logd: make liblogd just the core logd functionality

liblogd: LogBuffer classes and their support, LogReaderList and
LogReaderThread
logd: liblogd + the socket code that connects liblogd to liblog and
therefore the world.

The goal here is to test liblogd offline of the socket connections or
the device.

Also, convert libaudit.c -> libaudit.cpp and modernize a bit.

Test: build
Change-Id: If5adf5e775a251d9a703c0583be0988f48017347
diff --git a/logd/Android.bp b/logd/Android.bp
index d203062..d79e258 100644
--- a/logd/Android.bp
+++ b/logd/Android.bp
@@ -28,46 +28,53 @@
     "-DLIBLOG_LOG_TAG=1006",
 ]
 
-cc_library_static {
-    name: "liblogd",
-
-    srcs: [
-        "ChattyLogBuffer.cpp",
-        "CommandListener.cpp",
-        "LogListener.cpp",
-        "LogPermissions.cpp",
-        "LogReader.cpp",
-        "LogReaderList.cpp",
-        "LogReaderThread.cpp",
-        "LogBufferElement.cpp",
-        "LogStatistics.cpp",
-        "LogWhiteBlackList.cpp",
-        "libaudit.c",
-        "LogAudit.cpp",
-        "LogKlog.cpp",
-        "LogTags.cpp",
-    ],
-    logtags: ["event.logtags"],
+cc_defaults {
+    name: "logd_defaults",
 
     shared_libs: ["libbase"],
-
-    export_include_dirs: ["."],
-
     cflags: [
         "-Wextra",
         "-Wthread-safety",
     ] + event_flag,
 
     lto: {
-        thin: true
-    }
+        thin: true,
+    },
+}
+
+cc_library_static {
+    name: "liblogd",
+    defaults: ["logd_defaults"],
+
+    srcs: [
+        "ChattyLogBuffer.cpp",
+        "LogReaderList.cpp",
+        "LogReaderThread.cpp",
+        "LogBufferElement.cpp",
+        "LogStatistics.cpp",
+        "LogWhiteBlackList.cpp",
+        "LogTags.cpp",
+    ],
+    logtags: ["event.logtags"],
+
+    export_include_dirs: ["."],
 }
 
 cc_binary {
     name: "logd",
+    defaults: ["logd_defaults"],
     init_rc: ["logd.rc"],
 
-    srcs: ["main.cpp"],
+    srcs: [
+        "main.cpp",
+        "LogPermissions.cpp",
+        "CommandListener.cpp",
+        "LogListener.cpp",
+        "LogReader.cpp",
+        "LogAudit.cpp",
+        "LogKlog.cpp",
+        "libaudit.cpp",
+    ],
 
     static_libs: [
         "liblog",
@@ -77,34 +84,23 @@
     shared_libs: [
         "libsysutils",
         "libcutils",
-        "libbase",
         "libpackagelistparser",
         "libprocessgroup",
         "libcap",
     ],
-
-    cflags: [
-        "-Wextra",
-    ],
-
-    lto: {
-        thin: true
-    }
 }
 
 cc_binary {
     name: "auditctl",
 
-    srcs: ["auditctl.cpp"],
-
-    static_libs: [
-        "liblogd",
+    srcs: [
+        "auditctl.cpp",
+        "libaudit.cpp",
     ],
 
     shared_libs: ["libbase"],
 
     cflags: [
-        "-Wconversion",
         "-Wextra",
     ],
 }
diff --git a/logd/libaudit.c b/logd/libaudit.cpp
similarity index 67%
rename from logd/libaudit.c
rename to logd/libaudit.cpp
index f452c71..ccea0a2 100644
--- a/logd/libaudit.c
+++ b/logd/libaudit.cpp
@@ -18,11 +18,13 @@
  *
  */
 
