Mon Apr 30 07:36:34 2007

Asterisk developer's documentation

---

config.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2005, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief Configuration File Parser
 *
 * \author Mark Spencer <markster@digium.com>
 *
 * Includes the Asterisk Realtime API - ARA
 * See doc/realtime.txt and doc/extconfig.txt
 */

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision$")

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <sys/stat.h>
#define AST_INCLUDE_GLOB 1
#ifdef AST_INCLUDE_GLOB
#if defined(__Darwin__) || defined(__CYGWIN__)
#define GLOB_ABORTED GLOB_ABEND
#endif
# include <glob.h>
#endif

#include "asterisk/config.h"
#include "asterisk/cli.h"
#include "asterisk/lock.h"
#include "asterisk/options.h"
#include "asterisk/logger.h"
#include "asterisk/utils.h"
#include "asterisk/channel.h"
#include "asterisk/app.h"

#define MAX_NESTED_COMMENTS 128
#define COMMENT_START ";--"
#define COMMENT_END "--;"
#define COMMENT_META ';'
#define COMMENT_TAG '-'

static char *extconfig_conf = "extconfig.conf";


/*! \brief Structure to keep comments for rewriting configuration files */
struct ast_comment {
   struct ast_comment *next;
   char cmt[0];
};

#define CB_INCR 250

static void CB_INIT(char **comment_buffer, int *comment_buffer_size, char **lline_buffer, int *lline_buffer_size)
{
   if (!(*comment_buffer)) {
      *comment_buffer = ast_malloc(CB_INCR);
      if (!(*comment_buffer))
         return;
      (*comment_buffer)[0] = 0;
      *comment_buffer_size = CB_INCR;
      *lline_buffer = ast_malloc(CB_INCR);
      if (!(*lline_buffer))
         return;
      (*lline_buffer)[0] = 0;
      *lline_buffer_size = CB_INCR;
   } else {
      (*comment_buffer)[0] = 0;
      (*lline_buffer)[0] = 0;
   }
}

static void  CB_ADD(char **comment_buffer, int *comment_buffer_size, char *str)
{
   int rem = *comment_buffer_size - strlen(*comment_buffer) - 1;
   int siz = strlen(str);
   if (rem < siz+1) {
      *comment_buffer = ast_realloc(*comment_buffer, *comment_buffer_size + CB_INCR + siz + 1);
      if (!(*comment_buffer))
         return;
      *comment_buffer_size += CB_INCR+siz+1;
   }
   strcat(*comment_buffer,str);
}

static void  CB_ADD_LEN(char **comment_buffer, int *comment_buffer_size, char *str, int len)
{
   int cbl = strlen(*comment_buffer) + 1;
   int rem = *comment_buffer_size - cbl;
   if (rem < len+1) {
      *comment_buffer = ast_realloc(*comment_buffer, *comment_buffer_size + CB_INCR + len + 1);
      if (!(*comment_buffer))
         return;
      *comment_buffer_size += CB_INCR+len+1;
   }
   strncat(*comment_buffer,str,len);
   (*comment_buffer)[cbl+len-1] = 0;
}

static void  LLB_ADD(char **lline_buffer, int *lline_buffer_size, char *str)
{
   int rem = *lline_buffer_size - strlen(*lline_buffer) - 1;
   int siz = strlen(str);
   if (rem < siz+1) {
      *lline_buffer = ast_realloc(*lline_buffer, *lline_buffer_size + CB_INCR + siz + 1);
      if (!(*lline_buffer)) 
         return;
      *lline_buffer_size += CB_INCR + siz + 1;
   }
   strcat(*lline_buffer,str);
}

static void CB_RESET(char **comment_buffer, char **lline_buffer)  
{ 
   (*comment_buffer)[0] = 0; 
   (*lline_buffer)[0] = 0;
}


static struct ast_comment *ALLOC_COMMENT(const char *buffer)
{ 
   struct ast_comment *x = ast_calloc(1,sizeof(struct ast_comment)+strlen(buffer)+1);
   strcpy(x->cmt, buffer);
   return x;
}


static struct ast_config_map {
   struct ast_config_map *next;
   char *name;
   char *driver;
   char *database;
   char *table;
   char stuff[0];
} *config_maps = NULL;

AST_MUTEX_DEFINE_STATIC(config_lock);
static struct ast_config_engine *config_engine_list;

#define MAX_INCLUDE_LEVEL 10

struct ast_category {
   char name[80];
   int ignored;         /*!< do not let user of the config see this category */
   int include_level;   
   struct ast_comment *precomments;
   struct ast_comment *sameline;
   struct ast_variable *root;
   struct ast_variable *last;
   struct ast_category *next;
};

struct ast_config {
   struct ast_category *root;
   struct ast_category *last;
   struct ast_category *current;
   struct ast_category *last_browse;      /*!< used to cache the last category supplied via category_browse */
   int include_level;
   int max_include_level;
};

struct ast_variable *ast_variable_new(const char *name, const char *value) 
{
   struct ast_variable *variable;
   int name_len = strlen(name) + 1; 

   if ((variable = ast_calloc(1, name_len + strlen(value) + 1 + sizeof(*variable)))) {
      variable->name = variable->stuff;
      variable->value = variable->stuff + name_len;      
      strcpy(variable->name,name);
      strcpy(variable->value,value);
   }

