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314 lines
11 KiB
314 lines
11 KiB
/*
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* Copyright (C) 2012-2013 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <linux/capability.h>
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#include <poll.h>
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#include <sched.h>
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#include <semaphore.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/capability.h>
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#include <sys/klog.h>
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#include <sys/prctl.h>
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#include <sys/resource.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <syslog.h>
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#include <unistd.h>
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#include <memory>
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#include <android-base/logging.h>
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#include <android-base/macros.h>
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#include <android-base/properties.h>
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#include <android-base/stringprintf.h>
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#include <cutils/android_get_control_file.h>
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#include <cutils/sockets.h>
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#include <log/event_tag_map.h>
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#include <private/android_filesystem_config.h>
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#include <private/android_logger.h>
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#include <processgroup/sched_policy.h>
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#include <utils/threads.h>
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#include "ChattyLogBuffer.h"
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#include "CommandListener.h"
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#include "LogAudit.h"
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#include "LogBuffer.h"
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#include "LogKlog.h"
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#include "LogListener.h"
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#include "LogReader.h"
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#include "LogStatistics.h"
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#include "LogTags.h"
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#include "LogUtils.h"
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#include "SerializedLogBuffer.h"
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#include "SimpleLogBuffer.h"
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using android::base::GetBoolProperty;
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using android::base::GetProperty;
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using android::base::SetProperty;
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#define KMSG_PRIORITY(PRI) \
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'<', '0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) / 10, \
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'0' + LOG_MAKEPRI(LOG_DAEMON, LOG_PRI(PRI)) % 10, '>'
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// The service is designed to be run by init, it does not respond well to starting up manually. Init
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// has a 'sigstop' feature that sends SIGSTOP to a service immediately before calling exec(). This
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// allows debuggers, etc to be attached to logd at the very beginning, while still having init
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// handle the user, groups, capabilities, files, etc setup.
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static void DropPrivs(bool klogd, bool auditd) {
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if (set_sched_policy(0, SP_BACKGROUND) < 0) {
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PLOG(FATAL) << "failed to set background scheduling policy";
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}
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if (!GetBoolProperty("ro.debuggable", false)) {
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if (prctl(PR_SET_DUMPABLE, 0) == -1) {
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PLOG(FATAL) << "failed to clear PR_SET_DUMPABLE";
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}
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}
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std::unique_ptr<struct _cap_struct, int (*)(void*)> caps(cap_init(), cap_free);
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if (cap_clear(caps.get()) < 0) {
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PLOG(FATAL) << "cap_clear() failed";
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}
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if (klogd) {
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cap_value_t cap_syslog = CAP_SYSLOG;
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if (cap_set_flag(caps.get(), CAP_PERMITTED, 1, &cap_syslog, CAP_SET) < 0 ||
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cap_set_flag(caps.get(), CAP_EFFECTIVE, 1, &cap_syslog, CAP_SET) < 0) {
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PLOG(FATAL) << "Failed to set CAP_SYSLOG";
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}
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}
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if (auditd) {
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cap_value_t cap_audit_control = CAP_AUDIT_CONTROL;
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if (cap_set_flag(caps.get(), CAP_PERMITTED, 1, &cap_audit_control, CAP_SET) < 0 ||
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cap_set_flag(caps.get(), CAP_EFFECTIVE, 1, &cap_audit_control, CAP_SET) < 0) {
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PLOG(FATAL) << "Failed to set CAP_AUDIT_CONTROL";
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}
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}
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if (cap_set_proc(caps.get()) < 0) {
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PLOG(FATAL) << "cap_set_proc() failed";
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}
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}
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// GetBoolProperty that defaults to true if `ro.debuggable == true && ro.config.low_rawm == false`.
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static bool GetBoolPropertyEngSvelteDefault(const std::string& name) {
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bool default_value =
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GetBoolProperty("ro.debuggable", false) && !GetBoolProperty("ro.config.low_ram", false);
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return GetBoolProperty(name, default_value);
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}
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static void readDmesg(LogAudit* al, LogKlog* kl) {
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if (!al && !kl) {
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return;
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}
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int rc = klogctl(KLOG_SIZE_BUFFER, nullptr, 0);
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if (rc <= 0) {
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return;
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}
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// Margin for additional input race or trailing nul
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ssize_t len = rc + 1024;
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std::unique_ptr<char[]> buf(new char[len]);
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rc = klogctl(KLOG_READ_ALL, buf.get(), len);
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if (rc <= 0) {
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return;
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}
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if (rc < len) {
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len = rc + 1;
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}
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buf[--len] = '\0';
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ssize_t sublen;
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for (char *ptr = nullptr, *tok = buf.get();
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(rc >= 0) && !!(tok = android::log_strntok_r(tok, len, ptr, sublen));
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tok = nullptr) {
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if ((sublen <= 0) || !*tok) continue;
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if (al) {
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rc = al->log(tok, sublen);
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}
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if (kl) {
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rc = kl->log(tok, sublen);
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}
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}
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}
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static int issueReinit() {
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int sock = TEMP_FAILURE_RETRY(socket_local_client(
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"logd", ANDROID_SOCKET_NAMESPACE_RESERVED, SOCK_STREAM));
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if (sock < 0) return -errno;
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static const char reinitStr[] = "reinit";
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ssize_t ret = TEMP_FAILURE_RETRY(write(sock, reinitStr, sizeof(reinitStr)));
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if (ret < 0) return -errno;
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struct pollfd p;
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memset(&p, 0, sizeof(p));
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p.fd = sock;
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p.events = POLLIN;
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ret = TEMP_FAILURE_RETRY(poll(&p, 1, 1000));
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if (ret < 0) return -errno;
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if ((ret == 0) || !(p.revents & POLLIN)) return -ETIME;
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static const char success[] = "success";
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char buffer[sizeof(success) - 1];
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memset(buffer, 0, sizeof(buffer));
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ret = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
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if (ret < 0) return -errno;
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return strncmp(buffer, success, sizeof(success) - 1) != 0;
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}
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// Foreground waits for exit of the main persistent threads
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// that are started here. The threads are created to manage
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// UNIX domain client sockets for writing, reading and
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// controlling the user space logger, and for any additional
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// logging plugins like auditd and restart control. Additional
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// transitory per-client threads are created for each reader.
