client/Response: add method Fmt() based on libfmt

src/SongPrint.cxx

@@ -27,6 +27,8 @@
 #include "time/ChronoUtil.hxx"
 #include "util/UriUtil.hxx"
 
+#include <fmt/format.h>
+
 #define SONG_FILE "file: "
 
 static void
@@ -42,14 +44,15 @@ song_print_uri(Response &r, const char *uri, bool base) noexcept
 			uri = allocated.c_str();
 	}
 
-	r.Format(SONG_FILE "%s\n", uri);
+	r.Fmt(FMT_STRING(SONG_FILE "{}\n"), uri);
 }
 
 void
 song_print_uri(Response &r, const LightSong &song, bool base) noexcept
 {
 	if (!base && song.directory != nullptr)
-		r.Format(SONG_FILE "%s/%s\n", song.directory, song.uri);
+		r.Fmt(FMT_STRING(SONG_FILE "{}/{}\n"),
+		      song.directory, song.uri);
 	else
 		song_print_uri(r, song.uri, base);
 }
@@ -67,15 +70,15 @@ PrintRange(Response &r, SongTime start_time, SongTime end_time) noexcept
 	const unsigned end_ms = end_time.ToMS();
 
 	if (end_ms > 0)
-		r.Format("Range: %u.%03u-%u.%03u\n",
-			 start_ms / 1000,
-			 start_ms % 1000,
-			 end_ms / 1000,
-			 end_ms % 1000);
+		r.Fmt(FMT_STRING("Range: {}.{:03}-{}.{:03}\n"),
+		      start_ms / 1000,
+		      start_ms % 1000,
+		      end_ms / 1000,
+		      end_ms % 1000);
 	else if (start_ms > 0)
-		r.Format("Range: %u.%03u-\n",
-			 start_ms / 1000,
-			 start_ms % 1000);
+		r.Fmt(FMT_STRING("Range: {}.{:03}-\n"),
+		      start_ms / 1000,
+		      start_ms % 1000);
 }
 
 void
@@ -89,16 +92,16 @@ song_print_info(Response &r, const LightSong &song, bool base) noexcept
 		time_print(r, "Last-Modified", song.mtime);
 
 	if (song.audio_format.IsDefined())
-		r.Format("Format: %s\n", ToString(song.audio_format).c_str());
+		r.Fmt(FMT_STRING("Format: {}\n"), ToString(song.audio_format));
 
 	tag_print_values(r, song.tag);
 
 	const auto duration = song.GetDuration();
 	if (!duration.IsNegative())
-		r.Format("Time: %i\n"
-			 "duration: %1.3f\n",
-			 duration.RoundS(),
-			 duration.ToDoubleS());
+		r.Fmt(FMT_STRING("Time: {}\n"
+				 "duration: {:1.3}\n"),
+		      duration.RoundS(),
+		      duration.ToDoubleS());
 }
 
 void
@@ -112,14 +115,14 @@ song_print_info(Response &r, const DetachedSong &song, bool base) noexcept
 		time_print(r, "Last-Modified", song.GetLastModified());
 
 	if (const auto &f = song.GetAudioFormat(); f.IsDefined())
-		r.Format("Format: %s\n", ToString(f).c_str());
+		r.Fmt(FMT_STRING("Format: {}\n"), ToString(f));
 
 	tag_print_values(r, song.GetTag());
 
 	const auto duration = song.GetDuration();
 	if (!duration.IsNegative())
-		r.Format("Time: %i\n"
-			 "duration: %1.3f\n",
-			 duration.RoundS(),
-			 duration.ToDoubleS());
+		r.Fmt(FMT_STRING("Time: {}\n"
+				 "duration: {:1.3}\n"),
+		      duration.RoundS(),
+		      duration.ToDoubleS());
 }

src/Stats.cxx

@@ -34,6 +34,8 @@
 #include "system/Clock.hxx"
 #endif
 
+#include <fmt/format.h>
+
 #include <chrono>
 
 #ifndef _WIN32
@@ -97,19 +99,19 @@ db_stats_print(Response &r, const Database &db)
 	unsigned total_duration_s =
 		std::chrono::duration_cast<std::chrono::seconds>(stats.total_duration).count();
 
-	r.Format("artists: %u\n"
-		 "albums: %u\n"
-		 "songs: %u\n"
-		 "db_playtime: %u\n",
-		 stats.artist_count,
-		 stats.album_count,
-		 stats.song_count,
-		 total_duration_s);
+	r.Fmt(FMT_STRING("artists: {}\n"
+			 "albums: {}\n"
+			 "songs: {}\n"
+			 "db_playtime: {}\n"),
+	      stats.artist_count,
+	      stats.album_count,
+	      stats.song_count,
+	      total_duration_s);
 
 	const auto update_stamp = db.GetUpdateStamp();
 	if (!IsNegative(update_stamp))
-		r.Format("db_update: %lu\n",
-			 (unsigned long)std::chrono::system_clock::to_time_t(update_stamp));
+		r.Fmt(FMT_STRING("db_update: {}\n"),
+		      std::chrono::system_clock::to_time_t(update_stamp));
 }
 