   return variable;
}

void ast_variable_append(struct ast_category *category, struct ast_variable *variable)
{
   if (!variable)
      return;
   if (category->last)
      category->last->next = variable;
   else
      category->root = variable;
   category->last = variable;
   while (category->last->next)
      category->last = category->last->next;
}

void ast_variables_destroy(struct ast_variable *v)
{
   struct ast_variable *vn;

   while(v) {
      vn = v;
      v = v->next;
      free(vn);
   }
}

struct ast_variable *ast_variable_browse(const struct ast_config *config, const char *category)
{
   struct ast_category *cat = NULL;

   if (category && config->last_browse && (config->last_browse->name == category))
      cat = config->last_browse;
   else
      cat = ast_category_get(config, category);

   return (cat) ? cat->root : NULL;
}

const char *ast_config_option(struct ast_config *cfg, const char *cat, const char *var)
{
   const char *tmp;
   tmp = ast_variable_retrieve(cfg, cat, var);
   if (!tmp)
      tmp = ast_variable_retrieve(cfg, "general", var);
   return tmp;
}


const char *ast_variable_retrieve(const struct ast_config *config, const char *category, const char *variable)
{
   struct ast_variable *v;

   if (category) {
      for (v = ast_variable_browse(config, category); v; v = v->next) {
         if (!strcasecmp(variable, v->name))
            return v->value;
      }
   } else {
      struct ast_category *cat;

      for (cat = config->root; cat; cat = cat->next)
         for (v = cat->root; v; v = v->next)
            if (!strcasecmp(variable, v->name))
               return v->value;
   }

   return NULL;
}

static struct ast_variable *variable_clone(const struct ast_variable *old)
{
   struct ast_variable *new = ast_variable_new(old->name, old->value);

   if (new) {
      new->lineno = old->lineno;
      new->object = old->object;
      new->blanklines = old->blanklines;
      /* TODO: clone comments? */
   }

   return new;
}
 
static void move_variables(struct ast_category *old, struct ast_category *new)
{
   struct ast_variable *var = old->root;
   old->root = NULL;
#if 1
   /* we can just move the entire list in a single op */
   ast_variable_append(new, var);
#else
   while (var) {
      struct ast_variable *next = var->next;
      var->next = NULL;
      ast_variable_append(new, var);
      var = next;
   }
#endif
}

struct ast_category *ast_category_new(const char *name) 
{
   struct ast_category *category;

   if ((category = ast_calloc(1, sizeof(*category))))
      ast_copy_string(category->name, name, sizeof(category->name));
   return category;
}

static struct ast_category *category_get(const struct ast_config *config, const char *category_name, int ignored)
{
   struct ast_category *cat;

   /* try exact match first, then case-insensitive match */
   for (cat = config->root; cat; cat = cat->next) {
      if (cat->name == category_name && (ignored || !cat->ignored))
         return cat;
   }

   for (cat = config->root; cat; cat = cat->next) {
      if (!strcasecmp(cat->name, category_name) && (ignored || !cat->ignored))
         return cat;
   }

   return NULL;
}

struct ast_category *ast_category_get(const struct ast_config *config, const char *category_name)
{
   return category_get(config, category_name, 0);
}

int ast_category_exist(const struct ast_config *config, const char *category_name)
{
   return !!ast_category_get(config, category_name);
}

void ast_category_append(struct ast_config *config, struct ast_category *category)
{
   if (config->last)
      config->last->next = category;
   else
      config->root = category;
   category->include_level = config->include_level;
   config->last = category;
   config->current = category;
}

void ast_category_destroy(struct ast_category *cat)
{
   ast_variables_destroy(cat->root);
   free(cat);
}

static struct ast_category *next_available_category(struct ast_category *cat)
{
   for (; cat && cat->ignored; cat = cat->next);

   return cat;
}

char *ast_category_browse(struct ast_config *config, const char *prev)
{  
   struct ast_category *cat = NULL;

   if (prev && config->last_browse && (config->last_browse->name == prev))
      cat = config->last_browse->next;
   else if (!prev && config->root)
      cat = config->root;
   else if (prev) {
      for (cat = config->root; cat; cat = cat->next) {
         if (cat->name == prev) {
            cat = cat->next;
            break;
         }
      }
      if (!cat) {
         for (cat = config->root; cat; cat = cat->next) {
            if (!strcasecmp(cat->name, prev)) {
               cat = cat->next;
               break;
            }
         }
      }
   }
   
   if (cat)
      cat = next_available_category(cat);

   config->last_browse = cat;
   return (cat) ? cat->name : NULL;
}

struct ast_variable *ast_category_detach_variables(struct ast_category *cat)
{
   struct ast_variable *v;

   v = cat->root;
   cat->root = NULL;
   cat->last = NULL;

   return v;
}

void ast_category_rename(struct ast_category *cat, const char *name)
{
   ast_copy_string(cat->name, name, sizeof(cat->name));
}

static void inherit_category(struct ast_category *new, const struct ast_category *base)
{
   struct ast_variable *var;

   for (var = base->root; var; var = var->next)
      ast_variable_append(new, variable_clone(var));
}

