extconf.c

		lline_buffer_size += CB_INCR + siz + 1;
	}
	strcat(lline_buffer,str);
}

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

/*! \brief Keep track of how many threads are currently trying to wait*() on
 *  a child process */
static unsigned int safe_system_level = 0;
static struct sigaction safe_system_prev_handler;

/*! \brief NULL handler so we can collect the child exit status */
static void _null_sig_handler(int sig)
{

}

static struct sigaction null_sig_handler = {
	.sa_handler = _null_sig_handler,
	.sa_flags = SA_RESTART,
};

void ast_replace_sigchld(void);

void ast_replace_sigchld(void)
{
	unsigned int level;

	level = safe_system_level++;

	/* only replace the handler if it has not already been done */
	if (level == 0) {
		sigaction(SIGCHLD, &null_sig_handler, &safe_system_prev_handler);
	}
}

void ast_unreplace_sigchld(void);

void ast_unreplace_sigchld(void)
{
	unsigned int level;

	level = --safe_system_level;

	/* only restore the handler if we are the last one */
	if (level == 0) {
		sigaction(SIGCHLD, &safe_system_prev_handler, NULL);
	}
}

int ast_safe_system(const char *s);

int ast_safe_system(const char *s)
{
	pid_t pid;
#ifdef HAVE_WORKING_FORK
	int x;
#endif
	int res;
	int status;

#if defined(HAVE_WORKING_FORK) || defined(HAVE_WORKING_VFORK)
	ast_replace_sigchld();

#ifdef HAVE_WORKING_FORK
	pid = fork();
#else
	pid = vfork();
#endif

	if (pid == 0) {
#ifdef HAVE_WORKING_FORK
		/* Close file descriptors and launch system command */
		for (x = STDERR_FILENO + 1; x < 4096; x++)
			close(x);
#endif
		execl("/bin/sh", "/bin/sh", "-c", s, (char *) NULL);
		_exit(1);
	} else if (pid > 0) {
		for(;;) {
			res = waitpid(pid, &status, 0);
			if (res > -1) {
				res = WIFEXITED(status) ? WEXITSTATUS(status) : -1;
				break;
			} else if (errno != EINTR)
				break;
		}
	} else {
		ast_log(LOG_WARNING, "Fork failed: %s\n", strerror(errno));
		res = -1;
	}

	ast_unreplace_sigchld();
#else
	res = -1;
#endif

	return res;
}

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;

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;
    char *file;                /*!< the file name from whence this declaration was read */
    int lineno;
	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_config_include *includes;  /*!< a list of inclusions, which should describe the entire tree */
};

struct ast_config_include {
	char *include_location_file;     /*!< file name in which the include occurs */
	int  include_location_lineno;    /*!< lineno where include occurred */
	int  exec;                       /*!< set to non-zero if itsa #exec statement */
	char *exec_file;                 /*!< if it's an exec, you'll have both the /var/tmp to read, and the original script */
	char *included_file;             /*!< file name included */
	int inclusion_count;             /*!< if the file is included more than once, a running count thereof -- but, worry not,
									   we explode the instances and will include those-- so all entries will be unique */
	int output;                      /*!< a flag to indicate if the inclusion has been output */
	struct ast_config_include *next; /*!< ptr to next inclusion in the list */
};

typedef struct ast_config *config_load_func(const char *database, const char *table, const char *configfile, struct ast_config *config, int withcomments, const char *suggested_include_file);
typedef struct ast_variable *realtime_var_get(const char *database, const char *table, va_list ap);
typedef struct ast_config *realtime_multi_get(const char *database, const char *table, va_list ap);
typedef int realtime_update(const char *database, const char *table, const char *keyfield, const char *entity, va_list ap);

/*! \brief Configuration engine structure, used to define realtime drivers */
struct ast_config_engine {
	char *name;
	config_load_func *load_func;
	realtime_var_get *realtime_func;
	realtime_multi_get *realtime_multi_func;
	realtime_update *update_func;
	struct ast_config_engine *next;
};

static struct ast_config_engine *config_engine_list;

/* taken from strings.h */

static force_inline int ast_strlen_zero(const char *s)
{
	return (!s || (*s == '\0'));
}

