fs/cifs/unc.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *   Copyright (C) 2020, Microsoft Corporation.
   4  *
   5  *   Author(s): Steve French <stfrench@microsoft.com>
   6  *              Suresh Jayaraman <sjayaraman@suse.de>
   7  *              Jeff Layton <jlayton@kernel.org>
   8  */
   9
  10 #include <linux/fs.h>
  11 #include <linux/slab.h>
  12 #include <linux/inet.h>
  13 #include <linux/ctype.h>
  14 #include "cifsglob.h"
  15 #include "cifsproto.h"
  16
  17 /* extract the host portion of the UNC string */
  18 char *extract_hostname(const char *unc)
  19 {
  20         const char *src;
  21         char *dst, *delim;
  22         unsigned int len;
  23
  24         /* skip double chars at beginning of string */
  25         /* BB: check validity of these bytes? */
  26         if (strlen(unc) < 3)
  27                 return ERR_PTR(-EINVAL);
  28         for (src = unc; *src && *src == '\\'; src++)
  29                 ;
  30         if (!*src)
  31                 return ERR_PTR(-EINVAL);
  32
  33         /* delimiter between hostname and sharename is always '\\' now */
  34         delim = strchr(src, '\\');
  35         if (!delim)
  36                 return ERR_PTR(-EINVAL);
  37
  38         len = delim - src;
  39         dst = kmalloc((len + 1), GFP_KERNEL);
  40         if (dst == NULL)
  41                 return ERR_PTR(-ENOMEM);
  42
  43         memcpy(dst, src, len);
  44         dst[len] = '\0';
  45
  46         return dst;
  47 }
  48
  49 char *extract_sharename(const char *unc)
  50 {
  51         const char *src;
  52         char *delim, *dst;
  53         int len;
  54
  55         /* skip double chars at the beginning */
  56         src = unc + 2;
  57
  58         /* share name is always preceded by '\\' now */
  59         delim = strchr(src, '\\');
  60         if (!delim)
  61                 return ERR_PTR(-EINVAL);
  62         delim++;
  63         len = strlen(delim);
  64
  65         /* caller has to free the memory */
  66         dst = kstrndup(delim, len, GFP_KERNEL);
  67         if (!dst)
  68                 return ERR_PTR(-ENOMEM);
  69
  70         return dst;
  71 }