Mon Mar 31 07:37:56 2008

Asterisk developer's documentation


app_stack.c

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00001 /*
00002  * Asterisk -- An open source telephony toolkit.
00003  *
00004  * Copyright (c) 2004-2006 Tilghman Lesher <app_stack_v003@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  * \author Tilghman Lesher <app_stack_v003@the-tilghman.com>
00024  * 
00025  * \ingroup applications
00026  */
00027 
00028 #include "asterisk.h"
00029  
00030 ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
00031 
00032 #include <stdio.h>
00033 #include <stdlib.h>
00034 #include <unistd.h>
00035 #include <string.h>
00036 
00037 #include "asterisk/options.h"
00038 #include "asterisk/logger.h"
00039 #include "asterisk/channel.h"
00040 #include "asterisk/chanvars.h"
00041 #include "asterisk/pbx.h"
00042 #include "asterisk/module.h"
00043 #include "asterisk/config.h"
00044 #include "asterisk/app.h"
00045 
00046 #define STACKVAR  "~GOSUB~STACK~"
00047 
00048 
00049 static const char *app_gosub = "Gosub";
00050 static const char *app_gosubif = "GosubIf";
00051 static const char *app_return = "Return";
00052 static const char *app_pop = "StackPop";
00053 
00054 static const char *gosub_synopsis = "Jump to label, saving return address";
00055 static const char *gosubif_synopsis = "Conditionally jump to label, saving return address";
00056 static const char *return_synopsis = "Return from gosub routine";
00057 static const char *pop_synopsis = "Remove one address from gosub stack";
00058 
00059 static const char *gosub_descrip =
00060 "Gosub([[context|]exten|]priority[(arg1[|...][|argN])])\n"
00061 "  Jumps to the label specified, saving the return address.\n";
00062 static const char *gosubif_descrip =
00063 "GosubIf(condition?labeliftrue[(arg1[|...])][:labeliffalse[(arg1[|...])]])\n"
00064 "  If the condition is true, then jump to labeliftrue.  If false, jumps to\n"
00065 "labeliffalse, if specified.  In either case, a jump saves the return point\n"
00066 "in the dialplan, to be returned to with a Return.\n";
00067 static const char *return_descrip =
00068 "Return([return-value])\n"
00069 "  Jumps to the last label on the stack, removing it.  The return value, if\n"
00070 "any, is saved in the channel variable GOSUB_RETVAL.\n";
00071 static const char *pop_descrip =
00072 "StackPop()\n"
00073 "  Removes last label on the stack, discarding it.\n";
00074 
00075 
00076 static int pop_exec(struct ast_channel *chan, void *data)
00077 {
00078    const char *frame = pbx_builtin_getvar_helper(chan, STACKVAR);
00079    int numargs = 0, i;
00080    char argname[15];
00081 
00082    /* Pop any arguments for this stack frame off the variable stack */
00083    if (frame) {
00084       numargs = atoi(frame);
00085       for (i = 1; i <= numargs; i++) {
00086          snprintf(argname, sizeof(argname), "ARG%d", i);
00087          pbx_builtin_setvar_helper(chan, argname, NULL);
00088       }
00089    }
00090 
00091    /* Remove the last frame from the Gosub stack */
00092    pbx_builtin_setvar_helper(chan, STACKVAR, NULL);
00093 
00094    return 0;
00095 }
00096 
00097 static int return_exec(struct ast_channel *chan, void *data)
00098 {
00099    const char *label = pbx_builtin_getvar_helper(chan, STACKVAR);
00100    char argname[15], *retval = data;
00101    int numargs, i;
00102 
00103    if (ast_strlen_zero(label)) {
00104       ast_log(LOG_ERROR, "Return without Gosub: stack is empty\n");
00105       return -1;
00106    }
00107 
00108    /* Pop any arguments for this stack frame off the variable stack */
00109    numargs = atoi(label);
00110    for (i = 1; i <= numargs; i++) {
00111       snprintf(argname, sizeof(argname), "ARG%d", i);
00112       pbx_builtin_setvar_helper(chan, argname, NULL);
00113    }
00114 
00115    /* If the label exists, it will always have a ':' */
00116    label = strchr(label, ':') + 1;
00117 
00118    if (ast_parseable_goto(chan, label)) {
00119       ast_log(LOG_WARNING, "No next statement after Gosub?\n");
00120       return -1;
00121    }
00122 
00123    /* Remove the current frame from the Gosub stack */
00124    pbx_builtin_setvar_helper(chan, STACKVAR, NULL);
00125 
00126    /* Set a return value, if any */
00127    pbx_builtin_setvar_helper(chan, "GOSUB_RETVAL", S_OR(retval, ""));
00128    return 0;
00129 }
00130 
00131 static int gosub_exec(struct ast_channel *chan, void *data)
