liblog/logd_write.c - platform/system/logging - Gitiles

 /*
  * Copyright (C) 2007-2014 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.
  */
 #if (FAKE_LOG_DEVICE == 0)
 #include <endian.h>
 #endif
 #include <errno.h>
 #include <fcntl.h>
 #if !defined(_WIN32)
 #include <pthread.h>
 #endif
 #include <stdarg.h>
 #include <stdatomic.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #if (FAKE_LOG_DEVICE == 0)
 #include <sys/socket.h>
 #include <sys/un.h>
 #endif
 #include <time.h>
 #include <unistd.h>

 #ifdef __BIONIC__
 #include <android/set_abort_message.h>
 #endif

 #include <log/event_tag_map.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 "log_cdefs.h"

 #define LOG_BUF_SIZE 1024

 #if FAKE_LOG_DEVICE
 /* This will be defined when building for the host. */
 #include "fake_log_device.h"
 #endif

 static int __write_to_log_init(log_id_t, struct iovec *vec, size_t nr);
 static int (*write_to_log)(log_id_t, struct iovec *vec, size_t nr) = __write_to_log_init;

 #if !defined(_WIN32)
 static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;

 static void lock()
 {
     /*
      * If we trigger a signal handler in the middle of locked activity and the
      * signal handler logs a message, we could get into a deadlock state.
      */
     pthread_mutex_lock(&log_init_lock);
 }

 static int trylock()
 {
     return pthread_mutex_trylock(&log_init_lock);
 }

 static void unlock()
 {
     pthread_mutex_unlock(&log_init_lock);
 }

 #else   /* !defined(_WIN32) */

 #define lock() ((void)0)
 #define trylock() (0) /* success */
 #define unlock() ((void)0)

 #endif  /* !defined(_WIN32) */

 #if FAKE_LOG_DEVICE
 static int log_fds[(int)LOG_ID_MAX] = { -1, -1, -1, -1, -1, -1 };
 #else
 static int logd_fd = -1;
 static int pstore_fd = -1;
 #endif

 /*
  * This is used by the C++ code to decide if it should write logs through
  * the C code.  Basically, if /dev/socket/logd is available, we're running in
  * the simulator rather than a desktop tool and want to use the device.
  */
 static enum {
     kLogUninitialized, kLogNotAvailable, kLogAvailable
 } g_log_status = kLogUninitialized;

 LIBLOG_ABI_PUBLIC int __android_log_dev_available()
 {
     if (g_log_status == kLogUninitialized) {
         if (access("/dev/socket/logdw", W_OK) == 0)
             g_log_status = kLogAvailable;
         else
             g_log_status = kLogNotAvailable;
     }

     return (g_log_status == kLogAvailable);
 }

 /* log_init_lock assumed */
 static int __write_to_log_initialize()
 {
     int i, ret = 0;

 #if FAKE_LOG_DEVICE
     for (i = 0; i < LOG_ID_MAX; i++) {
         char buf[sizeof("/dev/log_security")];
         snprintf(buf, sizeof(buf), "/dev/log_%s", android_log_id_to_name(i));
         log_fds[i] = fakeLogOpen(buf, O_WRONLY);
     }
 #else
     if (pstore_fd < 0) {
         pstore_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY));
     }

     if (logd_fd < 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 {
                 logd_fd = i;
             }
         }
     }
 #endif

     return ret;
 }

 static int __write_to_log_daemon(log_id_t log_id, struct iovec *vec, size_t nr)
 {
     ssize_t ret;
 #if FAKE_LOG_DEVICE
     int log_fd;

     if (/*(int)log_id >= 0 &&*/ (int)log_id < (int)LOG_ID_MAX) {
         log_fd = log_fds[(int)log_id];
     } else {
         return -EBADF;
     }
     do {
         ret = fakeLogWritev(log_fd, vec, nr);
         if (ret < 0) {
             ret = -errno;
         }
     } while (ret == -EINTR);
 #else
     static const unsigned header_length = 2;
     struct iovec newVec[nr + header_length];
     android_log_header_t header;
     android_pmsg_log_header_t pmsg_header;
     struct timespec ts;
     size_t i, payload_size;
     static uid_t last_uid = AID_ROOT; /* logd *always* starts up as AID_ROOT */
     static pid_t last_pid = (pid_t) -1;
     static atomic_int_fast32_t dropped;
     static atomic_int_fast32_t dropped_security;

     if (!nr) {
         return -EINVAL;
     }

     if (last_uid == AID_ROOT) { /* have we called to get the UID yet? */
         last_uid = getuid();
     }
     if (last_pid == (pid_t) -1) {
         last_pid = getpid();
     }
     if (log_id == LOG_ID_SECURITY) {
         if (vec[0].iov_len < 4) {
             return -EINVAL;
         }
         /* Matches clientHasLogCredentials() in logd */
         if ((last_uid != AID_SYSTEM) && (last_uid != AID_ROOT) && (last_uid != AID_LOG)) {
             uid_t uid = geteuid();
             if ((uid != AID_SYSTEM) && (uid != AID_ROOT) && (uid != AID_LOG)) {
                 gid_t gid = getgid();
                 if ((gid != AID_SYSTEM) && (gid != AID_ROOT) && (gid != AID_LOG)) {
                     gid = getegid();
                     if ((gid != AID_SYSTEM) && (gid != AID_ROOT) && (gid != AID_LOG)) {
                         int num_groups;
                         gid_t *groups;