 #endif
@@ -123,10 +125,10 @@ stats_print(Response &r, const Partition &partition)
 	const auto uptime = std::chrono::steady_clock::now() - start_time;
 #endif
 
-	r.Format("uptime: %u\n"
-		 "playtime: %lu\n",
-		 (unsigned)std::chrono::duration_cast<std::chrono::seconds>(uptime).count(),
-		 lround(partition.pc.GetTotalPlayTime().count()));
+	r.Fmt(FMT_STRING("uptime: {}\n"
+			 "playtime: {}\n"),
+	      std::chrono::duration_cast<std::chrono::seconds>(uptime).count(),
+	      lround(partition.pc.GetTotalPlayTime().count()));
 
 #ifdef ENABLE_DATABASE
 	const Database *db = partition.instance.GetDatabase();

src/TagPrint.cxx

@@ -23,26 +23,27 @@
 #include "client/Response.hxx"
 #include "util/StringView.hxx"
 
+#include <fmt/format.h>
+
 void
 tag_print_types(Response &r) noexcept
 {
 	const auto tag_mask = global_tag_mask & r.GetTagMask();
 	for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; i++)
 		if (tag_mask.Test(TagType(i)))
-			r.Format("tagtype: %s\n", tag_item_names[i]);
+			r.Fmt(FMT_STRING("tagtype: {}\n"), tag_item_names[i]);
 }
 
 void
 tag_print(Response &r, TagType type, StringView value) noexcept
 {
-	r.Format("%s: %.*s\n", tag_item_names[type],
-		 int(value.size), value.data);
+	r.Fmt(FMT_STRING("{}: {}\n"), tag_item_names[type], value);
 }
 
 void
 tag_print(Response &r, TagType type, const char *value) noexcept
 {
-	r.Format("%s: %s\n", tag_item_names[type], value);
+	r.Fmt(FMT_STRING("{}: {}\n"), tag_item_names[type], value);
 }
 
 void
@@ -58,10 +59,10 @@ void
 tag_print(Response &r, const Tag &tag) noexcept
 {
 	if (!tag.duration.IsNegative())
-		r.Format("Time: %i\n"
-			 "duration: %1.3f\n",
-			 tag.duration.RoundS(),
-			 tag.duration.ToDoubleS());
+		r.Fmt(FMT_STRING("Time: {}\n"
+				 "duration: {:1.3}\n"),
+		      tag.duration.RoundS(),
+		      tag.duration.ToDoubleS());
 
 	tag_print_values(r, tag);
 }

src/TimePrint.cxx

@@ -21,6 +21,8 @@
 #include "client/Response.hxx"
 #include "time/ISO8601.hxx"
 
+#include <fmt/format.h>
+
 void
 time_print(Response &r, const char *name,
 	   std::chrono::system_clock::time_point t)
@@ -33,5 +35,5 @@ time_print(Response &r, const char *name,
 		return;
 	}
 
-	r.Format("%s: %s\n", name, s.c_str());
+	r.Fmt(FMT_STRING("{}: {}\n"), name, s);
 }

src/client/Idle.cxx

@@ -22,6 +22,8 @@
 #include "Response.hxx"
 #include "Idle.hxx"
 
+#include <fmt/format.h>
+
 #include <cassert>
 
 static void
@@ -30,7 +32,7 @@ WriteIdleResponse(Response &r, unsigned flags) noexcept
 	const char *const*idle_names = idle_get_names();
 	for (unsigned i = 0; idle_names[i]; ++i) {
 		if (flags & (1 << i))
-			r.Format("changed: %s\n", idle_names[i]);
+			r.Fmt(FMT_STRING("changed: {}\n"), idle_names[i]);
 	}
 
 	r.Write("OK\n");

src/client/Response.cxx

@@ -22,6 +22,8 @@
 #include "util/FormatString.hxx"
 #include "util/AllocatedString.hxx"
 
+#include <fmt/format.h>
+
 TagMask
 Response::GetTagMask() const noexcept
 {
@@ -57,16 +59,20 @@ Response::Format(const char *fmt, ...) noexcept
 }
 
 bool
+Response::VFmt(fmt::string_view format_str, fmt::format_args args) noexcept
+{
+	fmt::memory_buffer buffer;
+	fmt::vformat_to(buffer, format_str, args);
+	return Write(buffer.data(), buffer.size());
+}
+
+bool
 Response::WriteBinary(ConstBuffer<void> payload) noexcept
 {
 	assert(payload.size <= client.binary_limit);
 
 	return
-#ifdef _WIN32
-		Format("binary: %lu\n", (unsigned long)payload.size) &&
-#else
-		Format("binary: %zu\n", payload.size) &&
-#endif
+		Fmt("binary: {}\n", payload.size) &&
 		Write(payload.data, payload.size) &&
 		Write("\n");
 }

src/client/Response.hxx

@@ -23,6 +23,11 @@
 #include "protocol/Ack.hxx"
 #include "util/Compiler.h"
 
+#include <fmt/core.h>
+#if FMT_VERSION < 70000
+#include <fmt/format.h>
+#endif
+
 #include <cstdarg>
 #include <cstddef>
 
