app_signal.c File Reference

Channel signaling applications. More...

#include "asterisk.h"
#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/app.h"

Include dependency graph for app_signal.c:

Go to the source code of this file.

Data Structures
struct	signalitem
struct	signals

Functions
static struct signalitem *	alloc_signal (const char *sname)
	AST_MODULE_INFO_STANDARD_EXTENDED (ASTERISK_GPL_KEY, "Channel Signaling Applications")
static int	dealloc_signal (struct signalitem *s)
static struct signalitem *	get_signal (char *sname, int addnew)
static int	load_module (void)
static int	remove_signal (char *sname)
static int	send_signal (char *signame, char *payload)
static int	signal_exec (struct ast_channel *chan, const char *data)
static int	unload_module (void)
static int	wait_for_signal_or_hangup (struct ast_channel *chan, char *signame, int timeout)
static int	waitsignal_exec (struct ast_channel *chan, const char *data)

Variables
static const char *const	app = "Signal"
static const char *const	app2 = "WaitForSignal"
static struct signals	signals = { .first = NULL, .last = NULL, .lock = { PTHREAD_RWLOCK_INITIALIZER , NULL, {1, 0} } , }

Detailed Description

Channel signaling applications.

Author

Naveen Albert aster.nosp@m.isk@.nosp@m.phrea.nosp@m.knet.nosp@m..org

Definition in file app_signal.c.

Function Documentation

alloc_signal()

static struct signalitem * alloc_signal ( const char *  sname )

static

Definition at line 137 of file app_signal.c.

{
    struct signalitem *s;
 
    if (!(s = ast_calloc(1, sizeof(*s)))) {
        return NULL;
    }
 
    ast_mutex_init(&s->lock);
    ast_copy_string(s->name, sname, sizeof(s->name));
 
    s->sig_alert_pipe[0] = -1;
    s->sig_alert_pipe[1] = -1;
    s->watchers = 0;
    s->payload = NULL;
    ast_alertpipe_init(s->sig_alert_pipe);
 
    return s;
}

References ast_alertpipe_init(), ast_calloc, ast_copy_string(), ast_mutex_init, signalitem::lock, signalitem::name, NULL, signalitem::payload, signalitem::sig_alert_pipe, and signalitem::watchers.

Referenced by get_signal().

AST_MODULE_INFO_STANDARD_EXTENDED()

AST_MODULE_INFO_STANDARD_EXTENDED	(	ASTERISK_GPL_KEY	,
		"Channel Signaling Applications"
	)

dealloc_signal()

static int dealloc_signal ( struct signalitem *  s )

static

Definition at line 157 of file app_signal.c.

{
    if (s->watchers) { /* somebody is still using us... refuse to go away */
        ast_debug(1, "Signal '%s' is still being used by %d listener(s)\n", s->name, s->watchers);
        return -1;
    }
    ast_alertpipe_close(s->sig_alert_pipe);
    ast_mutex_destroy(&s->lock);
    if (s->payload) {
        ast_free(s->payload);
        s->payload = NULL;
    }
    ast_free(s);
    s = NULL;
    return 0;
}

References ast_alertpipe_close(), ast_debug, ast_free, ast_mutex_destroy, signalitem::lock, signalitem::name, NULL, signalitem::payload, signalitem::sig_alert_pipe, and signalitem::watchers.

Referenced by remove_signal(), and unload_module().

get_signal()

static struct signalitem * get_signal ( char *  sname, int  addnew  )

static

Definition at line 191 of file app_signal.c.

{
    struct signalitem *s = NULL;
    AST_RWLIST_WRLOCK(&signals);
    AST_LIST_TRAVERSE(&signals, s, entry) {
        if (!strcasecmp(s->name, sname)) {
            ast_debug(1, "Using existing signal item '%s'\n", sname);
            break;
        }
    }
    if (!s) {
        if (addnew) { /* signal doesn't exist, so create it */
            s = alloc_signal(sname);
            /* Totally fail if we fail to find/create an entry */
            if (s) {
                ast_debug(1, "Created new signal item '%s'\n", sname);
                AST_RWLIST_INSERT_HEAD(&signals, s, entry);
            } else {
                ast_log(LOG_WARNING, "Failed to create signal item for '%s'\n", sname);
            }
        } else {
            ast_debug(1, "Signal '%s' doesn't exist, and not creating it\n", sname);
        }
    }
    AST_RWLIST_UNLOCK(&signals);
    return s;
}

References alloc_signal(), ast_debug, AST_LIST_TRAVERSE, ast_log, AST_RWLIST_INSERT_HEAD, AST_RWLIST_UNLOCK, AST_RWLIST_WRLOCK, LOG_WARNING, signalitem::name, and NULL.