                         num_groups = getgroups(0, NULL);
                         if (num_groups <= 0) {
                             return -EPERM;
                         }
                         groups = calloc(num_groups, sizeof(gid_t));
                         if (!groups) {
                             return -ENOMEM;
                         }
                         num_groups = getgroups(num_groups, groups);
                         while (num_groups > 0) {
                             if (groups[num_groups - 1] == AID_LOG) {
                                 break;
                             }
                             --num_groups;
                         }
                         free(groups);
                         if (num_groups <= 0) {
                             return -EPERM;
                         }
                     }
                 }
             }
         }
         if (!__android_log_security()) {
             atomic_store(&dropped_security, 0);
             return -EPERM;
         }
     } else if (log_id == LOG_ID_EVENTS) {
         static atomic_uintptr_t map;
         int ret;
         const char *tag;
         EventTagMap *m, *f;

         if (vec[0].iov_len < 4) {
             return -EINVAL;
         }

         tag = NULL;
         f = NULL;
         m = (EventTagMap *)atomic_load(&map);

         if (!m) {
             ret = trylock();
             m = (EventTagMap *)atomic_load(&map); /* trylock flush cache */
             if (!m) {
                 m = android_openEventTagMap(EVENT_TAG_MAP_FILE);
                 if (ret) { /* trylock failed, use local copy, mark for close */
                     f = m;
                 } else {
                     if (!m) { /* One chance to open map file */
                         m = (EventTagMap *)(uintptr_t)-1LL;
                     }
                     atomic_store(&map, (uintptr_t)m);
                 }
             }
             if (!ret) { /* trylock succeeded, unlock */
                 unlock();
             }
         }
         if (m && (m != (EventTagMap *)(uintptr_t)-1LL)) {
             tag = android_lookupEventTag(
                                     m,
                                     htole32(((uint32_t *)vec[0].iov_base)[0]));
         }
         ret = __android_log_is_loggable(ANDROID_LOG_INFO,
                                         tag,
                                         ANDROID_LOG_VERBOSE);
         if (f) { /* local copy marked for close */
             android_closeEventTagMap(f);
         }
         if (!ret) {
             return -EPERM;
         }
     } else {
         /* Validate the incoming tag, tag content can not split across iovec */
         char prio = ANDROID_LOG_VERBOSE;
         const char *tag = vec[0].iov_base;
         size_t len = vec[0].iov_len;
         if (!tag) {
             len = 0;
         }
         if (len > 0) {
             prio = *tag;
             if (len > 1) {
                 --len;
                 ++tag;
             } else {
                 len = vec[1].iov_len;
                 tag = ((const char *)vec[1].iov_base);
                 if (!tag) {
                     len = 0;
                 }
             }
         }
         /* tag must be nul terminated */
         if (strnlen(tag, len) >= len) {
             tag = NULL;
         }

         if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {
             return -EPERM;
         }
     }

     /*
      *  struct {
      *      // what we provide to pstore
      *      android_pmsg_log_header_t pmsg_header;
      *      // 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;
      *      };
      *  };
      */

     clock_gettime(android_log_clockid(), &ts);

     pmsg_header.magic = LOGGER_MAGIC;
     pmsg_header.len = sizeof(pmsg_header) + sizeof(header);
     pmsg_header.uid = last_uid;
     pmsg_header.pid = last_pid;

     header.tid = gettid();
     header.realtime.tv_sec = ts.tv_sec;
     header.realtime.tv_nsec = ts.tv_nsec;

     newVec[0].iov_base   = (unsigned char *) &pmsg_header;
     newVec[0].iov_len    = sizeof(pmsg_header);
     newVec[1].iov_base   = (unsigned char *) &header;
     newVec[1].iov_len    = sizeof(header);

     if (logd_fd > 0) {
         int32_t snapshot = atomic_exchange_explicit(&dropped_security, 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[2].iov_base = &buffer;
             newVec[2].iov_len  = sizeof(buffer);

             ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, 2));
             if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
                 atomic_fetch_add_explicit(&dropped_security, 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[2].iov_base = &buffer;
             newVec[2].iov_len  = sizeof(buffer);

             ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, 2));
             if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
                 atomic_fetch_add_explicit(&dropped, snapshot,
                                           memory_order_relaxed);
             }
         }
     }

     header.id = log_id;

     for (payload_size = 0, i = header_length; i < nr + header_length; i++) {
         newVec[i].iov_base = vec[i - header_length].iov_base;
         payload_size += newVec[i].iov_len = vec[i - header_length].iov_len;

         if (payload_size > LOGGER_ENTRY_MAX_PAYLOAD) {
             newVec[i].iov_len -= payload_size - LOGGER_ENTRY_MAX_PAYLOAD;
             if (newVec[i].iov_len) {
                 ++i;
             }
             payload_size = LOGGER_ENTRY_MAX_PAYLOAD;
             break;
         }
     }
     pmsg_header.len += payload_size;

     if (pstore_fd >= 0) {
         TEMP_FAILURE_RETRY(writev(pstore_fd, newVec, i));
     }

     if (last_uid == AID_LOGD) { /* logd, after initialization and priv drop */
         /*
          * 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;
     }

     if (logd_fd < 0) {
         return -EBADF;
     }

     /*
      * The write below could be lost, but will never block.
      *
      * To logd, we drop the pmsg_header
      *
      * ENOTCONN occurs if logd dies.
      * EAGAIN occurs if logd is overloaded.
      */
     ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, i - 1));
     if (ret < 0) {
         ret = -errno;
         if (ret == -ENOTCONN) {
             lock();
             close(logd_fd);
             logd_fd = -1;
             ret = __write_to_log_initialize();
             unlock();

             if (ret < 0) {
                 return ret;
             }

             ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, i - 1));
             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 (log_id == LOG_ID_SECURITY) {
             atomic_fetch_add_explicit(&dropped_security, 1,
                                       memory_order_relaxed);
         }
     }
 #endif

     return ret;
 }

 #if FAKE_LOG_DEVICE
 static const char *LOG_NAME[LOG_ID_MAX] = {
     [LOG_ID_MAIN] = "main",
     [LOG_ID_RADIO] = "radio",
     [LOG_ID_EVENTS] = "events",
     [LOG_ID_SYSTEM] = "system",
     [LOG_ID_CRASH] = "crash",
     [LOG_ID_SECURITY] = "security",
     [LOG_ID_KERNEL] = "kernel",
 };

 LIBLOG_ABI_PUBLIC const char *android_log_id_to_name(log_id_t log_id)
 {
     if (log_id >= LOG_ID_MAX) {
         log_id = LOG_ID_MAIN;
     }
     return LOG_NAME[log_id];
 }
 #endif

 static int __write_to_log_init(log_id_t log_id, struct iovec *vec, size_t nr)
 {
     lock();

     if (write_to_log == __write_to_log_init) {
         int ret;

         ret = __write_to_log_initialize();
         if (ret < 0) {
             unlock();
 #if (FAKE_LOG_DEVICE == 0)
             if (pstore_fd >= 0) {
                 __write_to_log_daemon(log_id, vec, nr);
             }
 #endif
             return ret;
         }

         write_to_log = __write_to_log_daemon;
     }

     unlock();

     return write_to_log(log_id, vec, nr);
 }

 LIBLOG_ABI_PUBLIC int __android_log_write(int prio, const char *tag,
                                           const char *msg)
 {
     return __android_log_buf_write(LOG_ID_MAIN, prio, tag, msg);
 }

 LIBLOG_ABI_PUBLIC int __android_log_buf_write(int bufID, int prio,
                                               const char *tag, const char *msg)
 {
     struct iovec vec[3];
     char tmp_tag[32];

     if (!tag)
         tag = "";

     /* XXX: This needs to go! */
     if ((bufID != LOG_ID_RADIO) &&
          (!strcmp(tag, "HTC_RIL") ||
         !strncmp(tag, "RIL", 3) || /* Any log tag with "RIL" as the prefix */
         !strncmp(tag, "IMS", 3) || /* Any log tag with "IMS" as the prefix */
         !strcmp(tag, "AT") ||
         !strcmp(tag, "GSM") ||
         !strcmp(tag, "STK") ||
         !strcmp(tag, "CDMA") ||
         !strcmp(tag, "PHONE") ||
         !strcmp(tag, "SMS"))) {
             bufID = LOG_ID_RADIO;
             /* Inform third party apps/ril/radio.. to use Rlog or RLOG */
             snprintf(tmp_tag, sizeof(tmp_tag), "use-Rlog/RLOG-%s", tag);
             tag = tmp_tag;
     }

