Source to ./parser.c


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/*
 * Cisco router simulation platform.
 * Copyright (c) 2006 Christophe Fillot (cf@utc.fr)
 *
 * Mini-parser.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <signal.h>
#include <fcntl.h>
#include <errno.h>
#include <assert.h>
#include <stdarg.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>

#include "utils.h"
#include "parser.h"

#define TOKEN_MAX_SIZE  512

/* Character types */
enum {
   PARSER_CHAR_BLANK,
   PARSER_CHAR_NEWLINE,
   PARSER_CHAR_COMMENT,
   PARSER_CHAR_QUOTE,
   PARSER_CHAR_OTHER,
};

/* Get a description given an error code */
char *parser_strerror(parser_context_t *ctx)
{
   printf("error = %d\n",ctx->error);

   switch(ctx->error) {
      case 0:
         return "no error";
      case PARSER_ERROR_NOMEM:
         return "insufficient memory";
      case PARSER_ERROR_UNEXP_QUOTE:
         return "unexpected quote";
      case PARSER_ERROR_UNEXP_EOL:
         return "unexpected end of line";
      default:
         return "unknown error";
   }
}

/* Dump a token list */
void parser_dump_tokens(parser_context_t *ctx)
{
   parser_token_t *tok;

   for(tok=ctx->tok_head;tok;tok=tok->next)
      printf("\"%s\" ",tok->value);
}

/* Map a token list to an array */
char **parser_map_array(parser_context_t *ctx)
{
   parser_token_t *tok;
   char **map;
   int i;

   if (ctx->tok_count <= 0)
      return NULL;

   if (!(map = calloc(ctx->tok_count,sizeof(char **))))
      return NULL;

   for(i=0,tok=ctx->tok_head;(i<ctx->tok_count) && tok;i++,tok=tok->next)
      map[i] = tok->value;

   return map;
}

/* Add a character to temporary token (resize if necessary) */
static int tmp_token_add_char(parser_context_t *ctx,char c)
{
   size_t new_size;
   char *new_str;

   if (!ctx->tmp_tok || (ctx->tmp_cur_len == (ctx->tmp_tot_len - 1))) {
      new_size = ctx->tmp_tot_len + TOKEN_MAX_SIZE;
      new_str  = realloc(ctx->tmp_tok,new_size);

      if (!new_str)
         return(-1);

      ctx->tmp_tok = new_str;
      ctx->tmp_tot_len = new_size;
   }

   ctx->tmp_tok[ctx->tmp_cur_len++] = c;
   ctx->tmp_tok[ctx->tmp_cur_len] = 0;
   return(0);
}

/* Move current token to the active token list */
static int parser_move_tmp_token(parser_context_t *ctx)
{
   parser_token_t *tok;

   /* no token ... */
   if (!ctx->tmp_tok)
      return(0);

   if (!(tok = malloc(sizeof(*tok))))
      return(-1);

   tok->value = ctx->tmp_tok;
   tok->next  = NULL;

   /* add it to the token list */
   if (ctx->tok_last != NULL)
      ctx->tok_last->next = tok;
   else
      ctx->tok_head = tok;

   ctx->tok_last = tok;
   ctx->tok_count++;

   /* start a new token */
   ctx->tmp_tok = NULL;
   ctx->tmp_tot_len = ctx->tmp_cur_len = 0;
   return(0);
}

/* Initialize parser context */
void parser_context_init(parser_context_t *ctx)
{
   ctx->tok_head = ctx->tok_last = NULL;
   ctx->tok_count = 0;

   ctx->tmp_tok = NULL;
   ctx->tmp_tot_len = ctx->tmp_cur_len = 0;

   ctx->state = PARSER_STATE_BLANK;
   ctx->error = 0;

   ctx->consumed_len = 0;
}

/* Free a token list */
void parser_free_tokens(parser_token_t *tok_list)
{
   parser_token_t *t,*next;

   for(t=tok_list;t;t=next) {
      next = t->next;
      free(t->value);
      free(t);
   }
}

/* Free memory used by a parser context */
void parser_context_free(parser_context_t *ctx)
{
   parser_free_tokens(ctx->tok_head);

   if (ctx->tmp_tok != NULL)
      free(ctx->tmp_tok);

   parser_context_init(ctx);
}

/* Determine the type of the input character */
static int parser_get_char_type(u_char c)
{
   switch(c) {
      case '\n':
      case '\r':
      case 0:
         return(PARSER_CHAR_NEWLINE);
      case '\t':
         //case '\r':
      case ' ':
         return(PARSER_CHAR_BLANK);
      case '!':
      case '#':
         return(PARSER_CHAR_COMMENT);
      case '"':
         return(PARSER_CHAR_QUOTE);
      default:
         return(PARSER_CHAR_OTHER);
   }
}

