liblog: add log/log_read.h

Move log reading definitions to their own home.

struct logger_entry
struct logger_entry_v2
struct logger_entry_v3
struct logger_entry_v4
LOGGER_ENTRY_MAX_PAYLOAD
LOGGER_ENTRY_MAX_LEN
struct log_msg
android_logger_get_id()
android_logger_clear()
android_logger_get_log_size()
android_logger_get_log_readable_size()
struct logger_list
android_logger_get_statistics()
android_logger_get_prune_list()
android_logger_set_prune_list()
android_logger_list_alloc()
android_logger_list_alloc_time()
android_logger_list_free()
android_logger_list_read()
android_logger_open()
android_logger_list_open()

Deal with a possible scenario where fcntl.h was not included at the
top of the source files, and log/log_read.h inclusion of fcntl.h
conflicts with a source file inclusion of sys/cdefs.h definition of
__unused macro.

Test: gTest liblog-unit-tests --gtest_filter=\
      liblog.__android_log_write__android_logger_list_read:\
      liblog.android_logger_get_
Bug: 34250038
Change-Id: Ib33544171563d6a351164754c254c4385686025b
diff --git a/liblog/include/log/log.h b/liblog/include/log/log.h
index 9192a70..db22211 100644
--- a/liblog/include/log/log.h
+++ b/liblog/include/log/log.h
@@ -31,6 +31,7 @@
 #include <log/log_id.h>
 #include <log/log_main.h>
 #include <log/log_radio.h>
+#include <log/log_read.h>
 #include <log/log_system.h>
 #include <log/log_time.h>
 #include <log/uio.h> /* helper to define iovec for portability */
@@ -145,253 +146,6 @@
         (void) __android_log_bswrite(_tag, _value);
 #endif
 
-/* --------------------------------------------------------------------- */
-
-/*
- * Native log reading interface section. See logcat for sample code.
- *
- * The preferred API is an exec of logcat. Likely uses of this interface
- * are if native code suffers from exec or filtration being too costly,
- * access to raw information, or parsing is an issue.
- */
-
-/*
- * The userspace structure for version 1 of the logger_entry ABI.
- */
-#ifndef __struct_logger_entry_defined
-#define __struct_logger_entry_defined
-struct logger_entry {
-    uint16_t    len;    /* length of the payload */
-    uint16_t    __pad;  /* no matter what, we get 2 bytes of padding */
-    int32_t     pid;    /* generating process's pid */
-    int32_t     tid;    /* generating process's tid */
-    int32_t     sec;    /* seconds since Epoch */
-    int32_t     nsec;   /* nanoseconds */
-#ifndef __cplusplus
-    char        msg[0]; /* the entry's payload */
-#endif
-};
-#endif
-
-/*
- * The userspace structure for version 2 of the logger_entry ABI.
- */
-#ifndef __struct_logger_entry_v2_defined
-#define __struct_logger_entry_v2_defined
-struct logger_entry_v2 {
-    uint16_t    len;       /* length of the payload */
-    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v2) */
-    int32_t     pid;       /* generating process's pid */
-    int32_t     tid;       /* generating process's tid */
-    int32_t     sec;       /* seconds since Epoch */
-    int32_t     nsec;      /* nanoseconds */
-    uint32_t    euid;      /* effective UID of logger */
-#ifndef __cplusplus
-    char        msg[0];    /* the entry's payload */
-#endif
-} __attribute__((__packed__));
-#endif
-
-/*
- * The userspace structure for version 3 of the logger_entry ABI.
- */
-#ifndef __struct_logger_entry_v3_defined
-#define __struct_logger_entry_v3_defined
-struct logger_entry_v3 {
-    uint16_t    len;       /* length of the payload */
-    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v3) */
-    int32_t     pid;       /* generating process's pid */
-    int32_t     tid;       /* generating process's tid */
-    int32_t     sec;       /* seconds since Epoch */
-    int32_t     nsec;      /* nanoseconds */
-    uint32_t    lid;       /* log id of the payload */
-#ifndef __cplusplus
-    char        msg[0];    /* the entry's payload */
-#endif
-} __attribute__((__packed__));
-#endif
-
-/*
- * The userspace structure for version 4 of the logger_entry ABI.
