// Copyright 2017 The Abseil Authors.

//

// 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

//

//      https://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.

//

// Thread-safe logging routines that do not allocate any memory or

// acquire any locks, and can therefore be used by low-level memory

// allocation, synchronization, and signal-handling code.

#ifndef ABSL_BASE_INTERNAL_RAW_LOGGING_H_

#define ABSL_BASE_INTERNAL_RAW_LOGGING_H_

#include <string>

#include "absl/base/attributes.h"

#include "absl/base/config.h"

#include "absl/base/internal/atomic_hook.h"

#include "absl/base/log_severity.h"

#include "absl/base/macros.h"

#include "absl/base/optimization.h"

#include "absl/base/port.h"

// This is similar to LOG(severity) << format..., but

// * it is to be used ONLY by low-level modules that can't use normal LOG()

// * it is designed to be a low-level logger that does not allocate any

//   memory and does not need any locks, hence:

// * it logs straight and ONLY to STDERR w/o buffering

// * it uses an explicit printf-format and arguments list

// * it will silently chop off really long message strings

// Usage example:

//   ABSL_RAW_LOG(ERROR, "Failed foo with %i: %s", status, error);

// This will print an almost standard log line like this to stderr only:

//   E0821 211317 file.cc:123] RAW: Failed foo with 22: bad_file

#define ABSL_RAW_LOG(severity, ...)                                            \

  do {                                                                         \

    constexpr const char* absl_raw_log_internal_basename =                     \

        ::absl::raw_log_internal::Basename(__FILE__, sizeof(__FILE__) - 1);    \

    ::absl::raw_log_internal::RawLog(ABSL_RAW_LOG_INTERNAL_##severity,         \

                                     absl_raw_log_internal_basename, __LINE__, \

                                     __VA_ARGS__);                             \

    ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_##severity;                        \

  } while (0)

// Similar to CHECK(condition) << message, but for low-level modules:

// we use only ABSL_RAW_LOG that does not allocate memory.

// We do not want to provide args list here to encourage this usage:

//   if (!cond)  ABSL_RAW_LOG(FATAL, "foo ...", hard_to_compute_args);

// so that the args are not computed when not needed.

#define ABSL_RAW_CHECK(condition, message)                             \

  do {                                                                 \

    if (ABSL_PREDICT_FALSE(!(condition))) {                            \

      ABSL_RAW_LOG(FATAL, "Check %s failed: %s", #condition, message); \

    }                                                                  \

  } while (0)

// ABSL_INTERNAL_LOG and ABSL_INTERNAL_CHECK work like the RAW variants above,

// except that if the richer log library is linked into the binary, we dispatch

// to that instead.  This is potentially useful for internal logging and

// assertions, where we are using RAW_LOG neither for its async-signal-safety

// nor for its non-allocating nature, but rather because raw logging has very

// few other dependencies.

//

// The API is a subset of the above: each macro only takes two arguments.  Use

// StrCat if you need to build a richer message.

#define ABSL_INTERNAL_LOG(severity, message)                              \

  do {                                                                    \

    constexpr const char* absl_raw_log_internal_filename = __FILE__;      \

    ::absl::raw_log_internal::internal_log_function(                      \

        ABSL_RAW_LOG_INTERNAL_##severity, absl_raw_log_internal_filename, \

        __LINE__, message);                                               \

    ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_##severity;                   \

  } while (0)

#define ABSL_INTERNAL_CHECK(condition, message)                    \

  do {                                                             \

    if (ABSL_PREDICT_FALSE(!(condition))) {                        \

      std::string death_message = "Check " #condition " failed: "; \

      death_message += std::string(message);                       \

      ABSL_INTERNAL_LOG(FATAL, death_message);                     \

    }                                                              \

  } while (0)

#ifndef NDEBUG

#define ABSL_RAW_DLOG(severity, ...) ABSL_RAW_LOG(severity, __VA_ARGS__)

#define ABSL_RAW_DCHECK(condition, message) ABSL_RAW_CHECK(condition, message)

#else  // NDEBUG

#define ABSL_RAW_DLOG(severity, ...)                   \

  while (false) ABSL_RAW_LOG(severity, __VA_ARGS__)

#define ABSL_RAW_DCHECK(condition, message) \

  while (false) ABSL_RAW_CHECK(condition, message)

