liblog: split out transports into separate files

Create config_logger, logger and logger_read to house the log
interfaces. Add fake_logger, logd_logger and pmsg_logger to
house the write and read transports. Allows for an easier and
direct path to add new transports to the library.

SideEffects: None, logger benchmark performance unaffected

Bug: 27176738
Bug: 27405083
Change-Id: I01b38637334a5242905c8c89f6ab0a92e2540008

1 files changed, 267 insertions, 0 deletions

diff --git a/liblog/logd_writer.c b/liblog/logd_writer.c
new file mode 100644
index 000000000..696237d34
--- /dev/null
+++ b/liblog/logd_writer.c
@@ -0,0 +1,267 @@
+/*
+ * Copyright (C) 2007-2016 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 <endian.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <poll.h>
+#include <stdarg.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <cutils/sockets.h>
+#include <log/logd.h>
+#include <log/logger.h>
+#include <log/log_read.h>
+#include <private/android_filesystem_config.h>
+#include <private/android_logger.h>
+
+#include "config_write.h"
+#include "log_portability.h"
+#include "logger.h"
+
+/* branchless on many architectures. */
+#define min(x,y) ((y) ^ (((x) ^ (y)) & -((x) < (y))))
+
+static int logdAvailable(log_id_t LogId);
+static int logdOpen();
+static void logdClose();
+static int logdWrite(log_id_t logId, struct timespec *ts,
+                     struct iovec *vec, size_t nr);
+
+LIBLOG_HIDDEN struct android_log_transport_write logdLoggerWrite = {
+    .node = { &logdLoggerWrite.node, &logdLoggerWrite.node },
+    .context.sock = -1,
+    .name = "logd",
+    .available = logdAvailable,
+    .open = logdOpen,
+    .close = logdClose,
+    .write = logdWrite,
+};
+
+/* log_init_lock assumed */
+static int logdOpen()
+{
+    int i, ret = 0;
+
+    if (logdLoggerWrite.context.sock < 0) {
+        i = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC, 0));
+        if (i < 0) {
+            ret = -errno;
+        } else if (TEMP_FAILURE_RETRY(fcntl(i, F_SETFL, O_NONBLOCK)) < 0) {
+            ret = -errno;
+            close(i);
+        } else {
+            struct sockaddr_un un;
+            memset(&un, 0, sizeof(struct sockaddr_un));
+            un.sun_family = AF_UNIX;
+            strcpy(un.sun_path, "/dev/socket/logdw");
+
+            if (TEMP_FAILURE_RETRY(connect(i, (struct sockaddr *)&un,
+                                           sizeof(struct sockaddr_un))) < 0) {
+                ret = -errno;
+                close(i);
+            } else {
+                logdLoggerWrite.context.sock = i;
+            }
+        }
+    }
+
+    return ret;
+}
+
+static void logdClose()
+{
+    if (logdLoggerWrite.context.sock >= 0) {
+        close(logdLoggerWrite.context.sock);
+        logdLoggerWrite.context.sock = -1;
+    }
+}
+
+static int logdAvailable(log_id_t logId)
+{
+    if (logId > LOG_ID_SECURITY) {
+        return -EINVAL;
+    }
+    if (logId == LOG_ID_SECURITY) {
+        uid_t uid = __android_log_uid();
+        if ((uid != AID_LOG) && (uid != AID_ROOT) && (uid != AID_SYSTEM)) {
+            return -EPERM;
+        }
+    }
+    if (logdLoggerWrite.context.sock < 0) {
+        if (access("/dev/socket/logdw", W_OK) == 0) {
+            return 0;
+        }
+        return -EBADF;
+    }
+    return 1;
+}
+
+static int logdWrite(log_id_t logId, struct timespec *ts,
+                     struct iovec *vec, size_t nr)
+{
+    ssize_t ret;
+    static const unsigned headerLength = 1;
+    struct iovec newVec[nr + headerLength];
+    android_log_header_t header;
+    size_t i, payloadSize;
+    static atomic_int_fast32_t dropped;
+    static atomic_int_fast32_t droppedSecurity;
+
+    if (logdLoggerWrite.context.sock < 0) {
+        return -EBADF;
+    }
+
+    /* logd, after initialization and priv drop */
+    if (__android_log_uid() == AID_LOGD) {
+        /*
+         * ignore log messages we send to ourself (logd).
+         * Such log messages are often generated by libraries we depend on
+         * which use standard Android logging.
+         */
+        return 0;
+    }
+
+    /*
+     *  struct {