Referenced by send_signal(), and wait_for_signal_or_hangup().

load_module()

static int load_module ( void  )

static

Definition at line 461 of file app_signal.c.

{
    int res;
 
    res = ast_register_application_xml(app, signal_exec);
    res |= ast_register_application_xml(app2, waitsignal_exec);
 
    return res;
}

References app, app2, ast_register_application_xml, signal_exec(), and waitsignal_exec().

remove_signal()

static int remove_signal ( char *  sname )

static

Definition at line 174 of file app_signal.c.

{
    int res = -1;
    struct signalitem *s;
 
    AST_LIST_TRAVERSE_SAFE_BEGIN(&signals, s, entry) {
        if (!strcmp(s->name, sname)) {
            AST_LIST_REMOVE_CURRENT(entry);
            res = dealloc_signal(s);
            ast_debug(1, "Removed signal '%s'\n", sname);
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
 
    return res;
}

References ast_debug, AST_LIST_REMOVE_CURRENT, AST_LIST_TRAVERSE_SAFE_BEGIN, AST_LIST_TRAVERSE_SAFE_END, dealloc_signal(), and signalitem::name.

Referenced by wait_for_signal_or_hangup().

send_signal()

static int send_signal ( char *  signame, char *  payload  )

static

Definition at line 296 of file app_signal.c.

{
    struct signalitem *s;
    int save_errno = errno;
    int res = 0;
 
    s = get_signal(signame, 0); /* if signal doesn't exist already, no point in creating it, because nobody could be waiting for it! */
 
    if (!s) {
        return -1; /* this signal didn't exist, so we can't send a signal for it */
    }
 
    /* at this point, we know someone is listening, since signals are destroyed when watchers gets down to 0 */
    ast_mutex_lock(&s->lock);
    s->signaled = 1;
    if (payload && *payload) {
        int len = strlen(payload);
        if (s->payload) {
            ast_free(s->payload); /* if there was already a payload, replace it */
            s->payload = NULL;
        }
        s->payload = ast_malloc(len + 1);
        if (!s->payload) {
            ast_log(LOG_WARNING, "Failed to allocate signal payload '%s'\n", payload);
        } else {
            ast_copy_string(s->payload, payload, len + 1);
        }
    }
    if (ast_alertpipe_write(s->sig_alert_pipe)) {
        ast_log(LOG_WARNING, "%s: write() failed: %s\n", __FUNCTION__, strerror(errno));
        s->signaled = 0; /* okay, so we didn't send a signal after all... */
        res = -1;
    }
    errno = save_errno;
    ast_debug(1, "Sent '%s' signal to %d listeners\n", signame, s->watchers);
    ast_mutex_unlock(&s->lock);
 
    return res;
}

References ast_alertpipe_write(), ast_copy_string(), ast_debug, ast_free, ast_log, ast_malloc, ast_mutex_lock, ast_mutex_unlock, errno, get_signal(), len(), signalitem::lock, LOG_WARNING, NULL, signalitem::payload, signalitem::sig_alert_pipe, signalitem::signaled, and signalitem::watchers.

Referenced by signal_exec().

signal_exec()

static int signal_exec ( struct ast_channel *  chan, const char *  data  )

static

Definition at line 394 of file app_signal.c.

{
    char *argcopy;
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(signame);
        AST_APP_ARG(payload);
    );
 
    if (ast_strlen_zero(data)) {
        ast_log(LOG_WARNING, "Signal() requires arguments\n");
        return -1;
    }
 
    argcopy = ast_strdupa(data);
    AST_STANDARD_APP_ARGS(args, argcopy);
 
    if (ast_strlen_zero(args.signame)) {
        ast_log(LOG_WARNING, "Missing signal name\n");
        return -1;
    }
    if (strlen(args.signame) >= AST_MAX_CONTEXT) {
        ast_log(LOG_WARNING, "Signal name '%s' is too long\n", args.signame);
        return -1;
    }
 
    if (send_signal(args.signame, args.payload)) {
        pbx_builtin_setvar_helper(chan, "SIGNALSTATUS", "FAILURE");
    } else {
        pbx_builtin_setvar_helper(chan, "SIGNALSTATUS", "SUCCESS");
    }
 
    return 0;
}

References args, AST_APP_ARG, AST_DECLARE_APP_ARGS, ast_log, AST_MAX_CONTEXT, AST_STANDARD_APP_ARGS, ast_strdupa, ast_strlen_zero(), LOG_WARNING, signalitem::payload, pbx_builtin_setvar_helper(), and send_signal().

