io/FileDescriptor: add Read()/Write() overloads with std::span

src/event/InotifyEvent.cxx

@@ -64,8 +64,7 @@ try {
 	static_assert(sizeof(buffer) >= sizeof(struct inotify_event) + NAME_MAX + 1,
 		      "inotify buffer too small");
 
-	ssize_t nbytes = event.GetFileDescriptor().Read(buffer.data(),
-							buffer.size());
+	ssize_t nbytes = event.GetFileDescriptor().Read(buffer);
 	if (nbytes <= 0) [[unlikely]] {
 		if (nbytes == 0)
 			throw std::runtime_error{"EOF from inotify"};

src/io/FileDescriptor.hxx

@@ -217,6 +217,10 @@ public:
 	}
 #endif
 
+	ssize_t Read(std::span<std::byte> dest) const noexcept {
+		return ::read(fd, dest.data(), dest.size());
+	}
+
 	ssize_t Read(void *buffer, std::size_t length) const noexcept {
 		return ::read(fd, buffer, length);
 	}
@@ -227,6 +231,10 @@ public:
 	 */
 	void FullRead(std::span<std::byte> dest) const;
 
+	ssize_t Write(std::span<const std::byte> src) const noexcept {
+		return ::write(fd, src.data(), src.size());
+	}
+
 	ssize_t Write(const void *buffer, std::size_t length) const noexcept {
 		return ::write(fd, buffer, length);
 	}

src/output/plugins/OssOutputPlugin.cxx

@@ -671,7 +671,7 @@ OssOutput::Play(std::span<const std::byte> src)
 		return src.size();
 
 	while (true) {
-		const ssize_t ret = fd.Write(e.data(), e.size());
+		const ssize_t ret = fd.Write(e);
 		if (ret > 0)
 			return pcm_export->CalcInputSize(ret);
 

src/output/plugins/SolarisOutputPlugin.cxx

@@ -125,7 +125,7 @@ SolarisOutput::Close() noexcept
 std::size_t
 SolarisOutput::Play(std::span<const std::byte> src)
 {
-	ssize_t nbytes = fd.Write(src.data(), src.size());
+	ssize_t nbytes = fd.Write(src);
 	if (nbytes <= 0)
 		throw MakeErrno("Write failed");
 

src/system/EventFD.cxx

@@ -21,7 +21,7 @@ EventFD::Read() noexcept
 	assert(fd.IsDefined());
 
 	eventfd_t value;
-	return fd.Read(&value, sizeof(value)) == (ssize_t)sizeof(value);
+	return fd.Read(std::as_writable_bytes(std::span{&value, 1})) == (ssize_t)sizeof(value);
 }
 
 void

test/run_convert.cxx

@@ -99,7 +99,7 @@ RunConvert(PcmConvert &convert, size_t in_frame_size,
 			const auto dest = buffer.Write();
 			assert(!dest.empty());
 
-			ssize_t nbytes = in_fd.Read(dest.data(), dest.size());
+			ssize_t nbytes = in_fd.Read(dest);
 			if (nbytes <= 0)
 				break;
 

test/run_output.cxx

@@ -124,7 +124,7 @@ RunOutput(AudioOutput &ao, AudioFormat audio_format,
 			const auto dest = buffer.Write();
 			assert(!dest.empty());
 
-			ssize_t nbytes = in_fd.Read(dest.data(), dest.size());
+			ssize_t nbytes = in_fd.Read(dest);
 			if (nbytes <= 0)
 				break;