@@ -79,6 +84,21 @@ public:
 	gcc_printf(2,3)
 	bool Format(const char *fmt, ...) noexcept;
 
+	bool VFmt(fmt::string_view format_str, fmt::format_args args) noexcept;
+
+	template<typename S, typename... Args>
+	bool Fmt(const S &format_str, Args&&... args) noexcept {
+#if FMT_VERSION >= 70000
+		return VFmt(fmt::to_string_view(format_str),
+			    fmt::make_args_checked<Args...>(format_str,
+							    args...));
+#else
+		/* expensive fallback for older libfmt versions */
+		const auto result = fmt::format(format_str, args...);
+		return Write(result.data(), result.size());
+#endif
+	}
+
 	/**
 	 * Write a binary chunk; this writes the "binary" line, the
 	 * given chunk and the trailing newline.

src/command/AllCommands.cxx

@@ -48,6 +48,8 @@
 #include "StickerCommands.hxx"
 #endif
 
+#include <fmt/format.h>
+
 #include <cassert>
 #include <iterator>
 
@@ -253,7 +255,7 @@ PrintAvailableCommands(Response &r, const Partition &partition,
 
 		if (cmd->permission == (permission & cmd->permission) &&
 		    command_available(partition, cmd))
-			r.Format("command: %s\n", cmd->cmd);
+			r.Fmt(FMT_STRING("command: {}\n"), cmd->cmd);
 	}
 
 	return CommandResult::OK;
@@ -266,7 +268,7 @@ PrintUnavailableCommands(Response &r, unsigned permission) noexcept
 		const struct command *cmd = &i;
 
 		if (cmd->permission != (permission & cmd->permission))
-			r.Format("command: %s\n", cmd->cmd);
+			r.Fmt(FMT_STRING("command: {}\n"), cmd->cmd);
 	}
 
 	return CommandResult::OK;

src/command/FileCommands.cxx

@@ -17,8 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define __STDC_FORMAT_MACROS /* for PRIu64 */
-
 #include "config.h"
 #include "FileCommands.hxx"
 #include "Request.hxx"
@@ -43,9 +41,10 @@
 #include "thread/Mutex.hxx"
 #include "Log.hxx"
 
+#include <fmt/format.h>
+
 #include <algorithm>
 #include <cassert>
-#include <cinttypes> /* for PRIu64 */
 
 gcc_pure
 static bool
@@ -61,13 +60,6 @@ skip_path(Path name_fs) noexcept
 	return name_fs.HasNewline();
 }
 
-#if defined(_WIN32) && GCC_CHECK_VERSION(4,6)
-/* PRIu64 causes bogus compiler warning */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat"
-#pragma GCC diagnostic ignored "-Wformat-extra-args"
-#endif
-
 CommandResult
 handle_listfiles_local(Response &r, Path path_fs)
 {
@@ -88,12 +80,12 @@ handle_listfiles_local(Response &r, Path path_fs)
 			continue;
 
 		if (fi.IsRegular())
-			r.Format("file: %s\n"
-				 "size: %" PRIu64 "\n",
-				 name_utf8.c_str(),
-				 fi.GetSize());
+			r.Fmt(FMT_STRING("file: {}\n"
+					 "size: {}\n"),
+			      name_utf8,
+			      fi.GetSize());
 		else if (fi.IsDirectory())
-			r.Format("directory: %s\n", name_utf8.c_str());
+			r.Fmt(FMT_STRING("directory: {}\n"), name_utf8);
 		else
 			continue;
 
@@ -135,9 +127,7 @@ public:
 
 	void OnPair(StringView key, StringView value) noexcept override {
 		if (IsValidName(key) && IsValidValue(value))
-			response.Format("%.*s: %.*s\n",
-					int(key.size), key.data,
-					int(value.size), value.data);
+			response.Fmt(FMT_STRING("{}: {}\n"), key, value);
 	}
 };
 
@@ -228,11 +218,7 @@ read_stream_art(Response &r, const char *uri, size_t offset)
 		read_size = is->Read(lock, buffer.get(), buffer_size);
 	}
 
-#ifdef _WIN32
-	r.Format("size: %lu\n", (unsigned long)art_file_size);
-#else
-	r.Format("size: %" PRIoffset "\n", art_file_size);
-#endif
+	r.Fmt(FMT_STRING("size: {}\n"), art_file_size);
 
 	r.WriteBinary({buffer.get(), read_size});
 
@@ -315,14 +301,10 @@ public:
 			return;
 		}
 
-#ifdef _WIN32
-		response.Format("size: %lu\n", (unsigned long)buffer.size);
-#else
-		response.Format("size: %zu\n", buffer.size);
-#endif
+		response.Fmt(FMT_STRING("size: {}\n"), buffer.size);
 
 		if (mime_type != nullptr)
-			response.Format("type: %s\n", mime_type);
+			response.Fmt(FMT_STRING("type: {}\n"), mime_type);
 
 		buffer.size -= offset;
 

src/command/FingerprintCommands.cxx

@@ -37,6 +37,8 @@
 #include "util/MimeType.hxx"
 #include "util/UriExtract.hxx"
 