- */
-#ifndef __struct_logger_entry_v4_defined
-#define __struct_logger_entry_v4_defined
-struct logger_entry_v4 {
-    uint16_t    len;       /* length of the payload */
-    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v4) */
-    int32_t     pid;       /* generating process's pid */
-    uint32_t    tid;       /* generating process's tid */
-    uint32_t    sec;       /* seconds since Epoch */
-    uint32_t    nsec;      /* nanoseconds */
-    uint32_t    lid;       /* log id of the payload, bottom 4 bits currently */
-    uint32_t    uid;       /* generating process's uid */
-#ifndef __cplusplus
-    char        msg[0];    /* the entry's payload */
-#endif
-};
-#endif
-
-/*
- * The maximum size of the log entry payload that can be
- * written to the logger. An attempt to write more than
- * this amount will result in a truncated log entry.
- */
-#define LOGGER_ENTRY_MAX_PAYLOAD 4068
-
-/*
- * The maximum size of a log entry which can be read from the
- * kernel logger driver. An attempt to read less than this amount
- * may result in read() returning EINVAL.
- */
-#define LOGGER_ENTRY_MAX_LEN    (5*1024)
-
-#ifndef __struct_log_msg_defined
-#define __struct_log_msg_defined
-struct log_msg {
-    union {
-        unsigned char buf[LOGGER_ENTRY_MAX_LEN + 1];
-        struct logger_entry_v4 entry;
-        struct logger_entry_v4 entry_v4;
-        struct logger_entry_v3 entry_v3;
-        struct logger_entry_v2 entry_v2;
-        struct logger_entry    entry_v1;
-    } __attribute__((aligned(4)));
-#ifdef __cplusplus
-    /* Matching log_time operators */
-    bool operator== (const log_msg& T) const
-    {
-        return (entry.sec == T.entry.sec) && (entry.nsec == T.entry.nsec);
-    }
-    bool operator!= (const log_msg& T) const
-    {
-        return !(*this == T);
-    }
-    bool operator< (const log_msg& T) const
-    {
-        return (entry.sec < T.entry.sec)
-            || ((entry.sec == T.entry.sec)
-             && (entry.nsec < T.entry.nsec));
-    }
-    bool operator>= (const log_msg& T) const
-    {
-        return !(*this < T);
-    }
-    bool operator> (const log_msg& T) const
-    {
-        return (entry.sec > T.entry.sec)
-            || ((entry.sec == T.entry.sec)
-             && (entry.nsec > T.entry.nsec));
-    }
-    bool operator<= (const log_msg& T) const
-    {
-        return !(*this > T);
-    }
-    uint64_t nsec() const
-    {
-        return static_cast<uint64_t>(entry.sec) * NS_PER_SEC + entry.nsec;
-    }
-
-    /* packet methods */
-    log_id_t id()
-    {
-        return static_cast<log_id_t>(entry.lid);
-    }
-    char* msg()
-    {
-        unsigned short hdr_size = entry.hdr_size;
-        if (!hdr_size) {
-            hdr_size = sizeof(entry_v1);
-        }
-        if ((hdr_size < sizeof(entry_v1)) || (hdr_size > sizeof(entry))) {
-            return NULL;
-        }
-        return reinterpret_cast<char*>(buf) + hdr_size;
-    }
-    unsigned int len()
-    {
-        return (entry.hdr_size ?
