// SPDX-License-Identifier: GPL-2.0
/*
 * SMB root file system support
 *
 * Copyright (c) 2019 Paulo Alcantara <palcantara@suse.de>
 */
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/root_dev.h>
#include <linux/kernel.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <net/ipconfig.h>

#define DEFAULT_MNT_OPTS \
        "vers=1.0,cifsacl,mfsymlinks,rsize=1048576,wsize=65536,uid=0,gid=0," \
        "hard,rootfs"

static char root_dev[2048] __initdata = "";
static char root_opts[1024] __initdata = DEFAULT_MNT_OPTS;

static __be32 __init parse_srvaddr(char *start, char *end)
{
        /* TODO: ipv6 support */
        char addr[sizeof("aaa.bbb.ccc.ddd")];
        int i = 0;

        while (start < end && i < sizeof(addr) - 1) {
                if (isdigit(*start) || *start == '.')
                        addr[i++] = *start;
                start++;
        }
        addr[i] = '\0';
        return in_aton(addr);
}

/* cifsroot=//<server-ip>/<share>[,options] */
static int __init cifs_root_setup(char *line)
{
        char *s;
        int len;
        __be32 srvaddr = htonl(INADDR_NONE);

        ROOT_DEV = Root_CIFS;

        if (strlen(line) > 3 && line[0] == '/' && line[1] == '/') {
                s = strchr(&line[2], '/');
                if (!s || s[1] == '\0')
                        return 1;

                /* make s point to ',' or '\0' at end of line */
                s = strchrnul(s, ',');
                /* len is strlen(unc) + '\0' */
                len = s - line + 1;
                if (len > sizeof(root_dev)) {
                        pr_err("Root-CIFS: UNC path too long\n");
                        return 1;
                }
                strscpy(root_dev, line, len);
                srvaddr = parse_srvaddr(&line[2], s);
                if (*s) {
                        int n = snprintf(root_opts,
                                         sizeof(root_opts), "%s,%s",
                                         DEFAULT_MNT_OPTS, s + 1);
                        if (n >= sizeof(root_opts)) {
                                pr_err("Root-CIFS: mount options string too long\n");
                                root_opts[sizeof(root_opts)-1] = '\0';
                                return 1;
                        }
                }
        }

        root_server_addr = srvaddr;

        return 1;
}

__setup("cifsroot=", cifs_root_setup);

int __init cifs_root_data(char **dev, char **opts)
{
        if (!root_dev[0] || root_server_addr == htonl(INADDR_NONE)) {
                pr_err("Root-CIFS: no SMB server address\n");
                return -1;
        }

        *dev = root_dev;
        *opts = root_opts;

        return 0;
}