liblog/logd_reader.cpp - third_party/android/platform/system/core - Git at Google

 /*
  * 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/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/un.h>
 #include <time.h>
 #include <unistd.h>

 #include <cutils/sockets.h>
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>

 #include "config_read.h"
 #include "log_portability.h"
 #include "logd_reader.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 logdVersion(struct android_log_logger* logger,
                        struct android_log_transport_context* transp);
 static int logdRead(struct android_log_logger_list* logger_list,
                     struct android_log_transport_context* transp, struct log_msg* log_msg);
 static int logdPoll(struct android_log_logger_list* logger_list,
                     struct android_log_transport_context* transp);
 static void logdClose(struct android_log_logger_list* logger_list,
                       struct android_log_transport_context* transp);
 static int logdClear(struct android_log_logger* logger,
                      struct android_log_transport_context* transp);
 static ssize_t logdSetSize(struct android_log_logger* logger,
                            struct android_log_transport_context* transp, size_t size);
 static ssize_t logdGetSize(struct android_log_logger* logger,
                            struct android_log_transport_context* transp);
 static ssize_t logdGetReadableSize(struct android_log_logger* logger,
                                    struct android_log_transport_context* transp);
 static ssize_t logdGetPrune(struct android_log_logger_list* logger,
                             struct android_log_transport_context* transp, char* buf, size_t len);
 static ssize_t logdSetPrune(struct android_log_logger_list* logger,
                             struct android_log_transport_context* transp, char* buf, size_t len);
 static ssize_t logdGetStats(struct android_log_logger_list* logger,
                             struct android_log_transport_context* transp, char* buf, size_t len);

 struct android_log_transport_read logdLoggerRead = {
     .node = {&logdLoggerRead.node, &logdLoggerRead.node},
     .name = "logd",
     .available = logdAvailable,
     .version = logdVersion,
     .read = logdRead,
     .poll = logdPoll,
     .close = logdClose,
     .clear = logdClear,
     .getSize = logdGetSize,
     .setSize = logdSetSize,
     .getReadableSize = logdGetReadableSize,
     .getPrune = logdGetPrune,
     .setPrune = logdSetPrune,
     .getStats = logdGetStats,
 };

 static int logdAvailable(log_id_t logId) {
   if (logId >= LOG_ID_MAX) {
     return -EINVAL;
   }
   if (logId == LOG_ID_SECURITY) {
     uid_t uid = __android_log_uid();
     if (uid != AID_SYSTEM) {
       return -EPERM;
     }
   }
   if (access("/dev/socket/logdw", W_OK) == 0) {
     return 0;
   }
   return -EBADF;
 }

 // Connects to /dev/socket/<name> and returns the associated fd or returns -1 on error.
 // O_CLOEXEC is always set.
 static int socket_local_client(const std::string& name, int type) {
   sockaddr_un addr = {.sun_family = AF_LOCAL};

   std::string path = "/dev/socket/" + name;
   if (path.size() + 1 > sizeof(addr.sun_path)) {
     return -1;
   }
   strlcpy(addr.sun_path, path.c_str(), sizeof(addr.sun_path));

   int fd = socket(AF_LOCAL, type | SOCK_CLOEXEC, 0);
   if (fd == 0) {
     return -1;
   }

   if (connect(fd, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) == -1) {
     close(fd);
     return -1;
   }

   return fd;
 }

 /* worker for sending the command to the logger */
 static ssize_t send_log_msg(struct android_log_logger* logger, const char* msg, char* buf,
                             size_t buf_size) {
   ssize_t ret;
   size_t len;
   char* cp;
   int errno_save = 0;
   int sock = socket_local_client("logd", SOCK_STREAM);
   if (sock < 0) {
     return sock;
   }

   if (msg) {
     snprintf(buf, buf_size, msg, logger ? logger->logId : (unsigned)-1);
   }

   len = strlen(buf) + 1;
   ret = TEMP_FAILURE_RETRY(write(sock, buf, len));
   if (ret <= 0) {
     goto done;
   }

   len = buf_size;
   cp = buf;
   while ((ret = TEMP_FAILURE_RETRY(read(sock, cp, len))) > 0) {
     struct pollfd p;

     if (((size_t)ret == len) || (buf_size < PAGE_SIZE)) {
       break;
     }

     len -= ret;
     cp += ret;

     memset(&p, 0, sizeof(p));
     p.fd = sock;
     p.events = POLLIN;