+#include <fmt/format.h>
+
 class GetChromaprintCommand final
 	: public ThreadBackgroundCommand, ChromaprintDecoderClient, InputStreamHandler
 {
@@ -60,8 +62,8 @@ protected:
 	void Run() override;
 
 	void SendResponse(Response &r) noexcept override {
-		r.Format("chromaprint: %s\n",
-			 GetFingerprint().c_str());
+		r.Fmt(FMT_STRING("chromaprint: {}\n"),
+		      GetFingerprint());
 	}
 
 	void CancelThread() noexcept override {

src/command/MessageCommands.cxx

@@ -25,6 +25,8 @@
 #include "util/ConstBuffer.hxx"
 #include "Partition.hxx"
 
+#include <fmt/format.h>
+
 #include <cassert>
 #include <set>
 #include <string>
@@ -85,7 +87,7 @@ handle_channels(Client &client, [[maybe_unused]] Request args, Response &r)
 	}
 
 	for (const auto &channel : channels)
-		r.Format("channel: %s\n", channel.c_str());
+		r.Fmt(FMT_STRING("channel: {}\n"), channel);
 
 	return CommandResult::OK;
 }
@@ -97,8 +99,8 @@ handle_read_messages(Client &client,
 	assert(args.empty());
 
 	client.ConsumeMessages([&r](const auto &msg){
-		r.Format("channel: %s\nmessage: %s\n",
-			 msg.GetChannel(), msg.GetMessage());
+		r.Fmt(FMT_STRING("channel: {}\nmessage: {}\n"),
+		      msg.GetChannel(), msg.GetMessage());
 	});
 
 	return CommandResult::OK;

src/command/NeighborCommands.cxx

@@ -25,6 +25,8 @@
 #include "neighbor/Glue.hxx"
 #include "neighbor/Info.hxx"
 
+#include <fmt/format.h>
+
 #include <string>
 
 bool
@@ -44,9 +46,9 @@ handle_listneighbors(Client &client, [[maybe_unused]] Request args, Response &r)
 	}
 
 	for (const auto &i : neighbors->GetList())
-		r.Format("neighbor: %s\n"
-			 "name: %s\n",
-			 i.uri.c_str(),
-			 i.display_name.c_str());
+		r.Fmt(FMT_STRING("neighbor: {}\n"
+				 "name: {}\n"),
+		      i.uri,
+		      i.display_name);
 	return CommandResult::OK;
 }

src/command/OtherCommands.cxx

@@ -55,13 +55,15 @@
 #include "db/update/Service.hxx"
 #endif
 
+#include <fmt/format.h>
+
 #include <cassert>
 
 static void
 print_spl_list(Response &r, const PlaylistVector &list)
 {
 	for (const auto &i : list) {
-		r.Format("playlist: %s\n", i.name.c_str());
+		r.Fmt(FMT_STRING("playlist: {}\n"), i.name);
 
 		if (!IsNegative(i.mtime))
 			time_print(r, "Last-Modified", i.mtime);
@@ -72,7 +74,7 @@ CommandResult
 handle_urlhandlers(Client &client, [[maybe_unused]] Request args, Response &r)
 {
 	if (client.IsLocal())
-		r.Format("handler: file://\n");
+		r.Write("handler: file://\n");
 	print_supported_uri_schemes(r);
 	return CommandResult::OK;
 }
@@ -248,7 +250,7 @@ handle_update(Response &r, UpdateService &update,
 	      const char *uri_utf8, bool discard)
 {
 	unsigned ret = update.Enqueue(uri_utf8, discard);
-	r.Format("updating_db: %i\n", ret);
+	r.Fmt(FMT_STRING("updating_db: {}\n"), ret);
 	return CommandResult::OK;
 }
 
@@ -258,7 +260,7 @@ handle_update(Response &r, Database &db,
 {
 	unsigned id = db.Update(uri_utf8, discard);
 	if (id > 0) {
-		r.Format("updating_db: %i\n", id);
+		r.Fmt(FMT_STRING("updating_db: {}\n"), id);
 		return CommandResult::OK;
 	} else {
 		/* Database::Update() has returned 0 without setting
@@ -325,7 +327,7 @@ handle_getvol(Client &client, Request, Response &r)
 
 	const auto volume = volume_level_get(partition.outputs);
 	if (volume >= 0)
-		r.Format("volume: %i\n", volume);
+		r.Fmt(FMT_STRING("volume: {}\n"), volume);
 
 	return CommandResult::OK;
 }
@@ -391,7 +393,7 @@ handle_config(Client &client, [[maybe_unused]] Request args, Response &r)
 	const Storage *storage = client.GetStorage();
 	if (storage != nullptr) {
 		const auto path = storage->MapUTF8("");
-		r.Format("music_directory: %s\n", path.c_str());
+		r.Fmt(FMT_STRING("music_directory: {}\n"), path);
 	}
 #endif
 

src/command/PartitionCommands.cxx

@@ -27,6 +27,8 @@
 #include "client/Response.hxx"
 #include "util/CharUtil.hxx"
 