-                    entry.hdr_size :
-                    static_cast<uint16_t>(sizeof(entry_v1))) +
-               entry.len;
-    }
-#endif
-};
-#endif
-
-#ifndef __ANDROID_USE_LIBLOG_READER_INTERFACE
-#ifndef __ANDROID_API__
-#define __ANDROID_USE_LIBLOG_READER_INTERFACE 3
-#elif __ANDROID_API__ > 23 /* > Marshmallow */
-#define __ANDROID_USE_LIBLOG_READER_INTERFACE 3
-#elif __ANDROID_API__ > 22 /* > Lollipop */
-#define __ANDROID_USE_LIBLOG_READER_INTERFACE 2
-#elif __ANDROID_API__ > 19 /* > KitKat */
-#define __ANDROID_USE_LIBLOG_READER_INTERFACE 1
-#else
-#define __ANDROID_USE_LIBLOG_READER_INTERFACE 0
-#endif
-#endif
-
-#if __ANDROID_USE_LIBLOG_READER_INTERFACE
-
-struct logger;
-
-log_id_t android_logger_get_id(struct logger* logger);
-
-int android_logger_clear(struct logger* logger);
-long android_logger_get_log_size(struct logger* logger);
-int android_logger_set_log_size(struct logger* logger, unsigned long size);
-long android_logger_get_log_readable_size(struct logger* logger);
-int android_logger_get_log_version(struct logger* logger);
-
-struct logger_list;
-
-#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 1
-ssize_t android_logger_get_statistics(struct logger_list* logger_list,
-                                      char* buf, size_t len);
-ssize_t android_logger_get_prune_list(struct logger_list* logger_list,
-                                      char* buf, size_t len);
-int android_logger_set_prune_list(struct logger_list* logger_list,
-                                  char* buf, size_t len);
-#endif
-
-#define ANDROID_LOG_RDONLY   O_RDONLY
-#define ANDROID_LOG_WRONLY   O_WRONLY
-#define ANDROID_LOG_RDWR     O_RDWR
-#define ANDROID_LOG_ACCMODE  O_ACCMODE
-#define ANDROID_LOG_NONBLOCK O_NONBLOCK
-#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 2
-#define ANDROID_LOG_WRAP     0x40000000 /* Block until buffer about to wrap */
-#define ANDROID_LOG_WRAP_DEFAULT_TIMEOUT 7200 /* 2 hour default */
-#endif
-#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 1
-#define ANDROID_LOG_PSTORE   0x80000000
-#endif
-
-struct logger_list* android_logger_list_alloc(int mode,
-                                              unsigned int tail,
-                                              pid_t pid);
-struct logger_list* android_logger_list_alloc_time(int mode,
-                                                   log_time start,
-                                                   pid_t pid);
-void android_logger_list_free(struct logger_list* logger_list);
-/* In the purest sense, the following two are orthogonal interfaces */
-int android_logger_list_read(struct logger_list* logger_list,
-                             struct log_msg* log_msg);
-
-/* Multiple log_id_t opens */
-struct logger* android_logger_open(struct logger_list* logger_list,
-                                   log_id_t id);
-#define android_logger_close android_logger_free
-/* Single log_id_t open */
-struct logger_list* android_logger_list_open(log_id_t id,
-                                             int mode,
-                                             unsigned int tail,
-                                             pid_t pid);
-#define android_logger_list_close android_logger_list_free
-
-#endif /* __ANDROID_USE_LIBLOG_READER_INTERFACE */
-
 #ifdef __linux__
 
 #ifndef __ANDROID_USE_LIBLOG_CLOCK_INTERFACE
diff --git a/liblog/include/log/log_read.h b/liblog/include/log/log_read.h
new file mode 100644
index 0000000..5b5eebc
--- /dev/null
+++ b/liblog/include/log/log_read.h
@@ -0,0 +1,291 @@
+/*
+ * Copyright (C) 2005-2017 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.
+ */
+
+#ifndef _LIBS_LOG_LOG_READ_H
+#define _LIBS_LOG_LOG_READ_H
+
+/* deal with possible sys/cdefs.h conflict with fcntl.h */
+#ifdef __unused
+#define __unused_defined __unused
+#undef __unused
+#endif
+
+#include <fcntl.h> /* Pick up O_* macros */
+
+/* restore definitions from above */
+#ifdef __unused_defined
+#define __unused __attribute__((__unused__))
+#endif
+
+#include <stdint.h>
+
+#include <log/log_id.h>
+#include <log/log_time.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Native log reading interface section. See logcat for sample code.