/* Send a buffer to the tokenizer */
int parser_scan_buffer(parser_context_t *ctx,char *buf,size_t buf_size)
{
   int i,type;
   u_char c;

   for(i=0;(i<buf_size) && (ctx->state != PARSER_STATE_DONE);i++)
   {
      ctx->consumed_len++;
      c = buf[i];
      
      /* Determine character type */
      type = parser_get_char_type(c);

      /* Basic finite state machine */
      switch(ctx->state) {
         case PARSER_STATE_SKIP:
            if (type == PARSER_CHAR_NEWLINE)
               ctx->state = PARSER_STATE_DONE;

            /* Simply ignore character until we reach end of line */
            break;

         case PARSER_STATE_BLANK:
            switch(type) {
               case PARSER_CHAR_BLANK:
                  /* Eat space */
                  break;

               case PARSER_CHAR_COMMENT:
                  ctx->state = PARSER_STATE_SKIP;
                  break;

               case PARSER_CHAR_NEWLINE:
                  ctx->state = PARSER_STATE_DONE;
                  break;

               case PARSER_CHAR_QUOTE:
                  ctx->state = PARSER_STATE_QUOTED_STRING;
                  break;
                  
               default:
                  /* Begin a new string */
                  if (!tmp_token_add_char(ctx,c)) {
                     ctx->state = PARSER_STATE_STRING;
                  } else {
                     ctx->state = PARSER_STATE_SKIP;
                     ctx->error = PARSER_ERROR_NOMEM;
                  }
            }
            break;

         case PARSER_STATE_STRING:
            switch(type) {
               case PARSER_CHAR_BLANK:
                  if (!parser_move_tmp_token(ctx)) {
                     ctx->state = PARSER_STATE_BLANK;
                  } else {
                     ctx->state = PARSER_STATE_SKIP;
                     ctx->error = PARSER_ERROR_NOMEM;
                  }
                  break;

               case PARSER_CHAR_NEWLINE:
                  if (parser_move_tmp_token(ctx) == -1)
                     ctx->error = PARSER_ERROR_NOMEM;

                  ctx->state = PARSER_STATE_DONE;
                  break;

               case PARSER_CHAR_COMMENT:
                  if (parser_move_tmp_token(ctx) == -1)
                     ctx->error = PARSER_ERROR_NOMEM;

                  ctx->state = PARSER_STATE_SKIP;
                  break;

               case PARSER_CHAR_QUOTE:
                  ctx->error = PARSER_ERROR_UNEXP_QUOTE;
                  ctx->state = PARSER_STATE_SKIP;
                  break;

               default:
                  /* Add the character to the buffer */
                  if (tmp_token_add_char(ctx,c) == -1) {
                     ctx->state = PARSER_STATE_SKIP;
                     ctx->error = PARSER_ERROR_NOMEM;
                  }
            }
            break;

         case PARSER_STATE_QUOTED_STRING:
            switch(type) {
               case PARSER_CHAR_NEWLINE:
                  /* Unterminated string! */
                  ctx->error = PARSER_ERROR_UNEXP_EOL;
                  ctx->state = PARSER_STATE_DONE;
                  break;

               case PARSER_CHAR_QUOTE:
                  if (!parser_move_tmp_token(ctx)) {
                     ctx->state = PARSER_STATE_BLANK;
                  } else {
                     ctx->state = PARSER_STATE_SKIP;
                     ctx->error = PARSER_ERROR_NOMEM;
                  }
                  break;

               default:
                  /* Add the character to the buffer */
                  if (tmp_token_add_char(ctx,c) == -1) {
                     ctx->state = PARSER_STATE_SKIP;
                     ctx->error = PARSER_ERROR_NOMEM;
                  }
            }
            break;
      }
   }

   return(ctx->state == PARSER_STATE_DONE);
}

/* Parser tests */
static char *parser_test_str[] = {
   "c7200 show_hardware R1",
   "c7200 show_hardware \"R1\"",
   "   c7200    show_hardware   \"R1\"    ",
   "\"c7200\" \"show_hardware\" \"R1\"",
   "hypervisor set_working_dir \"C:\\Program Files\\Dynamips Test\"",
   "hypervisor # This is a comment set_working_dir \"C:\\Program Files\"",
   "\"c7200\" \"show_hardware\" \"R1",
   NULL,
};

void parser_run_tests(void)
{
   parser_context_t ctx;
   int i,res;

   for(i=0;parser_test_str[i];i++) {
      parser_context_init(&ctx);

      res = parser_scan_buffer(&ctx,parser_test_str[i],
                               strlen(parser_test_str[i])+1);

      printf("\n%d: Test string: [%s] => res=%d, state=%d\n",
             i,parser_test_str[i],res,ctx.state);
      
      if ((res != 0) && (ctx.error == 0)) {
         if (ctx.tok_head) {
            printf("Tokens: ");
            parser_dump_tokens(&ctx);
            printf("\n");
         }
      }

      parser_context_free(&ctx);
   }
}