     /* Give other side 20ms to refill pipe */
     ret = TEMP_FAILURE_RETRY(poll(&p, 1, 20));

     if (ret <= 0) {
       break;
     }

     if (!(p.revents & POLLIN)) {
       ret = 0;
       break;
     }
   }

   if (ret >= 0) {
     ret += buf_size - len;
   }

 done:
   if ((ret == -1) && errno) {
     errno_save = errno;
   }
   close(sock);
   if (errno_save) {
     errno = errno_save;
   }
   return ret;
 }

 ssize_t __send_log_msg(char* buf, size_t buf_size) {
   return send_log_msg(NULL, NULL, buf, buf_size);
 }

 static int check_log_success(char* buf, ssize_t ret) {
   if (ret < 0) {
     return ret;
   }

   if (strncmp(buf, "success", 7)) {
     errno = EINVAL;
     return -1;
   }

   return 0;
 }

 static int logdClear(struct android_log_logger* logger,
                      struct android_log_transport_context* transp __unused) {
   char buf[512];

   return check_log_success(buf, send_log_msg(logger, "clear %d", buf, sizeof(buf)));
 }

 /* returns the total size of the log's ring buffer */
 static ssize_t logdGetSize(struct android_log_logger* logger,
                            struct android_log_transport_context* transp __unused) {
   char buf[512];

   ssize_t ret = send_log_msg(logger, "getLogSize %d", buf, sizeof(buf));
   if (ret < 0) {
     return ret;
   }

   if ((buf[0] < '0') || ('9' < buf[0])) {
     return -1;
   }

   return atol(buf);
 }

 static ssize_t logdSetSize(struct android_log_logger* logger,
                            struct android_log_transport_context* transp __unused, size_t size) {
   char buf[512];

   snprintf(buf, sizeof(buf), "setLogSize %d %zu", logger->logId, size);

   return check_log_success(buf, send_log_msg(NULL, NULL, buf, sizeof(buf)));
 }

 /*
  * returns the readable size of the log's ring buffer (that is, amount of the
  * log consumed)
  */
 static ssize_t logdGetReadableSize(struct android_log_logger* logger,
                                    struct android_log_transport_context* transp __unused) {
   char buf[512];

   ssize_t ret = send_log_msg(logger, "getLogSizeUsed %d", buf, sizeof(buf));
   if (ret < 0) {
     return ret;
   }

   if ((buf[0] < '0') || ('9' < buf[0])) {
     return -1;
   }

   return atol(buf);
 }

 /*
  * returns the logger version
  */
 static int logdVersion(struct android_log_logger* logger __unused,
                        struct android_log_transport_context* transp __unused) {
   uid_t uid = __android_log_uid();
   return ((uid != AID_ROOT) && (uid != AID_LOG) && (uid != AID_SYSTEM)) ? 3 : 4;
 }

 /*
  * returns statistics
  */
 static ssize_t logdGetStats(struct android_log_logger_list* logger_list,
                             struct android_log_transport_context* transp __unused, char* buf,
                             size_t len) {
   struct android_log_logger* logger;
   char* cp = buf;
   size_t remaining = len;
   size_t n;

   n = snprintf(cp, remaining, "getStatistics");
   n = min(n, remaining);
   remaining -= n;
   cp += n;

   logger_for_each(logger, logger_list) {
     n = snprintf(cp, remaining, " %d", logger->logId);
     n = min(n, remaining);
     remaining -= n;
     cp += n;
   }

   if (logger_list->pid) {
     snprintf(cp, remaining, " pid=%u", logger_list->pid);
   }

   return send_log_msg(NULL, NULL, buf, len);
 }

 static ssize_t logdGetPrune(struct android_log_logger_list* logger_list __unused,
                             struct android_log_transport_context* transp __unused, char* buf,
                             size_t len) {
   return send_log_msg(NULL, "getPruneList", buf, len);
 }

