identifier.go, unsafe.go: Document unsafe usage

2 files changed, 5 insertions, 0 deletions

diff --git a/identifier.go b/identifier.go
index 6da0e7c..a291f99 100644
--- a/identifier.go
+++ b/identifier.go
@@ -20,6 +20,8 @@ func makeIdentifierMAC(request *http.Request) (identifier []byte, mac []byte) {
 
 	remoteIP := getRemoteIP(request)
 
+	// It is safe to use stringToBytes here as h.Write does not modify its
+	// argument.
 	h := sha256.New()
 	h.Write(timeBuf)
 	h.Write(stringToBytes(remoteIP))
diff --git a/unsafe.go b/unsafe.go
index 7661ace..ed1e56c 100644
--- a/unsafe.go
+++ b/unsafe.go
@@ -5,6 +5,9 @@ package main
 
 import "unsafe"
 
+// Converts a string to a byte slice without copying the string.
+// Memory is borrowed from the string.
+// The resulting byte slice must not be modified in any form.
 func stringToBytes(s string) (bytes []byte) {
 	return unsafe.Slice(unsafe.StringData(s), len(s))
 }