Referenced by load_module().

unload_module()

static int unload_module ( void  )

static

Definition at line 428 of file app_signal.c.

{
    struct signalitem *s;
    int res = 0;
 
    /* To avoid a locking nightmare, and for logistical reasons, this module
     * will refuse to unload if watchers > 0. That way we know a signal's
     * pipe won't disappear while it's being used. */
 
    AST_RWLIST_WRLOCK(&signals);
    /* Don't just use AST_RWLIST_REMOVE_HEAD, because if dealloc_signal fails, it should stay in the list. */
    AST_LIST_TRAVERSE_SAFE_BEGIN(&signals, s, entry) {
        int mres = dealloc_signal(s);
        res |= mres;
        if (!mres) {
            AST_LIST_REMOVE_CURRENT(entry);
        }
    }
    AST_LIST_TRAVERSE_SAFE_END;
    AST_RWLIST_UNLOCK(&signals);
 
    /* One or more signals still has watchers. */
    if (res) {
        ast_log(LOG_WARNING, "One or more signals is currently in use. Unload failed.\n");
        return res;
    }
 
    res |= ast_unregister_application(app);
    res |= ast_unregister_application(app2);
 
    return res;
}

References app, app2, AST_LIST_REMOVE_CURRENT, AST_LIST_TRAVERSE_SAFE_BEGIN, AST_LIST_TRAVERSE_SAFE_END, ast_log, AST_RWLIST_UNLOCK, AST_RWLIST_WRLOCK, ast_unregister_application(), dealloc_signal(), and LOG_WARNING.

wait_for_signal_or_hangup()

static int wait_for_signal_or_hangup ( struct ast_channel *  chan, char *  signame, int  timeout  )

static

Definition at line 219 of file app_signal.c.

{
    struct signalitem *s = NULL;
    int ms, remaining_time, res = 1, goaway = 0;
    struct timeval start;
    struct ast_frame *frame = NULL;
 
    remaining_time = timeout;
    start = ast_tvnow();
 
    s = get_signal(signame, 1);
 
    ast_mutex_lock(&s->lock);
    s->watchers = s->watchers + 1; /* we unlock, because a) other people need to use this and */
    ast_mutex_unlock(&s->lock); /* b) the signal will be available to us as long as watchers > 0 */
 
    while (timeout == 0 || remaining_time > 0) {
        int ofd, exception;
 
        ms = 1000;
        errno = 0;
        if (ast_waitfor_nandfds(&chan, 1, &s->sig_alert_pipe[0], 1, &exception, &ofd, &ms)) { /* channel won */
            if (!(frame = ast_read(chan))) { /* channel hung up */
                ast_debug(1, "Channel '%s' did not return a frame; probably hung up.\n", ast_channel_name(chan));
                res = -1;
                break;
            } else {
                ast_frfree(frame); /* handle frames */
            }
        } else if (ofd == s->sig_alert_pipe[0]) { /* fd won */
            if (ast_alertpipe_read(s->sig_alert_pipe) == AST_ALERT_READ_SUCCESS) {
                ast_debug(1, "Alert pipe has data for us\n");
                res = 0;
                break;
            } else {
                ast_debug(1, "Alert pipe does not have data for us\n");
            }
        } else { /* nobody won */
            if (ms && (ofd < 0)) {
                if (!((errno == 0) || (errno == EINTR))) {
                    ast_log(LOG_WARNING, "Something bad happened while channel '%s' was polling.\n", ast_channel_name(chan));
                    break;
                }
            } /* else, nothing happened */
        }
        if (timeout) {
            remaining_time = ast_remaining_ms(start, timeout);
        }
    }
 