 #if __BIONIC__
     if (prio == ANDROID_LOG_FATAL) {
         android_set_abort_message(msg);
     }
 #endif

     vec[0].iov_base   = (unsigned char *) &prio;
     vec[0].iov_len    = 1;
     vec[1].iov_base   = (void *) tag;
     vec[1].iov_len    = strlen(tag) + 1;
     vec[2].iov_base   = (void *) msg;
     vec[2].iov_len    = strlen(msg) + 1;

     return write_to_log(bufID, vec, 3);
 }

 LIBLOG_ABI_PUBLIC int __android_log_vprint(int prio, const char *tag,
                                            const char *fmt, va_list ap)
 {
     char buf[LOG_BUF_SIZE];

     vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);

     return __android_log_write(prio, tag, buf);
 }

 LIBLOG_ABI_PUBLIC int __android_log_print(int prio, const char *tag,
                                           const char *fmt, ...)
 {
     va_list ap;
     char buf[LOG_BUF_SIZE];

     va_start(ap, fmt);
     vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
     va_end(ap);

     return __android_log_write(prio, tag, buf);
 }

 LIBLOG_ABI_PUBLIC int __android_log_buf_print(int bufID, int prio,
                                               const char *tag,
                                               const char *fmt, ...)
 {
     va_list ap;
     char buf[LOG_BUF_SIZE];

     va_start(ap, fmt);
     vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
     va_end(ap);

     return __android_log_buf_write(bufID, prio, tag, buf);
 }

 LIBLOG_ABI_PUBLIC void __android_log_assert(
         const char *cond,
         const char *tag,
         const char *fmt, ...)
 {
     char buf[LOG_BUF_SIZE];

     if (fmt) {
         va_list ap;
         va_start(ap, fmt);
         vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
         va_end(ap);
     } else {
         /* Msg not provided, log condition.  N.B. Do not use cond directly as
          * format string as it could contain spurious '%' syntax (e.g.
          * "%d" in "blocks%devs == 0").
          */
         if (cond)
             snprintf(buf, LOG_BUF_SIZE, "Assertion failed: %s", cond);
         else
             strcpy(buf, "Unspecified assertion failed");
     }

     __android_log_write(ANDROID_LOG_FATAL, tag, buf);
     abort(); /* abort so we have a chance to debug the situation */
     /* NOTREACHED */
 }

 LIBLOG_ABI_PUBLIC int __android_log_bwrite(int32_t tag,
                                            const void *payload, size_t len)
 {
     struct iovec vec[2];

     vec[0].iov_base = &tag;
     vec[0].iov_len = sizeof(tag);
     vec[1].iov_base = (void*)payload;
     vec[1].iov_len = len;

     return write_to_log(LOG_ID_EVENTS, vec, 2);
 }

 LIBLOG_ABI_PUBLIC int __android_log_security_bwrite(int32_t tag,
                                                     const void *payload,
                                                     size_t len)
 {
     struct iovec vec[2];

     vec[0].iov_base = &tag;
     vec[0].iov_len = sizeof(tag);
     vec[1].iov_base = (void*)payload;
     vec[1].iov_len = len;

     return write_to_log(LOG_ID_SECURITY, vec, 2);
 }

 /*
  * Like __android_log_bwrite, but takes the type as well.  Doesn't work
  * for the general case where we're generating lists of stuff, but very
  * handy if we just want to dump an integer into the log.
  */
 LIBLOG_ABI_PUBLIC int __android_log_btwrite(int32_t tag, char type,
                                             const void *payload, size_t len)
 {
     struct iovec vec[3];

     vec[0].iov_base = &tag;
     vec[0].iov_len = sizeof(tag);
     vec[1].iov_base = &type;
     vec[1].iov_len = sizeof(type);
     vec[2].iov_base = (void*)payload;
     vec[2].iov_len = len;

     return write_to_log(LOG_ID_EVENTS, vec, 3);
 }

 /*
  * Like __android_log_bwrite, but used for writing strings to the
  * event log.
  */
 LIBLOG_ABI_PUBLIC int __android_log_bswrite(int32_t tag, const char *payload)
 {
     struct iovec vec[4];
     char type = EVENT_TYPE_STRING;
     uint32_t len = strlen(payload);

     vec[0].iov_base = &tag;
     vec[0].iov_len = sizeof(tag);
     vec[1].iov_base = &type;
     vec[1].iov_len = sizeof(type);
     vec[2].iov_base = &len;
     vec[2].iov_len = sizeof(len);
     vec[3].iov_base = (void*)payload;
     vec[3].iov_len = len;

     return write_to_log(LOG_ID_EVENTS, vec, 4);
 }

 /*
  * Like __android_log_security_bwrite, but used for writing strings to the
  * security log.
  */
 LIBLOG_ABI_PUBLIC int __android_log_security_bswrite(int32_t tag,
                                                      const char *payload)
 {
     struct iovec vec[4];
     char type = EVENT_TYPE_STRING;
     uint32_t len = strlen(payload);

     vec[0].iov_base = &tag;
     vec[0].iov_len = sizeof(tag);
     vec[1].iov_base = &type;
     vec[1].iov_len = sizeof(type);
     vec[2].iov_base = &len;
     vec[2].iov_len = sizeof(len);
     vec[3].iov_base = (void*)payload;
     vec[3].iov_len = len;

     return write_to_log(LOG_ID_SECURITY, vec, 4);
 }
	/*
	* Copyright (C) 2007-2014 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.
	*/
	#if (FAKE_LOG_DEVICE == 0)
	#include <endian.h>
	#endif
	#include <errno.h>
	#include <fcntl.h>
	#if !defined(_WIN32)
	#include <pthread.h>
	#endif
	#include <stdarg.h>
	#include <stdatomic.h>
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#if (FAKE_LOG_DEVICE == 0)
	#include <sys/socket.h>
	#include <sys/un.h>
	#endif
	#include <time.h>
	#include <unistd.h>