 static ssize_t logdSetPrune(struct android_log_logger_list* logger_list __unused,
                             struct android_log_transport_context* transp __unused, char* buf,
                             size_t len) {
   const char cmd[] = "setPruneList ";
   const size_t cmdlen = sizeof(cmd) - 1;

   if (strlen(buf) > (len - cmdlen)) {
     return -ENOMEM; /* KISS */
   }
   memmove(buf + cmdlen, buf, len - cmdlen);
   buf[len - 1] = '\0';
   memcpy(buf, cmd, cmdlen);

   return check_log_success(buf, send_log_msg(NULL, NULL, buf, len));
 }

 static void caught_signal(int signum __unused) {}

 static int logdOpen(struct android_log_logger_list* logger_list,
                     struct android_log_transport_context* transp) {
   struct android_log_logger* logger;
   struct sigaction ignore;
   struct sigaction old_sigaction;
   unsigned int old_alarm = 0;
   char buffer[256], *cp, c;
   int e, ret, remaining, sock;

   if (!logger_list) {
     return -EINVAL;
   }

   sock = atomic_load(&transp->context.sock);
   if (sock > 0) {
     return sock;
   }

   sock = socket_local_client("logdr", SOCK_SEQPACKET);
   if (sock == 0) {
     /* Guarantee not file descriptor zero */
     int newsock = socket_local_client("logdr", SOCK_SEQPACKET);
     close(sock);
     sock = newsock;
   }
   if (sock <= 0) {
     if ((sock == -1) && errno) {
       return -errno;
     }
     return sock;
   }

   strcpy(buffer, (logger_list->mode & ANDROID_LOG_NONBLOCK) ? "dumpAndClose" : "stream");
   cp = buffer + strlen(buffer);

   strcpy(cp, " lids");
   cp += 5;
   c = '=';
   remaining = sizeof(buffer) - (cp - buffer);
   logger_for_each(logger, logger_list) {
     ret = snprintf(cp, remaining, "%c%u", c, logger->logId);
     ret = min(ret, remaining);
     remaining -= ret;
     cp += ret;
     c = ',';
   }

   if (logger_list->tail) {
     ret = snprintf(cp, remaining, " tail=%u", logger_list->tail);
     ret = min(ret, remaining);
     remaining -= ret;
     cp += ret;
   }

   if (logger_list->start.tv_sec || logger_list->start.tv_nsec) {
     if (logger_list->mode & ANDROID_LOG_WRAP) {
       // ToDo: alternate API to allow timeout to be adjusted.
       ret = snprintf(cp, remaining, " timeout=%u", ANDROID_LOG_WRAP_DEFAULT_TIMEOUT);
       ret = min(ret, remaining);
       remaining -= ret;
       cp += ret;
     }
     ret = snprintf(cp, remaining, " start=%" PRIu32 ".%09" PRIu32, logger_list->start.tv_sec,
                    logger_list->start.tv_nsec);
     ret = min(ret, remaining);
     remaining -= ret;
     cp += ret;
   }

   if (logger_list->pid) {
     ret = snprintf(cp, remaining, " pid=%u", logger_list->pid);
     ret = min(ret, remaining);
     cp += ret;
   }

   if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
     /* Deal with an unresponsive logd */
     memset(&ignore, 0, sizeof(ignore));
     ignore.sa_handler = caught_signal;
     sigemptyset(&ignore.sa_mask);
     /* particularily useful if tombstone is reporting for logd */
     sigaction(SIGALRM, &ignore, &old_sigaction);
     old_alarm = alarm(30);
   }
   ret = write(sock, buffer, cp - buffer);
   e = errno;
   if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
     if (e == EINTR) {
       e = ETIMEDOUT;
     }
     alarm(old_alarm);
     sigaction(SIGALRM, &old_sigaction, NULL);
   }

   if (ret <= 0) {
     close(sock);
     if ((ret == -1) && e) {
       return -e;
     }
     if (ret == 0) {
       return -EIO;
     }
     return ret;
   }

   ret = atomic_exchange(&transp->context.sock, sock);
   if ((ret > 0) && (ret != sock)) {
     close(ret);
   }
   return sock;
 }