struct ast_config *ast_config_new(void) 
{
   struct ast_config *config;

   if ((config = ast_calloc(1, sizeof(*config))))
      config->max_include_level = MAX_INCLUDE_LEVEL;
   return config;
}

int ast_variable_delete(struct ast_category *category, char *variable, char *match)
{
   struct ast_variable *cur, *prev=NULL, *curn;
   int res = -1;
   cur = category->root;
   while (cur) {
      if (cur->name == variable) {
         if (prev) {
            prev->next = cur->next;
            if (cur == category->last)
               category->last = prev;
         } else {
            category->root = cur->next;
            if (cur == category->last)
               category->last = NULL;
         }
         cur->next = NULL;
         ast_variables_destroy(cur);
         return 0;
      }
      prev = cur;
      cur = cur->next;
   }

   prev = NULL;
   cur = category->root;
   while (cur) {
      curn = cur->next;
      if (!strcasecmp(cur->name, variable) && (ast_strlen_zero(match) || !strcasecmp(cur->value, match))) {
         if (prev) {
            prev->next = cur->next;
            if (cur == category->last)
               category->last = prev;
         } else {
            category->root = cur->next;
            if (cur == category->last)
               category->last = NULL;
         }
         cur->next = NULL;
         ast_variables_destroy(cur);
         res = 0;
      } else
         prev = cur;

      cur = curn;
   }
   return res;
}

int ast_variable_update(struct ast_category *category, const char *variable, 
   const char *value, const char *match, unsigned int object)
{
   struct ast_variable *cur, *prev=NULL, *newer;

   if (!(newer = ast_variable_new(variable, value)))
      return -1;
   
   newer->object = object;

   for (cur = category->root; cur; prev = cur, cur = cur->next) {
      if (strcasecmp(cur->name, variable) ||
         (!ast_strlen_zero(match) && strcasecmp(cur->value, match)))
         continue;

      newer->next = cur->next;
      newer->object = cur->object || object;
      if (prev)
         prev->next = newer;
      else
         category->root = newer;
      if (category->last == cur)
         category->last = newer;

      cur->next = NULL;
      ast_variables_destroy(cur);

      return 0;
   }

   if (prev)
      prev->next = newer;
   else
      category->root = newer;

   return 0;
}

int ast_category_delete(struct ast_config *cfg, char *category)
{
   struct ast_category *prev=NULL, *cat;
   cat = cfg->root;
   while(cat) {
      if (cat->name == category) {
         ast_variables_destroy(cat->root);
         if (prev) {
            prev->next = cat->next;
            if (cat == cfg->last)
               cfg->last = prev;
         } else {
            cfg->root = cat->next;
            if (cat == cfg->last)
               cfg->last = NULL;
         }
         free(cat);
         return 0;
      }
      prev = cat;
      cat = cat->next;
   }

   prev = NULL;
   cat = cfg->root;
   while(cat) {
      if (!strcasecmp(cat->name, category)) {
         ast_variables_destroy(cat->root);
         if (prev) {
            prev->next = cat->next;
            if (cat == cfg->last)
               cfg->last = prev;
         } else {
            cfg->root = cat->next;
            if (cat == cfg->last)
               cfg->last = NULL;
         }
         free(cat);
         return 0;
      }
      prev = cat;
      cat = cat->next;
   }
   return -1;
}

void ast_config_destroy(struct ast_config *cfg)
{
   struct ast_category *cat, *catn;

   if (!cfg)
      return;

   cat = cfg->root;
   while(cat) {
      ast_variables_destroy(cat->root);
      catn = cat;
      cat = cat->next;
      free(catn);
   }
   free(cfg);
}

struct ast_category *ast_config_get_current_category(const struct ast_config *cfg)
{
   return cfg->current;
}

void ast_config_set_current_category(struct ast_config *cfg, const struct ast_category *cat)
{
   /* cast below is just to silence compiler warning about dropping "const" */
   cfg->current = (struct ast_category *) cat;
}

static int process_text_line(struct ast_config *cfg, struct ast_category **cat, char *buf, int lineno, const char *configfile, int withcomments,
            char **comment_buffer, int *comment_buffer_size, char **lline_buffer, int *lline_buffer_size)
{
   char *c;
   char *cur = buf;
   struct ast_variable *v;
   char cmd[512], exec_file[512];
   int object, do_exec, do_include;

   /* Actually parse the entry */
   if (cur[0] == '[') {
      struct ast_category *newcat = NULL;
      char *catname;

      /* A category header */
      c = strchr(cur, ']');
      if (!c) {
         ast_log(LOG_WARNING, "parse error: no closing ']', line %d of %s\n", lineno, configfile);
         return -1;
      }
      *c++ = '\0';
      cur++;
      if (*c++ != '(')
         c = NULL;
      catname = cur;
      if (!(*cat = newcat = ast_category_new(catname))) {
         return -1;
      }
      /* add comments */
      if (withcomments && *comment_buffer && (*comment_buffer)[0] ) {
         newcat->precomments = ALLOC_COMMENT(*comment_buffer);
      }
      if (withcomments && *lline_buffer && (*lline_buffer)[0] ) {
         newcat->sameline = ALLOC_COMMENT(*lline_buffer);
      }
      if( withcomments )
         CB_RESET(comment_buffer, lline_buffer);
      
