Shared space for variables (instead of letting other channels muck with your own)
(closes issue #11943) Reported by: ramonpeek Patches: 20080208__bug11943__2.diff.txt uploaded by Corydon76 (license 14) Tested by: jmls git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@104098 65c4cc65-6c06-0410-ace0-fbb531ad65f3
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Tilghman Lesher
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465b0c098d
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@ -33,6 +33,27 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
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#include "asterisk/module.h"
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#include "asterisk/pbx.h"
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#include "asterisk/channel.h"
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#include "asterisk/app.h"
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#include "asterisk/manager.h"
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static void shared_variable_free(void *data);
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static struct ast_datastore_info shared_variable_info = {
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.type = "SHARED_VARIABLES",
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.destroy = shared_variable_free,
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};
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static void shared_variable_free(void *data)
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{
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struct varshead *varshead = data;
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struct ast_var_t *var;
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while ((var = AST_LIST_REMOVE_HEAD(varshead, entries))) {
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ast_var_delete(var);
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}
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ast_free(varshead);
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}
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static int global_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
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{
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@ -61,11 +82,151 @@ static struct ast_custom_function global_function = {
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.write = global_write,
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};
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static int shared_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
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{
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struct ast_datastore *varstore;
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struct varshead *varshead;
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struct ast_var_t *var;
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AST_DECLARE_APP_ARGS(args,
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AST_APP_ARG(var);
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AST_APP_ARG(chan);
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);
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if (ast_strlen_zero(data)) {
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ast_log(LOG_WARNING, "SHARED() requires an argument: SHARED(<var>[,<chan>])\n");
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return -1;
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}
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AST_STANDARD_APP_ARGS(args, data);
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if (!ast_strlen_zero(args.chan)) {
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char *prefix = alloca(strlen(args.chan) + 2);
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sprintf(prefix, "%s-", args.chan);
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if (!(chan = ast_get_channel_by_name_locked(args.chan)) && !(chan = ast_get_channel_by_name_prefix_locked(prefix, strlen(prefix)))) {
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ast_log(LOG_ERROR, "Channel '%s' not found! Variable '%s' will be blank.\n", args.chan, args.var);
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return -1;
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}
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} else
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ast_channel_lock(chan);
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if (!(varstore = ast_channel_datastore_find(chan, &shared_variable_info, NULL)))
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return -1;
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varshead = varstore->data;
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*buf = '\0';
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/* Protected by the channel lock */
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AST_LIST_TRAVERSE(varshead, var, entries) {
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if (!strcmp(args.var, ast_var_name(var))) {
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ast_copy_string(buf, ast_var_value(var), len);
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break;
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}
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}
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return 0;
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}
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static int shared_write(struct ast_channel *chan, const char *cmd, char *data, const char *value)
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{
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struct ast_datastore *varstore;
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struct varshead *varshead;
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struct ast_var_t *var;
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AST_DECLARE_APP_ARGS(args,
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AST_APP_ARG(var);
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AST_APP_ARG(chan);
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);
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if (ast_strlen_zero(data)) {
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ast_log(LOG_WARNING, "SHARED() requires an argument: SHARED(<var>[,<chan>])\n");
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return -1;
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}
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AST_STANDARD_APP_ARGS(args, data);
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if (!ast_strlen_zero(args.chan)) {
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char *prefix = alloca(strlen(args.chan) + 2);
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sprintf(prefix, "%s-", args.chan);
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if (!(chan = ast_get_channel_by_name_locked(args.chan)) && !(chan = ast_get_channel_by_name_prefix_locked(prefix, strlen(prefix)))) {
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ast_log(LOG_ERROR, "Channel '%s' not found! Variable '%s' not set to '%s'.\n", args.chan, args.var, value);
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return -1;
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}
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} else
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ast_channel_lock(chan);
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if (!(varstore = ast_channel_datastore_find(chan, &shared_variable_info, NULL))) {
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if (!(varstore = ast_channel_datastore_alloc(&shared_variable_info, NULL))) {
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ast_log(LOG_ERROR, "Unable to allocate new datastore. Shared variable not set.\n");
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ast_channel_unlock(chan);
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return -1;
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}
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if (!(varshead = ast_calloc(1, sizeof(*varshead)))) {
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ast_log(LOG_ERROR, "Unable to allocate variable structure. Shared variable not set.\n");
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ast_channel_datastore_free(varstore);
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ast_channel_unlock(chan);
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return -1;
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}
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varstore->data = varshead;
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ast_channel_datastore_add(chan, varstore);
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}
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varshead = varstore->data;
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/* Protected by the channel lock */
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AST_LIST_TRAVERSE(varshead, var, entries) {
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/* If there's a previous value, remove it */
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if (!strcmp(args.var, ast_var_name(var))) {
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AST_LIST_REMOVE(varshead, var, entries);
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ast_var_delete(var);
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break;
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}
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}
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var = ast_var_assign(args.var, S_OR(value, ""));
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AST_LIST_INSERT_HEAD(varshead, var, entries);
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manager_event(EVENT_FLAG_DIALPLAN, "VarSet",
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"Channel: %s\r\n"
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"Variable: SHARED(%s)\r\n"
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"Value: %s\r\n"
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"Uniqueid: %s\r\n",
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chan ? chan->name : "none", args.var, value,
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chan ? chan->uniqueid : "none");
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ast_channel_unlock(chan);
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return 0;
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}
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static struct ast_custom_function shared_function = {
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.name = "SHARED",
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.synopsis = "Gets or sets the shared variable specified",
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.syntax = "SHARED(<varname>[,<channel>])",
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.desc =
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"Implements a shared variable area, in which you may share variables between\n"
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"channels. If channel is unspecified, defaults to the current channel. Note\n"
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"that the channel name may be the complete name (i.e. SIP/12-abcd1234) or the\n"
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"prefix only (i.e. SIP/12).\n"
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"\n"
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"The variables used in this space are separate from the general namespace of\n"
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"the channel and thus ${SHARED(foo)} and ${foo} represent two completely\n"
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"different variables, despite sharing the same name.\n"
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"\n"
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"Finally, realize that there is an inherent race between channels operating\n"
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"at the same time, fiddling with each others' internal variables, which is why\n"
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"this special variable namespace exists; it is to remind you that variables in\n"
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"the SHARED namespace may change at any time, without warning. You should\n"
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"therefore take special care to ensure that when using the SHARED namespace,\n"
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"you retrieve the variable and store it in a regular channel variable before\n"
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"using it in a set of calculations (or you might be surprised by the result).\n",
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.read = shared_read,
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.write = shared_write,
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};
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static int unload_module(void)
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{
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int res = 0;
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res |= ast_custom_function_unregister(&global_function);
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res |= ast_custom_function_unregister(&shared_function);
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return res;
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}
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@ -75,8 +236,9 @@ static int load_module(void)
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int res = 0;
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res |= ast_custom_function_register(&global_function);
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res |= ast_custom_function_register(&shared_function);
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return res;
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}
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AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Global variable dialplan functions");
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AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "Variable dialplan functions");
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