#define S_OR(a, b)	(!ast_strlen_zero(a) ? (a) : (b))

AST_INLINE_API(
void ast_copy_string(char *dst, const char *src, size_t size),
{
	while (*src && size) {
		*dst++ = *src++;
		size--;
	}
	if (__builtin_expect(!size, 0))
		dst--;
	*dst = '\0';
}
)

AST_INLINE_API(
char *ast_skip_blanks(const char *str),
{
	while (*str && *str < 33)
		str++;
	return (char *)str;
}
)

/*!
  \brief Trims trailing whitespace characters from a string.
  \param ast_trim_blanks function being used
  \param str the input string
  \return a pointer to the modified string
 */
AST_INLINE_API(
char *ast_trim_blanks(char *str),
{
	char *work = str;

	if (work) {
		work += strlen(work) - 1;
		/* It's tempting to only want to erase after we exit this loop,
		   but since ast_trim_blanks *could* receive a constant string
		   (which we presumably wouldn't have to touch), we shouldn't
		   actually set anything unless we must, and it's easier just
		   to set each position to \0 than to keep track of a variable
		   for it */
		while ((work >= str) && *work < 33)
			*(work--) = '\0';
	}
	return str;
}
)

/*!
  \brief Strip leading/trailing whitespace from a string.
  \param s The string to be stripped (will be modified).
  \return The stripped string.

  This functions strips all leading and trailing whitespace
  characters from the input string, and returns a pointer to
  the resulting string. The string is modified in place.
*/
AST_INLINE_API(
char *ast_strip(char *s),
{
	s = ast_skip_blanks(s);
	if (s)
		ast_trim_blanks(s);
	return s;
}
)


/* from config.h */

struct ast_variable {
	char *name;
	char *value;
	char *file;
	int lineno;
	int object;		/*!< 0 for variable, 1 for object */
	int blanklines; 	/*!< Number of blanklines following entry */
	struct ast_comment *precomments;
	struct ast_comment *sameline;
	struct ast_variable *next;
	char stuff[0];
};

static const char *ast_variable_retrieve(const struct ast_config *config, const char *category, const char *variable);
static struct ast_config *config_text_file_load(const char *database, const char *table, const char *filename, struct ast_config *cfg, int withcomments, const char *suggested_include_file);

struct ast_config *localized_config_load_with_comments(const char *filename);
static char *ast_category_browse(struct ast_config *config, const char *prev);
static struct ast_variable *ast_variable_browse(const struct ast_config *config, const char *category);
static void ast_variables_destroy(struct ast_variable *v);
static void ast_config_destroy(struct ast_config *cfg);
static struct ast_config_include *ast_include_new(struct ast_config *conf, const char *from_file, const char *included_file, int is_exec, const char *exec_file, int from_lineno, char *real_included_file_name, int real_included_file_name_size);
static struct ast_config_include *ast_include_find(struct ast_config *conf, const char *included_file);
void localized_ast_include_rename(struct ast_config *conf, const char *from_file, const char *to_file);

static struct ast_variable *ast_variable_new(const char *name, const char *value, const char *filename);

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

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

	return variable;
}

static struct ast_config_include *ast_include_new(struct ast_config *conf, const char *from_file, const char *included_file, int is_exec, const char *exec_file, int from_lineno, char *real_included_file_name, int real_included_file_name_size)
{
	/* a file should be included ONCE. Otherwise, if one of the instances is changed,
       then all be changed. -- how do we know to include it? -- Handling modified
       instances is possible, I'd have
       to create a new master for each instance. */
	struct ast_config_include *inc;

	inc = ast_include_find(conf, included_file);
	if (inc)
	{
		inc->inclusion_count++;
		snprintf(real_included_file_name, real_included_file_name_size, "%s~~%d", included_file, inc->inclusion_count);
		ast_log(LOG_WARNING,"'%s', line %d:  Same File included more than once! This data will be saved in %s if saved back to disk.\n", from_file, from_lineno, real_included_file_name);
	} else
		*real_included_file_name = 0;

	inc = ast_calloc(1,sizeof(struct ast_config_include));
	inc->include_location_file = ast_strdup(from_file);
	inc->include_location_lineno = from_lineno;
	if (!ast_strlen_zero(real_included_file_name))
		inc->included_file = ast_strdup(real_included_file_name);
	else
		inc->included_file = ast_strdup(included_file);

	inc->exec = is_exec;
	if (is_exec)
		inc->exec_file = ast_strdup(exec_file);