+#include <fmt/format.h>
+
 CommandResult
 handle_partition(Client &client, Request request, Response &response)
 {
@@ -46,7 +48,7 @@ CommandResult
 handle_listpartitions(Client &client, Request, Response &r)
 {
 	for (const auto &partition : client.GetInstance().partitions) {
-		r.Format("partition: %s\n", partition.name.c_str());
+		r.Fmt(FMT_STRING("partition: {}\n"), partition.name);
 	}
 
 	return CommandResult::OK;

src/command/PlayerCommands.cxx

@@ -38,6 +38,8 @@
 #include "db/update/Service.hxx"
 #endif
 
+#include <fmt/format.h>
+
 #define COMMAND_STATUS_STATE            "state"
 #define COMMAND_STATUS_REPEAT           "repeat"
 #define COMMAND_STATUS_SINGLE           "single"
@@ -131,60 +133,60 @@ handle_status(Client &client, [[maybe_unused]] Request args, Response &r)
 
 	const auto volume = volume_level_get(partition.outputs);
 	if (volume >= 0)
-		r.Format("volume: %i\n", volume);
-
-	r.Format(COMMAND_STATUS_REPEAT ": %i\n"
-		 COMMAND_STATUS_RANDOM ": %i\n"
-		 COMMAND_STATUS_SINGLE ": %s\n"
-		 COMMAND_STATUS_CONSUME ": %i\n"
-		 "partition: %s\n"
-		 COMMAND_STATUS_PLAYLIST ": %li\n"
-		 COMMAND_STATUS_PLAYLIST_LENGTH ": %i\n"
-		 COMMAND_STATUS_MIXRAMPDB ": %f\n"
-		 COMMAND_STATUS_STATE ": %s\n",
-		 playlist.GetRepeat(),
-		 playlist.GetRandom(),
-		 SingleToString(playlist.GetSingle()),
-		 playlist.GetConsume(),
-		 partition.name.c_str(),
-		 (unsigned long)playlist.GetVersion(),
-		 playlist.GetLength(),
-		 (double)pc.GetMixRampDb(),
-		 state);
+		r.Fmt(FMT_STRING("volume: {}\n"), volume);
+
+	r.Fmt(FMT_STRING(COMMAND_STATUS_REPEAT ": {}\n"
+			 COMMAND_STATUS_RANDOM ": {}\n"
+			 COMMAND_STATUS_SINGLE ": {}\n"
+			 COMMAND_STATUS_CONSUME ": {}\n"
+			 "partition: {}\n"
+			 COMMAND_STATUS_PLAYLIST ": {}\n"
+			 COMMAND_STATUS_PLAYLIST_LENGTH ": {}\n"
+			 COMMAND_STATUS_MIXRAMPDB ": {}\n"
+			 COMMAND_STATUS_STATE ": {}\n"),
+	      playlist.GetRepeat(),
+	      playlist.GetRandom(),
+	      SingleToString(playlist.GetSingle()),
+	      playlist.GetConsume(),
+	      partition.name.c_str(),
+	      playlist.GetVersion(),
+	      playlist.GetLength(),
+	      pc.GetMixRampDb(),
+	      state);
 
 	if (pc.GetCrossFade() > FloatDuration::zero())
-		r.Format(COMMAND_STATUS_CROSSFADE ": %lu\n",
-			 lround(pc.GetCrossFade().count()));
+		r.Fmt(FMT_STRING(COMMAND_STATUS_CROSSFADE ": {}\n"),
+		      lround(pc.GetCrossFade().count()));
 
 	if (pc.GetMixRampDelay() > FloatDuration::zero())
-		r.Format(COMMAND_STATUS_MIXRAMPDELAY ": %f\n",
-			 pc.GetMixRampDelay().count());
+		r.Fmt(FMT_STRING(COMMAND_STATUS_MIXRAMPDELAY ": {}\n"),
+		      pc.GetMixRampDelay().count());
 
 	song = playlist.GetCurrentPosition();
 	if (song >= 0) {
-		r.Format(COMMAND_STATUS_SONG ": %i\n"
-			 COMMAND_STATUS_SONGID ": %u\n",
-			 song, playlist.PositionToId(song));
+		r.Fmt(FMT_STRING(COMMAND_STATUS_SONG ": {}\n"
+				 COMMAND_STATUS_SONGID ": {}\n"),
+		      song, playlist.PositionToId(song));
 	}
 
 	if (player_status.state != PlayerState::STOP) {
-		r.Format(COMMAND_STATUS_TIME ": %i:%i\n"
-			 "elapsed: %1.3f\n"
-			 COMMAND_STATUS_BITRATE ": %u\n",
-			 player_status.elapsed_time.RoundS(),
-			 player_status.total_time.IsNegative()
-			 ? 0U
-			 : unsigned(player_status.total_time.RoundS()),
-			 player_status.elapsed_time.ToDoubleS(),
-			 player_status.bit_rate);
+		r.Fmt(FMT_STRING(COMMAND_STATUS_TIME ": {}:{}\n"
+				 "elapsed: {:1.3}\n"
+				 COMMAND_STATUS_BITRATE ": {}\n"),
+		      player_status.elapsed_time.RoundS(),
+		      player_status.total_time.IsNegative()
+		      ? 0U
+		      : unsigned(player_status.total_time.RoundS()),
+		      player_status.elapsed_time.ToDoubleS(),
+		      player_status.bit_rate);
 
