systemd/src/shared/device-nodes.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <errno.h>
#include <stdio.h>
#include <string.h>

#include "device-nodes.h"
#include "string-util.h"
#include "utf8.h"

int allow_listed_char_for_devnode(char c, const char *additional) {
        return
                ascii_isdigit(c) ||
                ascii_isalpha(c) ||
                strchr("#+-.:=@_", c) ||
                (additional && strchr(additional, c));
}

int encode_devnode_name(const char *str, char *str_enc, size_t len) {
        size_t i, j;

        if (!str || !str_enc)
                return -EINVAL;

        for (i = 0, j = 0; str[i] != '\0'; i++) {
                int seqlen;

                seqlen = utf8_encoded_valid_unichar(str + i, SIZE_MAX);
                if (seqlen > 1) {

                        if (len-j < (size_t) seqlen)
                                return -EINVAL;

                        memcpy(&str_enc[j], &str[i], seqlen);
                        j += seqlen;
                        i += (seqlen-1);

                } else if (str[i] == '\\' || !allow_listed_char_for_devnode(str[i], NULL)) {

                        if (len-j < 4)
                                return -EINVAL;

                        sprintf(&str_enc[j], "\\x%02x", (unsigned char) str[i]);
                        j += 4;

                } else {
                        if (len-j < 1)
                                return -EINVAL;

                        str_enc[j] = str[i];
                        j++;
                }
        }

        if (len-j < 1)
                return -EINVAL;

        str_enc[j] = '\0';
        return 0;
}