+ *
+ * The preferred API is an exec of logcat. Likely uses of this interface
+ * are if native code suffers from exec or filtration being too costly,
+ * access to raw information, or parsing is an issue.
+ */
+
+/*
+ * The userspace structure for version 1 of the logger_entry ABI.
+ */
+#ifndef __struct_logger_entry_defined
+#define __struct_logger_entry_defined
+struct logger_entry {
+    uint16_t    len;    /* length of the payload */
+    uint16_t    __pad;  /* no matter what, we get 2 bytes of padding */
+    int32_t     pid;    /* generating process's pid */
+    int32_t     tid;    /* generating process's tid */
+    int32_t     sec;    /* seconds since Epoch */
+    int32_t     nsec;   /* nanoseconds */
+#ifndef __cplusplus
+    char        msg[0]; /* the entry's payload */
+#endif
+};
+#endif
+
+/*
+ * The userspace structure for version 2 of the logger_entry ABI.
+ */
+#ifndef __struct_logger_entry_v2_defined
+#define __struct_logger_entry_v2_defined
+struct logger_entry_v2 {
+    uint16_t    len;       /* length of the payload */
+    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v2) */
+    int32_t     pid;       /* generating process's pid */
+    int32_t     tid;       /* generating process's tid */
+    int32_t     sec;       /* seconds since Epoch */
+    int32_t     nsec;      /* nanoseconds */
+    uint32_t    euid;      /* effective UID of logger */
+#ifndef __cplusplus
+    char        msg[0];    /* the entry's payload */
+#endif
+} __attribute__((__packed__));
+#endif
+
+/*
+ * The userspace structure for version 3 of the logger_entry ABI.
+ */
+#ifndef __struct_logger_entry_v3_defined
+#define __struct_logger_entry_v3_defined
+struct logger_entry_v3 {
+    uint16_t    len;       /* length of the payload */
+    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v3) */
+    int32_t     pid;       /* generating process's pid */
+    int32_t     tid;       /* generating process's tid */
+    int32_t     sec;       /* seconds since Epoch */
+    int32_t     nsec;      /* nanoseconds */
+    uint32_t    lid;       /* log id of the payload */
+#ifndef __cplusplus
+    char        msg[0];    /* the entry's payload */
+#endif
+} __attribute__((__packed__));
+#endif
+
+/*
+ * The userspace structure for version 4 of the logger_entry ABI.
+ */
+#ifndef __struct_logger_entry_v4_defined
+#define __struct_logger_entry_v4_defined
+struct logger_entry_v4 {
+    uint16_t    len;       /* length of the payload */
+    uint16_t    hdr_size;  /* sizeof(struct logger_entry_v4) */
+    int32_t     pid;       /* generating process's pid */
+    uint32_t    tid;       /* generating process's tid */
+    uint32_t    sec;       /* seconds since Epoch */
+    uint32_t    nsec;      /* nanoseconds */
+    uint32_t    lid;       /* log id of the payload, bottom 4 bits currently */
+    uint32_t    uid;       /* generating process's uid */
+#ifndef __cplusplus
+    char        msg[0];    /* the entry's payload */
+#endif
+};
+#endif
+
+/*
+ * The maximum size of the log entry payload that can be
+ * written to the logger. An attempt to write more than
+ * this amount will result in a truncated log entry.
+ */
+#define LOGGER_ENTRY_MAX_PAYLOAD 4068
+
+/*
+ * The maximum size of a log entry which can be read.
+ * An attempt to read less than this amount may result
+ * in read() returning EINVAL.
