src/lib/diagnostics/accessor2logger/log_message.cc - fuchsia - Git at Google

 // Copyright 2020 The Fuchsia Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 #include <lib/syslog/cpp/macros.h>
 #include <lib/zx/stream.h>
 #include <lib/zx/vmo.h>
 #include <zircon/types.h>

 #include <sstream>

 #include <rapidjson/document.h>
 #include <rapidjson/error/en.h>
 #include <rapidjson/pointer.h>
 #include <src/lib/diagnostics/accessor2logger/log_message.h>
 #include <src/lib/fsl/vmo/strings.h>

 using fuchsia::diagnostics::FormattedContent;
 using fuchsia::logger::LogMessage;

 namespace diagnostics::accessor2logger {

 namespace {
 const char kPidLabel[] = "pid";
 const char kTidLabel[] = "tid";
 const char kFileLabel[] = "file";
 const char kLineLabel[] = "line";
 const char kTagsLabel[] = "tags";
 const char kMessageLabel[] = "value";
 const char kVerbosityLabel[] = "verbosity";

 inline fuchsia::logger::LogLevelFilter StringToSeverity(const std::string& input) {
   if (strcasecmp(input.c_str(), "trace") == 0) {
     return fuchsia::logger::LogLevelFilter::TRACE;
   }
   if (strcasecmp(input.c_str(), "debug") == 0) {
     return fuchsia::logger::LogLevelFilter::DEBUG;
   }
   if (strcasecmp(input.c_str(), "info") == 0) {
     return fuchsia::logger::LogLevelFilter::INFO;
   }
   if (strcasecmp(input.c_str(), "warn") == 0) {
     return fuchsia::logger::LogLevelFilter::WARN;
   }
   if (strcasecmp(input.c_str(), "error") == 0) {
     return fuchsia::logger::LogLevelFilter::ERROR;
   }
   if (strcasecmp(input.c_str(), "fatal") == 0) {
     return fuchsia::logger::LogLevelFilter::FATAL;
   }

   return fuchsia::logger::LOG_LEVEL_DEFAULT;
 }

 inline fpromise::result<LogMessage, std::string> JsonToHostLogMessage(rapidjson::Value& value) {
   LogMessage ret = {};
   std::stringstream kv_mapping;

   if (!value.IsObject()) {
     return fpromise::error("Value is not an object");
   }

   auto metadata = value.FindMember("metadata");
   auto payload = value.FindMember("payload");

   if (metadata == value.MemberEnd() || payload == value.MemberEnd() ||
       !metadata->value.IsObject() || !payload->value.IsObject()) {
     return fpromise::error("Expected metadata and payload objects");
   }
   auto root = payload->value.FindMember("root");
   if (!root->value.IsObject()) {
     return fpromise::error("Expected payload.root to be an object if present");
   }

   auto timestamp = metadata->value.FindMember("timestamp");
   if (timestamp == metadata->value.MemberEnd() || !timestamp->value.IsUint64()) {
     return fpromise::error("Expected metadata.timestamp key");
   }
   ret.time = timestamp->value.GetUint64();

   auto severity = metadata->value.FindMember("severity");
   if (severity == metadata->value.MemberEnd() || !severity->value.IsString()) {
     return fpromise::error("Expected metadata.severity key");
   }
   ret.severity = static_cast<int32_t>(StringToSeverity(severity->value.GetString()));

   auto moniker = value.FindMember("moniker");
   std::string moniker_string;
   if (moniker != value.MemberEnd() && moniker->value.IsString()) {
     moniker_string = std::move(moniker->value.GetString());
   }

   uint32_t dropped_logs = 0;
   if (metadata->value.HasMember("errors")) {
     auto& errors = metadata->value["errors"];
     if (errors.IsArray()) {
       for (rapidjson::SizeType i = 0; i < errors.Size(); i++) {
         auto* val = rapidjson::Pointer("/dropped_logs/count").Get(errors[i]);
         if (val && val->IsUint()) {
           dropped_logs += val->GetUint();
         }
       }
     }
   }