      /* If there are options or categories to inherit from, process them now */
      if (c) {
         if (!(cur = strchr(c, ')'))) {
            ast_log(LOG_WARNING, "parse error: no closing ')', line %d of %s\n", lineno, configfile);
            return -1;
         }
         *cur = '\0';
         while ((cur = strsep(&c, ","))) {
            if (!strcasecmp(cur, "!")) {
               (*cat)->ignored = 1;
            } else if (!strcasecmp(cur, "+")) {
               *cat = category_get(cfg, catname, 1);
               if (!(*cat)) {
                  ast_config_destroy(cfg);
                  if (newcat)
                     ast_category_destroy(newcat);
                  ast_log(LOG_WARNING, "Category addition requested, but category '%s' does not exist, line %d of %s\n", catname, lineno, configfile);
                  return -1;
               }
               if (newcat) {
                  move_variables(newcat, *cat);
                  ast_category_destroy(newcat);
                  newcat = NULL;
               }
            } else {
               struct ast_category *base;
            
               base = category_get(cfg, cur, 1);
               if (!base) {
                  ast_log(LOG_WARNING, "Inheritance requested, but category '%s' does not exist, line %d of %s\n", cur, lineno, configfile);
                  return -1;
               }
               inherit_category(*cat, base);
            }
         }
      }
      if (newcat)
         ast_category_append(cfg, *cat);
   } else if (cur[0] == '#') {
      /* A directive */
      cur++;
      c = cur;
      while(*c && (*c > 32)) c++;
      if (*c) {
         *c = '\0';
         /* Find real argument */
         c = ast_skip_blanks(c + 1);
         if (!(*c))
            c = NULL;
      } else 
         c = NULL;
      do_include = !strcasecmp(cur, "include");
      if(!do_include)
         do_exec = !strcasecmp(cur, "exec");
      else
         do_exec = 0;
      if (do_exec && !ast_opt_exec_includes) {
         ast_log(LOG_WARNING, "Cannot perform #exec unless execincludes option is enabled in asterisk.conf (options section)!\n");
         do_exec = 0;
      }
      if (do_include || do_exec) {
         if (c) {
            /* Strip off leading and trailing "'s and <>'s */
            while((*c == '<') || (*c == '>') || (*c == '\"')) c++;
            /* Get rid of leading mess */
            cur = c;
            while (!ast_strlen_zero(cur)) {
               c = cur + strlen(cur) - 1;
               if ((*c == '>') || (*c == '<') || (*c == '\"'))
                  *c = '\0';
               else
                  break;
            }
            /* #exec </path/to/executable>
               We create a tmp file, then we #include it, then we delete it. */
            if (do_exec) { 
               snprintf(exec_file, sizeof(exec_file), "/var/tmp/exec.%d.%ld", (int)time(NULL), (long)pthread_self());
               snprintf(cmd, sizeof(cmd), "%s > %s 2>&1", cur, exec_file);
               ast_safe_system(cmd);
               cur = exec_file;
            } else
               exec_file[0] = '\0';
            /* A #include */
            do_include = ast_config_internal_load(cur, cfg, withcomments) ? 1 : 0;
            if(!ast_strlen_zero(exec_file))
               unlink(exec_file);
            if(!do_include)
               return 0;

         } else {
            ast_log(LOG_WARNING, "Directive '#%s' needs an argument (%s) at line %d of %s\n", 
                  do_exec ? "exec" : "include",
                  do_exec ? "/path/to/executable" : "filename",
                  lineno,
                  configfile);
         }
      }
      else 
         ast_log(LOG_WARNING, "Unknown directive '%s' at line %d of %s\n", cur, lineno, configfile);
   } else {
      /* Just a line (variable = value) */
      if (!(*cat)) {
         ast_log(LOG_WARNING,
            "parse error: No category context for line %d of %s\n", lineno, configfile);
         return -1;
      }
      c = strchr(cur, '=');
      if (c) {
         *c = 0;
         c++;
         /* Ignore > in => */
         if (*c== '>') {
            object = 1;
            c++;
         } else
            object = 0;
         if ((v = ast_variable_new(ast_strip(cur), ast_strip(c)))) {
            v->lineno = lineno;
            v->object = object;
            /* Put and reset comments */
            v->blanklines = 0;
            ast_variable_append(*cat, v);
            /* add comments */
            if (withcomments && *comment_buffer && (*comment_buffer)[0] ) {
               v->precomments = ALLOC_COMMENT(*comment_buffer);
            }
            if (withcomments && *lline_buffer && (*lline_buffer)[0] ) {
               v->sameline = ALLOC_COMMENT(*lline_buffer);
            }
            if( withcomments )
               CB_RESET(comment_buffer, lline_buffer);
            
