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Commit ff464b12 authored by Tom Cherry's avatar Tom Cherry
Browse files

liblog: always restore errno in logging functions 

Some recent changes can have these logging functions potentially set
errno.  This change places android::base::ErrnoRestorer at the entry
point of the public functions where we want to guarantee errno is
restored to ensure this will not happen again.

Test: build
Change-Id: Iab4170ab16b9c7301474a509ee42d38b370b91a4
parent 347d6406

base/include/android-base/errno_restorer.h

0 → 100644
+42 −0
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2020 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.

 */



#pragma once



#include "errno.h"



#include "android-base/macros.h"



namespace android {

namespace base {



class ErrnoRestorer {

 public:

  ErrnoRestorer() : saved_errno_(errno) {}



  ~ErrnoRestorer() { errno = saved_errno_; }



  // Allow this object to be used as part of && operation.

  operator bool() const { return true; }



 private:

  const int saved_errno_;



  DISALLOW_COPY_AND_ASSIGN(ErrnoRestorer);

};



}  // namespace base

}  // namespace android

base/include/android-base/logging.h

+1 −21
Original line number Diff line number Diff line
@@ -64,6 +64,7 @@ 
#include <memory>

#include <ostream>



#include "android-base/errno_restorer.h"

#include "android-base/macros.h"



// Note: DO NOT USE DIRECTLY. Use LOG_TAG instead.
@@ -154,27 +155,6 @@ void SetLogger(LogFunction&& logger); 
// Replace the current aborter.

void SetAborter(AbortFunction&& aborter);



class ErrnoRestorer {

 public:

  ErrnoRestorer()

      : saved_errno_(errno) {

  }



  ~ErrnoRestorer() {

    errno = saved_errno_;

  }



  // Allow this object to be used as part of && operation.

  operator bool() const {

    return true;

  }



 private:

  const int saved_errno_;



  DISALLOW_COPY_AND_ASSIGN(ErrnoRestorer);

};



// A helper macro that produces an expression that accepts both a qualified name and an

// unqualified name for a LogSeverity, and returns a LogSeverity value.

// Note: DO NOT USE DIRECTLY. This is an implementation detail.

liblog/logger_write.cpp

+26 −8
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 


#include <shared_mutex>



#include <android-base/errno_restorer.h>

#include <android-base/macros.h>

#include <private/android_filesystem_config.h>

#include <private/android_logger.h>
@@ -54,6 +55,8 @@ 
#include <windows.h>

#endif



using android::base::ErrnoRestorer;



#define LOG_BUF_SIZE 1024



#if defined(__ANDROID__)
@@ -196,11 +199,9 @@ void __android_log_call_aborter(const char* abort_message) { 


#ifdef __ANDROID__

static int write_to_log(log_id_t log_id, struct iovec* vec, size_t nr) {

  int ret, save_errno;

  int ret;

  struct timespec ts;



  save_errno = errno;



  if (log_id == LOG_ID_KERNEL) {

    return -EINVAL;

  }
@@ -209,23 +210,19 @@ static int write_to_log(log_id_t log_id, struct iovec* vec, size_t nr) { 


  if (log_id == LOG_ID_SECURITY) {

    if (vec[0].iov_len < 4) {

      errno = save_errno;

      return -EINVAL;

    }



    ret = check_log_uid_permissions();

    if (ret < 0) {

      errno = save_errno;

      return ret;

    }

    if (!__android_log_security()) {

      /* If only we could reset downstream logd counter */

      errno = save_errno;

      return -EPERM;

    }

  } else if (log_id == LOG_ID_EVENTS || log_id == LOG_ID_STATS) {

    if (vec[0].iov_len < 4) {

      errno = save_errno;

      return -EINVAL;

    }

  }
@@ -233,7 +230,6 @@ static int write_to_log(log_id_t log_id, struct iovec* vec, size_t nr) { 
  ret = LogdWrite(log_id, &ts, vec, nr);

  PmsgWrite(log_id, &ts, vec, nr);



  errno = save_errno;

  return ret;

}

#else
@@ -313,6 +309,8 @@ int __android_log_write(int prio, const char* tag, const char* msg) { 
}



void __android_log_write_logger_data(__android_logger_data* logger_data, const char* msg) {

  ErrnoRestorer errno_restorer;



  auto tag_lock = std::shared_lock{default_tag_lock, std::defer_lock};

  if (logger_data->tag == nullptr) {

    tag_lock.lock();
@@ -330,6 +328,8 @@ void __android_log_write_logger_data(__android_logger_data* logger_data, const c 
}



int __android_log_buf_write(int bufID, int prio, const char* tag, const char* msg) {

  ErrnoRestorer errno_restorer;



  if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {

    return 0;

  }
@@ -340,6 +340,8 @@ int __android_log_buf_write(int bufID, int prio, const char* tag, const char* ms 
}



int __android_log_vprint(int prio, const char* tag, const char* fmt, va_list ap) {

  ErrnoRestorer errno_restorer;



  if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {

    return 0;

  }
@@ -355,6 +357,8 @@ int __android_log_vprint(int prio, const char* tag, const char* fmt, va_list ap) 
}



int __android_log_print(int prio, const char* tag, const char* fmt, ...) {

  ErrnoRestorer errno_restorer;



  if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {

    return 0;

  }
@@ -373,6 +377,8 @@ int __android_log_print(int prio, const char* tag, const char* fmt, ...) { 
}



int __android_log_buf_print(int bufID, int prio, const char* tag, const char* fmt, ...) {

  ErrnoRestorer errno_restorer;



  if (!__android_log_is_loggable(prio, tag, ANDROID_LOG_VERBOSE)) {

    return 0;

  }
@@ -419,6 +425,8 @@ void __android_log_assert(const char* cond, const char* tag, const char* fmt, .. 
}



int __android_log_bwrite(int32_t tag, const void* payload, size_t len) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[2];



  vec[0].iov_base = &tag;
@@ -430,6 +438,8 @@ int __android_log_bwrite(int32_t tag, const void* payload, size_t len) { 
}



int __android_log_stats_bwrite(int32_t tag, const void* payload, size_t len) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[2];



  vec[0].iov_base = &tag;
@@ -441,6 +451,8 @@ int __android_log_stats_bwrite(int32_t tag, const void* payload, size_t len) { 
}



int __android_log_security_bwrite(int32_t tag, const void* payload, size_t len) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[2];



  vec[0].iov_base = &tag;
@@ -457,6 +469,8 @@ int __android_log_security_bwrite(int32_t tag, const void* payload, size_t len) 
 * handy if we just want to dump an integer into the log.

 */

int __android_log_btwrite(int32_t tag, char type, const void* payload, size_t len) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[3];



  vec[0].iov_base = &tag;
@@ -474,6 +488,8 @@ int __android_log_btwrite(int32_t tag, char type, const void* payload, size_t le 
 * event log.

 */

int __android_log_bswrite(int32_t tag, const char* payload) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[4];

  char type = EVENT_TYPE_STRING;

  uint32_t len = strlen(payload);
@@ -495,6 +511,8 @@ int __android_log_bswrite(int32_t tag, const char* payload) { 
 * security log.

 */

int __android_log_security_bswrite(int32_t tag, const char* payload) {

  ErrnoRestorer errno_restorer;



  struct iovec vec[4];

  char type = EVENT_TYPE_STRING;

  uint32_t len = strlen(payload);