   // Flatten payloads containing a "root" node.
   // TODO(fxbug.dev/63409): Remove this when "root" is omitted from logs.
   if (payload->value.MemberCount() == 1 && payload->value.HasMember("root")) {
     payload = payload->value.FindMember("root");
     if (!payload->value.IsObject()) {
       return fpromise::error("Expected payload.root to be an object if present");
     }
     payload = payload->value.FindMember("message");
     if (!payload->value.IsObject()) {
       return fpromise::error("Expected payload.root.message to be an object if present");
     }
   }
   std::string msg;
   std::string filename;
   std::optional<int> verbosity;
   std::optional<int> line_number;

   for (auto it = payload->value.MemberBegin(); it != payload->value.MemberEnd(); ++it) {
     if (!it->name.IsString()) {
       return fpromise::error("A key is not a string");
     }
     std::string name = it->name.GetString();
     if (name == kMessageLabel && it->value.IsString()) {
       msg = std::move(it->value.GetString());
     }
     if ((name == kVerbosityLabel) && it->value.IsInt()) {
       verbosity = it->value.GetInt();
       if (ret.severity != verbosity.value_or(ret.severity)) {
         ret.severity = GetSeverityFromVerbosity(static_cast<uint8_t>(verbosity.value()));
       }
     }
   }

   for (auto it = metadata->value.MemberBegin(); it != metadata->value.MemberEnd(); ++it) {
     if (!it->name.IsString()) {
       return fpromise::error("A key is not a string");
     }
     std::string name = it->name.GetString();
     if (name == kTagsLabel) {
       if (it->value.IsString()) {
         ret.tags.emplace_back(std::move(it->value.GetString()));
       } else if (it->value.IsArray()) {
         for (rapidjson::SizeType i = 0; i < it->value.Size(); ++i) {
           auto& val = it->value[i];
           if (!val.IsString()) {
             return fpromise::error("Tags array must contain strings");
           }
           ret.tags.emplace_back(std::move(val.GetString()));
         }
       } else {
         return fpromise::error("Tags must be a string or array of strings");
       }
     } else if (name == kTidLabel && it->value.IsUint64()) {
       ret.tid = it->value.GetUint64();
     } else if (name == kPidLabel && it->value.IsUint64()) {
       ret.pid = it->value.GetUint64();
     } else if (name == kFileLabel && it->value.IsString()) {
       filename = it->value.GetString();
     } else if (name == kLineLabel && it->value.IsUint64()) {
       line_number = it->value.GetUint64();
     }
   }

   auto kvps = root->value.FindMember("keys");

   if ((kvps != root->value.MemberEnd()) && kvps->value.IsObject() && (kvps->name == "keys")) {
     for (auto it = kvps->value.MemberBegin(); it != kvps->value.MemberEnd(); ++it) {
       if (!it->name.IsString()) {
         return fpromise::error("A key is not a string");
       }
       std::string name = it->name.GetString();
       // If the name of the field is not a known special field, treat it as a key/value pair and
       // append to the message.
       kv_mapping << " " << std::move(name) << "=";
       if (it->value.IsInt64()) {
         kv_mapping << it->value.GetInt64();
       } else if (it->value.IsUint64()) {
         kv_mapping << it->value.GetUint64();
       } else if (it->value.IsDouble()) {
         kv_mapping << std::to_string(it->value.GetDouble());
       } else if (it->value.IsString()) {
         kv_mapping << "\"";
         auto str_value = it->value.GetString();
         if (strchr(str_value, '"') != nullptr) {
           // Escape quotes in strings per host encoding.
           size_t len = strlen(str_value);
           for (size_t i = 0; i < len; ++i) {
             char c = str_value[i];
             if (c == '"') {
               kv_mapping << '\\';
             }
             kv_mapping << c;
           }
         } else {
           kv_mapping << std::move(it->value.GetString());
         }
         kv_mapping << "\"";
       } else {
         kv_mapping << "<unknown>";
       }
     }
   }

   if (!filename.empty() && line_number.has_value()) {
     std::stringstream enc;
     enc << "[" << filename << "(" << line_number.value() << ")] ";
     ret.msg = enc.str();
   }
   ret.msg += msg;
   bool needs_add = true;