	/* attach this new struct to the conf struct */
	inc->next = conf->includes;
	conf->includes = inc;

	return inc;
}

void localized_ast_include_rename(struct ast_config *conf, const char *from_file, const char *to_file)
{
	struct ast_config_include *incl;
	struct ast_category *cat;
	struct ast_variable *v;

	int from_len = strlen(from_file);
	int to_len = strlen(to_file);

	if (strcmp(from_file, to_file) == 0) /* no use wasting time if the name is the same */
		return;

	/* the manager code allows you to read in one config file, then
       write it back out under a different name. But, the new arrangement
	   ties output lines to the file name. So, before you try to write
       the config file to disk, better riffle thru the data and make sure
       the file names are changed.
	*/
	/* file names are on categories, includes (of course), and on variables. So,
	   traverse all this and swap names */

	for (incl = conf->includes; incl; incl=incl->next) {
		if (strcmp(incl->include_location_file,from_file) == 0) {
			if (from_len >= to_len)
				strcpy(incl->include_location_file, to_file);
			else {
				free(incl->include_location_file);
				incl->include_location_file = strdup(to_file);
			}
		}
	}
	for (cat = conf->root; cat; cat = cat->next) {
		if (strcmp(cat->file,from_file) == 0) {
			if (from_len >= to_len)
				strcpy(cat->file, to_file);
			else {
				free(cat->file);
				cat->file = strdup(to_file);
			}
		}
		for (v = cat->root; v; v = v->next) {
			if (strcmp(v->file,from_file) == 0) {
				if (from_len >= to_len)
					strcpy(v->file, to_file);
				else {
					free(v->file);
					v->file = strdup(to_file);
				}
			}
		}
	}
}

static struct ast_config_include *ast_include_find(struct ast_config *conf, const char *included_file)
{
	struct ast_config_include *x;
	for (x=conf->includes;x;x=x->next)
	{
		if (strcmp(x->included_file,included_file) == 0)
			return x;
	}
	return 0;
}


static void ast_variable_append(struct ast_category *category, struct ast_variable *variable);

static 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;
}

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

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;
}

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

static 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;
}

static 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, old->file);

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

	return new;
}

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

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

static void ast_includes_destroy(struct ast_config_include *incls)
{
	struct ast_config_include *incl,*inclnext;

	for (incl=incls; incl; incl = inclnext) {
		inclnext = incl->next;
		if (incl->include_location_file)
			free(incl->include_location_file);
		if (incl->exec_file)
			free(incl->exec_file);
		if (incl->included_file)
			free(incl->included_file);
		free(incl);
	}
}

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

	if (!cfg)
		return;

	ast_includes_destroy(cfg->includes);