         } else {
            return -1;
         }
      } else {
         ast_log(LOG_WARNING, "No '=' (equal sign) in line %d of %s\n", lineno, configfile);
      }
   }
   return 0;
}

static struct ast_config *config_text_file_load(const char *database, const char *table, const char *filename, struct ast_config *cfg, int withcomments)
{
   char fn[256];
   char buf[8192];
   char *new_buf, *comment_p, *process_buf;
   FILE *f;
   int lineno=0;
   int comment = 0, nest[MAX_NESTED_COMMENTS];
   struct ast_category *cat = NULL;
   int count = 0;
   struct stat statbuf;
   /*! Growable string buffer */
   char *comment_buffer=0;   /*!< this will be a comment collector.*/
   int   comment_buffer_size=0;  /*!< the amount of storage so far alloc'd for the comment_buffer */

   char *lline_buffer=0;    /*!< A buffer for stuff behind the ; */
   int  lline_buffer_size=0;

   
   cat = ast_config_get_current_category(cfg);

   if (filename[0] == '/') {
      ast_copy_string(fn, filename, sizeof(fn));
   } else {
      snprintf(fn, sizeof(fn), "%s/%s", (char *)ast_config_AST_CONFIG_DIR, filename);
   }

   if (withcomments) {
      CB_INIT(&comment_buffer, &comment_buffer_size, &lline_buffer, &lline_buffer_size);
      if (!lline_buffer || !comment_buffer) {
         ast_log(LOG_ERROR, "Failed to initialize the comment buffer!\n");
         return NULL;
      }
   }
#ifdef AST_INCLUDE_GLOB
   {
      int glob_ret;
      glob_t globbuf;
      globbuf.gl_offs = 0; /* initialize it to silence gcc */
#ifdef SOLARIS
      glob_ret = glob(fn, GLOB_NOCHECK, NULL, &globbuf);
#else
      glob_ret = glob(fn, GLOB_NOMAGIC|GLOB_BRACE, NULL, &globbuf);
#endif
      if (glob_ret == GLOB_NOSPACE)
         ast_log(LOG_WARNING,
            "Glob Expansion of pattern '%s' failed: Not enough memory\n", fn);
      else if (glob_ret  == GLOB_ABORTED)
         ast_log(LOG_WARNING,
            "Glob Expansion of pattern '%s' failed: Read error\n", fn);
      else  {
         /* loop over expanded files */
         int i;
         for (i=0; i<globbuf.gl_pathc; i++) {
            ast_copy_string(fn, globbuf.gl_pathv[i], sizeof(fn));
#endif
   do {
      if (stat(fn, &statbuf))
         continue;

      if (!S_ISREG(statbuf.st_mode)) {
         ast_log(LOG_WARNING, "'%s' is not a regular file, ignoring\n", fn);
         continue;
      }
      if (option_verbose > 1) {
         ast_verbose(VERBOSE_PREFIX_2 "Parsing '%s': ", fn);
         fflush(stdout);
      }
      if (!(f = fopen(fn, "r"))) {
         if (option_debug)
            ast_log(LOG_DEBUG, "No file to parse: %s\n", fn);
         if (option_verbose > 1)
            ast_verbose( "Not found (%s)\n", strerror(errno));
         continue;
      }
      count++;
      if (option_debug)
         ast_log(LOG_DEBUG, "Parsing %s\n", fn);
      if (option_verbose > 1)
         ast_verbose("Found\n");
      while(!feof(f)) {
         lineno++;
         if (fgets(buf, sizeof(buf), f)) {
            if ( withcomments ) {
               CB_ADD(&comment_buffer, &comment_buffer_size, lline_buffer);       /* add the current lline buffer to the comment buffer */
               lline_buffer[0] = 0;        /* erase the lline buffer */
            }
            
            new_buf = buf;
            if (comment) 
               process_buf = NULL;
            else
               process_buf = buf;
            
            while ((comment_p = strchr(new_buf, COMMENT_META))) {
               if ((comment_p > new_buf) && (*(comment_p-1) == '\\')) {
                  /* Yuck, gotta memmove */
                  memmove(comment_p - 1, comment_p, strlen(comment_p) + 1);
                  new_buf = comment_p;
               } else if(comment_p[1] == COMMENT_TAG && comment_p[2] == COMMENT_TAG && (comment_p[3] != '-')) {
                  /* Meta-Comment start detected ";--" */
                  if (comment < MAX_NESTED_COMMENTS) {
                     *comment_p = '\0';
                     new_buf = comment_p + 3;
                     comment++;
                     nest[comment-1] = lineno;
                  } else {
                     ast_log(LOG_ERROR, "Maximum nest limit of %d reached.\n", MAX_NESTED_COMMENTS);
                  }
               } else if ((comment_p >= new_buf + 2) &&
                     (*(comment_p - 1) == COMMENT_TAG) &&
                     (*(comment_p - 2) == COMMENT_TAG)) {
                  /* Meta-Comment end detected */
                  comment--;
                  new_buf = comment_p + 1;
                  if (!comment) {
                     /* Back to non-comment now */
                     if (process_buf) {
                        /* Actually have to move what's left over the top, then continue */
                        char *oldptr;
                        oldptr = process_buf + strlen(process_buf);
                        if ( withcomments ) {
                           CB_ADD(&comment_buffer, &comment_buffer_size, ";");
                           CB_ADD_LEN(&comment_buffer, &comment_buffer_size, oldptr+1, new_buf-oldptr-1);
                        }
                        
