Add codecs.nulTerminatedString codec

build.sbt

@@ -15,9 +15,6 @@ ThisBuild / scmInfo := Some(
   ScmInfo(url("https://github.com/scodec/scodec"), "git@github.com:scodec/scodec.git")
 )
 
-// Disabled due to erroneous unused import warnings on scala.js
-ThisBuild / tlFatalWarnings := false
-
 ThisBuild / licenses := List(
   ("BSD-3-Clause", url("https://github.com/scodec/scodec/blob/main/LICENSE"))
 )

shared/src/main/scala/scodec/Attempt.scala

@@ -31,7 +31,6 @@
 package scodec
 
 import scala.util.Try
-import scala.util.control.NonFatal
 
 /** Right biased `Either[Err, A]`.
   *

shared/src/main/scala/scodec/Codec.scala

@@ -34,7 +34,6 @@ import scala.deriving.*
 import scala.compiletime.*
 
 import scodec.bits.{BitVector, ByteVector}
-import scala.collection.mutable
 
 /** Supports encoding a value of type `A` to a `BitVector` and decoding a `BitVector` to a value of `A`.
   *

shared/src/main/scala/scodec/codecs/PaddedVarAlignedCodec.scala

@@ -31,7 +31,6 @@
 package scodec
 package codecs
 
-import scodec.{Codec, Err}
 import scodec.bits.BitVector
 
 private class PaddedVarAlignedCodec[A](

shared/src/main/scala/scodec/codecs/codecs.scala

@@ -461,19 +461,24 @@ val utf8 = string(Platform.utf8)
   * and decodes a string up to the next `NUL` termination byte.
   * It fails to decode if the bit vector ends before a `NUL` termination byte can be found.
   */
-val cstring: Codec[String] = filtered(
-  ascii,
-  new Codec[BitVector] {
-    val nul = BitVector.lowByte
-    override def sizeBound: SizeBound = SizeBound.unknown
-    override def encode(bits: BitVector): Attempt[BitVector] = Attempt.successful(bits ++ nul)
-    override def decode(bits: BitVector): Attempt[DecodeResult[BitVector]] =
-      bits.bytes.indexOfSlice(nul.bytes) match {
-        case -1 => Attempt.failure(Err("Does not contain a 'NUL' termination byte."))
-        case i  => Attempt.successful(DecodeResult(bits.take(i * 8L), bits.drop(i * 8L + 8L)))
-      }
-  }
-).withToString("cstring")
+val cstring: Codec[String] = nulTerminatedString(ascii)
+
+/** String codec that encodes strings with a trailing `NUL` termination byte and decodes strings up to the next
+  * `NUL` termination byte.
+  * It fails to decode if the bit vector ends before a `NUL` termination byte can be found.
+  */
+def nulTerminatedString(stringCodec: Codec[String]): Codec[String] =
+  filtered(
+    stringCodec,
+    new Codec[BitVector]:
+      val nul = BitVector.lowByte
+      override def sizeBound: SizeBound = SizeBound.unknown
+      override def encode(bits: BitVector): Attempt[BitVector] = Attempt.successful(bits ++ nul)
+      override def decode(bits: BitVector): Attempt[DecodeResult[BitVector]] =
+        bits.bytes.indexOfSlice(nul.bytes) match
+          case -1 => Attempt.failure(Err("Does not contain a 'NUL' termination byte."))
+          case i  => Attempt.successful(DecodeResult(bits.take(i * 8L), bits.drop(i * 8L + 8L)))
+  ).withToString(s"nulTerminatedString($stringCodec)")
 
 /** String codec that uses the given `Charset` and prefixes the encoded string by the byte size
   * in a 32-bit 2s complement big endian field.

unitTests/shared/src/test/scala/scodec/codecs/StringCodecTest.scala

@@ -67,6 +67,10 @@ class StringCodecTest extends CodecSuite:
     )
   }
 
+  test("nulTerminatedString - roundtrip") {
+    roundtripAll(nulTerminatedString(utf8), Seq("test", "", "withλ"))
+  }
+
   test("utf8 - roundtrip") {
     roundtripAll(utf8, Seq("test", "", "with\ttabs", "withλ"))
   }