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

enum ast_option_flags {
	/*! Allow \#exec in config files */
	AST_OPT_FLAG_EXEC_INCLUDES = (1 << 0),
	/*! Do not fork() */
	AST_OPT_FLAG_NO_FORK = (1 << 1),
	/*! Keep quiet */
	AST_OPT_FLAG_QUIET = (1 << 2),
	/*! Console mode */
	AST_OPT_FLAG_CONSOLE = (1 << 3),
	/*! Run in realtime Linux priority */
	AST_OPT_FLAG_HIGH_PRIORITY = (1 << 4),
	/*! Initialize keys for RSA authentication */
	AST_OPT_FLAG_INIT_KEYS = (1 << 5),
	/*! Remote console */
	AST_OPT_FLAG_REMOTE = (1 << 6),
	/*! Execute an asterisk CLI command upon startup */
	AST_OPT_FLAG_EXEC = (1 << 7),
	/*! Don't use termcap colors */
	AST_OPT_FLAG_NO_COLOR = (1 << 8),
	/*! Are we fully started yet? */
	AST_OPT_FLAG_FULLY_BOOTED = (1 << 9),
	/*! Trascode via signed linear */
	AST_OPT_FLAG_TRANSCODE_VIA_SLIN = (1 << 10),
	/*! Dump core on a seg fault */
	AST_OPT_FLAG_DUMP_CORE = (1 << 12),
	/*! Cache sound files */
	AST_OPT_FLAG_CACHE_RECORD_FILES = (1 << 13),
	/*! Display timestamp in CLI verbose output */
	AST_OPT_FLAG_TIMESTAMP = (1 << 14),
	/*! Override config */
	AST_OPT_FLAG_OVERRIDE_CONFIG = (1 << 15),
	/*! Reconnect */
	AST_OPT_FLAG_RECONNECT = (1 << 16),
	/*! Transmit Silence during Record() and DTMF Generation */
	AST_OPT_FLAG_TRANSMIT_SILENCE = (1 << 17),
	/*! Suppress some warnings */
	AST_OPT_FLAG_DONT_WARN = (1 << 18),
	/*! End CDRs before the 'h' extension */
	AST_OPT_FLAG_END_CDR_BEFORE_H_EXTEN = (1 << 19),
	/*! Always fork, even if verbose or debug settings are non-zero */
	AST_OPT_FLAG_ALWAYS_FORK = (1 << 21),
	/*! Disable log/verbose output to remote consoles */
	AST_OPT_FLAG_MUTE = (1 << 22),
	/*! There is a per-file debug setting */
	AST_OPT_FLAG_DEBUG_FILE = (1 << 23),
	/*! There is a per-file verbose setting */
	AST_OPT_FLAG_VERBOSE_FILE = (1 << 24),
	/*! Terminal colors should be adjusted for a light-colored background */
	AST_OPT_FLAG_LIGHT_BACKGROUND = (1 << 25),
	/*! Count Initiated seconds in CDR's */
	AST_OPT_FLAG_INITIATED_SECONDS = (1 << 26),
	/*! Force black background */
	AST_OPT_FLAG_FORCE_BLACK_BACKGROUND = (1 << 27),
};

/* options.h declares ast_options extern; I need it static? */
#define AST_CACHE_DIR_LEN 	512
#define AST_FILENAME_MAX	80

/*! These are the options that set by default when Asterisk starts */
#define AST_DEFAULT_OPTIONS AST_OPT_FLAG_TRANSCODE_VIA_SLIN

struct ast_flags ast_options = { AST_DEFAULT_OPTIONS };

#define ast_opt_exec_includes		ast_test_flag(&ast_options, AST_OPT_FLAG_EXEC_INCLUDES)
#define ast_opt_no_fork			ast_test_flag(&ast_options, AST_OPT_FLAG_NO_FORK)
#define ast_opt_quiet			ast_test_flag(&ast_options, AST_OPT_FLAG_QUIET)
#define ast_opt_console			ast_test_flag(&ast_options, AST_OPT_FLAG_CONSOLE)
#define ast_opt_high_priority		ast_test_flag(&ast_options, AST_OPT_FLAG_HIGH_PRIORITY)
#define ast_opt_init_keys		ast_test_flag(&ast_options, AST_OPT_FLAG_INIT_KEYS)
#define ast_opt_remote			ast_test_flag(&ast_options, AST_OPT_FLAG_REMOTE)
#define ast_opt_exec			ast_test_flag(&ast_options, AST_OPT_FLAG_EXEC)
#define ast_opt_no_color		ast_test_flag(&ast_options, AST_OPT_FLAG_NO_COLOR)
#define ast_fully_booted		ast_test_flag(&ast_options, AST_OPT_FLAG_FULLY_BOOTED)
#define ast_opt_transcode_via_slin	ast_test_flag(&ast_options, AST_OPT_FLAG_TRANSCODE_VIA_SLIN)
#define ast_opt_priority_jumping	ast_test_flag(&ast_options, AST_OPT_FLAG_PRIORITY_JUMPING)
#define ast_opt_dump_core		ast_test_flag(&ast_options, AST_OPT_FLAG_DUMP_CORE)
#define ast_opt_cache_record_files	ast_test_flag(&ast_options, AST_OPT_FLAG_CACHE_RECORD_FILES)
#define ast_opt_timestamp		ast_test_flag(&ast_options, AST_OPT_FLAG_TIMESTAMP)
#define ast_opt_override_config		ast_test_flag(&ast_options, AST_OPT_FLAG_OVERRIDE_CONFIG)
#define ast_opt_reconnect		ast_test_flag(&ast_options, AST_OPT_FLAG_RECONNECT)
#define ast_opt_transmit_silence	ast_test_flag(&ast_options, AST_OPT_FLAG_TRANSMIT_SILENCE)
#define ast_opt_dont_warn		ast_test_flag(&ast_options, AST_OPT_FLAG_DONT_WARN)
#define ast_opt_end_cdr_before_h_exten	ast_test_flag(&ast_options, AST_OPT_FLAG_END_CDR_BEFORE_H_EXTEN)
#define ast_opt_always_fork		ast_test_flag(&ast_options, AST_OPT_FLAG_ALWAYS_FORK)
#define ast_opt_mute			ast_test_flag(&ast_options, AST_OPT_FLAG_MUTE)