   if (!ret.msg.empty()) {
     if (ret.msg[ret.msg.size() - 1] == ' ') {
       std::string truncated = kv_mapping.str();
       truncated.erase(0, 1);
       ret.msg += truncated;
       needs_add = false;
     }
   }

   if (needs_add) {
     ret.msg += kv_mapping.str();
   }

   // If there are no tags, automatically tag with the component moniker.
   if (ret.tags.size() == 0 && !moniker_string.empty()) {
     ret.tags.emplace_back(std::move(moniker_string));
   }

   if (dropped_logs > 0) {
     ret.dropped_logs = dropped_logs;
   }

   return fpromise::ok(std::move(ret));
 }

 inline fpromise::result<LogMessage, std::string> JsonToLogMessage(rapidjson::Value& value) {
   LogMessage ret = {};
   std::stringstream kv_mapping;

   if (!value.IsObject()) {
     return fpromise::error("Value is not an object");
   }

   auto metadata = value.FindMember("metadata");
   auto payload = value.FindMember("payload");

   if (metadata == value.MemberEnd() || payload == value.MemberEnd() ||
       !metadata->value.IsObject() || !payload->value.IsObject()) {
     return fpromise::error("Expected metadata and payload objects");
   }
   auto root = payload->value.FindMember("root");
   if (!root->value.IsObject()) {
     return fpromise::error("Expected payload.root to be an object if present");
   }

   auto timestamp = metadata->value.FindMember("timestamp");
   if (timestamp == metadata->value.MemberEnd() || !timestamp->value.IsUint64()) {
     return fpromise::error("Expected metadata.timestamp key");
   }
   ret.time = timestamp->value.GetUint64();

   auto severity = metadata->value.FindMember("severity");
   if (severity == metadata->value.MemberEnd() || !severity->value.IsString()) {
     return fpromise::error("Expected metadata.severity key");
   }
   ret.severity = static_cast<int32_t>(StringToSeverity(severity->value.GetString()));

   auto moniker = value.FindMember("moniker");
   std::string moniker_string;
   if (moniker != value.MemberEnd() && moniker->value.IsString()) {
     moniker_string = std::move(moniker->value.GetString());
   }

   uint32_t dropped_logs = 0;
   if (metadata->value.HasMember("errors")) {
     auto& errors = metadata->value["errors"];
     if (errors.IsArray()) {
       for (rapidjson::SizeType i = 0; i < errors.Size(); i++) {
         auto* val = rapidjson::Pointer("/dropped_logs/count").Get(errors[i]);
         if (val && val->IsUint()) {
           dropped_logs += val->GetUint();
         }
       }
     }
   }