                        memmove(oldptr, new_buf, strlen(new_buf) + 1);
                        new_buf = oldptr;
                     } else
                        process_buf = new_buf;
                  }
               } else {
                  if (!comment) {
                     /* If ; is found, and we are not nested in a comment, 
                        we immediately stop all comment processing */
                     if ( withcomments ) {
                        LLB_ADD(&lline_buffer, &lline_buffer_size, comment_p);
                     }
                     *comment_p = '\0'; 
                     new_buf = comment_p;
                  } else
                     new_buf = comment_p + 1;
               }
            }
            if( withcomments && comment && !process_buf )
            {
               CB_ADD(&comment_buffer, &comment_buffer_size, buf);  /* the whole line is a comment, store it */
            }
            
            if (process_buf) {
               char *buf = ast_strip(process_buf);
               if (!ast_strlen_zero(buf)) {
                  if (process_text_line(cfg, &cat, buf, lineno, fn, withcomments, &comment_buffer, &comment_buffer_size, &lline_buffer, &lline_buffer_size)) {
                     cfg = NULL;
                     break;
                  }
               }
            }
         }
      }
      fclose(f);     
   } while(0);
   if (comment) {
      ast_log(LOG_WARNING,"Unterminated comment detected beginning on line %d\n", nest[comment]);
   }
#ifdef AST_INCLUDE_GLOB
               if (!cfg)
                  break;
            }
            globfree(&globbuf);
         }
      }
#endif

   if (cfg && cfg->include_level == 1 && withcomments && comment_buffer) {
      free(comment_buffer);
      free(lline_buffer);
      comment_buffer = NULL;
      lline_buffer = NULL;
      comment_buffer_size = 0;
      lline_buffer_size = 0;
   }
   
   if (count == 0)
      return NULL;

   return cfg;
}

int config_text_file_save(const char *configfile, const struct ast_config *cfg, const char *generator)
{
   FILE *f;
   char fn[256];
   char date[256]="";
   time_t t;
   struct ast_variable *var;
   struct ast_category *cat;
   struct ast_comment *cmt;
   int blanklines = 0;

   if (configfile[0] == '/') {
      ast_copy_string(fn, configfile, sizeof(fn));
   } else {
      snprintf(fn, sizeof(fn), "%s/%s", ast_config_AST_CONFIG_DIR, configfile);
   }
   time(&t);
   ast_copy_string(date, ctime(&t), sizeof(date));
#ifdef __CYGWIN__ 
   if ((f = fopen(fn, "w+"))) {
#else
   if ((f = fopen(fn, "w"))) {
#endif       
      if (option_verbose > 1)
         ast_verbose(VERBOSE_PREFIX_2 "Saving '%s': ", fn);
      fprintf(f, ";!\n");
      fprintf(f, ";! Automatically generated configuration file\n");
      if (strcmp(configfile, fn))
         fprintf(f, ";! Filename: %s (%s)\n", configfile, fn);
      else
         fprintf(f, ";! Filename: %s\n", configfile);
      fprintf(f, ";! Generator: %s\n", generator);
      fprintf(f, ";! Creation Date: %s", date);
      fprintf(f, ";!\n");
      cat = cfg->root;
      while(cat) {
         /* Dump section with any appropriate comment */
         for (cmt = cat->precomments; cmt; cmt=cmt->next)
         {
            if (cmt->cmt[0] != ';' || cmt->cmt[1] != '!')
               fprintf(f,"%s", cmt->cmt);
         }
         if (!cat->precomments)
            fprintf(f,"\n");
         fprintf(f, "[%s]", cat->name);
         for(cmt = cat->sameline; cmt; cmt=cmt->next)
         {
            fprintf(f,"%s", cmt->cmt);
         }
         if (!cat->sameline)
            fprintf(f,"\n");
         var = cat->root;
         while(var) {
            for (cmt = var->precomments; cmt; cmt=cmt->next)
            {
               if (cmt->cmt[0] != ';' || cmt->cmt[1] != '!')
                  fprintf(f,"%s", cmt->cmt);
            }
            if (var->sameline) 
               fprintf(f, "%s %s %s  %s", var->name, (var->object ? "=>" : "="), var->value, var->sameline->cmt);
            else  
               fprintf(f, "%s %s %s\n", var->name, (var->object ? "=>" : "="), var->value);
            if (var->blanklines) {
               blanklines = var->blanklines;
               while (blanklines--)
                  fprintf(f, "\n");
            }
               
            var = var->next;
         }
#if 0
         /* Put an empty line */
         fprintf(f, "\n");
#endif
         cat = cat->next;
      }
      if ((option_verbose > 1) && !option_debug)
         ast_verbose("Saved\n");
   } else {
      if (option_debug)
         ast_log(LOG_DEBUG, "Unable to open for writing: %s\n", fn);
      if (option_verbose > 1)
         ast_verbose(VERBOSE_PREFIX_2 "Unable to write (%s)", strerror(errno));
      return -1;
   }
   fclose(f);
   return 0;
}

static void clear_config_maps(void) 
{
   struct ast_config_map *map;

   ast_mutex_lock(&config_lock);

   while (config_maps) {
      map = config_maps;
      config_maps = config_maps->next;
      free(map);
   }
      