 /* Read from the selected logs */
 static int logdRead(struct android_log_logger_list* logger_list,
                     struct android_log_transport_context* transp, struct log_msg* log_msg) {
   int ret, e;
   struct sigaction ignore;
   struct sigaction old_sigaction;
   unsigned int old_alarm = 0;

   ret = logdOpen(logger_list, transp);
   if (ret < 0) {
     return ret;
   }

   memset(log_msg, 0, sizeof(*log_msg));

   unsigned int new_alarm = 0;
   if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
     if ((logger_list->mode & ANDROID_LOG_WRAP) &&
         (logger_list->start.tv_sec || logger_list->start.tv_nsec)) {
       /* b/64143705 */
       new_alarm = (ANDROID_LOG_WRAP_DEFAULT_TIMEOUT * 11) / 10 + 10;
       logger_list->mode &= ~ANDROID_LOG_WRAP;
     } else {
       new_alarm = 30;
     }

     memset(&ignore, 0, sizeof(ignore));
     ignore.sa_handler = caught_signal;
     sigemptyset(&ignore.sa_mask);
     /* particularily useful if tombstone is reporting for logd */
     sigaction(SIGALRM, &ignore, &old_sigaction);
     old_alarm = alarm(new_alarm);
   }

   /* NOTE: SOCK_SEQPACKET guarantees we read exactly one full entry */
   ret = recv(ret, log_msg, LOGGER_ENTRY_MAX_LEN, 0);
   e = errno;

   if (new_alarm) {
     if ((ret == 0) || (e == EINTR)) {
       e = EAGAIN;
       ret = -1;
     }
     alarm(old_alarm);
     sigaction(SIGALRM, &old_sigaction, NULL);
   }

   if ((ret == -1) && e) {
     return -e;
   }
   return ret;
 }

 static int logdPoll(struct android_log_logger_list* logger_list,
                     struct android_log_transport_context* transp) {
   struct pollfd p;

   int ret = logdOpen(logger_list, transp);
   if (ret < 0) {
     return ret;
   }

   memset(&p, 0, sizeof(p));
   p.fd = ret;
   p.events = POLLIN;
   ret = poll(&p, 1, 20);
   if ((ret > 0) && !(p.revents & POLLIN)) {
     ret = 0;
   }
   if ((ret == -1) && errno) {
     return -errno;
   }
   return ret;
 }

 /* Close all the logs */
 static void logdClose(struct android_log_logger_list* logger_list __unused,
                       struct android_log_transport_context* transp) {
   int sock = atomic_exchange(&transp->context.sock, -1);
   if (sock > 0) {
     close(sock);
   }
 }
	/*
	* 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/socket.h>
	#include <sys/stat.h>
	#include <sys/types.h>
	#include <sys/un.h>
	#include <time.h>
	#include <unistd.h>

	#include <cutils/sockets.h>
	#include <private/android_filesystem_config.h>
	#include <private/android_logger.h>

	#include "config_read.h"
	#include "log_portability.h"
	#include "logd_reader.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 logdVersion(struct android_log_logger* logger,
	struct android_log_transport_context* transp);
	static int logdRead(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp, struct log_msg* log_msg);
	static int logdPoll(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp);
	static void logdClose(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp);
	static int logdClear(struct android_log_logger* logger,
	struct android_log_transport_context* transp);
	static ssize_t logdSetSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp, size_t size);
	static ssize_t logdGetSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp);
	static ssize_t logdGetReadableSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp);
	static ssize_t logdGetPrune(struct android_log_logger_list* logger,
	struct android_log_transport_context* transp, char* buf, size_t len);
	static ssize_t logdSetPrune(struct android_log_logger_list* logger,
	struct android_log_transport_context* transp, char* buf, size_t len);
	static ssize_t logdGetStats(struct android_log_logger_list* logger,
	struct android_log_transport_context* transp, char* buf, size_t len);

	struct android_log_transport_read logdLoggerRead = {
	.node = {&logdLoggerRead.node, &logdLoggerRead.node},
	.name = "logd",
	.available = logdAvailable,
	.version = logdVersion,
	.read = logdRead,
	.poll = logdPoll,
	.close = logdClose,
	.clear = logdClear,
	.getSize = logdGetSize,
	.setSize = logdSetSize,
	.getReadableSize = logdGetReadableSize,
	.getPrune = logdGetPrune,
	.setPrune = logdSetPrune,
	.getStats = logdGetStats,
	};

	static int logdAvailable(log_id_t logId) {
	if (logId >= LOG_ID_MAX) {
	return -EINVAL;
	}
	if (logId == LOG_ID_SECURITY) {
	uid_t uid = __android_log_uid();
	if (uid != AID_SYSTEM) {
	return -EPERM;
	}
	}
	if (access("/dev/socket/logdw", W_OK) == 0) {
	return 0;
	}
	return -EBADF;
	}