   // Flatten payloads containing a "root" node.
   // TODO(fxbug.dev/63409): Remove this when "root" is omitted from logs.
   if (payload->value.MemberCount() == 1 && payload->value.HasMember("root")) {
     payload = payload->value.FindMember("root");
     if (!payload->value.IsObject()) {
       return fpromise::error("Expected payload.root to be an object if present");
     }
     payload = payload->value.FindMember("message");
     if (!payload->value.IsObject()) {
       return fpromise::error("Expected payload.root.message to be an object if present");
     }
   }
   std::string msg;
   std::string filename;
   std::optional<int> line_number;
   for (auto it = payload->value.MemberBegin(); it != payload->value.MemberEnd(); ++it) {
     if (!it->name.IsString()) {
       return fpromise::error("A key is not a string");
     }
     std::string name = it->name.GetString();
     if (name == kMessageLabel && it->value.IsString()) {
       msg = std::move(it->value.GetString());
     }
   }
   for (auto it = metadata->value.MemberBegin(); it != metadata->value.MemberEnd(); ++it) {
     if (!it->name.IsString()) {
       return fpromise::error("A key is not a string");
     }
     std::string name = it->name.GetString();
     if (name == kTagsLabel) {
       if (it->value.IsString()) {
         ret.tags.emplace_back(std::move(it->value.GetString()));
       } else if (it->value.IsArray()) {
         for (rapidjson::SizeType i = 0; i < it->value.Size(); ++i) {
           auto& val = it->value[i];
           if (!val.IsString()) {
             return fpromise::error("Tags array must contain strings");
           }
           ret.tags.emplace_back(std::move(val.GetString()));
         }
       } else {
         return fpromise::error("Tags must be a string or array of strings");
       }
     } else if (name == kTidLabel && it->value.IsUint64()) {
       ret.tid = it->value.GetUint64();
     } else if (name == kPidLabel && it->value.IsUint64()) {
       ret.pid = it->value.GetUint64();
     } else if (name == kFileLabel && it->value.IsString()) {
       filename = it->value.GetString();
     } else if (name == kLineLabel && it->value.IsUint64()) {
       line_number = it->value.GetUint64();
     }
   }
   auto kvps = root->value.FindMember("keys");
   if ((kvps != root->value.MemberEnd()) && kvps->value.IsObject() && (kvps->name == "keys")) {
     for (auto it = kvps->value.MemberBegin(); it != kvps->value.MemberEnd(); ++it) {
       if (!it->name.IsString()) {
         return fpromise::error("A key is not a string");
       }
       std::string name = it->name.GetString();
       // If the name of the field is not a known special field, treat it as a key/value pair and
       // append to the message.
       kv_mapping << " " << std::move(name) << "=";
       if (it->value.IsInt64()) {
         kv_mapping << it->value.GetInt64();
       } else if (it->value.IsUint64()) {
         kv_mapping << it->value.GetUint64();
       } else if (it->value.IsDouble()) {
         kv_mapping << it->value.GetDouble();
       } else if (it->value.IsString()) {
         kv_mapping << std::move(it->value.GetString());
       } else {
         kv_mapping << "<unknown>";
       }
     }
   }
   if (!filename.empty() && line_number.has_value()) {
     std::stringstream enc;
     enc << "[" << filename << "(" << line_number.value() << ")] ";
     ret.msg = enc.str();
   }
   ret.msg += msg;
   ret.msg += kv_mapping.str();

   // If there are no tags, automatically tag with the component moniker.
   if (ret.tags.size() == 0 && !moniker_string.empty()) {
     ret.tags.emplace_back(std::move(moniker_string));
   }

   if (dropped_logs > 0) {
     ret.dropped_logs = dropped_logs;
   }

   return fpromise::ok(std::move(ret));
 }
 }  // namespace

 fpromise::result<std::vector<fpromise::result<fuchsia::logger::LogMessage, std::string>>,
                  std::string>
 ConvertFormattedContentToLogMessages(FormattedContent content) {
   std::vector<fpromise::result<LogMessage, std::string>> output;

   if (!content.is_json()) {
     // Expecting JSON in all cases.
     return fpromise::error("Expected json content");
   }

   std::string data;
   if (!fsl::StringFromVmo(content.json(), &data)) {
     return fpromise::error("Failed to read string from VMO");
   }
   content.json().vmo.reset();

   rapidjson::Document d;
   d.Parse(std::move(data));
   if (d.HasParseError()) {
     std::string error = "Failed to parse content as JSON. Offset " +
                         std::to_string(d.GetErrorOffset()) + ": " +
                         rapidjson::GetParseError_En(d.GetParseError());
     return fpromise::error(std::move(error));
   }

   if (!d.IsArray()) {
     return fpromise::error("Expected content to contain an array");
   }

   for (rapidjson::SizeType i = 0; i < d.Size(); ++i) {
     output.emplace_back(JsonToLogMessage(d[i]));
   }

   return fpromise::ok(std::move(output));
 }

 fpromise::result<std::vector<fpromise::result<fuchsia::logger::LogMessage, std::string>>,
                  std::string>
 ConvertFormattedContentToHostLogMessages(FormattedContent content) {
   std::vector<fpromise::result<LogMessage, std::string>> output;

   if (!content.is_json()) {
     // Expecting JSON in all cases.
     return fpromise::error("Expected json content");
   }

   std::string data;
   if (!fsl::StringFromVmo(content.json(), &data)) {
     return fpromise::error("Failed to read string from VMO");
   }
   content.json().vmo.reset();

   rapidjson::Document d;
   d.Parse(std::move(data));
   if (d.HasParseError()) {
     std::string error = "Failed to parse content as JSON. Offset " +
                         std::to_string(d.GetErrorOffset()) + ": " +
                         rapidjson::GetParseError_En(d.GetParseError());
     return fpromise::error(std::move(error));
   }