	#ifdef __BIONIC__
	#include <android/set_abort_message.h>
	#endif

	#include <log/event_tag_map.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 "log_cdefs.h"

	#define LOG_BUF_SIZE 1024

	#if FAKE_LOG_DEVICE
	/* This will be defined when building for the host. */
	#include "fake_log_device.h"
	#endif

	static int __write_to_log_init(log_id_t, struct iovec *vec, size_t nr);
	static int (write_to_log)(log_id_t, struct iovec vec, size_t nr) = __write_to_log_init;

	#if !defined(_WIN32)
	static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER;

	static void lock()
	{
	/*
	* If we trigger a signal handler in the middle of locked activity and the
	* signal handler logs a message, we could get into a deadlock state.
	*/
	pthread_mutex_lock(&log_init_lock);
	}

	static int trylock()
	{
	return pthread_mutex_trylock(&log_init_lock);
	}

	static void unlock()
	{
	pthread_mutex_unlock(&log_init_lock);
	}

	#else /* !defined(_WIN32) */

	#define lock() ((void)0)
	#define trylock() (0) /* success */
	#define unlock() ((void)0)

	#endif /* !defined(_WIN32) */

	#if FAKE_LOG_DEVICE
	static int log_fds[(int)LOG_ID_MAX] = { -1, -1, -1, -1, -1, -1 };
	#else
	static int logd_fd = -1;
	static int pstore_fd = -1;
	#endif

	/*
	* This is used by the C++ code to decide if it should write logs through
	* the C code. Basically, if /dev/socket/logd is available, we're running in
	* the simulator rather than a desktop tool and want to use the device.
	*/
	static enum {
	kLogUninitialized, kLogNotAvailable, kLogAvailable
	} g_log_status = kLogUninitialized;

	LIBLOG_ABI_PUBLIC int __android_log_dev_available()
	{
	if (g_log_status == kLogUninitialized) {
	if (access("/dev/socket/logdw", W_OK) == 0)
	g_log_status = kLogAvailable;
	else
	g_log_status = kLogNotAvailable;
	}

	return (g_log_status == kLogAvailable);
	}

	/* log_init_lock assumed */
	static int __write_to_log_initialize()
	{
	int i, ret = 0;

	#if FAKE_LOG_DEVICE
	for (i = 0; i < LOG_ID_MAX; i++) {
	char buf[sizeof("/dev/log_security")];
	snprintf(buf, sizeof(buf), "/dev/log_%s", android_log_id_to_name(i));
	log_fds[i] = fakeLogOpen(buf, O_WRONLY);
	}
	#else
	if (pstore_fd < 0) {
	pstore_fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY));
	}

	if (logd_fd < 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 {
	logd_fd = i;
	}
	}
	}
	#endif

	return ret;
	}

	static int __write_to_log_daemon(log_id_t log_id, struct iovec *vec, size_t nr)
	{
	ssize_t ret;
	#if FAKE_LOG_DEVICE
	int log_fd;

	if (/(int)log_id >= 0 &&/ (int)log_id < (int)LOG_ID_MAX) {
	log_fd = log_fds[(int)log_id];
	} else {
	return -EBADF;
	}
	do {
	ret = fakeLogWritev(log_fd, vec, nr);
	if (ret < 0) {
	ret = -errno;
	}
	} while (ret == -EINTR);
	#else
	static const unsigned header_length = 2;
	struct iovec newVec[nr + header_length];
	android_log_header_t header;
	android_pmsg_log_header_t pmsg_header;
	struct timespec ts;
	size_t i, payload_size;
	static uid_t last_uid = AID_ROOT; /* logd always starts up as AID_ROOT */
	static pid_t last_pid = (pid_t) -1;
	static atomic_int_fast32_t dropped;
	static atomic_int_fast32_t dropped_security;

