// 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 <stddef.h> 
#include <cstdarg> 
#include <cstdio> 
#include <cstdlib> 
#include <cstring> 
 
#include "absl/base/attributes.h" 
#include "absl/base/config.h" 
#include "absl/base/internal/atomic_hook.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(__Fuchsia__) || defined(__native_client__) || \ 
    defined(__EMSCRIPTEN__) || defined(__ASYLO__)

#include <unistd.h> 
 
#define ABSL_HAVE_POSIX_WRITE 1 
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED 1 
#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 1 
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED 1 
#else 
#undef ABSL_HAVE_SYSCALL_WRITE 
#endif 
 
#ifdef _WIN32 
#include <io.h> 
 
#define ABSL_HAVE_RAW_IO 1 
#define ABSL_LOW_LEVEL_WRITE_SUPPORTED 1 
#else 
#undef ABSL_HAVE_RAW_IO 
#endif 
 
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace raw_logging_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.
 
ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
    absl::base_internal::AtomicHook<LogPrefixHook>
        log_prefix_hook;
ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
    absl::base_internal::AtomicHook<AbortHook>
        abort_hook;
 
#ifdef ABSL_LOW_LEVEL_WRITE_SUPPORTED 
constexpr char kTruncated[] = " ... (message truncated)\n";
 
// 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) {
  int n = vsnprintf(*buf, *size, format, ap); 
  bool result = true; 
  if (n < 0 || n > *size) { 
    result = false; 
    if (static_cast<size_t>(*size) > sizeof(kTruncated)) { 
      n = *size - sizeof(kTruncated);  // room for truncation message 
    } else { 
      n = 0;  // no room for truncation message
    } 
  } 
  *size -= n; 
  *buf += n; 
  return result; 
} 
#endif  // ABSL_LOW_LEVEL_WRITE_SUPPORTED 
 
constexpr int kLogBufSize = 3000;
 
// 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, ...) { 
  va_list ap; 
  va_start(ap, format); 
  int n = vsnprintf(*buf, *size, format, ap); 
  va_end(ap); 
  if (n < 0 || n > *size) return false; 
  *size -= n; 
  *buf += n; 
  return true; 
} 
 
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) { 
  char buffer[kLogBufSize]; 
  char* buf = buffer; 
  int size = sizeof(buffer); 
#ifdef ABSL_LOW_LEVEL_WRITE_SUPPORTED 
  bool enabled = true; 
#else 
  bool enabled = false; 
#endif 
 
#ifdef ABSL_MIN_LOG_LEVEL 
  if (severity < static_cast<absl::LogSeverity>(ABSL_MIN_LOG_LEVEL) && 
      severity < absl::LogSeverity::kFatal) { 
    enabled = false; 
  } 
#endif 
 
  auto log_prefix_hook_ptr = log_prefix_hook.Load(); 
  if (log_prefix_hook_ptr) { 
    enabled = log_prefix_hook_ptr(severity, file, line, &buf, &size); 
  } else { 
    if (enabled) { 
      DoRawLog(&buf, &size, "[%s : %d] RAW: ", file, line); 
    } 
  } 
  const char* const prefix_end = buf; 
 
#ifdef ABSL_LOW_LEVEL_WRITE_SUPPORTED 
  if (enabled) { 
    bool no_chop = VADoRawLog(&buf, &size, format, ap); 
    if (no_chop) { 
      DoRawLog(&buf, &size, "\n"); 
    } else { 
      DoRawLog(&buf, &size, "%s", kTruncated); 
    } 
    SafeWriteToStderr(buffer, strlen(buffer));
  } 
#else 
  static_cast<void>(format); 
  static_cast<void>(ap); 
#endif 
 
  // Abort the process after logging a FATAL message, even if the output itself 
  // was suppressed. 
  if (severity == absl::LogSeverity::kFatal) { 
    abort_hook(file, line, buffer, prefix_end, buffer + kLogBufSize); 
    abort(); 
  } 
} 
 
// 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) {
  RawLog(severity, file, line, "%.*s", static_cast<int>(message.size()),
         message.data());
}

}  // namespace 
 
void SafeWriteToStderr(const char *s, size_t len) { 
#if defined(ABSL_HAVE_SYSCALL_WRITE) 
  syscall(SYS_write, STDERR_FILENO, s, len); 
#elif defined(ABSL_HAVE_POSIX_WRITE) 
  write(STDERR_FILENO, s, len); 
#elif defined(ABSL_HAVE_RAW_IO) 
  _write(/* stderr */ 2, s, len); 
#else 
  // stderr logging unsupported on this platform 
  (void) s; 
  (void) len; 
#endif 
} 
 
void RawLog(absl::LogSeverity severity, const char* file, int line, 
            const char* format, ...) { 
  va_list ap; 
  va_start(ap, format); 
  RawLogVA(severity, file, line, format, ap); 
  va_end(ap); 
} 
 
bool RawLoggingFullySupported() { 
#ifdef ABSL_LOW_LEVEL_WRITE_SUPPORTED 
  return true; 
#else  // !ABSL_LOW_LEVEL_WRITE_SUPPORTED 
  return false; 
#endif  // !ABSL_LOW_LEVEL_WRITE_SUPPORTED 
} 
 
ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES ABSL_DLL
    absl::base_internal::AtomicHook<InternalLogFunction>
        internal_log_function(DefaultInternalLog);
 
void RegisterLogPrefixHook(LogPrefixHook func) { log_prefix_hook.Store(func); }

void RegisterAbortHook(AbortHook func) { abort_hook.Store(func); }

void RegisterInternalLogFunction(InternalLogFunction func) { 
  internal_log_function.Store(func); 
} 
 
}  // namespace raw_logging_internal 
ABSL_NAMESPACE_END
}  // namespace absl