	// Connects to /dev/socket/<name> and returns the associated fd or returns -1 on error.
	// O_CLOEXEC is always set.
	static int socket_local_client(const std::string& name, int type) {
	sockaddr_un addr = {.sun_family = AF_LOCAL};

	std::string path = "/dev/socket/" + name;
	if (path.size() + 1 > sizeof(addr.sun_path)) {
	return -1;
	}
	strlcpy(addr.sun_path, path.c_str(), sizeof(addr.sun_path));

	int fd = socket(AF_LOCAL, type \| SOCK_CLOEXEC, 0);
	if (fd == 0) {
	return -1;
	}

	if (connect(fd, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) == -1) {
	close(fd);
	return -1;
	}

	return fd;
	}

	/* worker for sending the command to the logger */
	static ssize_t send_log_msg(struct android_log_logger* logger, const char* msg, char* buf,
	size_t buf_size) {
	ssize_t ret;
	size_t len;
	char* cp;
	int errno_save = 0;
	int sock = socket_local_client("logd", SOCK_STREAM);
	if (sock < 0) {
	return sock;
	}

	if (msg) {
	snprintf(buf, buf_size, msg, logger ? logger->logId : (unsigned)-1);
	}

	len = strlen(buf) + 1;
	ret = TEMP_FAILURE_RETRY(write(sock, buf, len));
	if (ret <= 0) {
	goto done;
	}

	len = buf_size;
	cp = buf;
	while ((ret = TEMP_FAILURE_RETRY(read(sock, cp, len))) > 0) {
	struct pollfd p;

	if (((size_t)ret == len) \|\| (buf_size < PAGE_SIZE)) {
	break;
	}

	len -= ret;
	cp += ret;

	memset(&p, 0, sizeof(p));
	p.fd = sock;
	p.events = POLLIN;

	/* Give other side 20ms to refill pipe */
	ret = TEMP_FAILURE_RETRY(poll(&p, 1, 20));

	if (ret <= 0) {
	break;
	}

	if (!(p.revents & POLLIN)) {
	ret = 0;
	break;
	}
	}

	if (ret >= 0) {
	ret += buf_size - len;
	}

	done:
	if ((ret == -1) && errno) {
	errno_save = errno;
	}
	close(sock);
	if (errno_save) {
	errno = errno_save;
	}
	return ret;
	}

	ssize_t __send_log_msg(char* buf, size_t buf_size) {
	return send_log_msg(NULL, NULL, buf, buf_size);
	}

	static int check_log_success(char* buf, ssize_t ret) {
	if (ret < 0) {
	return ret;
	}

	if (strncmp(buf, "success", 7)) {
	errno = EINVAL;
	return -1;
	}

	return 0;
	}

	static int logdClear(struct android_log_logger* logger,
	struct android_log_transport_context* transp __unused) {
	char buf[512];

	return check_log_success(buf, send_log_msg(logger, "clear %d", buf, sizeof(buf)));
	}

	/* returns the total size of the log's ring buffer */
	static ssize_t logdGetSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp __unused) {
	char buf[512];

	ssize_t ret = send_log_msg(logger, "getLogSize %d", buf, sizeof(buf));
	if (ret < 0) {
	return ret;
	}

	if ((buf[0] < '0') \|\| ('9' < buf[0])) {
	return -1;
	}

	return atol(buf);
	}

	static ssize_t logdSetSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp __unused, size_t size) {
	char buf[512];

	snprintf(buf, sizeof(buf), "setLogSize %d %zu", logger->logId, size);

	return check_log_success(buf, send_log_msg(NULL, NULL, buf, sizeof(buf)));
	}

	/*
	* returns the readable size of the log's ring buffer (that is, amount of the
	* log consumed)
	*/
	static ssize_t logdGetReadableSize(struct android_log_logger* logger,
	struct android_log_transport_context* transp __unused) {
	char buf[512];