+#include "libaudit.h"
+
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
 
-#include "libaudit.h"
+#include <limits>
 
 /**
  * Waits for an ack from the kernel
@@ -32,22 +34,15 @@
  *  This function returns 0 on success, else -errno.
  */
 static int get_ack(int fd) {
-    int rc;
-    struct audit_message rep;
-
-    /* Sanity check, this is an internal interface this shouldn't happen */
-    if (fd < 0) {
-        return -EINVAL;
-    }
-
-    rc = audit_get_reply(fd, &rep, GET_REPLY_BLOCKING, MSG_PEEK);
+    struct audit_message rep = {};
+    int rc = audit_get_reply(fd, &rep, GET_REPLY_BLOCKING, MSG_PEEK);
     if (rc < 0) {
         return rc;
     }
 
     if (rep.nlh.nlmsg_type == NLMSG_ERROR) {
         audit_get_reply(fd, &rep, GET_REPLY_BLOCKING, 0);
-        rc = ((struct nlmsgerr*)rep.data)->error;
+        rc = reinterpret_cast<struct nlmsgerr*>(rep.data)->error;
         if (rc) {
             return -rc;
         }
@@ -70,19 +65,11 @@
  *  This function returns a positive sequence number on success, else -errno.
  */
 static int audit_send(int fd, int type, const void* data, size_t size) {
-    int rc;
-    static int16_t sequence = 0;
-    struct audit_message req;
-    struct sockaddr_nl addr;
-
-    memset(&req, 0, sizeof(req));
-    memset(&addr, 0, sizeof(addr));
-
-    /* We always send netlink messaged */
-    addr.nl_family = AF_NETLINK;
+    struct sockaddr_nl addr = {.nl_family = AF_NETLINK};
 
     /* Set up the netlink headers */
-    req.nlh.nlmsg_type = type;
+    struct audit_message req = {};
+    req.nlh.nlmsg_type = static_cast<uint16_t>(type);
     req.nlh.nlmsg_len = NLMSG_SPACE(size);
     req.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
 
@@ -107,29 +94,23 @@
     /*
      * Only increment the sequence number on a guarantee
      * you will send it to the kernel.
-     *
-     * Also, the sequence is defined as a u32 in the kernel
-     * struct. Using an int here might not work on 32/64 bit splits. A
-     * signed 64 bit value can overflow a u32..but a u32
-     * might not fit in the response, so we need to use s32.
-     * Which is still kind of hackish since int could be 16 bits
-     * in size. The only safe type to use here is a signed 16
-     * bit value.
      */
-    req.nlh.nlmsg_seq = ++sequence;
+    static uint32_t sequence = 0;
+    if (sequence == std::numeric_limits<uint32_t>::max()) {
+        sequence = 1;
+    } else {
+        sequence++;
+    }
+    req.nlh.nlmsg_seq = sequence;
 
-    /* While failing and its due to interrupts */
-
-    rc = TEMP_FAILURE_RETRY(sendto(fd, &req, req.nlh.nlmsg_len, 0,
-                                   (struct sockaddr*)&addr, sizeof(addr)));
+    ssize_t rc = TEMP_FAILURE_RETRY(
+            sendto(fd, &req, req.nlh.nlmsg_len, 0, (struct sockaddr*)&addr, sizeof(addr)));
 
     /* Not all the bytes were sent */
     if (rc < 0) {
-        rc = -errno;
-        goto out;
+        return -errno;
     } else if ((uint32_t)rc != req.nlh.nlmsg_len) {
-        rc = -EPROTO;
-        goto out;
+        return -EPROTO;
     }
 
     /* We sent all the bytes, get the ack */
@@ -138,32 +119,22 @@
     /* If the ack failed, return the error, else return the sequence number */
     rc = (rc == 0) ? (int)sequence : rc;
 
-out:
-    /* Don't let sequence roll to negative */
-    if (sequence < 0) {
-        sequence = 0;
-    }
-
     return rc;
 }
 
 int audit_setup(int fd, pid_t pid) {
-    int rc;
-    struct audit_message rep;
-    struct audit_status status;
-
-    memset(&status, 0, sizeof(status));
-
     /*
      * In order to set the auditd PID we send an audit message over the netlink
      * socket with the pid field of the status struct set to our current pid,
      * and the the mask set to AUDIT_STATUS_PID
      */
-    status.pid = pid;
-    status.mask = AUDIT_STATUS_PID;
+    struct audit_status status = {
+            .mask = AUDIT_STATUS_PID,
+            .pid = static_cast<uint32_t>(pid),
+    };
 
