256 lines
8.0 KiB
C
256 lines
8.0 KiB
C
/*
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* Copyright (C) 2007-2016 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <string.h>
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#include <sys/types.h>
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#include <private/android_filesystem_config.h>
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#include <private/android_logger.h>
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#include "config_read.h"
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#include "logger.h"
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static int pmsgAvailable(log_id_t logId);
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static int pmsgVersion(struct android_log_logger *logger,
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struct android_log_transport_context *transp);
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static int pmsgRead(struct android_log_logger_list *logger_list,
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struct android_log_transport_context *transp,
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struct log_msg *log_msg);
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static void pmsgClose(struct android_log_logger_list *logger_list,
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struct android_log_transport_context *transp);
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static int pmsgClear(struct android_log_logger *logger,
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struct android_log_transport_context *transp);
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LIBLOG_HIDDEN struct android_log_transport_read pmsgLoggerRead = {
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.node = { &pmsgLoggerRead.node, &pmsgLoggerRead.node },
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.name = "pmsg",
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.available = pmsgAvailable,
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.version = pmsgVersion,
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.read = pmsgRead,
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.poll = NULL,
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.close = pmsgClose,
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.clear = pmsgClear,
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.setSize = NULL,
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.getSize = NULL,
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.getReadableSize = NULL,
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.getPrune = NULL,
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.setPrune = NULL,
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.getStats = NULL,
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};
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static int pmsgAvailable(log_id_t logId)
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{
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if (logId > LOG_ID_SECURITY) {
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return -EINVAL;
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}
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if (access("/dev/pmsg0", W_OK) == 0) {
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return 0;
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}
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return -EBADF;
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}
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/* Determine the credentials of the caller */
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static bool uid_has_log_permission(uid_t uid)
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{
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return (uid == AID_SYSTEM) || (uid == AID_LOG) || (uid == AID_ROOT);
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}
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static uid_t get_best_effective_uid()
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{
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uid_t euid;
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uid_t uid;
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gid_t gid;
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ssize_t i;
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static uid_t last_uid = (uid_t) -1;
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if (last_uid != (uid_t) -1) {
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return last_uid;
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}
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uid = __android_log_uid();
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if (uid_has_log_permission(uid)) {
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return last_uid = uid;
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}
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euid = geteuid();
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if (uid_has_log_permission(euid)) {
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return last_uid = euid;
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}
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gid = getgid();
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if (uid_has_log_permission(gid)) {
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return last_uid = gid;
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}
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gid = getegid();
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if (uid_has_log_permission(gid)) {
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return last_uid = gid;
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}
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i = getgroups((size_t) 0, NULL);
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if (i > 0) {
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gid_t list[i];
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getgroups(i, list);
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while (--i >= 0) {
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if (uid_has_log_permission(list[i])) {
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return last_uid = list[i];
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}
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}
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}
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return last_uid = uid;
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}
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static int pmsgClear(struct android_log_logger *logger __unused,
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struct android_log_transport_context *transp __unused)
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{
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if (uid_has_log_permission(get_best_effective_uid())) {
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return unlink("/sys/fs/pstore/pmsg-ramoops-0");
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}
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errno = EPERM;
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return -1;
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}
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/*
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* returns the logger version
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*/
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static int pmsgVersion(struct android_log_logger *logger __unused,
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struct android_log_transport_context *transp __unused)
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{
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return 4;
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}
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static int pmsgRead(struct android_log_logger_list *logger_list,
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struct android_log_transport_context *transp,
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struct log_msg *log_msg)
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{
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ssize_t ret;
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off_t current, next;