+     *      // what we provide to socket
+     *      android_log_header_t header;
+     *      // caller provides
+     *      union {
+     *          struct {
+     *              char     prio;
+     *              char     payload[];
+     *          } string;
+     *          struct {
+     *              uint32_t tag
+     *              char     payload[];
+     *          } binary;
+     *      };
+     *  };
+     */
+
+    header.tid = gettid();
+    header.realtime.tv_sec = ts->tv_sec;
+    header.realtime.tv_nsec = ts->tv_nsec;
+
+    newVec[0].iov_base = (unsigned char *)&header;
+    newVec[0].iov_len  = sizeof(header);
+
+    if (logdLoggerWrite.context.sock > 0) {
+        int32_t snapshot = atomic_exchange_explicit(&droppedSecurity, 0,
+                                                    memory_order_relaxed);
+        if (snapshot) {
+            android_log_event_int_t buffer;
+
+            header.id = LOG_ID_SECURITY;
+            buffer.header.tag = htole32(LIBLOG_LOG_TAG);
+            buffer.payload.type = EVENT_TYPE_INT;
+            buffer.payload.data = htole32(snapshot);
+
+            newVec[headerLength].iov_base = &buffer;
+            newVec[headerLength].iov_len  = sizeof(buffer);
+
+            ret = TEMP_FAILURE_RETRY(writev(logdLoggerWrite.context.sock, newVec, 2));
+            if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
+                atomic_fetch_add_explicit(&droppedSecurity, snapshot,
+                                          memory_order_relaxed);
+            }
+        }
+        snapshot = atomic_exchange_explicit(&dropped, 0, memory_order_relaxed);
+        if (snapshot && __android_log_is_loggable(ANDROID_LOG_INFO,
+                                                  "liblog",
+                                                  ANDROID_LOG_VERBOSE)) {
+            android_log_event_int_t buffer;
+
+            header.id = LOG_ID_EVENTS;
+            buffer.header.tag = htole32(LIBLOG_LOG_TAG);
+            buffer.payload.type = EVENT_TYPE_INT;
+            buffer.payload.data = htole32(snapshot);
+
+            newVec[headerLength].iov_base = &buffer;
+            newVec[headerLength].iov_len  = sizeof(buffer);
+
+            ret = TEMP_FAILURE_RETRY(writev(logdLoggerWrite.context.sock, newVec, 2));
+            if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
+                atomic_fetch_add_explicit(&dropped, snapshot,
+                                          memory_order_relaxed);
+            }
+        }
+    }
+
+    header.id = logId;
+
+    for (payloadSize = 0, i = headerLength; i < nr + headerLength; i++) {
+        newVec[i].iov_base = vec[i - headerLength].iov_base;
+        payloadSize += newVec[i].iov_len = vec[i - headerLength].iov_len;
+
+        if (payloadSize > LOGGER_ENTRY_MAX_PAYLOAD) {
+            newVec[i].iov_len -= payloadSize - LOGGER_ENTRY_MAX_PAYLOAD;
+            if (newVec[i].iov_len) {
+                ++i;
+            }
+            break;
+        }
+    }
+
+    /*
+     * The write below could be lost, but will never block.
+     *
+     * ENOTCONN occurs if logd dies.
+     * EAGAIN occurs if logd is overloaded.
+     */
+    ret = TEMP_FAILURE_RETRY(writev(logdLoggerWrite.context.sock, newVec, i));
+    if (ret < 0) {
+        ret = -errno;
+        if (ret == -ENOTCONN) {
+            __android_log_lock();
+            logdClose();
+            ret = logdOpen();
+            __android_log_unlock();
+
+            if (ret < 0) {
+                return ret;
+            }
+
+            ret = TEMP_FAILURE_RETRY(writev(logdLoggerWrite.context.sock, newVec, i));
+            if (ret < 0) {
+                ret = -errno;
+            }
+        }
+    }
+
+    if (ret > (ssize_t)sizeof(header)) {
+        ret -= sizeof(header);
+    } else if (ret == -EAGAIN) {
+        atomic_fetch_add_explicit(&dropped, 1, memory_order_relaxed);
+        if (logId == LOG_ID_SECURITY) {
+            atomic_fetch_add_explicit(&droppedSecurity, 1,
+                                      memory_order_relaxed);
+        }
+    }
+
+    return ret;
+}