 		if (!player_status.total_time.IsNegative())
-			r.Format("duration: %1.3f\n",
+			r.Fmt(FMT_STRING("duration: {:1.3}\n"),
 				 player_status.total_time.ToDoubleS());
 
 		if (player_status.audio_format.IsDefined())
-			r.Format(COMMAND_STATUS_AUDIO ": %s\n",
-				 ToString(player_status.audio_format).c_str());
+			r.Fmt(FMT_STRING(COMMAND_STATUS_AUDIO ": {}\n"),
+			      ToString(player_status.audio_format));
 	}
 
 #ifdef ENABLE_DATABASE
@@ -193,23 +195,23 @@ handle_status(Client &client, [[maybe_unused]] Request args, Response &r)
 		? update_service->GetId()
 		: 0;
 	if (updateJobId != 0) {
-		r.Format(COMMAND_STATUS_UPDATING_DB ": %i\n",
-			 updateJobId);
+		r.Fmt(FMT_STRING(COMMAND_STATUS_UPDATING_DB ": {}\n"),
+		      updateJobId);
 	}
 #endif
 
 	try {
 		pc.LockCheckRethrowError();
 	} catch (...) {
-		r.Format(COMMAND_STATUS_ERROR ": %s\n",
-			 GetFullMessage(std::current_exception()).c_str());
+		r.Fmt(FMT_STRING(COMMAND_STATUS_ERROR ": {}\n"),
+		      GetFullMessage(std::current_exception()));
 	}
 
 	song = playlist.GetNextPosition();
 	if (song >= 0)
-		r.Format(COMMAND_STATUS_NEXTSONG ": %i\n"
-			 COMMAND_STATUS_NEXTSONGID ": %u\n",
-			 song, playlist.PositionToId(song));
+		r.Fmt(FMT_STRING(COMMAND_STATUS_NEXTSONG ": {}\n"
+				 COMMAND_STATUS_NEXTSONGID ": {}\n"),
+		      song, playlist.PositionToId(song));
 
 	return CommandResult::OK;
 }
@@ -351,7 +353,7 @@ CommandResult
 handle_replay_gain_status(Client &client, [[maybe_unused]] Request args,
 			  Response &r)
 {
-	r.Format("replay_gain_mode: %s\n",
-		 ToString(client.GetPartition().replay_gain_mode));
+	r.Fmt(FMT_STRING("replay_gain_mode: {}\n"),
+	      ToString(client.GetPartition().replay_gain_mode));
 	return CommandResult::OK;
 }

src/command/PlaylistCommands.cxx

@@ -42,6 +42,8 @@
 #include "util/UriExtract.hxx"
 #include "LocateUri.hxx"
 
+#include <fmt/format.h>
+
 bool
 playlist_commands_available() noexcept
 {
@@ -52,7 +54,7 @@ static void
 print_spl_list(Response &r, const PlaylistVector &list)
 {
 	for (const auto &i : list) {
-		r.Format("playlist: %s\n", i.name.c_str());
+		r.Fmt(FMT_STRING("playlist: {}\n"), i.name);
 
 		if (!IsNegative(i.mtime))
 			time_print(r, "Last-Modified", i.mtime);

src/command/QueueCommands.cxx

@@ -39,6 +39,8 @@
 #include "util/StringAPI.hxx"
 #include "util/NumberParser.hxx"
 
+#include <fmt/format.h>
+
 #include <limits>
 
 static void
@@ -127,7 +129,7 @@ handle_addid(Client &client, Request args, Response &r)
 		}
 	}
 
-	r.Format("Id: %u\n", added_id);
+	r.Fmt(FMT_STRING("Id: {}\n"), added_id);
 	return CommandResult::OK;
 }
 

src/command/StorageCommands.cxx

@@ -17,8 +17,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
-#define __STDC_FORMAT_MACROS /* for PRIu64 */
-
 #include "config.h"
 #include "StorageCommands.hxx"
 #include "Request.hxx"
@@ -37,7 +35,8 @@
 #include "TimePrint.hxx"
 #include "IdleFlags.hxx"
 
-#include <cinttypes> /* for PRIu64 */
+#include <fmt/format.h>
+
 #include <memory>
 
 gcc_pure
@@ -47,13 +46,6 @@ skip_path(const char *name_utf8) noexcept
 	return std::strchr(name_utf8, '\n') != nullptr;
 }
 