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uid_t uid;
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struct android_log_logger *logger;
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struct __attribute__((__packed__)) {
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android_pmsg_log_header_t p;
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android_log_header_t l;
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} buf;
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static uint8_t preread_count;
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bool is_system;
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memset(log_msg, 0, sizeof(*log_msg));
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if (transp->context.fd <= 0) {
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int fd = open("/sys/fs/pstore/pmsg-ramoops-0", O_RDONLY);
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if (fd < 0) {
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return -errno;
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}
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if (fd == 0) { /* Argggg */
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fd = open("/sys/fs/pstore/pmsg-ramoops-0", O_RDONLY);
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close(0);
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if (fd < 0) {
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return -errno;
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}
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}
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transp->context.fd = fd;
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preread_count = 0;
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}
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while(1) {
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if (preread_count < sizeof(buf)) {
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ret = TEMP_FAILURE_RETRY(read(transp->context.fd,
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&buf.p.magic + preread_count,
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sizeof(buf) - preread_count));
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if (ret < 0) {
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return -errno;
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}
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preread_count += ret;
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}
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if (preread_count != sizeof(buf)) {
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return preread_count ? -EIO : -EAGAIN;
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}
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if ((buf.p.magic != LOGGER_MAGIC)
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|| (buf.p.len <= sizeof(buf))
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|| (buf.p.len > (sizeof(buf) + LOGGER_ENTRY_MAX_PAYLOAD))
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|| (buf.l.id >= LOG_ID_MAX)
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|| (buf.l.realtime.tv_nsec >= NS_PER_SEC)) {
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do {
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memmove(&buf.p.magic, &buf.p.magic + 1, --preread_count);
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} while (preread_count && (buf.p.magic != LOGGER_MAGIC));
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continue;
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}
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preread_count = 0;
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if ((transp->logMask & (1 << buf.l.id)) &&
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((!logger_list->start.tv_sec && !logger_list->start.tv_nsec) ||
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((logger_list->start.tv_sec <= buf.l.realtime.tv_sec) &&
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((logger_list->start.tv_sec != buf.l.realtime.tv_sec) ||
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(logger_list->start.tv_nsec <=
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buf.l.realtime.tv_nsec)))) &&
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(!logger_list->pid || (logger_list->pid == buf.p.pid))) {
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uid = get_best_effective_uid();
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is_system = uid_has_log_permission(uid);
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if (is_system || (uid == buf.p.uid)) {
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ret = TEMP_FAILURE_RETRY(read(transp->context.fd,
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is_system ?
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log_msg->entry_v4.msg :
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log_msg->entry_v3.msg,
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buf.p.len - sizeof(buf)));
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if (ret < 0) {
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return -errno;
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}
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if (ret != (ssize_t)(buf.p.len - sizeof(buf))) {
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return -EIO;
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}
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log_msg->entry_v4.len = buf.p.len - sizeof(buf);
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log_msg->entry_v4.hdr_size = is_system ?
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sizeof(log_msg->entry_v4) :
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sizeof(log_msg->entry_v3);
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log_msg->entry_v4.pid = buf.p.pid;
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log_msg->entry_v4.tid = buf.l.tid;
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log_msg->entry_v4.sec = buf.l.realtime.tv_sec;
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log_msg->entry_v4.nsec = buf.l.realtime.tv_nsec;
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log_msg->entry_v4.lid = buf.l.id;
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if (is_system) {
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log_msg->entry_v4.uid = buf.p.uid;
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}
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return ret;
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}
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}
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current = TEMP_FAILURE_RETRY(lseek(transp->context.fd,
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(off_t)0, SEEK_CUR));
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if (current < 0) {
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return -errno;
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}
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next = TEMP_FAILURE_RETRY(lseek(transp->context.fd,
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(off_t)(buf.p.len - sizeof(buf)),
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SEEK_CUR));
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if (next < 0) {
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return -errno;
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}
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if ((next - current) != (ssize_t)(buf.p.len - sizeof(buf))) {
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return -EIO;
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}
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}
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}
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static void pmsgClose(struct android_log_logger_list *logger_list __unused,
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struct android_log_transport_context *transp) {
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if (transp->context.fd > 0) {
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close (transp->context.fd);
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}
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transp->context.fd = 0;
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}
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