   if (!d.IsArray()) {
     return fpromise::error("Expected content to contain an array");
   }

   for (rapidjson::SizeType i = 0; i < d.Size(); ++i) {
     output.emplace_back(JsonToHostLogMessage(d[i]));
   }

   return fpromise::ok(std::move(output));
 }

 }  // namespace diagnostics::accessor2logger
	// Copyright 2020 The Fuchsia Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	#include <lib/syslog/cpp/macros.h>
	#include <lib/zx/stream.h>
	#include <lib/zx/vmo.h>
	#include <zircon/types.h>

	#include <sstream>

	#include <rapidjson/document.h>
	#include <rapidjson/error/en.h>
	#include <rapidjson/pointer.h>
	#include <src/lib/diagnostics/accessor2logger/log_message.h>
	#include <src/lib/fsl/vmo/strings.h>

	using fuchsia::diagnostics::FormattedContent;
	using fuchsia::logger::LogMessage;

	namespace diagnostics::accessor2logger {

	namespace {
	const char kPidLabel[] = "pid";
	const char kTidLabel[] = "tid";
	const char kFileLabel[] = "file";
	const char kLineLabel[] = "line";
	const char kTagsLabel[] = "tags";
	const char kMessageLabel[] = "value";
	const char kVerbosityLabel[] = "verbosity";

	inline fuchsia::logger::LogLevelFilter StringToSeverity(const std::string& input) {
	if (strcasecmp(input.c_str(), "trace") == 0) {
	return fuchsia::logger::LogLevelFilter::TRACE;
	}
	if (strcasecmp(input.c_str(), "debug") == 0) {
	return fuchsia::logger::LogLevelFilter::DEBUG;
	}
	if (strcasecmp(input.c_str(), "info") == 0) {
	return fuchsia::logger::LogLevelFilter::INFO;
	}
	if (strcasecmp(input.c_str(), "warn") == 0) {
	return fuchsia::logger::LogLevelFilter::WARN;
	}
	if (strcasecmp(input.c_str(), "error") == 0) {
	return fuchsia::logger::LogLevelFilter::ERROR;
	}
	if (strcasecmp(input.c_str(), "fatal") == 0) {
	return fuchsia::logger::LogLevelFilter::FATAL;
	}

	return fuchsia::logger::LOG_LEVEL_DEFAULT;
	}

	inline fpromise::result<LogMessage, std::string> JsonToHostLogMessage(rapidjson::Value& value) {
	LogMessage ret = {};
	std::stringstream kv_mapping;

	if (!value.IsObject()) {
	return fpromise::error("Value is not an object");
	}

	auto metadata = value.FindMember("metadata");
	auto payload = value.FindMember("payload");

	if (metadata == value.MemberEnd() \|\| payload == value.MemberEnd() \|\|
	!metadata->value.IsObject() \|\| !payload->value.IsObject()) {
	return fpromise::error("Expected metadata and payload objects");
	}
	auto root = payload->value.FindMember("root");
	if (!root->value.IsObject()) {
	return fpromise::error("Expected payload.root to be an object if present");
	}

	auto timestamp = metadata->value.FindMember("timestamp");
	if (timestamp == metadata->value.MemberEnd() \|\| !timestamp->value.IsUint64()) {
	return fpromise::error("Expected metadata.timestamp key");
	}
	ret.time = timestamp->value.GetUint64();

	auto severity = metadata->value.FindMember("severity");
	if (severity == metadata->value.MemberEnd() \|\| !severity->value.IsString()) {
	return fpromise::error("Expected metadata.severity key");
	}
	ret.severity = static_cast<int32_t>(StringToSeverity(severity->value.GetString()));

	auto moniker = value.FindMember("moniker");
	std::string moniker_string;
	if (moniker != value.MemberEnd() && moniker->value.IsString()) {
	moniker_string = std::move(moniker->value.GetString());
	}

	uint32_t dropped_logs = 0;
	if (metadata->value.HasMember("errors")) {
	auto& errors = metadata->value["errors"];
	if (errors.IsArray()) {
	for (rapidjson::SizeType i = 0; i < errors.Size(); i++) {
	auto* val = rapidjson::Pointer("/dropped_logs/count").Get(errors[i]);
	if (val && val->IsUint()) {
	dropped_logs += val->GetUint();
	}
	}
	}
	}

