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Commit 7ef5249a authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

liblog: suppress pmsg on user builds 

- add optimized & cached LIBLOG_HIDDEN __android_log_is_debuggable()
- check when writing, either LOG_ID_SECURITY, SafetyNet or
  debuggable when pushing content to the pmsg buffer.

Bug: 27566046
Change-Id: I85f1b55ec329b38e00f4183836b6ed53046c323d
parent fbdbf100

liblog/Android.bp

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ cc_library { 
        //       $(LOCAL_PATH)/event.logtags)

        // so make sure we do not regret hard-coding it as follows:

        "-DLIBLOG_LOG_TAG=1005",

        "-DSNET_EVENT_LOG_TAG=1397638484",

    ],

    compile_multilib: "both",

    stl: "none",

liblog/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ include $(CLEAR_VARS) 
#       $(LOCAL_PATH)/event.logtags)

# so make sure we do not regret hard-coding it as follows:

liblog_cflags := -DLIBLOG_LOG_TAG=1005

liblog_cflags += -DSNET_EVENT_LOG_TAG=1397638484



liblog_sources := log_event_list.c log_event_write.c logger_write.c

liblog_sources += config_write.c logger_name.c logger_lock.c

liblog/log_is_loggable.c

+31 −0
Original line number Diff line number Diff line
@@ -259,6 +259,37 @@ LIBLOG_ABI_PUBLIC int __android_log_is_loggable(int prio, const char *tag, 
    return logLevel >= 0 && prio >= logLevel;

}



LIBLOG_HIDDEN int __android_log_is_debuggable()

{

    static uint32_t serial;

    static struct cache tag_cache;

    static const char key[] = "ro.debuggable";

    int ret;



    if (tag_cache.c) { /* ro property does not change after set */

        ret = tag_cache.c == '1';

    } else if (lock()) {

        struct cache temp_cache = { NULL, -1, '\0' };

        refresh_cache(&temp_cache, key);

        ret = temp_cache.c == '1';

    } else {

        int change_detected = check_cache(&tag_cache);

        uint32_t current_serial = __system_property_area_serial();

        if (current_serial != serial) {

            change_detected = 1;

        }

        if (change_detected) {

            refresh_cache(&tag_cache, key);

            serial = current_serial;

        }

        ret = tag_cache.c == '1';



        unlock();

    }



    return ret;

}



/*

 * For properties that are read often, but generally remain constant.

 * Since a change is rare, we will accept a trylock failure gracefully.

liblog/logger.h

+1 −0
Original line number Diff line number Diff line
@@ -154,6 +154,7 @@ LIBLOG_HIDDEN pid_t __android_log_pid(); 
LIBLOG_HIDDEN void __android_log_lock();

LIBLOG_HIDDEN int __android_log_trylock();

LIBLOG_HIDDEN void __android_log_unlock();

LIBLOG_HIDDEN int __android_log_is_debuggable();



__END_DECLS

liblog/pmsg_writer.c

+23 −0
Original line number Diff line number Diff line
@@ -73,6 +73,11 @@ static int pmsgAvailable(log_id_t logId) 
    if (logId > LOG_ID_SECURITY) {

        return -EINVAL;

    }

    if ((logId != LOG_ID_SECURITY) &&

            (logId != LOG_ID_EVENTS) &&

            !__android_log_is_debuggable()) {

        return -EINVAL;

    }

    if (pmsgLoggerWrite.context.fd < 0) {

        if (access("/dev/pmsg0", W_OK) == 0) {

            return 0;
@@ -82,6 +87,14 @@ static int pmsgAvailable(log_id_t logId) 
    return 1;

}



/*

 * Extract a 4-byte value from a byte stream.

 */

static inline uint32_t get4LE(const uint8_t* src)

{

    return src[0] | (src[1] << 8) | (src[2] << 16) | (src[3] << 24);

}



static int pmsgWrite(log_id_t logId, struct timespec *ts,

                      struct iovec *vec, size_t nr)

{
@@ -92,6 +105,16 @@ static int pmsgWrite(log_id_t logId, struct timespec *ts, 
    size_t i, payloadSize;

    ssize_t ret;



    if ((logId == LOG_ID_EVENTS) && !__android_log_is_debuggable()) {

        if (vec[0].iov_len < 4) {

            return -EINVAL;

        }



        if (SNET_EVENT_LOG_TAG != get4LE(vec[0].iov_base)) {

            return -EPERM;

        }

    }



    if (pmsgLoggerWrite.context.fd < 0) {

        return -EBADF;

    }