logd: add reinit command

- respond to SIGHUP
- respond to logd command "reinit"
- respond to logd --reinit
- reopens files on /data, eg: re-read of persistent properties

Bug: 19681572
Change-Id: Iadac58e6653f027cb7355497bd675eef376ce0a8

5 files changed, 143 insertions, 19 deletions

diff --git a/logd/CommandListener.cpp b/logd/CommandListener.cpp
index d7088b4db..561ea3e50 100644
--- a/logd/CommandListener.cpp
+++ b/logd/CommandListener.cpp
@@ -44,6 +44,7 @@ CommandListener::CommandListener(LogBuffer *buf, LogReader * /*reader*/,
     registerCmd(new GetStatisticsCmd(buf));
     registerCmd(new SetPruneListCmd(buf));
     registerCmd(new GetPruneListCmd(buf));
+    registerCmd(new ReinitCmd());
 }
 
 CommandListener::ShutdownCmd::ShutdownCmd(LogBuffer *buf, LogReader *reader,
@@ -296,6 +297,21 @@ int CommandListener::SetPruneListCmd::runCommand(SocketClient *cli,
     return 0;
 }
 
+CommandListener::ReinitCmd::ReinitCmd()
+        : LogCommand("reinit")
+{ }
+
+int CommandListener::ReinitCmd::runCommand(SocketClient *cli,
+                                         int /*argc*/, char ** /*argv*/) {
+    setname();
+
+    reinit_signal_handler(SIGHUP);
+
+    cli->sendMsg("success");
+
+    return 0;
+}
+
 int CommandListener::getLogSocket() {
     static const char socketName[] = "logd";
     int sock = android_get_control_socket(socketName);
diff --git a/logd/CommandListener.h b/logd/CommandListener.h
index cd1c306ba..83e06b4b0 100644
--- a/logd/CommandListener.h
+++ b/logd/CommandListener.h
@@ -23,6 +23,9 @@
 #include "LogReader.h"
 #include "LogListener.h"
 
+// See main.cpp for implementation
+void reinit_signal_handler(int /*signal*/);
+
 class CommandListener : public FrameworkListener {
     LogBuffer &mBuf;
 
@@ -60,6 +63,14 @@ private:
     LogBufferCmd(GetStatistics)
     LogBufferCmd(GetPruneList)
     LogBufferCmd(SetPruneList)
+
+    class ReinitCmd : public LogCommand {
+    public:
+        ReinitCmd();
+        virtual ~ReinitCmd() {}
+        int runCommand(SocketClient *c, int argc, char ** argv);
+    };
+
 };
 
 #endif
diff --git a/logd/LogBuffer.cpp b/logd/LogBuffer.cpp
index edda6c4e2..2b495abfd 100644
--- a/logd/LogBuffer.cpp
+++ b/logd/LogBuffer.cpp
@@ -92,10 +92,7 @@ static unsigned long property_get_size(const char *key) {
     return value;
 }
 
-LogBuffer::LogBuffer(LastLogTimes *times)
-        : mTimes(*times) {
-    pthread_mutex_init(&mLogElementsLock, NULL);
-
+void LogBuffer::init() {
     static const char global_tuneable[] = "persist.logd.size"; // Settings App
     static const char global_default[] = "ro.logd.size";       // BoardConfig.mk
 
@@ -131,6 +128,13 @@ LogBuffer::LogBuffer(LastLogTimes *times)
     }
 }
 
+LogBuffer::LogBuffer(LastLogTimes *times)
+        : mTimes(*times) {
+    pthread_mutex_init(&mLogElementsLock, NULL);
+
+    init();
+}
+
 void LogBuffer::log(log_id_t log_id, log_time realtime,
                     uid_t uid, pid_t pid, pid_t tid,
                     const char *msg, unsigned short len) {
diff --git a/logd/LogBuffer.h b/logd/LogBuffer.h
index b0003ded2..86a2a2a68 100644
--- a/logd/LogBuffer.h
+++ b/logd/LogBuffer.h
@@ -46,6 +46,7 @@ public:
     LastLogTimes &mTimes;
 
     LogBuffer(LastLogTimes *times);
+    void init();
 
     void log(log_id_t log_id, log_time realtime,
              uid_t uid, pid_t pid, pid_t tid,
diff --git a/logd/main.cpp b/logd/main.cpp
index 243bee4cd..2d799bf7a 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -17,7 +17,10 @@
 #include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <poll.h>
 #include <sched.h>
+#include <semaphore.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -30,6 +33,7 @@
 
 #include <cutils/properties.h>
 #include <cutils/sched_policy.h>
+#include <cutils/sockets.h>
 
 #include "private/android_filesystem_config.h"
 #include "CommandListener.h"
@@ -127,17 +131,100 @@ static bool property_get_bool(const char *key, bool def) {
     return def;
 }
 