+ */
+#define LOGGER_ENTRY_MAX_LEN    (5*1024)
+
+#ifndef __struct_log_msg_defined
+#define __struct_log_msg_defined
+struct log_msg {
+    union {
+        unsigned char buf[LOGGER_ENTRY_MAX_LEN + 1];
+        struct logger_entry_v4 entry;
+        struct logger_entry_v4 entry_v4;
+        struct logger_entry_v3 entry_v3;
+        struct logger_entry_v2 entry_v2;
+        struct logger_entry    entry_v1;
+    } __attribute__((aligned(4)));
+#ifdef __cplusplus
+    /* Matching log_time operators */
+    bool operator== (const log_msg& T) const
+    {
+        return (entry.sec == T.entry.sec) && (entry.nsec == T.entry.nsec);
+    }
+    bool operator!= (const log_msg& T) const
+    {
+        return !(*this == T);
+    }
+    bool operator< (const log_msg& T) const
+    {
+        return (entry.sec < T.entry.sec)
+            || ((entry.sec == T.entry.sec)
+             && (entry.nsec < T.entry.nsec));
+    }
+    bool operator>= (const log_msg& T) const
+    {
+        return !(*this < T);
+    }
+    bool operator> (const log_msg& T) const
+    {
+        return (entry.sec > T.entry.sec)
+            || ((entry.sec == T.entry.sec)
+             && (entry.nsec > T.entry.nsec));
+    }
+    bool operator<= (const log_msg& T) const
+    {
+        return !(*this > T);
+    }
+    uint64_t nsec() const
+    {
+        return static_cast<uint64_t>(entry.sec) * NS_PER_SEC + entry.nsec;
+    }
+
+    /* packet methods */
+    log_id_t id()
+    {
+        return static_cast<log_id_t>(entry.lid);
+    }
+    char* msg()
+    {
+        unsigned short hdr_size = entry.hdr_size;
+        if (!hdr_size) {
+            hdr_size = sizeof(entry_v1);
+        }
+        if ((hdr_size < sizeof(entry_v1)) || (hdr_size > sizeof(entry))) {
+            return NULL;
+        }
+        return reinterpret_cast<char*>(buf) + hdr_size;
+    }
+    unsigned int len()
+    {
+        return (entry.hdr_size ?
+                    entry.hdr_size :
+                    static_cast<uint16_t>(sizeof(entry_v1))) +
+               entry.len;
+    }
+#endif
+};
+#endif
+
+#ifndef __ANDROID_USE_LIBLOG_READER_INTERFACE
+#ifndef __ANDROID_API__
+#define __ANDROID_USE_LIBLOG_READER_INTERFACE 3
+#elif __ANDROID_API__ > 23 /* > Marshmallow */
+#define __ANDROID_USE_LIBLOG_READER_INTERFACE 3
+#elif __ANDROID_API__ > 22 /* > Lollipop */
+#define __ANDROID_USE_LIBLOG_READER_INTERFACE 2
+#elif __ANDROID_API__ > 19 /* > KitKat */
+#define __ANDROID_USE_LIBLOG_READER_INTERFACE 1
+#else
+#define __ANDROID_USE_LIBLOG_READER_INTERFACE 0
+#endif
+#endif
+
+#if __ANDROID_USE_LIBLOG_READER_INTERFACE
+
+struct logger;
+
+log_id_t android_logger_get_id(struct logger* logger);
+
+int android_logger_clear(struct logger* logger);
+long android_logger_get_log_size(struct logger* logger);
+int android_logger_set_log_size(struct logger* logger, unsigned long size);
+long android_logger_get_log_readable_size(struct logger* logger);
+int android_logger_get_log_version(struct logger* logger);
+
+struct logger_list;
+
+#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 1
+ssize_t android_logger_get_statistics(struct logger_list* logger_list,
+                                      char* buf, size_t len);
+ssize_t android_logger_get_prune_list(struct logger_list* logger_list,
+                                      char* buf, size_t len);
+int android_logger_set_prune_list(struct logger_list* logger_list,
+                                  char* buf, size_t len);
+#endif
+
+#define ANDROID_LOG_RDONLY   O_RDONLY
+#define ANDROID_LOG_WRONLY   O_WRONLY
+#define ANDROID_LOG_RDWR     O_RDWR
+#define ANDROID_LOG_ACCMODE  O_ACCMODE
+#define ANDROID_LOG_NONBLOCK O_NONBLOCK
+#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 2
+#define ANDROID_LOG_WRAP     0x40000000 /* Block until buffer about to wrap */
+#define ANDROID_LOG_WRAP_DEFAULT_TIMEOUT 7200 /* 2 hour default */
+#endif
+#if __ANDROID_USE_LIBLOG_READER_INTERFACE > 1
+#define ANDROID_LOG_PSTORE   0x80000000
+#endif
+
+struct logger_list* android_logger_list_alloc(int mode,
+                                              unsigned int tail,
