1 /* Copyright (c) 2015 The Chromium OS Authors. All rights reserved.
2  * Use of this source code is governed by a BSD-style license that can be
3  * found in the LICENSE file.
4  */
5 
6 #include <errno.h>
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <syslog.h>
10 
11 #include "cras_main_message.h"
12 #include "cras_system_state.h"
13 #include "cras_util.h"
14 
15 
16 /* Callback to handle specific type of main thread message. */
17 struct cras_main_msg_callback {
18 	enum CRAS_MAIN_MESSAGE_TYPE type;
19 	cras_message_callback callback;
20 	void *callback_data;
21 	struct cras_main_msg_callback *prev, *next;
22 };
23 
24 static int main_msg_fds[2];
25 static struct cras_main_msg_callback *main_msg_callbacks;
26 
27 int cras_main_message_add_handler(enum CRAS_MAIN_MESSAGE_TYPE type,
28 				  cras_message_callback callback,
29 				  void *callback_data)
30 {
31 	struct cras_main_msg_callback *msg_cb;
32 
33 	DL_FOREACH(main_msg_callbacks, msg_cb) {
34 		if (msg_cb->type == type) {
35 			syslog(LOG_ERR, "Main message type %u already exists",
36 			       type);
37 			return -EEXIST;
38 		}
39 	}
40 
41 	msg_cb = (struct cras_main_msg_callback *)calloc(1, sizeof(*msg_cb));
42 	msg_cb->type = type;
43 	msg_cb->callback = callback;
44 	msg_cb->callback_data = callback_data;
45 
46 	DL_APPEND(main_msg_callbacks, msg_cb);
47 	return 0;
48 }
49 
50 int cras_main_message_send(struct cras_main_message *msg)
51 {
52 	int err;
53 
54 	err = write(main_msg_fds[1], msg, msg->length);
55 	if (err < 0) {
56 		syslog(LOG_ERR, "Failed to send main message, type %u",
57 		       msg->type);
58 		return err;
59 	}
60 	return 0;
61 }
62 
63 static int read_main_message(int msg_fd, uint8_t *buf, size_t max_len) {
64 	int to_read, nread, rc;
65 	struct cras_main_message *msg = (struct cras_main_message *)buf;
66 
67 	nread = read(msg_fd, buf, sizeof(msg->length));
68 	if (nread < 0)
69 		return nread;
70 	if (msg->length > max_len)
71 		return -ENOMEM;
72 
73 	to_read = msg->length - nread;
74 	rc = read(msg_fd, &buf[0] + nread, to_read);
75 	if (rc < 0)
76 		return rc;
77 	return 0;
78 }
79 
80 static void handle_main_messages(void *arg)
81 {
82 	uint8_t buf[256];
83 	int rc;
84 	struct cras_main_msg_callback *main_msg_cb;
85 	struct cras_main_message *msg = (struct cras_main_message *)buf;
86 
87 	rc = read_main_message(main_msg_fds[0], buf, sizeof(buf));
88 	if (rc < 0) {
89 		syslog(LOG_ERR, "Failed to read main message");
90 		return;
91 	}
92 
93 	DL_FOREACH(main_msg_callbacks, main_msg_cb) {
94 		if (main_msg_cb->type == msg->type) {
95 			main_msg_cb->callback(msg, main_msg_cb->callback_data);
96 			break;
97 		}
98 	}
99 }
100 
101 void cras_main_message_init() {
102 	int rc;
103 
104 	rc = pipe(main_msg_fds);
105 	if (rc < 0) {
106 		syslog(LOG_ERR, "Fatal: main message init");
107 		exit(-ENOMEM);
108 	}
109 
110 	/* When full it's preferred to get error instead of blocked. */
111 	cras_make_fd_nonblocking(main_msg_fds[0]);
112 	cras_make_fd_nonblocking(main_msg_fds[1]);
113 
114 	cras_system_add_select_fd(main_msg_fds[0],
115 				  handle_main_messages,
116 				  NULL);
117 }
118