   ast_mutex_unlock(&config_lock);
}

static int append_mapping(char *name, char *driver, char *database, char *table)
{
   struct ast_config_map *map;
   int length;

   length = sizeof(*map);
   length += strlen(name) + 1;
   length += strlen(driver) + 1;
   length += strlen(database) + 1;
   if (table)
      length += strlen(table) + 1;

   if (!(map = ast_calloc(1, length)))
      return -1;

   map->name = map->stuff;
   strcpy(map->name, name);
   map->driver = map->name + strlen(map->name) + 1;
   strcpy(map->driver, driver);
   map->database = map->driver + strlen(map->driver) + 1;
   strcpy(map->database, database);
   if (table) {
      map->table = map->database + strlen(map->database) + 1;
      strcpy(map->table, table);
   }
   map->next = config_maps;

   if (option_verbose > 1)
      ast_verbose(VERBOSE_PREFIX_2 "Binding %s to %s/%s/%s\n",
             map->name, map->driver, map->database, map->table ? map->table : map->name);

   config_maps = map;
   return 0;
}

int read_config_maps(void) 
{
   struct ast_config *config, *configtmp;
   struct ast_variable *v;
   char *driver, *table, *database, *stringp, *tmp;

   clear_config_maps();

   configtmp = ast_config_new();
   configtmp->max_include_level = 1;
   config = ast_config_internal_load(extconfig_conf, configtmp, 0);
   if (!config) {
      ast_config_destroy(configtmp);
      return 0;
   }

   for (v = ast_variable_browse(config, "settings"); v; v = v->next) {
      stringp = v->value;
      driver = strsep(&stringp, ",");

      if ((tmp = strchr(stringp, '\"')))
         stringp = tmp;

      /* check if the database text starts with a double quote */
      if (*stringp == '"') {
         stringp++;
         database = strsep(&stringp, "\"");
         strsep(&stringp, ",");
      } else {
         /* apparently this text has no quotes */
         database = strsep(&stringp, ",");
      }

      table = strsep(&stringp, ",");

      if (!strcmp(v->name, extconfig_conf)) {
         ast_log(LOG_WARNING, "Cannot bind '%s'!\n", extconfig_conf);
         continue;
      }

      if (!strcmp(v->name, "asterisk.conf")) {
         ast_log(LOG_WARNING, "Cannot bind 'asterisk.conf'!\n");
         continue;
      }

      if (!strcmp(v->name, "logger.conf")) {
         ast_log(LOG_WARNING, "Cannot bind 'logger.conf'!\n");
         continue;
      }

      if (!driver || !database)
         continue;
      if (!strcasecmp(v->name, "sipfriends")) {
         ast_log(LOG_WARNING, "The 'sipfriends' table is obsolete, update your config to use sipusers and sippeers, though they can point to the same table.\n");
         append_mapping("sipusers", driver, database, table ? table : "sipfriends");
         append_mapping("sippeers", driver, database, table ? table : "sipfriends");
      } else if (!strcasecmp(v->name, "iaxfriends")) {
         ast_log(LOG_WARNING, "The 'iaxfriends' table is obsolete, update your config to use iaxusers and iaxpeers, though they can point to the same table.\n");
         append_mapping("iaxusers", driver, database, table ? table : "iaxfriends");
         append_mapping("iaxpeers", driver, database, table ? table : "iaxfriends");
      } else 
         append_mapping(v->name, driver, database, table);
   }
      
   ast_config_destroy(config);
   return 0;
}

int ast_config_engine_register(struct ast_config_engine *new) 
{
   struct ast_config_engine *ptr;

   ast_mutex_lock(&config_lock);

   if (!config_engine_list) {
      config_engine_list = new;
   } else {
      for (ptr = config_engine_list; ptr->next; ptr=ptr->next);
      ptr->next = new;
   }

   ast_mutex_unlock(&config_lock);
   ast_log(LOG_NOTICE,"Registered Config Engine %s\n", new->name);

   return 1;
}

int ast_config_engine_deregister(struct ast_config_engine *del) 
{
   struct ast_config_engine *ptr, *last=NULL;

   ast_mutex_lock(&config_lock);

   for (ptr = config_engine_list; ptr; ptr=ptr->next) {
      if (ptr == del) {
         if (last)
            last->next = ptr->next;
         else
            config_engine_list = ptr->next;
         break;
      }
      last = ptr;
   }

   ast_mutex_unlock(&config_lock);

   return 0;
}

/*! \brief Find realtime engine for realtime family */
static struct ast_config_engine *find_engine(const char *family, char *database, int dbsiz, char *table, int tabsiz) 
{
   struct ast_config_engine *eng, *ret = NULL;
   struct ast_config_map *map;

   ast_mutex_lock(&config_lock);

   for (map = config_maps; map; map = map->next) {
      if (!strcasecmp(family, map->name)) {
         if (database)
            ast_copy_string(database, map->database, dbsiz);
         if (table)
            ast_copy_string(table, map->table ? map->table : family, tabsiz);
         break;
      }
   }

   /* Check if the required driver (engine) exist */
   if (map) {
      for (eng = config_engine_list; !ret && eng; eng = eng->next) {
         if (!strcasecmp(eng->name, map->driver))
            ret = eng;
      }
   }

   ast_mutex_unlock(&config_lock);
   
