From 09a2da89a2319191f4dd3716d7d0d4e79d4dcbe1 Mon Sep 17 00:00:00 2001
From: Max Kellermann <mk@cm4all.com>
Date: Tue, 26 Sep 2023 20:40:05 +0200
Subject: [PATCH] io/FileDescriptor: pass std::span to Full{Read,Write}()

---
 src/io/FileDescriptor.cxx | 22 ++++++++--------------
 src/io/FileDescriptor.hxx |  5 +++--
 test/ReadFrames.cxx       |  2 +-
 test/run_convert.cxx      |  4 ++--
 test/run_filter.cxx       |  4 ++--
 test/run_input.cxx        |  4 ++--
 6 files changed, 18 insertions(+), 23 deletions(-)

diff --git a/src/io/FileDescriptor.cxx b/src/io/FileDescriptor.cxx
index e1e437e90..45c740ee2 100644
--- a/src/io/FileDescriptor.cxx
+++ b/src/io/FileDescriptor.cxx
@@ -249,38 +249,32 @@ FileDescriptor::GetSize() const noexcept
 }
 
 void
-FileDescriptor::FullRead(void *_buffer, std::size_t length) const
+FileDescriptor::FullRead(std::span<std::byte> dest) const
 {
-	auto buffer = (std::byte *)_buffer;
-
-	while (length > 0) {
-		ssize_t nbytes = Read(buffer, length);
+	while (!dest.empty()) {
+		ssize_t nbytes = Read(dest.data(), dest.size());
 		if (nbytes <= 0) {
 			if (nbytes < 0)
 				throw MakeErrno("Failed to read");
 			throw std::runtime_error("Unexpected end of file");
 		}
 
-		buffer += nbytes;
-		length -= nbytes;
+		dest = dest.subspan(nbytes);
 	}
 }
 
 void
-FileDescriptor::FullWrite(const void *_buffer, std::size_t length) const
+FileDescriptor::FullWrite(std::span<const std::byte> src) const
 {
-	auto buffer = (const std::byte *)_buffer;
-
-	while (length > 0) {
-		ssize_t nbytes = Write(buffer, length);
+	while (!src.empty()) {
+		ssize_t nbytes = Write(src.data(), src.size());
 		if (nbytes <= 0) {
 			if (nbytes < 0)
 				throw MakeErrno("Failed to write");
 			throw std::runtime_error("Failed to write");
 		}
 
-		buffer += nbytes;
-		length -= nbytes;
+		src = src.subspan(nbytes);
 	}
 }
 
diff --git a/src/io/FileDescriptor.hxx b/src/io/FileDescriptor.hxx
index 628a0f3fc..283566147 100644
--- a/src/io/FileDescriptor.hxx
+++ b/src/io/FileDescriptor.hxx
@@ -4,6 +4,7 @@
 #pragma once
 
 #include <cstddef>
+#include <span>
 #include <utility>
 
 #include <unistd.h>
@@ -224,7 +225,7 @@ public:
 	 * Read until all of the given buffer has been filled.  Throws
 	 * on error.
 	 */
-	void FullRead(void *buffer, std::size_t length) const;
+	void FullRead(std::span<std::byte> dest) const;
 
 	ssize_t Write(const void *buffer, std::size_t length) const noexcept {
 		return ::write(fd, buffer, length);
@@ -234,7 +235,7 @@ public:
 	 * Write until all of the given buffer has been written.
 	 * Throws on error.
 	 */
-	void FullWrite(const void *buffer, std::size_t length) const;
+	void FullWrite(std::span<const std::byte> src) const;
 
 #ifndef _WIN32
 	int Poll(short events, int timeout) const noexcept;
diff --git a/test/ReadFrames.cxx b/test/ReadFrames.cxx
index dd6932ae0..cdf58baa3 100644
--- a/test/ReadFrames.cxx
+++ b/test/ReadFrames.cxx
@@ -28,7 +28,7 @@ ReadFrames(FileDescriptor fd, void *_buffer, std::size_t size,
 	const size_t modulo = nbytes % frame_size;
 	if (modulo > 0) {
 		size_t rest = frame_size - modulo;
-		fd.FullRead(buffer + nbytes, rest);
+		fd.FullRead({(std::byte *)buffer + nbytes, rest});
 		nbytes += rest;
 	}
 
diff --git a/test/run_convert.cxx b/test/run_convert.cxx
index 827084c28..75c9e58ab 100644
--- a/test/run_convert.cxx
+++ b/test/run_convert.cxx
@@ -116,7 +116,7 @@ RunConvert(PcmConvert &convert, size_t in_frame_size,
 		buffer.Consume(src.size());
 
 		auto output = convert.Convert(src);
-		out_fd.FullWrite(output.data(), output.size());
+		out_fd.FullWrite(output);
 	}
 
 	while (true) {
@@ -124,7 +124,7 @@ RunConvert(PcmConvert &convert, size_t in_frame_size,
 		if (output.data() == nullptr)
 			break;
 
-		out_fd.FullWrite(output.data(), output.size());
+		out_fd.FullWrite(output);
 	}
 }
 
diff --git a/test/run_filter.cxx b/test/run_filter.cxx
index a9404c2cc..7b58aa3ba 100644
--- a/test/run_filter.cxx
+++ b/test/run_filter.cxx
@@ -87,14 +87,14 @@ try {
 			break;
 
 		auto dest = filter->FilterPCM(std::span{buffer}.first(nbytes));
-		output_fd.FullWrite(dest.data(), dest.size());
+		output_fd.FullWrite(dest);
 	}
 
 	while (true) {
 		auto dest = filter->Flush();
 		if (dest.data() == nullptr)
 			break;
-		output_fd.FullWrite(dest.data(), dest.size());
+		output_fd.FullWrite(dest);
 	}
 
 	/* cleanup and exit */
diff --git a/test/run_input.cxx b/test/run_input.cxx
index f86a1129b..4e9729869 100644
--- a/test/run_input.cxx
+++ b/test/run_input.cxx
@@ -170,13 +170,13 @@ dump_input_stream(InputStream &is, FileDescriptor out,
 			}
 		}
 
-		char buffer[MAX_CHUNK_SIZE];
+		std::byte buffer[MAX_CHUNK_SIZE];
 		assert(chunk_size <= sizeof(buffer));
 		size_t num_read = is.Read(lock, buffer, chunk_size);
 		if (num_read == 0)
 			break;
 
-		out.FullWrite(buffer, num_read);
+		out.FullWrite({buffer, num_read});
 	}
 
 	is.Check();