+                                              pid_t pid);
+struct logger_list* android_logger_list_alloc_time(int mode,
+                                                   log_time start,
+                                                   pid_t pid);
+void android_logger_list_free(struct logger_list* logger_list);
+/* In the purest sense, the following two are orthogonal interfaces */
+int android_logger_list_read(struct logger_list* logger_list,
+                             struct log_msg* log_msg);
+
+/* Multiple log_id_t opens */
+struct logger* android_logger_open(struct logger_list* logger_list,
+                                   log_id_t id);
+#define android_logger_close android_logger_free
+/* Single log_id_t open */
+struct logger_list* android_logger_list_open(log_id_t id,
+                                             int mode,
+                                             unsigned int tail,
+                                             pid_t pid);
+#define android_logger_list_close android_logger_list_free
+
+#endif /* __ANDROID_USE_LIBLOG_READER_INTERFACE */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LIBS_LOG_LOG_H */
diff --git a/liblog/tests/Android.mk b/liblog/tests/Android.mk
index 8450675..097befc 100644
--- a/liblog/tests/Android.mk
+++ b/liblog/tests/Android.mk
@@ -58,6 +58,7 @@
     liblog_test.cpp \
     log_id_test.cpp \
     log_radio_test.cpp \
+    log_read_test.cpp \
     log_system_test.cpp \
     log_time_test.cpp
 
diff --git a/liblog/tests/liblog_test.cpp b/liblog/tests/liblog_test.cpp
index d03c6d1..8b9f0f0 100644
--- a/liblog/tests/liblog_test.cpp
+++ b/liblog/tests/liblog_test.cpp
@@ -1115,47 +1115,6 @@
 #endif
 }
 
-TEST(liblog, android_logger_get_) {
-#ifdef __ANDROID__
-    // This test assumes the log buffers are filled with noise from
-    // normal operations. It will fail if done immediately after a
-    // logcat -c.
-    struct logger_list * logger_list = android_logger_list_alloc(ANDROID_LOG_WRONLY, 0, 0);
-
-    for(int i = LOG_ID_MIN; i < LOG_ID_MAX; ++i) {
-        log_id_t id = static_cast<log_id_t>(i);
-        const char *name = android_log_id_to_name(id);
-        if (id != android_name_to_log_id(name)) {
-            continue;
-        }
-        fprintf(stderr, "log buffer %s\r", name);
-        struct logger * logger;
-        EXPECT_TRUE(NULL != (logger = android_logger_open(logger_list, id)));
-        EXPECT_EQ(id, android_logger_get_id(logger));
-        ssize_t get_log_size = android_logger_get_log_size(logger);
-        /* security buffer is allowed to be denied */
-        if (strcmp("security", name)) {
-            EXPECT_LT(0, get_log_size);
-            /* crash buffer is allowed to be empty, that is actually healthy! */
-            EXPECT_LE((strcmp("crash", name)) != 0,
-                      android_logger_get_log_readable_size(logger));
-        } else {
-            EXPECT_NE(0, get_log_size);
-            if (get_log_size < 0) {
-                EXPECT_GT(0, android_logger_get_log_readable_size(logger));
-            } else {
-                EXPECT_LE(0, android_logger_get_log_readable_size(logger));
-            }
-        }
-        EXPECT_LT(0, android_logger_get_log_version(logger));
-    }
-
-    android_logger_list_close(logger_list);
-#else
-    GTEST_LOG_(INFO) << "This test does nothing.\n";
-#endif
-}
-
 #ifdef __ANDROID__
 static bool checkPriForTag(AndroidLogFormat *p_format, const char *tag, android_LogPriority pri) {
     return android_log_shouldPrintLine(p_format, tag, pri)
diff --git a/liblog/tests/log_read_test.cpp b/liblog/tests/log_read_test.cpp
new file mode 100644
index 0000000..2e02407
--- /dev/null
+++ b/liblog/tests/log_read_test.cpp
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2013-2017 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 <sys/types.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android/log.h> // minimal logging API
+#include <android-base/stringprintf.h>
+#include <gtest/gtest.h>
+// Test the APIs in this standalone include file
+#include <log/log_read.h>
+// Do not use anything in log/log_time.h despite side effects of the above.
