kern/parser.c

   1 /* parser.c - the part of the parser that can return partial tokens */
   2 /*
   3  *  GRUB  --  GRand Unified Bootloader
   4  *  Copyright (C) 2005,2007  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 <grub/parser.h>
  21 #include <grub/env.h>
  22 #include <grub/misc.h>
  23 #include <grub/mm.h>
  24
  25
  26 /* All the possible state transitions on the command line.  If a
  27    transition can not be found, it is assumed that there is no
  28    transition and keep_value is assumed to be 1.  */
  29 static struct grub_parser_state_transition state_transitions[] =
  30 {
  31   { GRUB_PARSER_STATE_TEXT, GRUB_PARSER_STATE_QUOTE, '\'', 0},
  32   { GRUB_PARSER_STATE_TEXT, GRUB_PARSER_STATE_DQUOTE, '\"', 0},
  33   { GRUB_PARSER_STATE_TEXT, GRUB_PARSER_STATE_VAR, '$', 0},
  34   { GRUB_PARSER_STATE_TEXT, GRUB_PARSER_STATE_ESC, '\\', 0},
  35
  36   { GRUB_PARSER_STATE_ESC, GRUB_PARSER_STATE_TEXT, 0, 1},
  37
  38   { GRUB_PARSER_STATE_QUOTE, GRUB_PARSER_STATE_TEXT, '\'', 0},
  39
  40   { GRUB_PARSER_STATE_DQUOTE, GRUB_PARSER_STATE_TEXT, '\"', 0},
  41   { GRUB_PARSER_STATE_DQUOTE, GRUB_PARSER_STATE_QVAR, '$', 0},
  42
  43   { GRUB_PARSER_STATE_VAR, GRUB_PARSER_STATE_VARNAME2, '{', 0},
  44   { GRUB_PARSER_STATE_VAR, GRUB_PARSER_STATE_VARNAME, 0, 1},
  45   { GRUB_PARSER_STATE_VARNAME, GRUB_PARSER_STATE_TEXT, ' ', 1},
  46   { GRUB_PARSER_STATE_VARNAME2, GRUB_PARSER_STATE_TEXT, '}', 0},
  47
  48   { GRUB_PARSER_STATE_QVAR, GRUB_PARSER_STATE_QVARNAME2, '{', 0},
  49   { GRUB_PARSER_STATE_QVAR, GRUB_PARSER_STATE_QVARNAME, 0, 1},
  50   { GRUB_PARSER_STATE_QVARNAME, GRUB_PARSER_STATE_DQUOTE, ' ', 1},
  51   { GRUB_PARSER_STATE_QVARNAME, GRUB_PARSER_STATE_TEXT, '\"', 0},
  52   { GRUB_PARSER_STATE_QVARNAME2, GRUB_PARSER_STATE_DQUOTE, '}', 0},
  53
  54   { 0, 0, 0, 0}
  55 };
  56
  57
  58 /* Determines the state following STATE, determined by C.  */
  59 grub_parser_state_t
  60 grub_parser_cmdline_state (grub_parser_state_t state, char c, char *result)
  61 {
  62   struct grub_parser_state_transition *transition;
  63   struct grub_parser_state_transition *next_match = 0;
  64   struct grub_parser_state_transition default_transition;
  65   int found = 0;
  66
  67   default_transition.to_state = state;
  68   default_transition.keep_value = 1;
  69
  70   /* Look for a good translation.  */
  71   for (transition = state_transitions; transition->from_state; transition++)
  72     {
  73       /* An exact match was found, use it.  */
  74       if (transition->from_state == state && transition->input == c)
  75         {
  76           found = 1;
  77           break;
  78         }
  79
  80       /* A less perfect match was found, use this one if no exact
  81          match can be found.  */
  82       if (transition->from_state == state && transition->input == 0)
  83         next_match = transition;
  84     }
  85
  86   if (! found)
  87     {
  88       if (next_match)
  89         transition = next_match;
  90       else
  91         transition = &default_transition;
  92     }
  93
  94   if (transition->keep_value)
  95     *result = c;
  96   else
  97     *result = 0;
  98   return transition->to_state;
  99 }
 100
 101
 102 grub_err_t
 103 grub_parser_split_cmdline (const char *cmdline, grub_err_t (*getline) (char **),
 104                            int *argc, char ***argv)
 105 {
 106   grub_parser_state_t state = GRUB_PARSER_STATE_TEXT;
 107   /* XXX: Fixed size buffer, perhaps this buffer should be dynamically