extern int option_verbose;
extern int option_debug;		/*!< Debugging */
extern int ast_option_maxcalls;		/*!< Maximum number of simultaneous channels */
extern double ast_option_maxload;
extern char ast_defaultlanguage[];

extern pid_t ast_mainpid;

extern char record_cache_dir[AST_CACHE_DIR_LEN];
extern char debug_filename[AST_FILENAME_MAX];

extern int ast_language_is_prefix;



/* linkedlists.h */

/*!
  \brief Write locks a list.
  \param head This is a pointer to the list head structure

  This macro attempts to place an exclusive write lock in the
  list head structure pointed to by head.
  Returns non-zero on success, 0 on failure
*/
#define AST_RWLIST_WRLOCK(head)                                         \
        ast_rwlock_wrlock(&(head)->lock)

/*!
  \brief Read locks a list.
  \param head This is a pointer to the list head structure

  This macro attempts to place a read lock in the
  list head structure pointed to by head.
  Returns non-zero on success, 0 on failure
*/
#define AST_RWLIST_RDLOCK(head)                                         \
        ast_rwlock_rdlock(&(head)->lock)

/*!
  \brief Attempts to unlock a read/write based list.
  \param head This is a pointer to the list head structure

  This macro attempts to remove a read or write lock from the
  list head structure pointed to by head. If the list
  was not locked by this thread, this macro has no effect.
*/
#define AST_RWLIST_UNLOCK(head)                                         \
        ast_rwlock_unlock(&(head)->lock)

/*!
  \brief Defines a structure to be used to hold a list of specified type.
  \param name This will be the name of the defined structure.
  \param type This is the type of each list entry.

  This macro creates a structure definition that can be used
  to hold a list of the entries of type \a type. It does not actually
  declare (allocate) a structure; to do that, either follow this
  macro with the desired name of the instance you wish to declare,
  or use the specified \a name to declare instances elsewhere.

  Example usage:
  \code
  static AST_LIST_HEAD(entry_list, entry) entries;
  \endcode

  This would define \c struct \c entry_list, and declare an instance of it named
  \a entries, all intended to hold a list of type \c struct \c entry.
*/
#define AST_LIST_HEAD(name, type)					\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
}

/*!
  \brief Defines a structure to be used to hold a read/write list of specified type.
  \param name This will be the name of the defined structure.
  \param type This is the type of each list entry.

  This macro creates a structure definition that can be used
  to hold a list of the entries of type \a type. It does not actually
  declare (allocate) a structure; to do that, either follow this
  macro with the desired name of the instance you wish to declare,
  or use the specified \a name to declare instances elsewhere.

  Example usage:
  \code
  static AST_RWLIST_HEAD(entry_list, entry) entries;
  \endcode

  This would define \c struct \c entry_list, and declare an instance of it named
  \a entries, all intended to hold a list of type \c struct \c entry.
*/
#define AST_RWLIST_HEAD(name, type)                                     \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
}

/*!
  \brief Defines a structure to be used to hold a list of specified type (with no lock).
  \param name This will be the name of the defined structure.
  \param type This is the type of each list entry.

