raw_logging.cc | Explore in Territory

// 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.

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

#include <cstdarg>
#include <cstddef>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>

#ifdef __EMSCRIPTEN__
#include <emscripten/console.h>
#endif

#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/internal/atomic_hook.h"
#include "absl/base/internal/errno_saver.h"
#include "absl/base/log_severity.h"

// We know how to perform low-level writes to stderr in POSIX and Windows.  For
// these platforms, we define the token ABSL_LOW_LEVEL_WRITE_SUPPORTED.
// Much of raw_logging.cc becomes a no-op when we can't output messages,
// although a FATAL ABSL_RAW_LOG message will still abort the process.

// ABSL_HAVE_POSIX_WRITE is defined when the platform provides posix write()
// (as from unistd.h)
//
// This preprocessor token is also defined in raw_io.cc.  If you need to copy
// this, consider moving both to config.h instead.
#if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) || \
    defined(__hexagon__) || defined(__Fuchsia__) ||                     \
    defined(__native_client__) || defined(__OpenBSD__) ||               \
    defined(__EMSCRIPTEN__) || defined(__ASYLO__)

#include <unistd.h>

#define ABSL_HAVE_POSIX_WRITE …
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED …
#else
#undef ABSL_HAVE_POSIX_WRITE
#endif

// ABSL_HAVE_SYSCALL_WRITE is defined when the platform provides the syscall
//   syscall(SYS_write, /*int*/ fd, /*char* */ buf, /*size_t*/ len);
// for low level operations that want to avoid libc.
#if (defined(__linux__) || defined(__FreeBSD__)) && !defined(__ANDROID__)
#include <sys/syscall.h>
#define ABSL_HAVE_SYSCALL_WRITE …
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED …
#else
#undef ABSL_HAVE_SYSCALL_WRITE
#endif

#ifdef _WIN32
#include <io.h>

#define ABSL_HAVE_RAW_IO …
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED …
#else
#undef ABSL_HAVE_RAW_IO
#endif

namespace absl {
ABSL_NAMESPACE_BEGIN
namespace raw_log_internal {
namespace {

// TODO(gfalcon): We want raw-logging to work on as many platforms as possible.
// Explicitly `#error` out when not `ABSL_LOW_LEVEL_WRITE_SUPPORTED`, except for
// a selected set of platforms for which we expect not to be able to raw log.

#ifdef ABSL_LOW_LEVEL_WRITE_SUPPORTED
constexpr char kTruncated[] = …;

// sprintf the format to the buffer, adjusting *buf and *size to reflect the
// consumed bytes, and return whether the message fit without truncation.  If
// truncation occurred, if possible leave room in the buffer for the message
// kTruncated[].
bool VADoRawLog(char** buf, int* size, const char* format, va_list ap)
    ABSL_PRINTF_ATTRIBUTE(3, 0);
bool VADoRawLog(char** buf, int* size, const char* format, va_list ap) { … }
#endif  // ABSL_LOW_LEVEL_WRITE_SUPPORTED

constexpr int kLogBufSize = …;

// CAVEAT: vsnprintf called from *DoRawLog below has some (exotic) code paths
// that invoke malloc() and getenv() that might acquire some locks.

// Helper for RawLog below.
// *DoRawLog writes to *buf of *size and move them past the written portion.
// It returns true iff there was no overflow or error.
bool DoRawLog(char** buf, int* size, const char* format, ...)
    ABSL_PRINTF_ATTRIBUTE(3, 4);
bool DoRawLog(char** buf, int* size, const char* format, ...) { … }

bool DefaultLogFilterAndPrefix(absl::LogSeverity, const char* file, int line,
                               char** buf, int* buf_size) { … }

ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
absl::base_internal::AtomicHook<LogFilterAndPrefixHook>
    log_filter_and_prefix_hook(DefaultLogFilterAndPrefix);
ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
absl::base_internal::AtomicHook<AbortHook> abort_hook;

void RawLogVA(absl::LogSeverity severity, const char* file, int line,
              const char* format, va_list ap) ABSL_PRINTF_ATTRIBUTE(4, 0);
void RawLogVA(absl::LogSeverity severity, const char* file, int line,
              const char* format, va_list ap) { … }

// Non-formatting version of RawLog().
//
// TODO(gfalcon): When string_view no longer depends on base, change this
// interface to take its message as a string_view instead.
void DefaultInternalLog(absl::LogSeverity severity, const char* file, int line,
                        const std::string& message) { … }

}  // namespace

void AsyncSignalSafeWriteError(const char* s, size_t len) { … }

void RawLog(absl::LogSeverity severity, const char* file, int line,
            const char* format, ...) { … }

bool RawLoggingFullySupported() { … }

ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL
    absl::base_internal::AtomicHook<InternalLogFunction>
        internal_log_function(DefaultInternalLog);

void RegisterLogFilterAndPrefixHook(LogFilterAndPrefixHook func) { … }

void RegisterAbortHook(AbortHook func) { … }

void RegisterInternalLogFunction(InternalLogFunction func) { … }

}  // namespace raw_log_internal
ABSL_NAMESPACE_END
}  // namespace absl
chromium/third_party/abseil-cpp/absl/base/internal/raw_logging.cc