    /* WRLOCK the list so that if we're going to destroy the signal now, nobody else can grab it before that happens. */
    AST_RWLIST_WRLOCK(&signals);
    ast_mutex_lock(&s->lock);
    if (s->payload) {
        pbx_builtin_setvar_helper(chan, "WAITFORSIGNALPAYLOAD", s->payload);
    }
    s->watchers = s->watchers - 1;
    if (s->watchers) { /* folks are still waiting for this, pass it on... */
        int save_errno = errno;
        if (ast_alertpipe_write(s->sig_alert_pipe)) {
            ast_log(LOG_WARNING, "%s: write() failed: %s\n", __FUNCTION__, strerror(errno));
        }
        errno = save_errno;
    } else { /* nobody else is waiting for this */
        goaway = 1; /* we were the last guy using this, so mark signal item for destruction */
    }
    ast_mutex_unlock(&s->lock);
 
    if (goaway) {
        /* remove_signal calls ast_mutex_destroy, so don't call it with the mutex itself locked. */
        remove_signal(signame);
    }
    AST_RWLIST_UNLOCK(&signals);
 
    return res;
}

References AST_ALERT_READ_SUCCESS, ast_alertpipe_read(), ast_alertpipe_write(), ast_channel_name(), ast_debug, ast_frfree, ast_log, ast_mutex_lock, ast_mutex_unlock, ast_read(), ast_remaining_ms(), AST_RWLIST_UNLOCK, AST_RWLIST_WRLOCK, ast_tvnow(), ast_waitfor_nandfds(), errno, get_signal(), signalitem::lock, LOG_WARNING, NULL, signalitem::payload, pbx_builtin_setvar_helper(), remove_signal(), signalitem::sig_alert_pipe, and signalitem::watchers.

Referenced by waitsignal_exec().

waitsignal_exec()

static int waitsignal_exec ( struct ast_channel *  chan, const char *  data  )

static

Definition at line 336 of file app_signal.c.

{
    char *argcopy;
    int r = 0, timeoutms = 0;
    double timeout = 0;
 
    AST_DECLARE_APP_ARGS(args,
        AST_APP_ARG(signame);
        AST_APP_ARG(sigtimeout);
    );
 
    if (ast_strlen_zero(data)) {
        ast_log(LOG_WARNING, "Signal() requires arguments\n");
        return -1;
    }
 
    argcopy = ast_strdupa(data);
    AST_STANDARD_APP_ARGS(args, argcopy);
 
    if (ast_strlen_zero(args.signame)) {
        ast_log(LOG_WARNING, "Missing signal name\n");
        return -1;
    }
    if (strlen(args.signame) >= AST_MAX_CONTEXT) {
        ast_log(LOG_WARNING, "Signal name '%s' is too long\n", args.signame);
        return -1;
    }
    if (!ast_strlen_zero(args.sigtimeout)) {
        if (sscanf(args.sigtimeout, "%30lg", &timeout) != 1 || timeout < 0) {
            ast_log(LOG_WARNING, "Invalid timeout provided: %s. Defaulting to no timeout.\n", args.sigtimeout);
        } else {
            timeoutms = timeout * 1000; /* sec to msec */
        }
    }
 
    if (timeout > 0) {
        ast_debug(1, "Waiting for signal '%s' for %d ms\n", args.signame, timeoutms);
    } else {
        ast_debug(1, "Waiting for signal '%s', indefinitely\n", args.signame);
    }
 
    r = wait_for_signal_or_hangup(chan, args.signame, timeoutms);
 
    if (r == 1) {
        ast_verb(3, "Channel '%s' timed out, waiting for signal '%s'\n", ast_channel_name(chan), args.signame);
        pbx_builtin_setvar_helper(chan, "WAITFORSIGNALSTATUS", "TIMEOUT");
    } else if (!r) {
        ast_verb(3, "Received signal '%s' on channel '%s'\n", args.signame, ast_channel_name(chan));
        pbx_builtin_setvar_helper(chan, "WAITFORSIGNALSTATUS", "SIGNALED");
    } else {
        pbx_builtin_setvar_helper(chan, "WAITFORSIGNALSTATUS", "HANGUP");
        ast_verb(3, "Channel '%s' hung up\n", ast_channel_name(chan));
        return -1;
    }
 
    return 0;
}

References args, AST_APP_ARG, ast_channel_name(), ast_debug, AST_DECLARE_APP_ARGS, ast_log, AST_MAX_CONTEXT, AST_STANDARD_APP_ARGS, ast_strdupa, ast_strlen_zero(), ast_verb, LOG_WARNING, pbx_builtin_setvar_helper(), and wait_for_signal_or_hangup().

Referenced by load_module().

Variable Documentation

app

const char* const app = "Signal"

static

Definition at line 122 of file app_signal.c.

Referenced by load_module(), and unload_module().

app2

const char* const app2 = "WaitForSignal"

static

Definition at line 123 of file app_signal.c.

Referenced by load_module(), and unload_module().

signals

struct signals signals = { .first = NULL, .last = NULL, .lock = { PTHREAD_RWLOCK_INITIALIZER , NULL, {1, 0} } , }

static