  This macro creates a structure definition that can be used
  to hold a list of the entries of type \a type. It does not actually
  declare (allocate) a structure; to do that, either follow this
  macro with the desired name of the instance you wish to declare,
  or use the specified \a name to declare instances elsewhere.

  Example usage:
  \code
  static AST_LIST_HEAD_NOLOCK(entry_list, entry) entries;
  \endcode

  This would define \c struct \c entry_list, and declare an instance of it named
  \a entries, all intended to hold a list of type \c struct \c entry.
*/
#define AST_LIST_HEAD_NOLOCK(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
}

/*!
  \brief Defines initial values for a declaration of AST_LIST_HEAD
*/
#define AST_LIST_HEAD_INIT_VALUE	{		\
	.first = NULL,					\
	.last = NULL,					\
	.lock = AST_MUTEX_INIT_VALUE,			\
	}

/*!
  \brief Defines initial values for a declaration of AST_RWLIST_HEAD
*/
#define AST_RWLIST_HEAD_INIT_VALUE      {               \
        .first = NULL,                                  \
        .last = NULL,                                   \
        .lock = AST_RWLOCK_INIT_VALUE,                  \
        }

/*!
  \brief Defines initial values for a declaration of AST_LIST_HEAD_NOLOCK
*/
#define AST_LIST_HEAD_NOLOCK_INIT_VALUE	{	\
	.first = NULL,					\
	.last = NULL,					\
	}

/*!
  \brief Defines a structure to be used to hold a list of specified type, statically initialized.
  \param name This will be the name of the defined structure.
  \param type This is the type of each list entry.

  This macro creates a structure definition that can be used
  to hold a list of the entries of type \a type, and allocates an instance
  of it, initialized to be empty.

  Example usage:
  \code
  static AST_LIST_HEAD_STATIC(entry_list, entry);
  \endcode

  This would define \c struct \c entry_list, intended to hold a list of
  type \c struct \c entry.
*/
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS)
#define AST_LIST_HEAD_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
} name;									\
static void  __attribute__((constructor)) init_##name(void)		\
{									\
        AST_LIST_HEAD_INIT(&name);					\
}									\
static void  __attribute__((destructor)) fini_##name(void)		\
{									\
        AST_LIST_HEAD_DESTROY(&name);					\
}									\
struct __dummy_##name
#else
#define AST_LIST_HEAD_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
	ast_mutex_t lock;						\
} name = AST_LIST_HEAD_INIT_VALUE
#endif

/*!
  \brief Defines a structure to be used to hold a read/write list of specified type, statically initialized.
  \param name This will be the name of the defined structure.
  \param type This is the type of each list entry.

  This macro creates a structure definition that can be used
  to hold a list of the entries of type \a type, and allocates an instance
  of it, initialized to be empty.

  Example usage:
  \code
  static AST_RWLIST_HEAD_STATIC(entry_list, entry);
  \endcode

  This would define \c struct \c entry_list, intended to hold a list of
  type \c struct \c entry.
*/
#ifndef AST_RWLOCK_INIT_VALUE
#define AST_RWLIST_HEAD_STATIC(name, type)                              \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
} name;                                                                 \
static void  __attribute__((constructor)) init_##name(void)            \
{                                                                       \
        AST_RWLIST_HEAD_INIT(&name);                                    \
}                                                                       \
static void  __attribute__((destructor)) fini_##name(void)             \
{                                                                       \
        AST_RWLIST_HEAD_DESTROY(&name);                                 \
}                                                                       \
struct __dummy_##name
#else
#define AST_RWLIST_HEAD_STATIC(name, type)                              \
struct name {                                                           \
        struct type *first;                                             \
        struct type *last;                                              \
        ast_rwlock_t lock;                                              \
} name = AST_RWLIST_HEAD_INIT_VALUE
#endif

/*!
  \brief Defines a structure to be used to hold a list of specified type, statically initialized.

