[Core] Add new switch_channel_get_variable_strdup() and switch_channel_get_variable_buf() APIs that avoid allocating channel variables in a session's memory pool.

src/include/switch_channel.h

@@ -325,6 +325,24 @@ SWITCH_DECLARE(switch_status_t) switch_channel_get_scope_variables(switch_channe
 SWITCH_DECLARE(const char *) switch_channel_get_variable_dup(switch_channel_t *channel, const char *varname, switch_bool_t dup, int idx);
 #define switch_channel_get_variable(_c, _v) switch_channel_get_variable_dup(_c, _v, SWITCH_TRUE, -1)
 
+/*!
+  \brief Retrieve a copy of a variable from a given channel. switch_safe_free() call will be required.
+  \param channel channel to retrieve variable from
+  \param varname the name of the variable
+  \return a strdup copy the value of the requested variable without using a memory pool.
+*/
+SWITCH_DECLARE(const char *) switch_channel_get_variable_strdup(switch_channel_t *channel, const char *varname);
+
+/*!
+  \brief Retrieve a variable from a given channel to a pre-allocated buffer without using a memory pool.
+  \param channel channel to retrieve variable from
+  \param varname the name of the variable
+  \param buf a pre allocated buffer to put the value to
+  \param buflen size of the buffer
+  \return SWITCH_STATUS_SUCCESS if the value was copied to the buffer and it is not NULL, SWITCH_STATUS_FALSE otherwise.
+*/
+SWITCH_DECLARE(switch_status_t) switch_channel_get_variable_buf(switch_channel_t *channel, const char *varname, char *buf, switch_size_t buflen);
+
 SWITCH_DECLARE(switch_status_t) switch_channel_get_variables(switch_channel_t *channel, switch_event_t **event);
 SWITCH_DECLARE(switch_status_t) switch_channel_get_variables_prefix(switch_channel_t *channel, const char *prefix, switch_event_t **event);
 SWITCH_DECLARE(switch_status_t) switch_channel_pass_callee_id(switch_channel_t *channel, switch_channel_t *other_channel);

src/switch_channel.c

@@ -1022,6 +1022,24 @@ SWITCH_DECLARE(const char *) switch_channel_get_variable_dup(switch_channel_t *c
 	return r;
 }
 
+SWITCH_DECLARE(const char *) switch_channel_get_variable_strdup(switch_channel_t *channel, const char *varname)
+{
+	const char *value = switch_channel_get_variable_dup(channel, varname, SWITCH_FALSE, -1);
+
+	return value ? (const char *)strdup(value) : NULL;
+}
+
+SWITCH_DECLARE(switch_status_t) switch_channel_get_variable_buf(switch_channel_t *channel, const char *varname, char *buf, switch_size_t buflen)
+{
+	const char *value = switch_channel_get_variable_dup(channel, varname, SWITCH_FALSE, -1);
+
+	if (value && buf && buflen && switch_copy_string(buf, value, buflen)) {
+		return SWITCH_STATUS_SUCCESS;
+	}
+
+	return SWITCH_STATUS_FALSE;
+}
+
 SWITCH_DECLARE(const char *) switch_channel_get_variable_partner(switch_channel_t *channel, const char *varname)
 {
 	const char *uuid;

tests/unit/switch_core.c

@@ -416,6 +416,42 @@ FST_CORE_BEGIN("./conf")
 			fst_requires(hash == NULL);
 		}
 		FST_TEST_END()
+
+		FST_SESSION_BEGIN(test_switch_channel_get_variable_strdup)
+		{
+			const char *val;
+			switch_channel_t *channel = switch_core_session_get_channel(fst_session);
+
+			fst_check(channel);
+
+			switch_channel_set_variable(channel, "test_var", "test_value");
+
+			fst_check(!switch_channel_get_variable_strdup(channel, "test_var_does_not_exist"));
+
+			val = switch_channel_get_variable_strdup(channel, "test_var");
+
+			fst_check(val);
+			fst_check_string_equals(val, "test_value");
+
+			free((char *)val);
+		}
+		FST_SESSION_END()
+
+		FST_SESSION_BEGIN(test_switch_channel_get_variable_buf)
+		{
+			char buf[16] = { 0 };
+			switch_channel_t *channel = switch_core_session_get_channel(fst_session);
+
+			fst_check(channel);
+
+			switch_channel_set_variable(channel, "test_var", "test_value");
+
+			fst_check(switch_channel_get_variable_buf(channel, "test_var", buf, sizeof(buf)) == SWITCH_STATUS_SUCCESS);
+			fst_check_string_equals(buf, "test_value");
+
+			fst_check(switch_channel_get_variable_buf(channel, "test_var_does_not_exist", buf, sizeof(buf)) == SWITCH_STATUS_FALSE);
+		}
+		FST_SESSION_END()
 	}
 	FST_SUITE_END()
 }