 108      allocated.  */
 109   char buffer[1024];
 110   char *bp = buffer;
 111   char *rd = (char *) cmdline;
 112   char varname[200];
 113   char *vp = varname;
 114   char *args;
 115   int i;
 116
 117   auto int check_varstate (grub_parser_state_t s);
 118
 119   int check_varstate (grub_parser_state_t s)
 120     {
 121       return (s == GRUB_PARSER_STATE_VARNAME
 122               || s == GRUB_PARSER_STATE_VARNAME2
 123               || s == GRUB_PARSER_STATE_QVARNAME
 124               || s == GRUB_PARSER_STATE_QVARNAME2);
 125     }
 126
 127   auto void add_var (grub_parser_state_t newstate);
 128
 129   void add_var (grub_parser_state_t newstate)
 130     {
 131       char *val;
 132
 133       /* Check if a variable was being read in and the end of the name
 134          was reached.  */
 135       if (! (check_varstate (state) && !check_varstate (newstate)))
 136         return;
 137
 138       *(vp++) = '\0';
 139       val = grub_env_get (varname);
 140       vp = varname;
 141       if (! val)
 142         return;
 143
 144       /* Insert the contents of the variable in the buffer.  */
 145       for (; *val; val++)
 146         *(bp++) = *val;
 147     }
 148
 149   *argc = 1;
 150   do
 151     {
 152       if (! *rd)
 153         {
 154           if (getline)
 155             getline (&rd);
 156           else break;
 157         }
 158
 159       for (; *rd; rd++)
 160         {
 161           grub_parser_state_t newstate;
 162           char use;
 163
 164           newstate = grub_parser_cmdline_state (state, *rd, &use);
 165
 166           /* If a variable was being processed and this character does
 167              not describe the variable anymore, write the variable to
 168              the buffer.  */
 169           add_var (newstate);
 170
 171           if (check_varstate (newstate))
 172             {
 173               if (use)
 174                 *(vp++) = use;
 175             }
 176           else
 177             {
 178               if (newstate == GRUB_PARSER_STATE_TEXT
 179                   && state != GRUB_PARSER_STATE_ESC && use == ' ')
 180                 {
 181                   /* Don't add more than one argument if multiple
 182                      spaces are used.  */
 183                   if (bp != buffer && *(bp - 1))
 184                     {
 185                       *(bp++) = '\0';
 186                       (*argc)++;
 187                     }
 188                 }
 189               else if (use)
 190                 *(bp++) = use;
 191             }
 192           state = newstate;
 193         }
 194     } while (state != GRUB_PARSER_STATE_TEXT && !check_varstate (state));
 195   *(bp++) = '\0';
 196
 197   /* A special case for when the last character was part of a
 198      variable.  */
 199   add_var (GRUB_PARSER_STATE_TEXT);
 200
 201
 202   /* Reserve memory for the return values.  */
 203   args = grub_malloc (bp - buffer);
 204   if (! args)
 205     return grub_errno;
 206   grub_memcpy (args, buffer, bp - buffer);
 207
 208   *argv = grub_malloc (sizeof (char *) * (*argc + 1));
 209   if (! *argv)
 210     {
 211       grub_free (args);
 212       return grub_errno;
 213     }
 214
 215   /* The arguments are separated with 0's, setup argv so it points to
 216      the right values.  */
 217   bp = args;
 218   for (i = 0; i < *argc; i++)
 219     {
 220       (*argv)[i] = bp;
 221       while (*bp)
 222         bp++;
 223       bp++;
 224     }
 225
 226   (*argc)--;
 227
 228   return 0;
 229 }