     /* Let the kernel know this pid will be registering for audit events */
-    rc = audit_send(fd, AUDIT_SET, &status, sizeof(status));
+    int rc = audit_send(fd, AUDIT_SET, &status, sizeof(status));
     if (rc < 0) {
         return rc;
     }
@@ -178,6 +149,7 @@
      * so I went to non-blocking and it seemed to fix the bug.
      * Need to investigate further.
      */
+    struct audit_message rep = {};
     audit_get_reply(fd, &rep, GET_REPLY_NONBLOCKING, 0);
 
     return 0;
@@ -188,27 +160,18 @@
 }
 
 int audit_rate_limit(int fd, uint32_t limit) {
-    struct audit_status status;
-    memset(&status, 0, sizeof(status));
-    status.mask = AUDIT_STATUS_RATE_LIMIT;
-    status.rate_limit = limit; /* audit entries per second */
+    struct audit_status status = {
+            .mask = AUDIT_STATUS_RATE_LIMIT, .rate_limit = limit, /* audit entries per second */
+    };
     return audit_send(fd, AUDIT_SET, &status, sizeof(status));
 }
 
 int audit_get_reply(int fd, struct audit_message* rep, reply_t block, int peek) {
-    ssize_t len;
-    int flags;
-    int rc = 0;
-
-    struct sockaddr_nl nladdr;
-    socklen_t nladdrlen = sizeof(nladdr);
-
     if (fd < 0) {
         return -EBADF;
     }
 
-    /* Set up the flags for recv from */
-    flags = (block == GET_REPLY_NONBLOCKING) ? MSG_DONTWAIT : 0;
+    int flags = (block == GET_REPLY_NONBLOCKING) ? MSG_DONTWAIT : 0;
     flags |= peek;
 
     /*
@@ -216,19 +179,20 @@
      * the interface shows that EINTR can never be returned, other errors,
      * however, can be returned.
      */
-    len = TEMP_FAILURE_RETRY(recvfrom(fd, rep, sizeof(*rep), flags,
-                                      (struct sockaddr*)&nladdr, &nladdrlen));
+    struct sockaddr_nl nladdr;
+    socklen_t nladdrlen = sizeof(nladdr);
+    ssize_t len = TEMP_FAILURE_RETRY(
+            recvfrom(fd, rep, sizeof(*rep), flags, (struct sockaddr*)&nladdr, &nladdrlen));
 
     /*
      * EAGAIN should be re-tried until success or another error manifests.
      */
     if (len < 0) {
-        rc = -errno;
-        if (block == GET_REPLY_NONBLOCKING && rc == -EAGAIN) {
+        if (block == GET_REPLY_NONBLOCKING && errno == EAGAIN) {
             /* If request is non blocking and errno is EAGAIN, just return 0 */
             return 0;
         }
-        return rc;
+        return -errno;
     }
 
     if (nladdrlen != sizeof(nladdr)) {
@@ -242,10 +206,10 @@
 
     /* Check if the reply from the kernel was ok */
     if (!NLMSG_OK(&rep->nlh, (size_t)len)) {
-        rc = (len == sizeof(*rep)) ? -EFBIG : -EBADE;
+        return len == sizeof(*rep) ? -EFBIG : -EBADE;
     }
 
-    return rc;
+    return 0;
 }
 
 void audit_close(int fd) {
diff --git a/logd/libaudit.h b/logd/libaudit.h
index b4a92a8..27b0866 100644
--- a/logd/libaudit.h
+++ b/logd/libaudit.h
@@ -17,8 +17,7 @@
  * Written by William Roberts <w.roberts@sta.samsung.com>
  */
 
-#ifndef _LIBAUDIT_H_
-#define _LIBAUDIT_H_
+#pragma once
 
 #include <stdint.h>
 #include <sys/cdefs.h>
@@ -102,5 +101,3 @@
 extern int audit_rate_limit(int fd, uint32_t limit);
 
 __END_DECLS
-
-#endif