lib/envblk.c

   1 /* envblk.c - Common function for environment block.  */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2008  Free Software Foundation, Inc.
   5  *
   6  *  GRUB is free software: you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation, either version 3 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  GRUB is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <config.h>
  21 #include <grub/types.h>
  22 #include <grub/misc.h>
  23 #include <grub/lib/envblk.h>
  24
  25 grub_envblk_t
  26 grub_envblk_find (char *buf)
  27 {
  28   grub_uint32_t *pd;
  29   int len;
  30
  31   pd = (grub_uint32_t *) buf;
  32
  33   for (len = GRUB_ENVBLK_MAXLEN - 6; len > 0; len -= 4, pd++)
  34     if (*pd == GRUB_ENVBLK_SIGNATURE)
  35       {
  36         grub_envblk_t p;
  37
  38         p = (grub_envblk_t) pd;
  39         if (p->length <= len)
  40           return p;
  41       }
  42
  43   return 0;
  44 }
  45
  46 int
  47 grub_envblk_insert (grub_envblk_t envblk, char *name, char *value)
  48 {
  49   char *p, *pend;
  50   char *found = 0;
  51   int nl;
  52
  53   nl = grub_strlen (name);
  54   p = envblk->data;
  55   pend = p + envblk->length;
  56
  57   while (*p)
  58     {
  59       if ((! found) && (! grub_memcmp (name, p, nl)) && (p[nl] == '='))
  60         found = p + nl + 1;
  61
  62       p += grub_strlen (p) + 1;
  63       if (p >= pend)
  64         return 1;
  65     }
  66
  67   if (found)
  68     {
  69       int len1, len2;
  70
  71       len1 = grub_strlen (found);
  72       len2 = grub_strlen (value);
  73       if ((p - envblk->data) + 1 - len1 + len2 > envblk->length)
  74         return 1;
  75
  76       grub_memcpy (found + len2 + 1, found + len1 + 1, (p - found) - len1);
  77       grub_strcpy (found, value);
  78     }
  79   else
  80     {
  81       int len2 = grub_strlen (value);
  82
  83       if ((p - envblk->data) + nl + 1 + len2 + 2 > envblk->length)
  84         return 1;
  85
  86       grub_strcpy (p, name);
  87       p[nl] = '=';
  88       grub_strcpy (p + nl + 1, value);
  89       p[nl + 1 + len2 + 1] = 0;
  90     }
  91
  92   return 0;
  93 }
  94
  95 void
  96 grub_envblk_delete (grub_envblk_t envblk, char *name)
  97 {
  98   char *p, *pend;
  99   char *found = 0;
 100   int nl;
 101
 102   nl = grub_strlen (name);
 103   p = envblk->data;
 104   pend = p + envblk->length;
 105
 106   while (*p)
 107     {
 108       if ((! found) && (! grub_memcmp (name, p, nl)) && (p[nl] == '='))
 109         found = p;
 110
 111       p += grub_strlen (p) + 1;
 112       if (p >= pend)
 113         return;
 114     }
 115
 116   if (found)
 117     {
 118       int len;
 119
 120       len = grub_strlen (found);
 121       grub_memcpy (found, found + len + 1, (p - found) - len);
 122     }
 123 }
 124
 125 void
 126 grub_envblk_iterate (grub_envblk_t envblk,
 127                      int hook (char *name, char *value))
 128 {
 129   char *p, *pend;
 130
 131   p = envblk->data;
 132   pend = p + envblk->length;
 133
 134   while (*p)
 135     {
 136       char *v;
 137       int r;
 138
 139       v = grub_strchr (p, '=');
 140       if (v)
 141         {
 142           *v = 0;
 143           r = hook (p, v + 1);
 144           *v = '=';
 145         }
 146       else
 147         r = hook (p, "");
 148
 149       if (r)
 150         break;
 151
 152       p += grub_strlen (p) + 1;
 153       if (p >= pend)
 154         break;
 155     }
 156 }