Asterisk.org: Developer Documentation (28 Oct 2009)

Wed Oct 28 15:47:49 2009

## Asterisk developer's documentation

# app_stack.c

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    00001 /*
    00002  * Asterisk -- An open source telephony toolkit.
    00003  *
    00004  * Copyright (c) 2004-2005 Tilghman Lesher <app_stack_v002@the-tilghman.com>.
    00005  *
    00006  * This code is released by the author with no restrictions on usage.
    00007  *
    00008  * See http://www.asterisk.org for more information about
    00009  * the Asterisk project. Please do not directly contact
    00010  * any of the maintainers of this project for assistance;
    00011  * the project provides a web site, mailing lists and IRC
    00012  * channels for your use.
    00013  *
    00014  * This program is free software, distributed under the terms of
    00015  * the GNU General Public License Version 2. See the LICENSE file
    00016  * at the top of the source tree.
    00017  */
    00018
    00019 /*! \file
    00020  *
    00021  * \brief Stack applications Gosub, Return, etc.
    00022  *
    00023  * \ingroup applications
    00024  */
    00025
    00026 #include <stdio.h>
    00027 #include <stdlib.h>
    00028 #include <unistd.h>
    00029 #include <string.h>
    00030
    00031 #include "asterisk/options.h"
    00032 #include "asterisk/logger.h"
    00033 #include "asterisk/channel.h"
    00034 #include "asterisk/chanvars.h"
    00035 #include "asterisk/pbx.h"
    00036 #include "asterisk/module.h"
    00037 #include "asterisk/config.h"
    00038
    00039 #define STACKVAR  "~GOSUB~STACK~"
    00040
    00041 static const char *tdesc = "Stack Routines";
    00042
    00043 static const char *app_gosub = "Gosub";
    00044 static const char *app_gosubif = "GosubIf";
    00045 static const char *app_return = "Return";
    00046 static const char *app_pop = "StackPop";
    00047
    00048 static const char *gosub_synopsis = "Jump to label, saving return address";
    00049 static const char *gosubif_synopsis = "Jump to label, saving return address";
    00050 static const char *return_synopsis = "Return from gosub routine";
    00051 static const char *pop_synopsis = "Remove one address from gosub stack";
    00052
    00053 static const char *gosub_descrip =
    00054 "Gosub([[context|]exten|]priority)\n"
    00055 "  Jumps to the label specified, saving the return address.\n";
    00056 static const char *gosubif_descrip =
    00057 "GosubIf(condition?labeliftrue[:labeliffalse])\n"
    00058 "  If the condition is true, then jump to labeliftrue.  If false, jumps to\n"
    00059 "labeliffalse, if specified.  In either case, a jump saves the return point\n"
    00060 "in the dialplan, to be returned to with a Return.\n";
    00061 static const char *return_descrip =
    00062 "Return()\n"
    00063 "  Jumps to the last label on the stack, removing it.\n";
    00064 static const char *pop_descrip =
    00065 "StackPop()\n"
    00066 "  Removes last label on the stack, discarding it.\n";
    00067
    00068 STANDARD_LOCAL_USER;
    00069
    00070 LOCAL_USER_DECL;
    00071
    00072 static int pop_exec(struct ast_channel *chan, void *data)
    00073 {
    00074    pbx_builtin_setvar_helper(chan, STACKVAR, NULL);
    00075
    00076    return 0;
    00077 }
    00078
    00079 static int return_exec(struct ast_channel *chan, void *data)
    00080 {
    00081    char *label = pbx_builtin_getvar_helper(chan, STACKVAR);
    00082
    00083    if (ast_strlen_zero(label)) {
    00084       ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
    00085       return -1;
    00086    } else if (ast_parseable_goto(chan, label)) {
    00087       ast_log(LOG_WARNING, "No next statement after Gosub?\n");
    00088       return -1;
    00089    }
    00090
    00091    pbx_builtin_setvar_helper(chan, STACKVAR, NULL);
    00092    return 0;
    00093 }
    00094
    00095 static int gosub_exec(struct ast_channel *chan, void *data)
    00096 {
    00097    char newlabel[AST_MAX_EXTENSION * 2 + 3 + 11];
    00098    struct localuser *u;
    00099
    00100    if (ast_strlen_zero(data)) {
    00101       ast_log(LOG_ERROR, "%s requires an argument: %s([[context|]exten|]priority)\n", app_gosub, app_gosub);
    00102       return -1;
    00103    }
    00104
    00105    LOCAL_USER_ADD(u);
    00106    snprintf(newlabel, sizeof(newlabel), "%s|%s|%d", chan->context, chan->exten, chan->priority + 1);
    00107
    00108    if (ast_parseable_goto(chan, data)) {
    00109       LOCAL_USER_REMOVE(u);
    00110       return -1;
    00111    }
    00112
    00113    pbx_builtin_pushvar_helper(chan, STACKVAR, newlabel);
    00114    LOCAL_USER_REMOVE(u);
    00115
    00116    return 0;
    00117 }
    00118
    00119 static int gosubif_exec(struct ast_channel *chan, void *data)
    00120 {
    00121    struct localuser *u;
    00122    char *condition="", *label1, *label2, *args;
    00123    int res=0;
    00124
    00125    if (ast_strlen_zero(data)) {
    00126       ast_log(LOG_WARNING, "GosubIf requires an argument\n");
    00127       return 0;
    00128    }
    00129
    00130    args = ast_strdupa((char *)data);
    00131    if (!args) {
    00132       ast_log(LOG_ERROR, "Out of memory\n");
    00133       return -1;
    00134    }
    00135
    00136    LOCAL_USER_ADD(u);
    00137
    00138    condition = strsep(&args, "?");
    00139    label1 = strsep(&args, ":");
    00140    label2 = args;
    00141
    00142    if (pbx_checkcondition(condition)) {
    00143       if (label1) {
    00144          res = gosub_exec(chan, label1);
    00145       }
    00146    } else if (label2) {
    00147       res = gosub_exec(chan, label2);
    00148    }
    00149
    00150    LOCAL_USER_REMOVE(u);
    00151    return res;
    00152 }
    00153
    00154 int unload_module(void)
    00155 {
    00156    ast_unregister_application(app_return);
    00157    ast_unregister_application(app_pop);
    00158    ast_unregister_application(app_gosubif);
    00159    ast_unregister_application(app_gosub);
    00160
    00161    STANDARD_HANGUP_LOCALUSERS;
    00162
    00163    return 0;
    00164 }
    00165
    00166 int load_module(void)
    00167 {
    00168    ast_register_application(app_pop, pop_exec, pop_synopsis, pop_descrip);
    00169    ast_register_application(app_return, return_exec, return_synopsis, return_descrip);
    00170    ast_register_application(app_gosubif, gosubif_exec, gosubif_synopsis, gosubif_descrip);
    00171    ast_register_application(app_gosub, gosub_exec, gosub_synopsis, gosub_descrip);
    00172
    00173    return 0;
    00174 }
    00175
    00176 char *description(void)
    00177 {
    00178    return (char *) tdesc;
    00179 }
    00180
    00181 int usecount(void)
    00182 {
    00183    int res;
    00184
    00185    STANDARD_USECOUNT(res);
    00186
    00187    return res;
    00188 }
    00189
    00190 char *key()
    00191 {
    00192    return ASTERISK_GPL_KEY;
    00193 }