   /* if we found a mapping, but the engine is not available, then issue a warning */
   if (map && !ret)
      ast_log(LOG_WARNING, "Realtime mapping for '%s' found to engine '%s', but the engine is not available\n", map->name, map->driver);

   return ret;
}

static struct ast_config_engine text_file_engine = {
   .name = "text",
   .load_func = config_text_file_load,
};

struct ast_config *ast_config_internal_load(const char *filename, struct ast_config *cfg, int withcomments)
{
   char db[256];
   char table[256];
   struct ast_config_engine *loader = &text_file_engine;
   struct ast_config *result; 

   if (cfg->include_level == cfg->max_include_level) {
      ast_log(LOG_WARNING, "Maximum Include level (%d) exceeded\n", cfg->max_include_level);
      return NULL;
   }

   cfg->include_level++;

   if (strcmp(filename, extconfig_conf) && strcmp(filename, "asterisk.conf") && config_engine_list) {
      struct ast_config_engine *eng;

      eng = find_engine(filename, db, sizeof(db), table, sizeof(table));


      if (eng && eng->load_func) {
         loader = eng;
      } else {
         eng = find_engine("global", db, sizeof(db), table, sizeof(table));
         if (eng && eng->load_func)
            loader = eng;
      }
   }

   result = loader->load_func(db, table, filename, cfg, withcomments);

   if (result)
      result->include_level--;
   else
      cfg->include_level--;

   return result;
}

struct ast_config *ast_config_load(const char *filename)
{
   struct ast_config *cfg;
   struct ast_config *result;

   cfg = ast_config_new();
   if (!cfg)
      return NULL;

   result = ast_config_internal_load(filename, cfg, 0);
   if (!result)
      ast_config_destroy(cfg);

   return result;
}

struct ast_config *ast_config_load_with_comments(const char *filename)
{
   struct ast_config *cfg;
   struct ast_config *result;

   cfg = ast_config_new();
   if (!cfg)
      return NULL;

   result = ast_config_internal_load(filename, cfg, 1);
   if (!result)
      ast_config_destroy(cfg);

   return result;
}

struct ast_variable *ast_load_realtime(const char *family, ...)
{
   struct ast_config_engine *eng;
   char db[256]="";
   char table[256]="";
   struct ast_variable *res=NULL;
   va_list ap;

   va_start(ap, family);
   eng = find_engine(family, db, sizeof(db), table, sizeof(table));
   if (eng && eng->realtime_func) 
      res = eng->realtime_func(db, table, ap);
   va_end(ap);

   return res;
}

/*! \brief Check if realtime engine is configured for family */
int ast_check_realtime(const char *family)
{
   struct ast_config_engine *eng;

   eng = find_engine(family, NULL, 0, NULL, 0);
   if (eng)
      return 1;
   return 0;

}

struct ast_config *ast_load_realtime_multientry(const char *family, ...)
{
   struct ast_config_engine *eng;
   char db[256]="";
   char table[256]="";
   struct ast_config *res=NULL;
   va_list ap;

   va_start(ap, family);
   eng = find_engine(family, db, sizeof(db), table, sizeof(table));
   if (eng && eng->realtime_multi_func) 
      res = eng->realtime_multi_func(db, table, ap);
   va_end(ap);

   return res;
}

int ast_update_realtime(const char *family, const char *keyfield, const char *lookup, ...)
{
   struct ast_config_engine *eng;
   int res = -1;
   char db[256]="";
   char table[256]="";
   va_list ap;

   va_start(ap, lookup);
   eng = find_engine(family, db, sizeof(db), table, sizeof(table));
   if (eng && eng->update_func) 
      res = eng->update_func(db, table, keyfield, lookup, ap);
   va_end(ap);

   return res;
}

static int config_command(int fd, int argc, char **argv) 
{
   struct ast_config_engine *eng;
   struct ast_config_map *map;
   
   ast_mutex_lock(&config_lock);

   ast_cli(fd, "\n\n");
   for (eng = config_engine_list; eng; eng = eng->next) {
      ast_cli(fd, "\nConfig Engine: %s\n", eng->name);
      for (map = config_maps; map; map = map->next)
         if (!strcasecmp(map->driver, eng->name)) {
            ast_cli(fd, "===> %s (db=%s, table=%s)\n", map->name, map->database,
               map->table ? map->table : map->name);
         }
   }
   ast_cli(fd,"\n\n");
   
   ast_mutex_unlock(&config_lock);

   return 0;
}

static char show_config_help[] =
   "Usage: core show config mappings\n"
   "  Shows the filenames to config engines.\n";

static struct ast_cli_entry cli_show_config_mappings_deprecated = {
   { "show", "config", "mappings", NULL },
   config_command, NULL,
   NULL };

static struct ast_cli_entry cli_config[] = {
   { { "core", "show", "config", "mappings", NULL },
   config_command, "Display config mappings (file names to config engines)",
   show_config_help, NULL, &cli_show_config_mappings_deprecated },
};

int register_config_cli() 
{
   ast_cli_register_multiple(cli_config, sizeof(cli_config) / sizeof(struct ast_cli_entry));
   return 0;
}

---