#endif  // NDEBUG

#define ABSL_RAW_LOG_INTERNAL_INFO ::absl::LogSeverity::kInfo

#define ABSL_RAW_LOG_INTERNAL_WARNING ::absl::LogSeverity::kWarning

#define ABSL_RAW_LOG_INTERNAL_ERROR ::absl::LogSeverity::kError

#define ABSL_RAW_LOG_INTERNAL_FATAL ::absl::LogSeverity::kFatal

#define ABSL_RAW_LOG_INTERNAL_LEVEL(severity) \

  ::absl::NormalizeLogSeverity(severity)

#define ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_INFO

#define ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_WARNING

#define ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_ERROR

#define ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_FATAL ABSL_UNREACHABLE()

#define ABSL_RAW_LOG_INTERNAL_MAYBE_UNREACHABLE_LEVEL(severity)

namespace absl {

ABSL_NAMESPACE_BEGIN

namespace raw_log_internal {

// Helper function to implement ABSL_RAW_LOG

// Logs format... at "severity" level, reporting it

// as called from file:line.

// This does not allocate memory or acquire locks.

void RawLog(absl::LogSeverity severity, const char* file, int line,

            const char* format, ...) ABSL_PRINTF_ATTRIBUTE(4, 5);

// Writes the provided buffer directly to stderr, in a signal-safe, low-level

// manner.  Preserves errno.

void AsyncSignalSafeWriteError(const char* s, size_t len);

// compile-time function to get the "base" filename, that is, the part of

// a filename after the last "/" or "\" path separator.  The search starts at

// the end of the string; the second parameter is the length of the string.

constexpr const char* Basename(const char* fname, int offset) {

  return offset == 0 || fname[offset - 1] == '/' || fname[offset - 1] == '\\'

             ? fname + offset

             : Basename(fname, offset - 1);

}

// For testing only.

// Returns true if raw logging is fully supported. When it is not

// fully supported, no messages will be emitted, but a log at FATAL

// severity will cause an abort.

//

// TODO(gfalcon): Come up with a better name for this method.

bool RawLoggingFullySupported();

// Function type for a raw_log customization hook for suppressing messages

// by severity, and for writing custom prefixes on non-suppressed messages.

//

// The installed hook is called for every raw log invocation.  The message will

// be logged to stderr only if the hook returns true.  FATAL errors will cause

// the process to abort, even if writing to stderr is suppressed.  The hook is

// also provided with an output buffer, where it can write a custom log message

// prefix.

//

// The raw_log system does not allocate memory or grab locks.  User-provided

// hooks must avoid these operations, and must not throw exceptions.

//

// 'severity' is the severity level of the message being written.

// 'file' and 'line' are the file and line number where the ABSL_RAW_LOG macro

// was located.

// 'buf' and 'buf_size' are pointers to the buffer and buffer size.  If the

// hook writes a prefix, it must increment *buf and decrement *buf_size

// accordingly.

using LogFilterAndPrefixHook = bool (*)(absl::LogSeverity severity,

                                        const char* file, int line, char** buf,

                                        int* buf_size);

// Function type for a raw_log customization hook called to abort a process

// when a FATAL message is logged.  If the provided AbortHook() returns, the

// logging system will call abort().

//

// 'file' and 'line' are the file and line number where the ABSL_RAW_LOG macro

// was located.

// The NUL-terminated logged message lives in the buffer between 'buf_start'

// and 'buf_end'.  'prefix_end' points to the first non-prefix character of the

// buffer (as written by the LogFilterAndPrefixHook.)

//

// The lifetime of the filename and message buffers will not end while the

// process remains alive.

using AbortHook = void (*)(const char* file, int line, const char* buf_start,

                           const char* prefix_end, const char* buf_end);

// Internal logging function for ABSL_INTERNAL_LOG to dispatch to.

//

// TODO(gfalcon): When string_view no longer depends on base, change this

// interface to take its message as a string_view instead.

using InternalLogFunction = void (*)(absl::LogSeverity severity,

                                     const char* file, int line,

                                     const std::string& message);

ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL extern base_internal::AtomicHook<

    InternalLogFunction>

    internal_log_function;

// Registers hooks of the above types.  Only a single hook of each type may be

// registered.  It is an error to call these functions multiple times with

// different input arguments.

//

// These functions are safe to call at any point during initialization; they do

// not block or malloc, and are async-signal safe.

void RegisterLogFilterAndPrefixHook(LogFilterAndPrefixHook func);

void RegisterAbortHook(AbortHook func);

void RegisterInternalLogFunction(InternalLogFunction func);

}  // namespace raw_log_internal

ABSL_NAMESPACE_END

}  // namespace absl

#endif  // ABSL_BASE_INTERNAL_RAW_LOGGING_H_