-// Foreground waits for exit of the three main persistent threads that
-// are started here.  The three threads are created to manage UNIX
-// domain client sockets for writing, reading and controlling the user
-// space logger.  Additional transitory per-client threads are created
-// for each reader once they register.
-int main() {
-    bool auditd = property_get_bool("logd.auditd", true);
+static sem_t reinit;
+static bool reinit_running = false;
+static LogBuffer *logBuf = NULL;
+
+static void *reinit_thread_start(void * /*obj*/) {
+    prctl(PR_SET_NAME, "logd.daemon");
+    set_sched_policy(0, SP_BACKGROUND);
 
-    int fdDmesg = -1;
-    if (auditd && property_get_bool("logd.auditd.dmesg", true)) {
-        fdDmesg = open("/dev/kmsg", O_WRONLY);
+    setgid(AID_LOGD);
+    setuid(AID_LOGD);
+
+    while (reinit_running && !sem_wait(&reinit) && reinit_running) {
+        // Anything that reads persist.<property>
+        if (logBuf) {
+            logBuf->init();
+        }
+    }
+
+    return NULL;
+}
+
+// Serves as a global method to trigger reinitialization
+// and as a function that can be provided to signal().
+void reinit_signal_handler(int /*signal*/) {
+    sem_post(&reinit);
+}
+
+// Remove the static, and use this variable
+// globally for debugging if necessary. eg:
+//   write(fdDmesg, "I am here\n", 10);
+static int fdDmesg = -1;
+
+// Foreground waits for exit of the main persistent threads
+// that are started here. The threads are created to manage
+// UNIX domain client sockets for writing, reading and
+// controlling the user space logger, and for any additional
+// logging plugins like auditd and restart control. Additional
+// transitory per-client threads are created for each reader.
+int main(int argc, char *argv[]) {
+    fdDmesg = open("/dev/kmsg", O_WRONLY);
+
+    // issue reinit command. KISS argument parsing.
+    if ((argc > 1) && argv[1] && !strcmp(argv[1], "--reinit")) {
+        int sock = TEMP_FAILURE_RETRY(
+            socket_local_client("logd",
+                                ANDROID_SOCKET_NAMESPACE_RESERVED,
+                                SOCK_STREAM));
+        if (sock < 0) {
+            return -errno;
+        }
+        static const char reinit[] = "reinit";
+        ssize_t ret = TEMP_FAILURE_RETRY(write(sock, reinit, sizeof(reinit)));
+        if (ret < 0) {
+            return -errno;
+        }
+        struct pollfd p;
+        memset(&p, 0, sizeof(p));
+        p.fd = sock;
+        p.events = POLLIN;
+        ret = TEMP_FAILURE_RETRY(poll(&p, 1, 100));
+        if (ret < 0) {
+            return -errno;
+        }
+        if ((ret == 0) || !(p.revents & POLLIN)) {
+            return -ETIME;
+        }
+        static const char success[] = "success";
+        char buffer[sizeof(success) - 1];
+        memset(buffer, 0, sizeof(buffer));
+        ret = TEMP_FAILURE_RETRY(read(sock, buffer, sizeof(buffer)));
+        if (ret < 0) {
+            return -errno;
+        }
+        return strncmp(buffer, success, sizeof(success) - 1) != 0;
+    }
+
+    // Reinit Thread
+    sem_init(&reinit, 0, 0);
+    pthread_attr_t attr;
+    if (!pthread_attr_init(&attr)) {
+        struct sched_param param;
+
+        memset(&param, 0, sizeof(param));
+        pthread_attr_setschedparam(&attr, &param);
+        pthread_attr_setschedpolicy(&attr, SCHED_BATCH);
+        if (!pthread_attr_setdetachstate(&attr,
+                                         PTHREAD_CREATE_DETACHED)) {
+            pthread_t thread;
+            reinit_running = true;
+            if (pthread_create(&thread, &attr, reinit_thread_start, NULL)) {
+                reinit_running = false;
+            }
+        }
+        pthread_attr_destroy(&attr);
     }
 
     if (drop_privs() != 0) {
@@ -153,7 +240,9 @@ int main() {
     // LogBuffer is the object which is responsible for holding all
     // log entries.
 
-    LogBuffer *logBuf = new LogBuffer(times);
+    logBuf = new LogBuffer(times);
+
+    signal(SIGHUP, reinit_signal_handler);
 
     {
         char property[PROPERTY_VALUE_MAX];
@@ -195,9 +284,13 @@ int main() {
     // initiated log messages. New log entries are added to LogBuffer
     // and LogReader is notified to send updates to connected clients.
 
+    bool auditd = property_get_bool("logd.auditd", true);
+
     if (auditd) {
+        bool dmesg = property_get_bool("logd.auditd.dmesg", true);
+
         // failure is an option ... messages are in dmesg (required by standard)
-        LogAudit *al = new LogAudit(logBuf, reader, fdDmesg);
+        LogAudit *al = new LogAudit(logBuf, reader, dmesg ? fdDmesg : -1);
 
         int len = klogctl(KLOG_SIZE_BUFFER, NULL, 0);
         if (len > 0) {
@@ -217,11 +310,10 @@ int main() {
 
         if (al->startListener()) {
             delete al;
-            close(fdDmesg);
         }
     }
 
-    pause();
+    TEMP_FAILURE_RETRY(pause());
+
     exit(0);
 }
-