	if (!nr) {
	return -EINVAL;
	}

	if (last_uid == AID_ROOT) { /* have we called to get the UID yet? */
	last_uid = getuid();
	}
	if (last_pid == (pid_t) -1) {
	last_pid = getpid();
	}
	if (log_id == LOG_ID_SECURITY) {
	if (vec[0].iov_len < 4) {
	return -EINVAL;
	}
	/* Matches clientHasLogCredentials() in logd */
	if ((last_uid != AID_SYSTEM) && (last_uid != AID_ROOT) && (last_uid != AID_LOG)) {
	uid_t uid = geteuid();
	if ((uid != AID_SYSTEM) && (uid != AID_ROOT) && (uid != AID_LOG)) {
	gid_t gid = getgid();
	if ((gid != AID_SYSTEM) && (gid != AID_ROOT) && (gid != AID_LOG)) {
	gid = getegid();
	if ((gid != AID_SYSTEM) && (gid != AID_ROOT) && (gid != AID_LOG)) {
	int num_groups;
	gid_t *groups;

	num_groups = getgroups(0, NULL);
	if (num_groups <= 0) {
	return -EPERM;
	}
	groups = calloc(num_groups, sizeof(gid_t));
	if (!groups) {
	return -ENOMEM;
	}
	num_groups = getgroups(num_groups, groups);
	while (num_groups > 0) {
	if (groups[num_groups - 1] == AID_LOG) {
	break;
	}
	--num_groups;
	}
	free(groups);
	if (num_groups <= 0) {
	return -EPERM;
	}
	}
	}
	}
	}
	if (!__android_log_security()) {
	atomic_store(&dropped_security, 0);
	return -EPERM;
	}
	} else if (log_id == LOG_ID_EVENTS) {
	static atomic_uintptr_t map;
	int ret;
	const char *tag;
	EventTagMap m, f;

	if (vec[0].iov_len < 4) {
	return -EINVAL;
	}

	tag = NULL;
	f = NULL;
	m = (EventTagMap *)atomic_load(&map);

	if (!m) {
	ret = trylock();
	m = (EventTagMap )atomic_load(&map); / trylock flush cache */
	if (!m) {
	m = android_openEventTagMap(EVENT_TAG_MAP_FILE);
	if (ret) { /* trylock failed, use local copy, mark for close */
	f = m;
	} else {
	if (!m) { /* One chance to open map file */
	m = (EventTagMap *)(uintptr_t)-1LL;
	}
	atomic_store(&map, (uintptr_t)m);
	}
	}
	if (!ret) { /* trylock succeeded, unlock */
	unlock();
	}
	}
	if (m && (m != (EventTagMap *)(uintptr_t)-1LL)) {
	tag = android_lookupEventTag(
	m,
	htole32(((uint32_t *)vec[0].iov_base)[0]));
	}
	ret = __android_log_is_loggable(ANDROID_LOG_INFO,
	tag,
	ANDROID_LOG_VERBOSE);
	if (f) { /* local copy marked for close */
	android_closeEventTagMap(f);
	}
	if (!ret) {
	return -EPERM;
	}
	} else {
	/* Validate the incoming tag, tag content can not split across iovec */
	char prio = ANDROID_LOG_VERBOSE;
	const char *tag = vec[0].iov_base;
	size_t len = vec[0].iov_len;
	if (!tag) {
	len = 0;
	}
	if (len > 0) {
	prio = *tag;
	if (len > 1) {
	--len;
	++tag;
	} else {
	len = vec[1].iov_len;
	tag = ((const char *)vec[1].iov_base);
	if (!tag) {
	len = 0;
	}
	}
	}
	/* tag must be nul terminated */
	if (strnlen(tag, len) >= len) {
	tag = NULL;
	}

	if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {
	return -EPERM;
	}
	}

	/*
	* struct {
	* // what we provide to pstore
	* android_pmsg_log_header_t pmsg_header;
	* // 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;
	* };
	* };
	*/

	clock_gettime(android_log_clockid(), &ts);

	pmsg_header.magic = LOGGER_MAGIC;
	pmsg_header.len = sizeof(pmsg_header) + sizeof(header);
	pmsg_header.uid = last_uid;
	pmsg_header.pid = last_pid;

	header.tid = gettid();
	header.realtime.tv_sec = ts.tv_sec;
	header.realtime.tv_nsec = ts.tv_nsec;

	newVec[0].iov_base = (unsigned char *) &pmsg_header;
	newVec[0].iov_len = sizeof(pmsg_header);
	newVec[1].iov_base = (unsigned char *) &header;
	newVec[1].iov_len = sizeof(header);

	if (logd_fd > 0) {
	int32_t snapshot = atomic_exchange_explicit(&dropped_security, 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[2].iov_base = &buffer;
	newVec[2].iov_len = sizeof(buffer);

	ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, 2));
	if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
	atomic_fetch_add_explicit(&dropped_security, 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[2].iov_base = &buffer;
	newVec[2].iov_len = sizeof(buffer);

	ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, 2));
	if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) {
	atomic_fetch_add_explicit(&dropped, snapshot,
	memory_order_relaxed);
	}
	}
	}

	header.id = log_id;

	for (payload_size = 0, i = header_length; i < nr + header_length; i++) {
	newVec[i].iov_base = vec[i - header_length].iov_base;
	payload_size += newVec[i].iov_len = vec[i - header_length].iov_len;

	if (payload_size > LOGGER_ENTRY_MAX_PAYLOAD) {
	newVec[i].iov_len -= payload_size - LOGGER_ENTRY_MAX_PAYLOAD;
	if (newVec[i].iov_len) {
	++i;
	}
	payload_size = LOGGER_ENTRY_MAX_PAYLOAD;
	break;
	}
	}
	pmsg_header.len += payload_size;

	if (pstore_fd >= 0) {
	TEMP_FAILURE_RETRY(writev(pstore_fd, newVec, i));
	}

	if (last_uid == AID_LOGD) { /* logd, after initialization and priv drop */
	/*
	* 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;
	}

	if (logd_fd < 0) {
	return -EBADF;
	}

	/*
	* The write below could be lost, but will never block.
	*
	* To logd, we drop the pmsg_header
	*
	* ENOTCONN occurs if logd dies.
	* EAGAIN occurs if logd is overloaded.
	*/
	ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, i - 1));
	if (ret < 0) {
	ret = -errno;
	if (ret == -ENOTCONN) {
	lock();
	close(logd_fd);
	logd_fd = -1;
	ret = __write_to_log_initialize();
	unlock();

	if (ret < 0) {
	return ret;
	}

	ret = TEMP_FAILURE_RETRY(writev(logd_fd, newVec + 1, i - 1));
	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 (log_id == LOG_ID_SECURITY) {
	atomic_fetch_add_explicit(&dropped_security, 1,
	memory_order_relaxed);
	}
	}
	#endif

	return ret;
	}

	#if FAKE_LOG_DEVICE
	static const char *LOG_NAME[LOG_ID_MAX] = {
	[LOG_ID_MAIN] = "main",
	[LOG_ID_RADIO] = "radio",
	[LOG_ID_EVENTS] = "events",
	[LOG_ID_SYSTEM] = "system",
	[LOG_ID_CRASH] = "crash",
	[LOG_ID_SECURITY] = "security",
	[LOG_ID_KERNEL] = "kernel",
	};

	LIBLOG_ABI_PUBLIC const char *android_log_id_to_name(log_id_t log_id)
	{
	if (log_id >= LOG_ID_MAX) {
	log_id = LOG_ID_MAIN;
	}
	return LOG_NAME[log_id];
	}
	#endif

	static int __write_to_log_init(log_id_t log_id, struct iovec *vec, size_t nr)
	{
	lock();

	if (write_to_log == __write_to_log_init) {
	int ret;

	ret = __write_to_log_initialize();
	if (ret < 0) {
	unlock();
	#if (FAKE_LOG_DEVICE == 0)
	if (pstore_fd >= 0) {
	__write_to_log_daemon(log_id, vec, nr);
	}
	#endif
	return ret;
	}

	write_to_log = __write_to_log_daemon;
	}

	unlock();

	return write_to_log(log_id, vec, nr);
	}

	LIBLOG_ABI_PUBLIC int __android_log_write(int prio, const char *tag,
	const char *msg)
	{
	return __android_log_buf_write(LOG_ID_MAIN, prio, tag, msg);
	}

	LIBLOG_ABI_PUBLIC int __android_log_buf_write(int bufID, int prio,
	const char tag, const char msg)
	{
	struct iovec vec[3];
	char tmp_tag[32];

	if (!tag)
	tag = "";

	/* XXX: This needs to go! */
	if ((bufID != LOG_ID_RADIO) &&
	(!strcmp(tag, "HTC_RIL") \|\|
	!strncmp(tag, "RIL", 3) \|\| /* Any log tag with "RIL" as the prefix */
	!strncmp(tag, "IMS", 3) \|\| /* Any log tag with "IMS" as the prefix */
	!strcmp(tag, "AT") \|\|
	!strcmp(tag, "GSM") \|\|
	!strcmp(tag, "STK") \|\|
	!strcmp(tag, "CDMA") \|\|
	!strcmp(tag, "PHONE") \|\|
	!strcmp(tag, "SMS"))) {
	bufID = LOG_ID_RADIO;
	/* Inform third party apps/ril/radio.. to use Rlog or RLOG */
	snprintf(tmp_tag, sizeof(tmp_tag), "use-Rlog/RLOG-%s", tag);
	tag = tmp_tag;
	}