	ssize_t ret = send_log_msg(logger, "getLogSizeUsed %d", buf, sizeof(buf));
	if (ret < 0) {
	return ret;
	}

	if ((buf[0] < '0') \|\| ('9' < buf[0])) {
	return -1;
	}

	return atol(buf);
	}

	/*
	* returns the logger version
	*/
	static int logdVersion(struct android_log_logger* logger __unused,
	struct android_log_transport_context* transp __unused) {
	uid_t uid = __android_log_uid();
	return ((uid != AID_ROOT) && (uid != AID_LOG) && (uid != AID_SYSTEM)) ? 3 : 4;
	}

	/*
	* returns statistics
	*/
	static ssize_t logdGetStats(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp __unused, char* buf,
	size_t len) {
	struct android_log_logger* logger;
	char* cp = buf;
	size_t remaining = len;
	size_t n;

	n = snprintf(cp, remaining, "getStatistics");
	n = min(n, remaining);
	remaining -= n;
	cp += n;

	logger_for_each(logger, logger_list) {
	n = snprintf(cp, remaining, " %d", logger->logId);
	n = min(n, remaining);
	remaining -= n;
	cp += n;
	}

	if (logger_list->pid) {
	snprintf(cp, remaining, " pid=%u", logger_list->pid);
	}

	return send_log_msg(NULL, NULL, buf, len);
	}

	static ssize_t logdGetPrune(struct android_log_logger_list* logger_list __unused,
	struct android_log_transport_context* transp __unused, char* buf,
	size_t len) {
	return send_log_msg(NULL, "getPruneList", buf, len);
	}

	static ssize_t logdSetPrune(struct android_log_logger_list* logger_list __unused,
	struct android_log_transport_context* transp __unused, char* buf,
	size_t len) {
	const char cmd[] = "setPruneList ";
	const size_t cmdlen = sizeof(cmd) - 1;

	if (strlen(buf) > (len - cmdlen)) {
	return -ENOMEM; /* KISS */
	}
	memmove(buf + cmdlen, buf, len - cmdlen);
	buf[len - 1] = '\0';
	memcpy(buf, cmd, cmdlen);

	return check_log_success(buf, send_log_msg(NULL, NULL, buf, len));
	}

	static void caught_signal(int signum __unused) {}

	static int logdOpen(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp) {
	struct android_log_logger* logger;
	struct sigaction ignore;
	struct sigaction old_sigaction;
	unsigned int old_alarm = 0;
	char buffer[256], *cp, c;
	int e, ret, remaining, sock;

	if (!logger_list) {
	return -EINVAL;
	}

	sock = atomic_load(&transp->context.sock);
	if (sock > 0) {
	return sock;
	}

	sock = socket_local_client("logdr", SOCK_SEQPACKET);
	if (sock == 0) {
	/* Guarantee not file descriptor zero */
	int newsock = socket_local_client("logdr", SOCK_SEQPACKET);
	close(sock);
	sock = newsock;
	}
	if (sock <= 0) {
	if ((sock == -1) && errno) {
	return -errno;
	}
	return sock;
	}

	strcpy(buffer, (logger_list->mode & ANDROID_LOG_NONBLOCK) ? "dumpAndClose" : "stream");
	cp = buffer + strlen(buffer);

	strcpy(cp, " lids");
	cp += 5;
	c = '=';
	remaining = sizeof(buffer) - (cp - buffer);
	logger_for_each(logger, logger_list) {
	ret = snprintf(cp, remaining, "%c%u", c, logger->logId);
	ret = min(ret, remaining);
	remaining -= ret;
	cp += ret;
	c = ',';
	}

	if (logger_list->tail) {
	ret = snprintf(cp, remaining, " tail=%u", logger_list->tail);
	ret = min(ret, remaining);
	remaining -= ret;
	cp += ret;
	}