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int main(int argc, char* argv[]) {
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// We want EPIPE when a reader disconnects, not to terminate logd.
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signal(SIGPIPE, SIG_IGN);
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// logd is written under the assumption that the timezone is UTC.
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// If TZ is not set, persist.sys.timezone is looked up in some time utility
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// libc functions, including mktime. It confuses the logd time handling,
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// so here explicitly set TZ to UTC, which overrides the property.
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setenv("TZ", "UTC", 1);
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// issue reinit command. KISS argument parsing.
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if ((argc > 1) && argv[1] && !strcmp(argv[1], "--reinit")) {
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return issueReinit();
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}
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android::base::InitLogging(
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argv, [](android::base::LogId log_id, android::base::LogSeverity severity,
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const char* tag, const char* file, unsigned int line, const char* message) {
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if (tag && strcmp(tag, "logd") != 0) {
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auto prefixed_message = android::base::StringPrintf("%s: %s", tag, message);
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android::base::KernelLogger(log_id, severity, "logd", file, line,
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prefixed_message.c_str());
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} else {
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android::base::KernelLogger(log_id, severity, "logd", file, line, message);
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}
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});
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static const char dev_kmsg[] = "/dev/kmsg";
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int fdDmesg = android_get_control_file(dev_kmsg);
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if (fdDmesg < 0) {
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fdDmesg = TEMP_FAILURE_RETRY(open(dev_kmsg, O_WRONLY | O_CLOEXEC));
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}
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int fdPmesg = -1;
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bool klogd = GetBoolPropertyEngSvelteDefault("ro.logd.kernel");
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if (klogd) {
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SetProperty("ro.logd.kernel", "true");
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static const char proc_kmsg[] = "/proc/kmsg";
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fdPmesg = android_get_control_file(proc_kmsg);
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if (fdPmesg < 0) {
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fdPmesg = TEMP_FAILURE_RETRY(
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open(proc_kmsg, O_RDONLY | O_NDELAY | O_CLOEXEC));
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}
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if (fdPmesg < 0) PLOG(ERROR) << "Failed to open " << proc_kmsg;
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}
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bool auditd = GetBoolProperty("ro.logd.auditd", true);
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DropPrivs(klogd, auditd);
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// A cache of event log tags
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LogTags log_tags;
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// Pruning configuration.
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PruneList prune_list;
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std::string buffer_type = GetProperty("logd.buffer_type", "serialized");
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// Partial (required for chatty) or full logging statistics.
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LogStatistics log_statistics(GetBoolPropertyEngSvelteDefault("logd.statistics"),
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buffer_type == "serialized");
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// Serves the purpose of managing the last logs times read on a socket connection, and as a
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// reader lock on a range of log entries.
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LogReaderList reader_list;
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// LogBuffer is the object which is responsible for holding all log entries.
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LogBuffer* log_buffer = nullptr;
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if (buffer_type == "chatty") {
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log_buffer = new ChattyLogBuffer(&reader_list, &log_tags, &prune_list, &log_statistics);
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} else if (buffer_type == "serialized") {
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log_buffer = new SerializedLogBuffer(&reader_list, &log_tags, &log_statistics);
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} else if (buffer_type == "simple") {
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log_buffer = new SimpleLogBuffer(&reader_list, &log_tags, &log_statistics);
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} else {
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LOG(FATAL) << "buffer_type must be one of 'chatty', 'serialized', or 'simple'";
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}
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// LogReader listens on /dev/socket/logdr. When a client
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// connects, log entries in the LogBuffer are written to the client.
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LogReader* reader = new LogReader(log_buffer, &reader_list);
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if (reader->startListener()) {
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return EXIT_FAILURE;
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}
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// LogListener listens on /dev/socket/logdw for client
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// initiated log messages. New log entries are added to LogBuffer
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// and LogReader is notified to send updates to connected clients.
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LogListener* swl = new LogListener(log_buffer);
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if (!swl->StartListener()) {
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return EXIT_FAILURE;
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}
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// Command listener listens on /dev/socket/logd for incoming logd
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// administrative commands.
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CommandListener* cl = new CommandListener(log_buffer, &log_tags, &prune_list, &log_statistics);
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if (cl->startListener()) {
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return EXIT_FAILURE;
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}
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// LogAudit listens on NETLINK_AUDIT socket for selinux
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// initiated log messages. New log entries are added to LogBuffer
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// and LogReader is notified to send updates to connected clients.
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LogAudit* al = nullptr;
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if (auditd) {
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int dmesg_fd = GetBoolProperty("ro.logd.auditd.dmesg", true) ? fdDmesg : -1;
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al = new LogAudit(log_buffer, dmesg_fd, &log_statistics);
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}
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LogKlog* kl = nullptr;
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if (klogd) {
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kl = new LogKlog(log_buffer, fdDmesg, fdPmesg, al != nullptr, &log_statistics);
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}
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readDmesg(al, kl);
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// failure is an option ... messages are in dmesg (required by standard)
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if (kl && kl->startListener()) {
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delete kl;
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}
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if (al && al->startListener()) {
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delete al;
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}
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TEMP_FAILURE_RETRY(pause());
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return EXIT_SUCCESS;
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}
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