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//
// Copyright 2022 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/log/internal/log_format.h"
#include <string.h>
#ifdef _MSC_VER
#include <winsock2.h> // For timeval
#else
#include <sys/time.h>
#endif
#include <cstddef>
#include <cstdint>
#include <limits>
#include <string>
#include <type_traits>
#include "absl/base/config.h"
#include "absl/base/log_severity.h"
#include "absl/base/optimization.h"
#include "absl/log/internal/config.h"
#include "absl/log/internal/globals.h"
#include "absl/strings/numbers.h"
#include "absl/strings/str_format.h"
#include "absl/strings/string_view.h"
#include "absl/time/civil_time.h"
#include "absl/time/time.h"
#include "absl/types/span.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace log_internal {
namespace {
// This templated function avoids compiler warnings about tautological
// comparisons when log_internal::Tid is unsigned. It can be replaced with a
// constexpr if once the minimum C++ version Abseil suppports is C++17.
template <typename T>
inline std::enable_if_t<!std::is_signed<T>::value>
PutLeadingWhitespace(T tid, char*& p) {
if (tid < 10) *p++ = ' ';
if (tid < 100) *p++ = ' ';
if (tid < 1000) *p++ = ' ';
if (tid < 10000) *p++ = ' ';
if (tid < 100000) *p++ = ' ';
if (tid < 1000000) *p++ = ' ';
}
template <typename T>
inline std::enable_if_t<std::is_signed<T>::value>
PutLeadingWhitespace(T tid, char*& p) {
if (tid >= 0 && tid < 10) *p++ = ' ';
if (tid > -10 && tid < 100) *p++ = ' ';
if (tid > -100 && tid < 1000) *p++ = ' ';
if (tid > -1000 && tid < 10000) *p++ = ' ';
if (tid > -10000 && tid < 100000) *p++ = ' ';
if (tid > -100000 && tid < 1000000) *p++ = ' ';
}
// The fields before the filename are all fixed-width except for the thread ID,
// which is of bounded width.
size_t FormatBoundedFields(absl::LogSeverity severity, absl::Time timestamp,
log_internal::Tid tid, absl::Span<char>& buf) {
constexpr size_t kBoundedFieldsMaxLen =
sizeof("SMMDD HH:MM:SS.NNNNNN ") +
(1 + std::numeric_limits<log_internal::Tid>::digits10 + 1) - sizeof("");
if (ABSL_PREDICT_FALSE(buf.size() < kBoundedFieldsMaxLen)) {
// We don't bother trying to truncate these fields if the buffer is too
// short (or almost too short) because it would require doing a lot more
// length checking (slow) and it should never happen. A 15kB buffer should
// be enough for anyone. Instead we mark `buf` full without writing
// anything.
buf.remove_suffix(buf.size());
return 0;
}
// We can't call absl::LocalTime(), localtime_r(), or anything else here that
// isn't async-signal-safe. We can only use the time zone if it has already
// been loaded.
const absl::TimeZone* tz = absl::log_internal::TimeZone();
if (ABSL_PREDICT_FALSE(tz == nullptr)) {
// If a time zone hasn't been set yet because we are logging before the
// logging library has been initialized, we fallback to a simpler, slower
// method. Just report the raw Unix time in seconds. We cram this into the
// normal time format for the benefit of parsers.
auto tv = absl::ToTimeval(timestamp);
int snprintf_result = absl::SNPrintF(
buf.data(), buf.size(), "%c0000 00:00:%02d.%06d %7d ",
absl::LogSeverityName(severity)[0], static_cast<int>(tv.tv_sec),
static_cast<int>(tv.tv_usec), static_cast<int>(tid));
if (snprintf_result >= 0) {
buf.remove_prefix(static_cast<size_t>(snprintf_result));
return static_cast<size_t>(snprintf_result);
}
return 0;
}
char* p = buf.data();
*p++ = absl::LogSeverityName(severity)[0];
const absl::TimeZone::CivilInfo ci = tz->At(timestamp);
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(ci.cs.month()), p);
p += 2;
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(ci.cs.day()), p);
p += 2;
*p++ = ' ';
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(ci.cs.hour()), p);
p += 2;
*p++ = ':';
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(ci.cs.minute()), p);
p += 2;
*p++ = ':';
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(ci.cs.second()), p);
p += 2;
*p++ = '.';
const int64_t usecs = absl::ToInt64Microseconds(ci.subsecond);
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(usecs / 10000), p);
p += 2;
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(usecs / 100 % 100),
p);
p += 2;
absl::numbers_internal::PutTwoDigits(static_cast<size_t>(usecs % 100), p);
p += 2;
*p++ = ' ';
PutLeadingWhitespace(tid, p);
p = absl::numbers_internal::FastIntToBuffer(tid, p);
*p++ = ' ';
const size_t bytes_formatted = static_cast<size_t>(p - buf.data());
buf.remove_prefix(bytes_formatted);
return bytes_formatted;
}
// Copies into `dst` as many bytes of `src` as will fit, then advances `dst`
// past the copied bytes and returns the number of bytes written.
size_t AppendTruncated(absl::string_view src, absl::Span<char>& dst) {
if (src.size() > dst.size()) src = src.substr(0, dst.size());
memcpy(dst.data(), src.data(), src.size());
dst.remove_prefix(src.size());
return src.size();
}
size_t FormatLineNumber(int line, absl::Span<char>& buf) {
constexpr size_t kLineFieldMaxLen =
sizeof(":] ") + (1 + std::numeric_limits<int>::digits10 + 1) - sizeof("");
if (ABSL_PREDICT_FALSE(buf.size() < kLineFieldMaxLen)) {
// As above, we don't bother trying to truncate this if the buffer is too
// short and it should never happen.
buf.remove_suffix(buf.size());
return 0;
}
char* p = buf.data();
*p++ = ':';
p = absl::numbers_internal::FastIntToBuffer(line, p);
*p++ = ']';
*p++ = ' ';
const size_t bytes_formatted = static_cast<size_t>(p - buf.data());
buf.remove_prefix(bytes_formatted);
return bytes_formatted;
}
} // namespace
std::string FormatLogMessage(absl::LogSeverity severity,
absl::CivilSecond civil_second,
absl::Duration subsecond, log_internal::Tid tid,
absl::string_view basename, int line,
absl::string_view message) {
return absl::StrFormat(
"%c%02d%02d %02d:%02d:%02d.%06d %7d %s:%d] %s",
absl::LogSeverityName(severity)[0], civil_second.month(),
civil_second.day(), civil_second.hour(), civil_second.minute(),
civil_second.second(), absl::ToInt64Microseconds(subsecond), tid,
basename, line, message);
}
// This method is fairly hot, and the library always passes a huge `buf`, so we
// save some bounds-checking cycles by not trying to do precise truncation.
// Truncating at a field boundary is probably a better UX anyway.
//
// The prefix is written in three parts, each of which does a single
// bounds-check and truncation:
// 1. severity, timestamp, and thread ID
// 2. filename
// 3. line number and bracket
size_t FormatLogPrefix(absl::LogSeverity severity, absl::Time timestamp,
log_internal::Tid tid, absl::string_view basename,
int line, absl::Span<char>& buf) {
auto prefix_size = FormatBoundedFields(severity, timestamp, tid, buf);
prefix_size += AppendTruncated(basename, buf);
prefix_size += FormatLineNumber(line, buf);
return prefix_size;
}
} // namespace log_internal
ABSL_NAMESPACE_END
} // namespace absl
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