util/SpanCast: add ReferenceAsBytes()

CM4all · Oct 21, 2023 · 7d00543 · 7d00543
1 parent 0de09e0
commit 7d00543
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Showing 5 changed files with 16 additions and 4 deletions.
diff --git a/src/io/BufferedOutputStream.hxx b/src/io/BufferedOutputStream.hxx
@@ -51,7 +51,7 @@ public:
 	 */
 	template<typename T>
 	void WriteT(const T &value) {
-		Write(std::as_bytes(std::span{&value, 1}));
+		Write(ReferenceAsBytes(value));
 	}
 
 	/**

diff --git a/src/net/control/Builder.hxx b/src/net/control/Builder.hxx
@@ -65,6 +65,6 @@ private:
 	}
 
 	void AppendT(const auto &s) noexcept {
-		Append(std::as_bytes(std::span{&s, 1}));
+		Append(ReferenceAsBytes(s));
 	}
 };
diff --git a/src/spawn/ResourceLimits.cxx b/src/spawn/ResourceLimits.cxx
@@ -8,6 +8,7 @@
 #include "util/djb_hash.hxx"
 #include "util/CharUtil.hxx"
 #include "util/Sanitizer.hxx"
+#include "util/SpanCast.hxx"
 
 #include <cassert>
 
@@ -68,7 +69,7 @@ ResourceLimits::IsEmpty() const noexcept
 inline std::size_t
 ResourceLimits::GetHash() const noexcept
 {
-	return djb_hash(std::as_bytes(std::span{this, 1}));
+	return djb_hash(ReferenceAsBytes(*this));
 }
 
 char *

diff --git a/src/spawn/daemon/Builder.hxx b/src/spawn/daemon/Builder.hxx
@@ -8,6 +8,7 @@
 #include "net/SendMessage.hxx"
 #include "io/Iovec.hxx"
 #include "util/CRC32.hxx"
+#include "util/SpanCast.hxx"
 #include "util/StaticVector.hxx"
 
 class DatagramBuilder {
@@ -44,7 +45,7 @@ public:
 	}
 
 	void Append(const SpawnDaemon::RequestHeader &rh) noexcept {
-		AppendRaw(std::as_bytes(std::span{&rh, 1}));
+		AppendRaw(ReferenceAsBytes(rh));
 	}
 
 	void Append(const SpawnDaemon::ResponseHeader &rh) noexcept {

diff --git a/src/util/SpanCast.hxx b/src/util/SpanCast.hxx
@@ -59,6 +59,16 @@ AsBytes(std::string_view sv) noexcept
 	return std::as_bytes(ToSpan(sv));
 }
 
+/**
+ * Cast a reference to a fixed-size std::span<const std::byte>.
+ */
+template<typename T>
+constexpr auto
+ReferenceAsBytes(const T &value) noexcept
+{
+	return std::as_bytes(std::span<const T, 1>{&value, 1});
+}
+
 constexpr std::string_view
 ToStringView(std::span<const char> s) noexcept
 {