00132 {
00133    char newlabel[AST_MAX_EXTENSION + AST_MAX_CONTEXT + 11 + 11 + 4];
00134    char argname[15], *tmp = ast_strdupa(data), *label, *endparen;
00135    int i;
00136    struct ast_module_user *u;
00137    AST_DECLARE_APP_ARGS(args2,
00138       AST_APP_ARG(argval)[100];
00139    );
00140 
00141    if (ast_strlen_zero(data)) {
00142       ast_log(LOG_ERROR, "%s requires an argument: %s([[context|]exten|]priority[(arg1[|...][|argN])])\n", app_gosub, app_gosub);
00143       return -1;
00144    }
00145 
00146    u = ast_module_user_add(chan);
00147 
00148    /* Separate the arguments from the label */
00149    /* NOTE:  you cannot use ast_app_separate_args for this, because '(' cannot be used as a delimiter. */
00150    label = strsep(&tmp, "(");
00151    if (tmp) {
00152       endparen = strrchr(tmp, ')');
00153       if (endparen)
00154          *endparen = '\0';
00155       else
00156          ast_log(LOG_WARNING, "Ouch.  No closing paren: '%s'?\n", (char *)data);
00157       AST_STANDARD_APP_ARGS(args2, tmp);
00158    } else
00159       args2.argc = 0;
00160 
00161    /* Create the return address, but don't save it until we know that the Gosub destination exists */
00162    snprintf(newlabel, sizeof(newlabel), "%d:%s|%s|%d", args2.argc, chan->context, chan->exten, chan->priority + 1);
00163 
00164    if (ast_parseable_goto(chan, label)) {
00165       ast_log(LOG_ERROR, "Gosub address is invalid: '%s'\n", (char *)data);
00166       ast_module_user_remove(u);
00167       return -1;
00168    }
00169 
00170    /* Now that we know for certain that we're going to a new location, set our arguments */
00171    for (i = 0; i < args2.argc; i++) {
00172       snprintf(argname, sizeof(argname), "ARG%d", i + 1);
00173       pbx_builtin_pushvar_helper(chan, argname, args2.argval[i]);
00174       ast_log(LOG_DEBUG, "Setting '%s' to '%s'\n", argname, args2.argval[i]);
00175    }
00176 
00177    /* And finally, save our return address */
00178    pbx_builtin_pushvar_helper(chan, STACKVAR, newlabel);
00179    ast_log(LOG_DEBUG, "Setting gosub return address to '%s'\n", newlabel);
00180    ast_module_user_remove(u);
00181 
00182    return 0;
00183 }
00184 
00185 static int gosubif_exec(struct ast_channel *chan, void *data)
00186 {
00187    struct ast_module_user *u;
00188    char *args;
00189    int res=0;
00190    AST_DECLARE_APP_ARGS(cond,
00191       AST_APP_ARG(ition);
00192       AST_APP_ARG(labels);
00193    );
00194    AST_DECLARE_APP_ARGS(label,
00195       AST_APP_ARG(iftrue);
00196       AST_APP_ARG(iffalse);
00197    );
00198 
00199    if (ast_strlen_zero(data)) {
00200       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00201       return 0;
00202    }
00203 
00204    u = ast_module_user_add(chan);
00205 
00206    args = ast_strdupa(data);
00207    AST_NONSTANDARD_APP_ARGS(cond, args, '?');
00208    if (cond.argc != 2) {
00209       ast_log(LOG_WARNING, "GosubIf requires an argument: GosubIf(cond?label1(args):label2(args)\n");
00210       ast_module_user_remove(u);
00211       return 0;
00212    }
00213 
00214    AST_NONSTANDARD_APP_ARGS(label, cond.labels, ':');
00215 
00216    if (pbx_checkcondition(cond.ition)) {
00217       if (!ast_strlen_zero(label.iftrue))
00218          res = gosub_exec(chan, label.iftrue);
00219    } else if (!ast_strlen_zero(label.iffalse)) {
00220       res = gosub_exec(chan, label.iffalse);
00221    }
00222 
00223    ast_module_user_remove(u);
00224    return res;
00225 }
00226 
00227 static int unload_module(void)
00228 {
00229    ast_unregister_application(app_return);
00230    ast_unregister_application(app_pop);
00231    ast_unregister_application(app_gosubif);
00232    ast_unregister_application(app_gosub);
00233 
00234    ast_module_user_hangup_all();
00235 
00236    return 0;
00237 }
00238 
00239 static int load_module(void)
00240 {
00241    ast_register_application(app_pop, pop_exec, pop_synopsis, pop_descrip);
00242    ast_register_application(app_return, return_exec, return_synopsis, return_descrip);
00243    ast_register_application(app_gosubif, gosubif_exec, gosubif_synopsis, gosubif_descrip);
00244    ast_register_application(app_gosub, gosub_exec, gosub_synopsis, gosub_descrip);
00245 
00246    return 0;
00247 }
00248 
00249 AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Stack Routines");

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