tools/cfgparser.c

/****************************************************************************
 * tools/cfgparser.c
 *
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.  The
 * ASF licenses this file to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance with the
 * License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 ****************************************************************************/

/****************************************************************************
 * Included Files
 ****************************************************************************/

#include <string.h>
#include <stdlib.h>
#include <ctype.h>

#include "cfgparser.h"

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/

/****************************************************************************
 * Public Data
 ****************************************************************************/

char line[LINESIZE + 1];

/****************************************************************************
 * Private Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/* Skip over any spaces */

static char *skip_space(char *ptr)
{
  while (*ptr && isspace((int)*ptr)) ptr++;
  return ptr;
}

/* Find the end of a variable string */

static char *find_name_end(char *ptr)
{
  while (*ptr && (isalnum((int)*ptr) || *ptr == '_')) ptr++;
  return ptr;
}

/* Find the end of a value string */

static char *find_value_end(char *ptr)
{
  while (*ptr && !isspace((int)*ptr))
    {
      if (*ptr == '"')
        {
          do ptr++; while (*ptr && *ptr != '"');
          if (*ptr) ptr++;
        }
      else
        {
          do ptr++; while (*ptr && !isspace((int)*ptr) && *ptr != '"');
        }
    }

  return ptr;
}

/* Read the next line from the configuration file */

static char *read_line(FILE *stream)
{
  char *ptr;

  for (; ; )
    {
      line[LINESIZE] = '\0';
      if (!fgets(line, LINESIZE, stream))
        {
          return NULL;
        }
      else
        {
          ptr = skip_space(line);
          if (*ptr && *ptr != '#' && *ptr != '\n')
            {
              return ptr;
            }
        }
    }
}

/* Parse the line from the configuration file into a variable name
 * string and a value string.
 */

static void parse_line(char *ptr, char **varname, char **varval)
{
  /* Skip over any leading spaces */

  ptr = skip_space(ptr);

  /* The first no-space is the beginning of the variable name */

  *varname = skip_space(ptr);
  *varval = NULL;

  /* Parse to the end of the variable name */

  ptr = find_name_end(ptr);

  /* An equal sign is expected next, perhaps after some white space */

  if (*ptr && *ptr != '=')
    {
      /* Some else follows the variable name.  Terminate the variable
       * name and skip over any spaces.
       */

      *ptr = '\0';
       ptr = skip_space(ptr + 1);
    }

  /* Verify that the equal sign is present */

  if (*ptr == '=')
    {
      /* Make sure that the variable name is terminated (this was already
       * done if the name was followed by white space.
       */

      *ptr = '\0';

      /* The variable value should follow =, perhaps separated by some
       * white space.
       */

      ptr = skip_space(ptr + 1);
      if (*ptr)
        {
          /* Yes.. a variable follows.  Save the pointer to the start
           * of the variable string.
           */

          *varval = ptr;

          /* Find the end of the variable string and make sure that it
           * is terminated.
           */

          ptr = find_value_end(ptr);
          *ptr = '\0';
        }
    }
}

/****************************************************************************
 * Public Functions
 ****************************************************************************/

void parse_file(FILE *stream, struct variable_s **list)
{
  struct variable_s *curr;
  struct variable_s *prev;
  struct variable_s *next;
  char *varname;
  char *varval;
  char *ptr;

  /* Loop until the entire file has been parsed. */

  do
    {
      /* Read the next line from the file */

      ptr = read_line(stream);
      if (ptr)
        {
          /* Parse the line into a variable and a value field */

          parse_line(ptr, &varname, &varval);

          /* If the variable has no value (or the special value 'n'), then
           * ignore it.
           */

          if (!varval || strcmp(varval, "n") == 0)
            {
              continue;
            }

          /* Make sure that a variable name was found. */

          if (varname)
            {
              int varlen = strlen(varname) + 1;
              int vallen = 0;

              /* Get the size of the value, including the NUL terminating
               * character.
               */

              if (varval)
                {
                  vallen = strlen(varval) + 1;
                }

              /* Allocate memory to hold the struct variable_s with the
               * variable name and the value.
               */

              curr = (struct variable_s *)malloc(sizeof(struct variable_s) +
                                          varlen + vallen - 1);
              if (curr)
                {
                  /* Add the variable to the list */

                  curr->var = &curr->storage[0];
                  strcpy(curr->var, varname);

                  curr->val = NULL;
                  if (varval)
                    {
                      curr->val = &curr->storage[varlen];
                      strcpy(curr->val, varval);
                    }

                  prev = 0;
                  next = *list;
                  while (next && strcmp(next->var, curr->var) <= 0)
                    {
                      prev = next;
                      next = next->flink;
                    }

                  if (prev)
                    {
                      prev->flink = curr;
                    }
                  else
                    {
                      *list = curr;
                    }

                  curr->flink = next;
                }
            }
        }
    }
  while (ptr);
}

struct variable_s *find_variable(const char *varname,
                                 struct variable_s *list)
{
  while (list)
    {
      if (strcmp(varname, list->var) == 0)
        {
          return list;
        }

      list = list->flink;
    }

  return NULL;
}