	// Flatten payloads containing a "root" node.
	// TODO(fxbug.dev/63409): Remove this when "root" is omitted from logs.
	if (payload->value.MemberCount() == 1 && payload->value.HasMember("root")) {
	payload = payload->value.FindMember("root");
	if (!payload->value.IsObject()) {
	return fpromise::error("Expected payload.root to be an object if present");
	}
	payload = payload->value.FindMember("message");
	if (!payload->value.IsObject()) {
	return fpromise::error("Expected payload.root.message to be an object if present");
	}
	}
	std::string msg;
	std::string filename;
	std::optional<int> verbosity;
	std::optional<int> line_number;

	for (auto it = payload->value.MemberBegin(); it != payload->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	if (name == kMessageLabel && it->value.IsString()) {
	msg = std::move(it->value.GetString());
	}
	if ((name == kVerbosityLabel) && it->value.IsInt()) {
	verbosity = it->value.GetInt();
	if (ret.severity != verbosity.value_or(ret.severity)) {
	ret.severity = GetSeverityFromVerbosity(static_cast<uint8_t>(verbosity.value()));
	}
	}
	}

	for (auto it = metadata->value.MemberBegin(); it != metadata->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	if (name == kTagsLabel) {
	if (it->value.IsString()) {
	ret.tags.emplace_back(std::move(it->value.GetString()));
	} else if (it->value.IsArray()) {
	for (rapidjson::SizeType i = 0; i < it->value.Size(); ++i) {
	auto& val = it->value[i];
	if (!val.IsString()) {
	return fpromise::error("Tags array must contain strings");
	}
	ret.tags.emplace_back(std::move(val.GetString()));
	}
	} else {
	return fpromise::error("Tags must be a string or array of strings");
	}
	} else if (name == kTidLabel && it->value.IsUint64()) {
	ret.tid = it->value.GetUint64();
	} else if (name == kPidLabel && it->value.IsUint64()) {
	ret.pid = it->value.GetUint64();
	} else if (name == kFileLabel && it->value.IsString()) {
	filename = it->value.GetString();
	} else if (name == kLineLabel && it->value.IsUint64()) {
	line_number = it->value.GetUint64();
	}
	}

	auto kvps = root->value.FindMember("keys");

	if ((kvps != root->value.MemberEnd()) && kvps->value.IsObject() && (kvps->name == "keys")) {
	for (auto it = kvps->value.MemberBegin(); it != kvps->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	// If the name of the field is not a known special field, treat it as a key/value pair and
	// append to the message.
	kv_mapping << " " << std::move(name) << "=";
	if (it->value.IsInt64()) {
	kv_mapping << it->value.GetInt64();
	} else if (it->value.IsUint64()) {
	kv_mapping << it->value.GetUint64();
	} else if (it->value.IsDouble()) {
	kv_mapping << std::to_string(it->value.GetDouble());
	} else if (it->value.IsString()) {
	kv_mapping << "\"";
	auto str_value = it->value.GetString();
	if (strchr(str_value, '"') != nullptr) {
	// Escape quotes in strings per host encoding.
	size_t len = strlen(str_value);
	for (size_t i = 0; i < len; ++i) {
	char c = str_value[i];
	if (c == '"') {
	kv_mapping << '\\';
	}
	kv_mapping << c;
	}
	} else {
	kv_mapping << std::move(it->value.GetString());
	}
	kv_mapping << "\"";
	} else {
	kv_mapping << "<unknown>";
	}
	}
	}

	if (!filename.empty() && line_number.has_value()) {
	std::stringstream enc;
	enc << "[" << filename << "(" << line_number.value() << ")] ";
	ret.msg = enc.str();
	}
	ret.msg += msg;
	bool needs_add = true;

	if (!ret.msg.empty()) {
	if (ret.msg[ret.msg.size() - 1] == ' ') {
	std::string truncated = kv_mapping.str();
	truncated.erase(0, 1);
	ret.msg += truncated;
	needs_add = false;
	}
	}