-#if defined(_WIN32) && GCC_CHECK_VERSION(4,6)
-/* PRIu64 causes bogus compiler warning */
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat"
-#pragma GCC diagnostic ignored "-Wformat-extra-args"
-#endif
-
 static void
 handle_listfiles_storage(Response &r, StorageDirectoryReader &reader)
 {
@@ -75,14 +67,14 @@ handle_listfiles_storage(Response &r, StorageDirectoryReader &reader)
 			continue;
 
 		case StorageFileInfo::Type::REGULAR:
-			r.Format("file: %s\n"
-				 "size: %" PRIu64 "\n",
-				 name_utf8,
-				 info.size);
+			r.Fmt(FMT_STRING("file: {}\n"
+					 "size: {}\n"),
+			      name_utf8,
+			      info.size);
 			break;
 
 		case StorageFileInfo::Type::DIRECTORY:
-			r.Format("directory: %s\n", name_utf8);
+			r.Fmt(FMT_STRING("directory: {}\n"), name_utf8);
 			break;
 		}
 
@@ -139,7 +131,7 @@ print_storage_uri(Client &client, Response &r, const Storage &storage)
 			uri = std::move(allocated);
 	}
 
-	r.Format("storage: %s\n", uri.c_str());
+	r.Fmt(FMT_STRING("storage: {}\n"), uri);
 }
 
 CommandResult
@@ -155,7 +147,7 @@ handle_listmounts(Client &client, [[maybe_unused]] Request args, Response &r)
 
 	const auto visitor = [&client, &r](const char *mount_uri,
 					   const Storage &storage){
-		r.Format("mount: %s\n", mount_uri);
+		r.Fmt(FMT_STRING("mount: {}\n"), mount_uri);
 		print_storage_uri(client, r, storage);
 	};
 

src/db/Count.cxx

@@ -27,6 +27,8 @@
 #include "tag/VisitFallback.hxx"
 #include "TagPrint.hxx"
 
+#include <fmt/format.h>
+
 #include <functional>
 #include <map>
 
@@ -47,9 +49,9 @@ PrintSearchStats(Response &r, const SearchStats &stats) noexcept
 	unsigned total_duration_s =
 		std::chrono::duration_cast<std::chrono::seconds>(stats.total_duration).count();
 
-	r.Format("songs: %u\n"
-		 "playtime: %u\n",
-		 stats.n_songs, total_duration_s);
+	r.Fmt(FMT_STRING("songs: {}\n"
+			 "playtime: {}\n"),
+	      stats.n_songs, total_duration_s);
 }
 
 static void

src/db/DatabasePrint.cxx

@@ -32,6 +32,8 @@
 #include "time/ChronoUtil.hxx"
 #include "util/RecursiveMap.hxx"
 
+#include <fmt/format.h>
+
 #include <functional>
 
 gcc_pure
@@ -47,8 +49,8 @@ static void
 PrintDirectoryURI(Response &r, bool base,
 		  const LightDirectory &directory) noexcept
 {
-	r.Format("directory: %s\n",
-		 ApplyBaseFlag(directory.GetPath(), base));
+	r.Fmt(FMT_STRING("directory: {}\n"),
+	      ApplyBaseFlag(directory.GetPath(), base));
 }
 
 static void
@@ -77,11 +79,11 @@ print_playlist_in_directory(Response &r, bool base,
 			    const char *name_utf8) noexcept
 {
 	if (base || directory == nullptr)
-		r.Format("playlist: %s\n",
-			 ApplyBaseFlag(name_utf8, base));
+		r.Fmt(FMT_STRING("playlist: {}\n"),
+		      ApplyBaseFlag(name_utf8, base));
 	else
-		r.Format("playlist: %s/%s\n",
-			 directory, name_utf8);
+		r.Fmt(FMT_STRING("playlist: {}/{}\n"),
+		      directory, name_utf8);
 }
 
 static void
@@ -90,10 +92,10 @@ print_playlist_in_directory(Response &r, bool base,
 			    const char *name_utf8) noexcept
 {
 	if (base || directory == nullptr || directory->IsRoot())
-		r.Format("playlist: %s\n", name_utf8);
+		r.Fmt(FMT_STRING("playlist: {}\n"), name_utf8);
 	else
-		r.Format("playlist: %s/%s\n",
-			 directory->GetPath(), name_utf8);
+		r.Fmt(FMT_STRING("playlist: {}/{}\n"),
+		      directory->GetPath(), name_utf8);
 }
 
 static void
@@ -196,7 +198,7 @@ PrintUniqueTags(Response &r, ConstBuffer<TagType> tag_types,
 	tag_types.pop_front();
 
 	for (const auto &[key, tag] : map) {
-		r.Format("%s: %s\n", name, key.c_str());
+		r.Fmt(FMT_STRING("{}: {}\n"), name, key);
 
 		if (!tag_types.empty())
 			PrintUniqueTags(r, tag_types, tag);

src/db/meson.build

@@ -55,6 +55,7 @@ db_glue = static_library(
   include_directories: inc,
   dependencies: [
     boost_dep,
+    fmt_dep,
     log_dep,
   ],
 )

src/decoder/DecoderPrint.cxx

@@ -22,6 +22,8 @@
 #include "DecoderPlugin.hxx"
 #include "client/Response.hxx"
 
+#include <fmt/format.h>
+
 #include <cassert>
 #include <functional>
 
@@ -33,15 +35,15 @@ decoder_plugin_print(Response &r,
 
 	assert(plugin.name != nullptr);
 
