io/Reader: use std::span

src/io/BufferedReader.cxx

@@ -26,7 +26,7 @@ BufferedReader::Fill(bool need_more)
 		assert(!w.empty());
 	}
 
-	std::size_t nbytes = reader.Read(w.data(), w.size());
+	std::size_t nbytes = reader.Read(w);
 	if (nbytes == 0) {
 		eof = true;
 		return !need_more;
@@ -95,9 +95,9 @@ BufferedReader::ReadLine()
 	}
 
 	/* terminate the last line */
-	w[0] = 0;
+	w[0] = {};
 
-	char *line = buffer.Read().data();
+	char *line = reinterpret_cast<char *>(buffer.Read().data());
 	buffer.Clear();
 	++line_number;
 	return line;

src/io/BufferedReader.hxx

@@ -15,7 +15,7 @@ class BufferedReader {
 
 	Reader &reader;
 
-	DynamicFifoBuffer<char> buffer;
+	DynamicFifoBuffer<std::byte> buffer;
 
 	bool eof = false;
 

src/io/FileReader.cxx

@@ -30,12 +30,12 @@ FileReader::GetFileInfo() const
 }
 
 std::size_t
-FileReader::Read(void *data, std::size_t size)
+FileReader::Read(std::span<std::byte> dest)
 {
 	assert(IsDefined());
 
 	DWORD nbytes;
-	if (!ReadFile(handle, data, size, &nbytes, nullptr))
+	if (!ReadFile(handle, dest.data(), dest.size(), &nbytes, nullptr))
 		throw FmtLastError("Failed to read from {}", path);
 
 	return nbytes;
@@ -82,11 +82,11 @@ FileReader::GetFileInfo() const
 }
 
 std::size_t
-FileReader::Read(void *data, std::size_t size)
+FileReader::Read(std::span<std::byte> dest)
 {
 	assert(IsDefined());
 
-	ssize_t nbytes = fd.Read(data, size);
+	ssize_t nbytes = fd.Read(dest);
 	if (nbytes < 0)
 		throw FmtErrno("Failed to read from {}", path);
 

src/io/FileReader.hxx

@@ -100,5 +100,5 @@ public:
 	void Skip(off_t offset);
 
 	/* virtual methods from class Reader */
-	std::size_t Read(void *data, std::size_t size) override;
+	std::size_t Read(std::span<std::byte> dest) override;
 };

src/io/PeekReader.cxx

@@ -17,8 +17,7 @@ PeekReader::Peek(size_t size)
 	assert(buffer_position == 0);
 
 	do {
-		size_t nbytes = next.Read(buffer + buffer_size,
-					  size - buffer_size);
+		size_t nbytes = next.Read(std::span{buffer}.first(buffer_size).subspan(size));
 		if (nbytes == 0)
 			return nullptr;
 
@@ -29,15 +28,17 @@ PeekReader::Peek(size_t size)
 }
 
 size_t
-PeekReader::Read(void *data, size_t size)
+PeekReader::Read(std::span<std::byte> dest)
 {
-	size_t buffer_remaining = buffer_size - buffer_position;
-	if (buffer_remaining > 0) {
-		size_t nbytes = std::min(buffer_remaining, size);
-		memcpy(data, buffer + buffer_position, nbytes);
-		buffer_position += nbytes;
-		return nbytes;
+	auto src = std::span{buffer}.first(buffer_size).subspan(buffer_position);
+	if (!src.empty()) {
+		if (dest.size() < src.size())
+			src = src.first(dest.size());
+
+		std::copy(src.begin(), src.end(), dest.begin());
+		buffer_position += src.size();
+		return src.size();
 	}
 
-	return next.Read(data, size);
+	return next.Read(dest);
 }

src/io/PeekReader.hxx

@@ -18,7 +18,7 @@ class PeekReader final : public Reader {
 
 	size_t buffer_size = 0, buffer_position = 0;
 
-	uint8_t buffer[64];
+	std::byte buffer[64];
 
 public:
 	explicit PeekReader(Reader &_next)
@@ -27,7 +27,7 @@ public:
 	const void *Peek(size_t size);
 
 	/* virtual methods from class Reader */
-	size_t Read(void *data, size_t size) override;
+	size_t Read(std::span<std::byte> dest) override;
 };
 
 #endif

src/io/Reader.hxx

@@ -5,6 +5,7 @@
 #define READER_HXX
 
 #include <cstddef>
+#include <span>
 #include <type_traits>
 
 /**
@@ -25,14 +26,13 @@ public:
 	 * @return the number of bytes read into the given buffer or 0
 	 * on end-of-stream
 	 */
-	[[gnu::nonnull]]
-	virtual std::size_t Read(void *data, std::size_t size) = 0;
+	virtual std::size_t Read(std::span<std::byte> dest) = 0;
 
 	template<typename T>
 	requires std::is_standard_layout_v<T> && std::is_trivially_copyable_v<T>
 	void ReadT(T &dest) {
 		// TODO check return value
-		Read(&dest, sizeof(dest));
+		Read(std::as_writable_bytes(std::span{&dest, 1}));
 	}
 };