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/*
* Copyright (C) 2012-2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <limits.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>
#include <cutils/sockets.h>
#include <log/logger.h>
#include "LogListener.h"
LogListener::LogListener(LogBuffer *buf, LogReader *reader)
: SocketListener(getLogSocket(), false)
, logbuf(buf)
, reader(reader)
{ }
bool LogListener::onDataAvailable(SocketClient *cli) {
prctl(PR_SET_NAME, "logd.writer");
char buffer[sizeof_log_id_t + sizeof(uint16_t) + sizeof(log_time)
+ LOGGER_ENTRY_MAX_PAYLOAD];
struct iovec iov = { buffer, sizeof(buffer) };
memset(buffer, 0, sizeof(buffer));
char control[CMSG_SPACE(sizeof(struct ucred))];
struct msghdr hdr = {
NULL,
0,
&iov,
1,
control,
sizeof(control),
0,
};
int socket = cli->getSocket();
ssize_t n = recvmsg(socket, &hdr, 0);
if (n <= (ssize_t)(sizeof_log_id_t + sizeof(uint16_t) + sizeof(log_time))) {
return false;
}
struct ucred *cred = NULL;
struct cmsghdr *cmsg = CMSG_FIRSTHDR(&hdr);
while (cmsg != NULL) {
if (cmsg->cmsg_level == SOL_SOCKET
&& cmsg->cmsg_type == SCM_CREDENTIALS) {
cred = (struct ucred *)CMSG_DATA(cmsg);
break;
}
cmsg = CMSG_NXTHDR(&hdr, cmsg);
}
if (cred == NULL) {
return false;
}
if (cred->uid == getuid()) {
// ignore log messages we send to ourself.
// Such log messages are often generated by libraries we depend on
// which use standard Android logging.
return false;
}
// First log element is always log_id.
log_id_t log_id = (log_id_t) *((typeof_log_id_t *) buffer);
if (log_id < 0 || log_id >= LOG_ID_MAX) {
return false;
}
char *msg = ((char *)buffer) + sizeof_log_id_t;
n -= sizeof_log_id_t;
// second element is the thread id of the caller
pid_t tid = (pid_t) *((uint16_t *) msg);
msg += sizeof(uint16_t);
n -= sizeof(uint16_t);
// third element is the realtime at point of caller
log_time realtime(msg);
msg += sizeof(log_time);
n -= sizeof(log_time);
// NB: hdr.msg_flags & MSG_TRUNC is not tested, silently passing a
// truncated message to the logs.
logbuf->log(log_id, realtime, cred->uid, cred->pid, tid, msg,
((size_t) n <= USHRT_MAX) ? (unsigned short) n : USHRT_MAX);
reader->notifyNewLog();
return true;
}
int LogListener::getLogSocket() {
static const char socketName[] = "logdw";
int sock = android_get_control_socket(socketName);
if (sock < 0) {
sock = socket_local_server(socketName,
ANDROID_SOCKET_NAMESPACE_RESERVED,
SOCK_DGRAM);
}
int on = 1;
if (setsockopt(sock, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
return -1;
}
return sock;
}
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