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file2: platform-independent walk #2541

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merged 2 commits into from
Aug 6, 2021
Merged

file2: platform-independent walk #2541

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0e4f84a
Fix walk for platforms without fileKey
armanbilge Aug 6, 2021
6b87a2a
Implement isSameFile, generalize walk
armanbilge Aug 6, 2021
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3 changes: 3 additions & 0 deletions io/js/src/main/scala/fs2/io/file/FilesPlatform.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -228,6 +228,9 @@ private[fs2] trait FilesCompanionPlatform {
override def isWritable(path: Path): F[Boolean] =
access(path, fsMod.constants.W_OK)

override def isSameFile(path1: Path, path2: Path): F[Boolean] =
F.pure(path1.absolute == path2.absolute)

override def list(path: Path): Stream[F, Path] =
Stream
.bracket(F.fromPromise(F.delay(fsPromisesMod.opendir(path.toString))))(dir =>
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3 changes: 3 additions & 0 deletions io/jvm/src/main/scala/fs2/io/file/FilesPlatform.scala
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Expand Up @@ -233,6 +233,9 @@ private[file] trait FilesCompanionPlatform {
def isWritable(path: Path): F[Boolean] =
Sync[F].delay(JFiles.isWritable(path.toNioPath))

def isSameFile(path1: Path, path2: Path): F[Boolean] =
Sync[F].blocking(JFiles.isSameFile(path1.toNioPath, path2.toNioPath))

def list(path: Path): Stream[F, Path] =
_runJavaCollectionResource[JStream[JPath]](
Sync[F].blocking(JFiles.list(path.toNioPath)),
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38 changes: 25 additions & 13 deletions io/shared/src/main/scala/fs2/io/file/Files.scala
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Expand Up @@ -29,6 +29,7 @@ import cats.effect.std.Hotswap
import cats.syntax.all._

import scala.concurrent.duration._
import cats.Traverse

/** Provides operations related to working with files in the effect `F`.
*
Expand Down Expand Up @@ -136,6 +137,8 @@ sealed trait Files[F[_]] extends FilesPlatform[F] {
def isSymbolicLink(path: Path): F[Boolean]
def isWritable(path: Path): F[Boolean]

def isSameFile(path1: Path, path2: Path): F[Boolean]

/** Gets the contents of the specified directory.
*/
def list(path: Path): Stream[F, Path]
Expand Down Expand Up @@ -299,7 +302,7 @@ sealed trait Files[F[_]] extends FilesPlatform[F] {
}

object Files extends FilesCompanionPlatform {
private[file] abstract class UnsealedFiles[F[_]: Async] extends Files[F] {
private[file] abstract class UnsealedFiles[F[_]](implicit F: Async[F]) extends Files[F] {

def readAll(path: Path, chunkSize: Int, flags: Flags): Stream[F, Byte] =
Stream.resource(readCursor(path, flags)).flatMap { cursor =>
Expand Down Expand Up @@ -345,31 +348,40 @@ object Files extends FilesCompanionPlatform {

def walk(start: Path, maxDepth: Int, followLinks: Boolean): Stream[F, Path] = {

def go(start: Path, maxDepth: Int, ancestry: List[Option[FileKey]]): Stream[F, Path] =
def go(start: Path, maxDepth: Int, ancestry: List[Either[Path, FileKey]]): Stream[F, Path] =
if (maxDepth == 0)
Stream.eval(exists(start, followLinks)).as(start)
else
Stream.eval(getBasicFileAttributes(start, followLinks = false)).flatMap { attr =>
(if (attr.isDirectory)
list(start)
.flatMap { path =>
go(path, maxDepth - 1, attr.fileKey :: ancestry)
go(path, maxDepth - 1, attr.fileKey.toRight(start) :: ancestry)
}
.recoverWith { case _ =>
Stream.empty
}
else if (attr.isSymbolicLink && followLinks)
Stream.eval(getBasicFileAttributes(start, followLinks = true)).flatMap { attr =>
if (!ancestry.contains(attr.fileKey))
list(start)
.flatMap { path =>
go(path, maxDepth - 1, attr.fileKey :: ancestry)
}
.recoverWith { case _ =>
Stream.empty
}
else
Stream.raiseError(new FileSystemLoopException(start.toString))
val fileKey = attr.fileKey
val isCycle = Traverse[List].existsM(ancestry) {
case Right(ancestorKey) => F.pure(fileKey.contains(ancestorKey))
case Left(ancestorPath) => isSameFile(start, ancestorPath)
}

Stream.eval(isCycle).flatMap { isCycle =>
if (!isCycle)
list(start)
.flatMap { path =>
go(path, maxDepth - 1, attr.fileKey.toRight(start) :: ancestry)
}
.recoverWith { case _ =>
Stream.empty
}
else
Stream.raiseError(new FileSystemLoopException(start.toString))
}

}
else
Stream.empty) ++ Stream.emit(start)
Expand Down