graalvm/elide.runtime.gvm.internals.vfs/EmbeddedGuestVFSImpl

EmbeddedGuestVFSImpl

@Requires(property = "elide.gvm.vfs.enabled", notEquals = "false")
@Requires(property = "elide.gvm.vfs.mode", notEquals = "HOST")
class EmbeddedGuestVFSImpl : AbstractDelegateVFS<EmbeddedGuestVFSImpl>

VFS: Embedded.

This VFS implementation uses an in-memory file-system, loaded from a VFS filesystem bundle file. Bundle files can be plain tarballs, compressed tarballs, or they can make use of Elide's optimized production bundle format. In each case the embedded VFS implementation will load the bundle, initialize a Jimfs file-system with the decoded and verified contents, and then satisfy guest I/O requests with the resulting file-system.

Bundle formats

VFS bundle files can be plain tarballs, compressed tarballs, or they can make use of Elide's optimized production bundle format. Plain or compressed tarballs are ideal for quick development cycles, and Elide's production bundle format is optimal for production use.

Plain/compressed tarballs

Plain and compressed tarballs are supported by the embedded VFS implementation. The bundle file is expected to be a regular TAR file, with a .tar extension, unless compression is in use, in which case the file extension is expected to be .tar.gz. The tarball models the root of the file system.

Elide's bundle format

The bundle format used internally by Elide is also based on a plain (un-compressed) tarball, with a .evfs extension and the following structure:

  • metadata.cfb: Compressed Flatbuffer with metadata about the enclosed file-system

  • fsdata.tar.lz4: LZ4-compressed tarball containing the actual file-system data

  • artifacts.json.gz: GZIP-compressed JSON file containing a list of artifacts used to build the bundle

The metadata.cfb file explains the file tree to the runtime, and the fsdata.tar.lz4 file contains the actual data for each file. artifacts.json.gz is not used by the runtime, and is only present for easy debugging. Because a bundle is a valid tarball, it can be extracted with standard tools, or in OS GUIs by renaming to the .tar extension.

Parameters

config

Effective VFS configuration which should be applied to this instance.

backing

Backing file-system implementation which should receive allowable I/O calls.

tree

Tree of resolved file-system metadata.

deferred

Whether to defer reads/copies into the VFS; defaults to true.

Types

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data class Builder(var deferred: Boolean = Settings.DEFAULT_DEFERRED_READS, var readOnly: Boolean = true, var caseSensitive: Boolean = true, var enableSymlinks: Boolean = false, var root: String = ROOT_SYSTEM_DEFAULT, var workingDirectory: String = DEFAULT_CWD, var policy: GuestVFSPolicy = GuestVFSPolicy.DEFAULTS, var registry: MutableMap<String, EmbeddedGuestVFSImpl.VfsObjectInfo> = mutableMapOf(), var bundleMapping: MutableMap<Int, EmbeddedGuestVFSImpl.BundleInfo> = mutableMapOf(), bundle: Pair<FilesystemInfo, FileSystem>? = null, paths: List<URI> = emptyList(), files: List<File> = emptyList(), zip: URI? = null, file: URI? = null) : AbstractBaseVFS.VFSBuilder<EmbeddedGuestVFSImpl>

Builder to configure and spawn new embedded VFS implementations.

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enum BundleFormat : Enum<EmbeddedGuestVFSImpl.BundleFormat>

Enumerates supported embedded VFS bundle formats.

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@JvmRecord
data class BundleInfo(val id: Int, val location: String, val type: EmbeddedGuestVFSImpl.BundleFormat) : Record
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object EmbeddedVFSFactory : AbstractBaseVFS.VFSFactory<EmbeddedGuestVFSImpl, EmbeddedGuestVFSImpl.Builder>

Factory to create new embedded VFS implementations.

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@JvmRecord
data class VfsDirectory(val path: String, val bundle: Int, val info: Directory) : Record, EmbeddedGuestVFSImpl.VfsObjectInfo
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@JvmRecord
data class VfsFileInfo(val path: String, val bundle: Int, val info: File) : Record, EmbeddedGuestVFSImpl.VfsObjectInfo
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sealed interface VfsObjectInfo

Properties

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open override val compound: Boolean
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open override val deletable: Boolean
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open override val host: Boolean
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open override val logging: Logger

Subclass API: Logging.

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open override val supportsSymlinks: Boolean
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open override val virtual: Boolean
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open override val writable: Boolean

Functions

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open override fun allowsHostFileAccess(): Boolean
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open override fun allowsHostSocketAccess(): Boolean
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open override fun checkAccess(path: Path, modes: MutableSet<out AccessMode>, vararg linkOptions: LinkOption)
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fun checkPolicy(type: AccessType, domain: AccessDomain, path: Path, scope: AccessScope = AccessScope.UNSPECIFIED): AccessResponse
open override fun checkPolicy(request: AccessRequest): AccessResponse

Subclass API: Policy check.

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open override fun close()
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open override fun copy(source: Path, target: Path, vararg options: CopyOption?)
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open override fun createDirectory(dir: Path, vararg attrs: FileAttribute<*>)
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open override fun createLink(link: Path, existing: Path)
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open override fun createSymbolicLink(link: Path, target: Path, vararg attrs: FileAttribute<*>?)
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open override fun delete(path: Path)
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open override fun existsAny(path: Path): Boolean
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open override fun getEncoding(path: Path): Charset
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open override fun getMimeType(path: Path): String?
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open override fun getPath(vararg segments: String): Path

Subclass API: Parse a path.

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open override fun getPathSeparator(): String
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open override fun getSeparator(): String
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open override fun getTempDirectory(): Path
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open override fun isSameFile(path1: Path, path2: Path, vararg options: LinkOption): Boolean
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open override fun move(source: Path, target: Path, vararg options: CopyOption?)
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open override fun newByteChannel(path: Path, options: MutableSet<out OpenOption>, vararg attrs: FileAttribute<*>): SeekableByteChannel
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open override fun newDirectoryStream(dir: Path, filter: DirectoryStream.Filter<in Path>): DirectoryStream<Path>
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open override fun parsePath(uri: URI): Path
open override fun parsePath(path: String): Path
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open override fun readAttributes(path: Path, attributes: String, vararg options: LinkOption): MutableMap<String, Any>
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open override fun readStream(path: Path, vararg options: OpenOption): InputStream

Subclass API: Read a file.

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open override fun readSymbolicLink(link: Path): Path
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open override fun setAttribute(path: Path, attribute: String, value: Any, vararg options: LinkOption)
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open override fun setCurrentWorkingDirectory(currentWorkingDirectory: Path)
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open override fun toAbsolutePath(path: Path): Path
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open override fun toRealPath(path: Path, vararg linkOptions: LinkOption): Path
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open override fun writeStream(path: Path, vararg options: OpenOption): OutputStream

Subclass API: Write a file.