+
+TEST(liblog, __android_log_write__android_logger_list_read) {
+#ifdef __ANDROID__
+    pid_t pid = getpid();
+
+    struct logger_list *logger_list;
+    ASSERT_TRUE(NULL != (logger_list = android_logger_list_open(
+        LOG_ID_MAIN, ANDROID_LOG_RDONLY | ANDROID_LOG_NONBLOCK, 1000, pid)));
+
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    std::string buf = android::base::StringPrintf("pid=%u ts=%ld.%09ld",
+                                                  pid, ts.tv_sec, ts.tv_nsec);
+    static const char tag[] = "liblog.__android_log_write__android_logger_list_read";
+    static const char prio = ANDROID_LOG_DEBUG;
+    ASSERT_LT(0, __android_log_write(prio, tag, buf.c_str()));
+    usleep(1000000);
+
+    buf = std::string(&prio, sizeof(prio)) +
+          tag +
+          std::string("", 1) +
+          buf +
+          std::string("", 1);
+
+    int count = 0;
+
+    for (;;) {
+        log_msg log_msg;
+        if (android_logger_list_read(logger_list, &log_msg) <= 0) break;
+
+        EXPECT_EQ(log_msg.entry.pid, pid);
+        // There may be a future where we leak "liblog" tagged LOG_ID_EVENT
+        // binary messages through so that logger losses can be correlated?
+        EXPECT_EQ(log_msg.id(), LOG_ID_MAIN);
+
+        if (log_msg.entry.len != buf.length()) continue;
+
+        if (buf != std::string(log_msg.msg(), log_msg.entry.len)) continue;
+
+        ++count;
+    }
+    android_logger_list_close(logger_list);
+
+    EXPECT_EQ(1, count);
+#else
+    GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif
+}
+
+TEST(liblog, android_logger_get_) {
+#ifdef __ANDROID__
+    // This test assumes the log buffers are filled with noise from
+    // normal operations. It will fail if done immediately after a
+    // logcat -c.
+    struct logger_list * logger_list = android_logger_list_alloc(ANDROID_LOG_WRONLY, 0, 0);
+
+    for(int i = LOG_ID_MIN; i < LOG_ID_MAX; ++i) {
+        log_id_t id = static_cast<log_id_t>(i);
+        const char *name = android_log_id_to_name(id);
+        if (id != android_name_to_log_id(name)) {
+            continue;
+        }
+        fprintf(stderr, "log buffer %s\r", name);
+        struct logger * logger;
+        EXPECT_TRUE(NULL != (logger = android_logger_open(logger_list, id)));
+        EXPECT_EQ(id, android_logger_get_id(logger));
+        ssize_t get_log_size = android_logger_get_log_size(logger);
+        /* security buffer is allowed to be denied */
+        if (strcmp("security", name)) {
+            EXPECT_LT(0, get_log_size);
+            /* crash buffer is allowed to be empty, that is actually healthy! */
+            EXPECT_LE((strcmp("crash", name)) != 0,
+                      android_logger_get_log_readable_size(logger));
+        } else {
+            EXPECT_NE(0, get_log_size);
+            if (get_log_size < 0) {
+                EXPECT_GT(0, android_logger_get_log_readable_size(logger));
+            } else {
+                EXPECT_LE(0, android_logger_get_log_readable_size(logger));
+            }
+        }
+        EXPECT_LT(0, android_logger_get_log_version(logger));
+    }
+
+    android_logger_list_close(logger_list);
+#else
+    GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif
+}
+