	if (needs_add) {
	ret.msg += kv_mapping.str();
	}

	// If there are no tags, automatically tag with the component moniker.
	if (ret.tags.size() == 0 && !moniker_string.empty()) {
	ret.tags.emplace_back(std::move(moniker_string));
	}

	if (dropped_logs > 0) {
	ret.dropped_logs = dropped_logs;
	}

	return fpromise::ok(std::move(ret));
	}

	inline fpromise::result<LogMessage, std::string> JsonToLogMessage(rapidjson::Value& value) {
	LogMessage ret = {};
	std::stringstream kv_mapping;

	if (!value.IsObject()) {
	return fpromise::error("Value is not an object");
	}

	auto metadata = value.FindMember("metadata");
	auto payload = value.FindMember("payload");

	if (metadata == value.MemberEnd() \|\| payload == value.MemberEnd() \|\|
	!metadata->value.IsObject() \|\| !payload->value.IsObject()) {
	return fpromise::error("Expected metadata and payload objects");
	}
	auto root = payload->value.FindMember("root");
	if (!root->value.IsObject()) {
	return fpromise::error("Expected payload.root to be an object if present");
	}

	auto timestamp = metadata->value.FindMember("timestamp");
	if (timestamp == metadata->value.MemberEnd() \|\| !timestamp->value.IsUint64()) {
	return fpromise::error("Expected metadata.timestamp key");
	}
	ret.time = timestamp->value.GetUint64();

	auto severity = metadata->value.FindMember("severity");
	if (severity == metadata->value.MemberEnd() \|\| !severity->value.IsString()) {
	return fpromise::error("Expected metadata.severity key");
	}
	ret.severity = static_cast<int32_t>(StringToSeverity(severity->value.GetString()));

	auto moniker = value.FindMember("moniker");
	std::string moniker_string;
	if (moniker != value.MemberEnd() && moniker->value.IsString()) {
	moniker_string = std::move(moniker->value.GetString());
	}

	uint32_t dropped_logs = 0;
	if (metadata->value.HasMember("errors")) {
	auto& errors = metadata->value["errors"];
	if (errors.IsArray()) {
	for (rapidjson::SizeType i = 0; i < errors.Size(); i++) {
	auto* val = rapidjson::Pointer("/dropped_logs/count").Get(errors[i]);
	if (val && val->IsUint()) {
	dropped_logs += val->GetUint();
	}
	}
	}
	}

	// Flatten payloads containing a "root" node.
	// TODO(fxbug.dev/63409): Remove this when "root" is omitted from logs.
	if (payload->value.MemberCount() == 1 && payload->value.HasMember("root")) {
	payload = payload->value.FindMember("root");
	if (!payload->value.IsObject()) {
	return fpromise::error("Expected payload.root to be an object if present");
	}
	payload = payload->value.FindMember("message");
	if (!payload->value.IsObject()) {
	return fpromise::error("Expected payload.root.message to be an object if present");
	}
	}
	std::string msg;
	std::string filename;
	std::optional<int> line_number;
	for (auto it = payload->value.MemberBegin(); it != payload->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	if (name == kMessageLabel && it->value.IsString()) {
	msg = std::move(it->value.GetString());
	}
	}
	for (auto it = metadata->value.MemberBegin(); it != metadata->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	if (name == kTagsLabel) {
	if (it->value.IsString()) {
	ret.tags.emplace_back(std::move(it->value.GetString()));
	} else if (it->value.IsArray()) {
	for (rapidjson::SizeType i = 0; i < it->value.Size(); ++i) {
	auto& val = it->value[i];
	if (!val.IsString()) {
	return fpromise::error("Tags array must contain strings");
	}
	ret.tags.emplace_back(std::move(val.GetString()));
	}
	} else {
	return fpromise::error("Tags must be a string or array of strings");
	}
	} else if (name == kTidLabel && it->value.IsUint64()) {
	ret.tid = it->value.GetUint64();
	} else if (name == kPidLabel && it->value.IsUint64()) {
	ret.pid = it->value.GetUint64();
	} else if (name == kFileLabel && it->value.IsString()) {
	filename = it->value.GetString();
	} else if (name == kLineLabel && it->value.IsUint64()) {
	line_number = it->value.GetUint64();
	}
	}
	auto kvps = root->value.FindMember("keys");
	if ((kvps != root->value.MemberEnd()) && kvps->value.IsObject() && (kvps->name == "keys")) {
	for (auto it = kvps->value.MemberBegin(); it != kvps->value.MemberEnd(); ++it) {
	if (!it->name.IsString()) {
	return fpromise::error("A key is not a string");
	}
	std::string name = it->name.GetString();
	// If the name of the field is not a known special field, treat it as a key/value pair and
	// append to the message.
	kv_mapping << " " << std::move(name) << "=";
	if (it->value.IsInt64()) {
	kv_mapping << it->value.GetInt64();
	} else if (it->value.IsUint64()) {
	kv_mapping << it->value.GetUint64();
	} else if (it->value.IsDouble()) {
	kv_mapping << it->value.GetDouble();
	} else if (it->value.IsString()) {
	kv_mapping << std::move(it->value.GetString());
	} else {
	kv_mapping << "<unknown>";
	}
	}
	}
	if (!filename.empty() && line_number.has_value()) {
	std::stringstream enc;
	enc << "[" << filename << "(" << line_number.value() << ")] ";
	ret.msg = enc.str();
	}
	ret.msg += msg;
	ret.msg += kv_mapping.str();