	if (logger_list->start.tv_sec \|\| logger_list->start.tv_nsec) {
	if (logger_list->mode & ANDROID_LOG_WRAP) {
	// ToDo: alternate API to allow timeout to be adjusted.
	ret = snprintf(cp, remaining, " timeout=%u", ANDROID_LOG_WRAP_DEFAULT_TIMEOUT);
	ret = min(ret, remaining);
	remaining -= ret;
	cp += ret;
	}
	ret = snprintf(cp, remaining, " start=%" PRIu32 ".%09" PRIu32, logger_list->start.tv_sec,
	logger_list->start.tv_nsec);
	ret = min(ret, remaining);
	remaining -= ret;
	cp += ret;
	}

	if (logger_list->pid) {
	ret = snprintf(cp, remaining, " pid=%u", logger_list->pid);
	ret = min(ret, remaining);
	cp += ret;
	}

	if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
	/* Deal with an unresponsive logd */
	memset(&ignore, 0, sizeof(ignore));
	ignore.sa_handler = caught_signal;
	sigemptyset(&ignore.sa_mask);
	/* particularily useful if tombstone is reporting for logd */
	sigaction(SIGALRM, &ignore, &old_sigaction);
	old_alarm = alarm(30);
	}
	ret = write(sock, buffer, cp - buffer);
	e = errno;
	if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
	if (e == EINTR) {
	e = ETIMEDOUT;
	}
	alarm(old_alarm);
	sigaction(SIGALRM, &old_sigaction, NULL);
	}

	if (ret <= 0) {
	close(sock);
	if ((ret == -1) && e) {
	return -e;
	}
	if (ret == 0) {
	return -EIO;
	}
	return ret;
	}

	ret = atomic_exchange(&transp->context.sock, sock);
	if ((ret > 0) && (ret != sock)) {
	close(ret);
	}
	return sock;
	}

	/* Read from the selected logs */
	static int logdRead(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp, struct log_msg* log_msg) {
	int ret, e;
	struct sigaction ignore;
	struct sigaction old_sigaction;
	unsigned int old_alarm = 0;

	ret = logdOpen(logger_list, transp);
	if (ret < 0) {
	return ret;
	}

	memset(log_msg, 0, sizeof(*log_msg));

	unsigned int new_alarm = 0;
	if (logger_list->mode & ANDROID_LOG_NONBLOCK) {
	if ((logger_list->mode & ANDROID_LOG_WRAP) &&
	(logger_list->start.tv_sec \|\| logger_list->start.tv_nsec)) {
	/* b/64143705 */
	new_alarm = (ANDROID_LOG_WRAP_DEFAULT_TIMEOUT * 11) / 10 + 10;
	logger_list->mode &= ~ANDROID_LOG_WRAP;
	} else {
	new_alarm = 30;
	}

	memset(&ignore, 0, sizeof(ignore));
	ignore.sa_handler = caught_signal;
	sigemptyset(&ignore.sa_mask);
	/* particularily useful if tombstone is reporting for logd */
	sigaction(SIGALRM, &ignore, &old_sigaction);
	old_alarm = alarm(new_alarm);
	}

	/* NOTE: SOCK_SEQPACKET guarantees we read exactly one full entry */
	ret = recv(ret, log_msg, LOGGER_ENTRY_MAX_LEN, 0);
	e = errno;

	if (new_alarm) {
	if ((ret == 0) \|\| (e == EINTR)) {
	e = EAGAIN;
	ret = -1;
	}
	alarm(old_alarm);
	sigaction(SIGALRM, &old_sigaction, NULL);
	}

	if ((ret == -1) && e) {
	return -e;
	}
	return ret;
	}

	static int logdPoll(struct android_log_logger_list* logger_list,
	struct android_log_transport_context* transp) {
	struct pollfd p;

	int ret = logdOpen(logger_list, transp);
	if (ret < 0) {
	return ret;
	}

	memset(&p, 0, sizeof(p));
	p.fd = ret;
	p.events = POLLIN;
	ret = poll(&p, 1, 20);
	if ((ret > 0) && !(p.revents & POLLIN)) {
	ret = 0;
	}
	if ((ret == -1) && errno) {
	return -errno;
	}
	return ret;
	}

	/* Close all the logs */
	static void logdClose(struct android_log_logger_list* logger_list __unused,
	struct android_log_transport_context* transp) {
	int sock = atomic_exchange(&transp->context.sock, -1);
	if (sock > 0) {
	close(sock);
	}
	}