	#if __BIONIC__
	if (prio == ANDROID_LOG_FATAL) {
	android_set_abort_message(msg);
	}
	#endif

	vec[0].iov_base = (unsigned char *) &prio;
	vec[0].iov_len = 1;
	vec[1].iov_base = (void *) tag;
	vec[1].iov_len = strlen(tag) + 1;
	vec[2].iov_base = (void *) msg;
	vec[2].iov_len = strlen(msg) + 1;

	return write_to_log(bufID, vec, 3);
	}

	LIBLOG_ABI_PUBLIC int __android_log_vprint(int prio, const char *tag,
	const char *fmt, va_list ap)
	{
	char buf[LOG_BUF_SIZE];

	vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);

	return __android_log_write(prio, tag, buf);
	}

	LIBLOG_ABI_PUBLIC int __android_log_print(int prio, const char *tag,
	const char *fmt, ...)
	{
	va_list ap;
	char buf[LOG_BUF_SIZE];

	va_start(ap, fmt);
	vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
	va_end(ap);

	return __android_log_write(prio, tag, buf);
	}

	LIBLOG_ABI_PUBLIC int __android_log_buf_print(int bufID, int prio,
	const char *tag,
	const char *fmt, ...)
	{
	va_list ap;
	char buf[LOG_BUF_SIZE];

	va_start(ap, fmt);
	vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
	va_end(ap);

	return __android_log_buf_write(bufID, prio, tag, buf);
	}

	LIBLOG_ABI_PUBLIC void __android_log_assert(
	const char *cond,
	const char *tag,
	const char *fmt, ...)
	{
	char buf[LOG_BUF_SIZE];

	if (fmt) {
	va_list ap;
	va_start(ap, fmt);
	vsnprintf(buf, LOG_BUF_SIZE, fmt, ap);
	va_end(ap);
	} else {
	/* Msg not provided, log condition. N.B. Do not use cond directly as
	* format string as it could contain spurious '%' syntax (e.g.
	* "%d" in "blocks%devs == 0").
	*/
	if (cond)
	snprintf(buf, LOG_BUF_SIZE, "Assertion failed: %s", cond);
	else
	strcpy(buf, "Unspecified assertion failed");
	}

	__android_log_write(ANDROID_LOG_FATAL, tag, buf);
	abort(); /* abort so we have a chance to debug the situation */
	/* NOTREACHED */
	}

	LIBLOG_ABI_PUBLIC int __android_log_bwrite(int32_t tag,
	const void *payload, size_t len)
	{
	struct iovec vec[2];

	vec[0].iov_base = &tag;
	vec[0].iov_len = sizeof(tag);
	vec[1].iov_base = (void*)payload;
	vec[1].iov_len = len;

	return write_to_log(LOG_ID_EVENTS, vec, 2);
	}

	LIBLOG_ABI_PUBLIC int __android_log_security_bwrite(int32_t tag,
	const void *payload,
	size_t len)
	{
	struct iovec vec[2];

	vec[0].iov_base = &tag;
	vec[0].iov_len = sizeof(tag);
	vec[1].iov_base = (void*)payload;
	vec[1].iov_len = len;

	return write_to_log(LOG_ID_SECURITY, vec, 2);
	}

	/*
	* Like __android_log_bwrite, but takes the type as well. Doesn't work
	* for the general case where we're generating lists of stuff, but very
	* handy if we just want to dump an integer into the log.
	*/
	LIBLOG_ABI_PUBLIC int __android_log_btwrite(int32_t tag, char type,
	const void *payload, size_t len)
	{
	struct iovec vec[3];

	vec[0].iov_base = &tag;
	vec[0].iov_len = sizeof(tag);
	vec[1].iov_base = &type;
	vec[1].iov_len = sizeof(type);
	vec[2].iov_base = (void*)payload;
	vec[2].iov_len = len;

	return write_to_log(LOG_ID_EVENTS, vec, 3);
	}

	/*
	* Like __android_log_bwrite, but used for writing strings to the
	* event log.
	*/
	LIBLOG_ABI_PUBLIC int __android_log_bswrite(int32_t tag, const char *payload)
	{
	struct iovec vec[4];
	char type = EVENT_TYPE_STRING;
	uint32_t len = strlen(payload);

	vec[0].iov_base = &tag;
	vec[0].iov_len = sizeof(tag);
	vec[1].iov_base = &type;
	vec[1].iov_len = sizeof(type);
	vec[2].iov_base = &len;
	vec[2].iov_len = sizeof(len);
	vec[3].iov_base = (void*)payload;
	vec[3].iov_len = len;

	return write_to_log(LOG_ID_EVENTS, vec, 4);
	}

	/*
	* Like __android_log_security_bwrite, but used for writing strings to the
	* security log.
	*/
	LIBLOG_ABI_PUBLIC int __android_log_security_bswrite(int32_t tag,
	const char *payload)
	{
	struct iovec vec[4];
	char type = EVENT_TYPE_STRING;
	uint32_t len = strlen(payload);

	vec[0].iov_base = &tag;
	vec[0].iov_len = sizeof(tag);
	vec[1].iov_base = &type;
	vec[1].iov_len = sizeof(type);
	vec[2].iov_base = &len;
	vec[2].iov_len = sizeof(len);
	vec[3].iov_base = (void*)payload;
	vec[3].iov_len = len;

	return write_to_log(LOG_ID_SECURITY, vec, 4);
	}