	// If there are no tags, automatically tag with the component moniker.
	if (ret.tags.size() == 0 && !moniker_string.empty()) {
	ret.tags.emplace_back(std::move(moniker_string));
	}

	if (dropped_logs > 0) {
	ret.dropped_logs = dropped_logs;
	}

	return fpromise::ok(std::move(ret));
	}
	} // namespace

	fpromise::result<std::vector<fpromise::result<fuchsia::logger::LogMessage, std::string>>,
	std::string>
	ConvertFormattedContentToLogMessages(FormattedContent content) {
	std::vector<fpromise::result<LogMessage, std::string>> output;

	if (!content.is_json()) {
	// Expecting JSON in all cases.
	return fpromise::error("Expected json content");
	}

	std::string data;
	if (!fsl::StringFromVmo(content.json(), &data)) {
	return fpromise::error("Failed to read string from VMO");
	}
	content.json().vmo.reset();

	rapidjson::Document d;
	d.Parse(std::move(data));
	if (d.HasParseError()) {
	std::string error = "Failed to parse content as JSON. Offset " +
	std::to_string(d.GetErrorOffset()) + ": " +
	rapidjson::GetParseError_En(d.GetParseError());
	return fpromise::error(std::move(error));
	}

	if (!d.IsArray()) {
	return fpromise::error("Expected content to contain an array");
	}

	for (rapidjson::SizeType i = 0; i < d.Size(); ++i) {
	output.emplace_back(JsonToLogMessage(d[i]));
	}

	return fpromise::ok(std::move(output));
	}

	fpromise::result<std::vector<fpromise::result<fuchsia::logger::LogMessage, std::string>>,
	std::string>
	ConvertFormattedContentToHostLogMessages(FormattedContent content) {
	std::vector<fpromise::result<LogMessage, std::string>> output;

	if (!content.is_json()) {
	// Expecting JSON in all cases.
	return fpromise::error("Expected json content");
	}

	std::string data;
	if (!fsl::StringFromVmo(content.json(), &data)) {
	return fpromise::error("Failed to read string from VMO");
	}
	content.json().vmo.reset();

	rapidjson::Document d;
	d.Parse(std::move(data));
	if (d.HasParseError()) {
	std::string error = "Failed to parse content as JSON. Offset " +
	std::to_string(d.GetErrorOffset()) + ": " +
	rapidjson::GetParseError_En(d.GetParseError());
	return fpromise::error(std::move(error));
	}

	if (!d.IsArray()) {
	return fpromise::error("Expected content to contain an array");
	}

	for (rapidjson::SizeType i = 0; i < d.Size(); ++i) {
	output.emplace_back(JsonToHostLogMessage(d[i]));
	}

	return fpromise::ok(std::move(output));
	}

	} // namespace diagnostics::accessor2logger