From 5c0ab5214574ce4d5e0d4c1751bf580e464cb0e2 Mon Sep 17 00:00:00 2001 From: Georg Chini Date: Tue, 14 Jan 2020 11:00:20 +0100 Subject: [PATCH] core: add message handler This patch adds a small message handler to the core which enables clients to list available handlers via the list-handlers message. Command: pacmd send-message /core list-handlers pactl can be used with the same parameters. The patch also introduces a convention for the return string. It consists of a list of elements where curly braces are used to separate elements. Each element can itself contain further elements. For example consider a message that returns multiple elements which each contain an integer and an array of float. A response string would look like that: {{Integer} {{1st float} {2nd float} ...}}{...} Part-of: --- doc/messaging_api.txt | 21 +++++++++++++------ src/pulsecore/core.c | 45 +++++++++++++++++++++++++++++++++++++++++ src/pulsecore/message-handler.c | 24 ++++++++++++++++++++++ 3 files changed, 84 insertions(+), 6 deletions(-) diff --git a/doc/messaging_api.txt b/doc/messaging_api.txt index cbc06e7..431a5df 100644 --- a/doc/messaging_api.txt +++ b/doc/messaging_api.txt @@ -6,10 +6,19 @@ PA_COMMAND_SEND_OBJECT_MESSAGE. A message consists at least of an object path and a message command, both specified as strings. Additional parameters can be specified using a single string, but are not mandatory. The message handler returns an error number as defined in def.h and also returns a string in -the "response" variable. The following reference lists available messages, -their parameters and return values. +the "response" variable. If the string is not empty it consists of elements. +Curly braces are used to separate elements. Each element can itself contain +further elements. For example consider a message that returns multiple elements +which each contain an integer and an array of float. A response string would +look like that: +{{Integer} {{1st float} {2nd float} ...}}{...} +Any characters that are not enclosed in curly braces are ignored (all characters +between { and {, between } and } and between } and {). The same syntax is used +to specify message parameters. The following reference lists available messages, +their parameters and return values. If a return value is enclosed in {}, this +means that multiple elements of the same type may be returned. -Recipient: -Message: -Parameters: -Return value: +Object path: /core +Message: list-handlers +Parameters: None +Return value: {{{Handler name} {Description}} ...} diff --git a/src/pulsecore/core.c b/src/pulsecore/core.c index c28c531..cb824ed 100644 --- a/src/pulsecore/core.c +++ b/src/pulsecore/core.c @@ -33,11 +33,13 @@ #include #include #include +#include #include #include #include #include #include +#include #include "core.h" @@ -61,6 +63,45 @@ static int core_process_msg(pa_msgobject *o, int code, void *userdata, int64_t o static void core_free(pa_object *o); +/* Returns a list of handlers. */ +static char *message_handler_list(pa_core *c) { + pa_strbuf *buf; + void *state = NULL; + struct pa_message_handler *handler; + + buf = pa_strbuf_new(); + + pa_strbuf_putc(buf, '{'); + PA_HASHMAP_FOREACH(handler, c->message_handlers, state) { + pa_strbuf_putc(buf, '{'); + + pa_strbuf_printf(buf, "{%s} {", handler->object_path); + if (handler->description) + pa_strbuf_puts(buf, handler->description); + + pa_strbuf_puts(buf, "}}"); + } + pa_strbuf_putc(buf, '}'); + + return pa_strbuf_to_string_free(buf); +} + +static int core_message_handler(const char *object_path, const char *message, const char *message_parameters, char **response, void *userdata) { + pa_core *c; + + pa_assert(c = (pa_core *) userdata); + pa_assert(message); + pa_assert(response); + pa_assert(pa_safe_streq(object_path, "/core")); + + if (pa_streq(message, "list-handlers")) { + *response = message_handler_list(c); + return PA_OK; + } + + return -PA_ERR_NOTIMPLEMENTED; +} + pa_core* pa_core_new(pa_mainloop_api *m, bool shared, bool enable_memfd, size_t shm_size) { pa_core* c; pa_mempool *pool; @@ -105,6 +146,8 @@ pa_core* pa_core_new(pa_mainloop_api *m, bool shared, bool enable_memfd, size_t c->shared = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func); c->message_handlers = pa_hashmap_new(pa_idxset_string_hash_func, pa_idxset_string_compare_func); + pa_message_handler_register(c, "/core", "Core message handler", core_message_handler, (void *) c); + c->default_source = NULL; c->default_sink = NULL; @@ -202,6 +245,8 @@ static void core_free(pa_object *o) { pa_assert(pa_hashmap_isempty(c->shared)); pa_hashmap_free(c->shared); + pa_message_handler_unregister(c, "/core"); + pa_assert(pa_hashmap_isempty(c->message_handlers)); pa_hashmap_free(c->message_handlers); diff --git a/src/pulsecore/message-handler.c b/src/pulsecore/message-handler.c index 7555a18..18c62fc 100644 --- a/src/pulsecore/message-handler.c +++ b/src/pulsecore/message-handler.c @@ -31,6 +31,20 @@ #include "message-handler.h" +/* Check if a string does not contain control characters. Currently these are + * only "{" and "}". */ +static bool string_is_valid(const char *test_string) { + uint32_t i; + + for (i = 0; test_string[i]; i++) { + if (test_string[i] == '{' || + test_string[i] == '}') + return false; + } + + return true; +} + /* Message handler functions */ /* Register message handler for the specified object. object_path must be a unique name starting with "/". */ @@ -45,6 +59,11 @@ void pa_message_handler_register(pa_core *c, const char *object_path, const char /* Ensure that the object path is not empty and starts with "/". */ pa_assert(object_path[0] == '/'); + /* Ensure that object path and description are valid strings */ + pa_assert(string_is_valid(object_path)); + if (description) + pa_assert(string_is_valid(description)); + handler = pa_xnew0(struct pa_message_handler, 1); handler->userdata = userdata; handler->callback = cb; @@ -97,6 +116,11 @@ int pa_message_handler_set_description(pa_core *c, const char *object_path, cons if (!(handler = pa_hashmap_get(c->message_handlers, object_path))) return -PA_ERR_NOENTITY; + if (description) { + if (!string_is_valid(description)) + return -PA_ERR_INVALID; + } + pa_xfree(handler->description); handler->description = pa_xstrdup(description); -- 2.7.4