-	r.Format("plugin: %s\n", plugin.name);
+	r.Fmt(FMT_STRING("plugin: {}\n"), plugin.name);
 
 	if (plugin.suffixes != nullptr)
 		for (p = plugin.suffixes; *p != nullptr; ++p)
-			r.Format("suffix: %s\n", *p);
+			r.Fmt(FMT_STRING("suffix: {}\n"), *p);
 
 	if (plugin.mime_types != nullptr)
 		for (p = plugin.mime_types; *p != nullptr; ++p)
-			r.Format("mime_type: %s\n", *p);
+			r.Fmt(FMT_STRING("mime_type: {}\n"), *p);
 }
 
 void

src/ls.cxx

@@ -26,8 +26,9 @@
 #include "client/Response.hxx"
 #include "util/UriExtract.hxx"
 
-#include <cassert>
+#include <fmt/format.h>
 
+#include <cassert>
 #include <string>
 
 void print_supported_uri_schemes_to_fp(FILE *fp)
@@ -67,7 +68,7 @@ print_supported_uri_schemes(Response &r)
 	});
 
 	for (const auto& protocol : protocols) {
-		r.Format("handler: %s\n", protocol.c_str());
+		r.Fmt(FMT_STRING("handler: {}\n"), protocol);
 	}
 }
 

src/output/Print.cxx

@@ -26,21 +26,24 @@
 #include "MultipleOutputs.hxx"
 #include "client/Response.hxx"
 
+#include <fmt/format.h>
+
 void
 printAudioDevices(Response &r, const MultipleOutputs &outputs)
 {
 	for (unsigned i = 0, n = outputs.Size(); i != n; ++i) {
 		const auto &ao = outputs.Get(i);
 
-		r.Format("outputid: %u\n"
-			 "outputname: %s\n"
-			 "plugin: %s\n"
-			 "outputenabled: %i\n",
-			 i,
-			 ao.GetName(), ao.GetPluginName(),
-			 ao.IsEnabled());
+		r.Fmt(FMT_STRING("outputid: {}\n"
+				 "outputname: {}\n"
+				 "plugin: {}\n"
+				 "outputenabled: {}\n"),
+		      i,
+		      ao.GetName(), ao.GetPluginName(),
+		      ao.IsEnabled());
 
 		for (const auto &[attribute, value] : ao.GetAttributes())
-			r.Format("attribute: %s=%s\n", attribute.c_str(), value.c_str());
+			r.Fmt(FMT_STRING("attribute: {}={}\n"),
+			      attribute, value);
 	}
 }

src/output/meson.build

@@ -35,6 +35,9 @@ output_glue = static_library(
   'Finish.cxx',
   'Init.cxx',
   include_directories: inc,
+  dependencies: [
+    fmt_dep,
+  ],
 )
 
 output_glue_dep = declare_dependency(

src/queue/QueuePrint.cxx

@@ -25,6 +25,8 @@
 #include "song/LightSong.hxx"
 #include "client/Response.hxx"
 
+#include <fmt/format.h>
+
 /**
  * Send detailed information about a range of songs in the queue to a
  * client.
@@ -38,12 +40,12 @@ queue_print_song_info(Response &r, const Queue &queue,
 		      unsigned position)
 {
 	song_print_info(r, queue.Get(position));
-	r.Format("Pos: %u\nId: %u\n",
-		 position, queue.PositionToId(position));
+	r.Fmt(FMT_STRING("Pos: {}\nId: {}\n"),
+	      position, queue.PositionToId(position));
 
 	uint8_t priority = queue.GetPriorityAtPosition(position);
 	if (priority != 0)
-		r.Format("Prio: %u\n", priority);
+		r.Fmt(FMT_STRING("Prio: {}\n"), priority);
 }
 
 void
@@ -65,7 +67,7 @@ queue_print_uris(Response &r, const Queue &queue,
 	assert(end <= queue.GetLength());
 
 	for (unsigned i = start; i < end; ++i) {
-		r.Format("%i:", i);
+		r.Fmt(FMT_STRING("{}:"), i);
 		song_print_uri(r, queue.Get(i));
 	}
 }
@@ -93,8 +95,8 @@ queue_print_changes_position(Response &r, const Queue &queue,
 
 	for (unsigned i = start; i < end; i++)
 		if (queue.IsNewerAtPosition(i, version))
-			r.Format("cpos: %i\nId: %i\n",
-				 i, queue.PositionToId(i));
+			r.Fmt(FMT_STRING("cpos: {}\nId: {}\n"),
+			      i, queue.PositionToId(i));
 }
 
 void

src/sticker/Print.cxx

@@ -21,11 +21,13 @@
 #include "Sticker.hxx"
 #include "client/Response.hxx"
 
+#include <fmt/format.h>
+
 void
 sticker_print_value(Response &r,
 		    const char *name, const char *value)
 {
-	r.Format("sticker: %s=%s\n", name, value);
+	r.Fmt(FMT_STRING("sticker: {}={}\n"), name, value);
 }
 
 void