// 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
  ");

  			return 1;
  		}
  		strlcpy(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
  ");

  				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
  ");

  		return -1;
  	}
  
  	*dev = root_dev;
  	*opts = root_opts;
  
  	return 0;
  }