  This is the same as AST_LIST_HEAD_STATIC, except without the lock included.
*/
#define AST_LIST_HEAD_NOLOCK_STATIC(name, type)				\
struct name {								\
	struct type *first;						\
	struct type *last;						\
} name = AST_LIST_HEAD_NOLOCK_INIT_VALUE

/*!
  \brief Initializes a list head structure with a specified first entry.
  \param head This is a pointer to the list head structure
  \param entry pointer to the list entry that will become the head of the list

  This macro initializes a list head structure by setting the head
  entry to the supplied value and recreating the embedded lock.
*/
#define AST_LIST_HEAD_SET(head, entry) do {				\
	(head)->first = (entry);					\
	(head)->last = (entry);						\
	ast_mutex_init(&(head)->lock);					\
} while (0)

/*!
  \brief Initializes an rwlist head structure with a specified first entry.
  \param head This is a pointer to the list head structure
  \param entry pointer to the list entry that will become the head of the list

  This macro initializes a list head structure by setting the head
  entry to the supplied value and recreating the embedded lock.
*/
#define AST_RWLIST_HEAD_SET(head, entry) do {                           \
        (head)->first = (entry);                                        \
        (head)->last = (entry);                                         \
        ast_rwlock_init(&(head)->lock);                                 \
} while (0)

/*!
  \brief Initializes a list head structure with a specified first entry.
  \param head This is a pointer to the list head structure
  \param entry pointer to the list entry that will become the head of the list

  This macro initializes a list head structure by setting the head
  entry to the supplied value.
*/
#define AST_LIST_HEAD_SET_NOLOCK(head, entry) do {			\
	(head)->first = (entry);					\
	(head)->last = (entry);						\
} while (0)

/*!
  \brief Declare a forward link structure inside a list entry.
  \param type This is the type of each list entry.

  This macro declares a structure to be used to link list entries together.
  It must be used inside the definition of the structure named in
  \a type, as follows:

  \code
  struct list_entry {
  	...
  	AST_LIST_ENTRY(list_entry) list;
  }
  \endcode

  The field name \a list here is arbitrary, and can be anything you wish.
*/
#define AST_LIST_ENTRY(type)						\
struct {								\
	struct type *next;						\
}

#define AST_RWLIST_ENTRY AST_LIST_ENTRY

/*!
  \brief Returns the first entry contained in a list.
  \param head This is a pointer to the list head structure
 */
#define	AST_LIST_FIRST(head)	((head)->first)

#define AST_RWLIST_FIRST AST_LIST_FIRST

/*!
  \brief Returns the last entry contained in a list.
  \param head This is a pointer to the list head structure
 */
#define	AST_LIST_LAST(head)	((head)->last)

#define AST_RWLIST_LAST AST_LIST_LAST

/*!
  \brief Returns the next entry in the list after the given entry.
  \param elm This is a pointer to the current entry.
  \param field This is the name of the field (declared using AST_LIST_ENTRY())
  used to link entries of this list together.
*/
#define AST_LIST_NEXT(elm, field)	((elm)->field.next)

#define AST_RWLIST_NEXT AST_LIST_NEXT

/*!
  \brief Checks whether the specified list contains any entries.
  \param head This is a pointer to the list head structure

  Returns non-zero if the list has entries, zero if not.
 */
#define	AST_LIST_EMPTY(head)	(AST_LIST_FIRST(head) == NULL)

#define AST_RWLIST_EMPTY AST_LIST_EMPTY

/*!
  \brief Loops over (traverses) the entries in a list.
  \param head This is a pointer to the list head structure
  \param var This is the name of the variable that will hold a pointer to the
  current list entry on each iteration. It must be declared before calling
  this macro.
  \param field This is the name of the field (declared using AST_LIST_ENTRY())
  used to link entries of this list together.

  This macro is use to loop over (traverse) the entries in a list. It uses a
  \a for loop, and supplies the enclosed code with a pointer to each list
  entry as it loops. It is typically used as follows:
  \code
  static AST_LIST_HEAD(entry_list, list_entry) entries;
  ...
  struct list_entry {
  	...
  	AST_LIST_ENTRY(list_entry) list;
  }
  ...
  struct list_entry *current;
  ...
  AST_LIST_TRAVERSE(&entries, current, list) {
     (do something with current here)
  }
  \endcode
  \warning If you modify the forward-link pointer contained in the \a current entry while
  inside the loop, the behavior will be unpredictable. At a minimum, the following
  macros will modify the forward-link pointer, and should not be used inside