < 0)
0056                     goto out;
0057                 dst += ret;
0058             }
0059         } else {
0060             ret = snprintf(dst, rest(dst, end), "\"\"\n");
0061             if (ret < 0)
0062                 break;
0063             dst += ret;
0064         }
0065     }
0066 out:
0067     kfree(key);
0068
0069     return ret < 0 ? ret : dst - (end - size);
0070 }
0071
0072 static int __init proc_boot_config_init(void)
0073 {
0074     int len;
0075
0076     len = copy_xbc_key_value_list(NULL, 0);
0077     if (len < 0)
0078         return len;
0079
0080     if (len > 0) {
0081         saved_boot_config = kzalloc(len + 1, GFP_KERNEL);
0082         if (!saved_boot_config)
0083             return -ENOMEM;
0084
0085         len = copy_xbc_key_value_list(saved_boot_config, len + 1);
0086         if (len < 0) {
0087             kfree(saved_boot_config);
0088             return len;
0089         }
0090     }
0091
0092     proc_create_single("bootconfig", 0, NULL, boot_config_proc_show);
0093
0094     return 0;
0095 }
0096 fs_initcall(proc_boot_config_init);