Deny cyclic FSFolders #3

Merged
cyclane merged 2 commits from explicit-cyclic-logic into main 2024-01-07 14:56:17 +00:00
4 changed files with 97 additions and 13 deletions

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@ -1,21 +1,30 @@
package filesystem package filesystem
import java.nio.file.FileAlreadyExistsException import java.nio.file.FileAlreadyExistsException
import java.nio.file.FileSystemException
import java.nio.file.Files import java.nio.file.Files
import java.nio.file.Path import java.nio.file.Path
class FSCreator { class FSCreator {
/** /**
* Create entry, leaving existing folders' contents, but overwriting existing files. * Create entry, leaving existing folders' contents, but overwriting existing files.
* @throws CyclicFolderException Cyclic folders cannot be created.
*/ */
@Throws(FileSystemException::class) @Throws(CyclicFolderException::class)
fun create( fun create(
entryToCreate: FSEntry, entryToCreate: FSEntry,
destination: String, destination: String,
) { ) {
val queue = ArrayDeque<Pair<FSEntry, Path>>() // No point in running anything if we know the input is invalid.
queue.add(entryToCreate to Path.of(destination)) if (entryToCreate is FSFolder && entryToCreate.isCyclic()) {
throw CyclicFolderException()
}
val queue =
ArrayDeque(
listOf(
entryToCreate to Path.of(destination),
),
)
while (queue.isNotEmpty()) { while (queue.isNotEmpty()) {
val (entry, dest) = queue.removeFirst() val (entry, dest) = queue.removeFirst()
@ -33,4 +42,6 @@ class FSCreator {
} }
} }
} }
} }
class CyclicFolderException : Exception("Cyclic FSFolders are not supported")

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@ -6,4 +6,22 @@ sealed class FSEntry(val name: String)
class FSFile(name: String, val content: String) : FSEntry(name) class FSFile(name: String, val content: String) : FSEntry(name)
class FSFolder(name: String, val entries: List<FSEntry>) : FSEntry(name) class FSFolder(name: String, val entries: List<FSEntry>) : FSEntry(name) {
/**
* Check whether a folder is cyclic.
*/
fun isCyclic(): Boolean {
val seen = listOf(this).toHashSet<FSEntry>()
val queue = ArrayDeque(entries)
while (queue.isNotEmpty()) {
val entry = queue.removeFirst()
if (!seen.add(entry)) {
return true
}
if (entry is FSFolder) {
queue.addAll(entry.entries)
}
}
return false
}
}

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@ -1,7 +1,6 @@
package filesystem package filesystem
import org.junit.jupiter.api.* import org.junit.jupiter.api.*
import java.nio.file.FileSystemException
import java.nio.file.Files import java.nio.file.Files
import java.nio.file.Path import java.nio.file.Path
import java.util.concurrent.TimeUnit import java.util.concurrent.TimeUnit
@ -81,7 +80,7 @@ class FSCreatorTest {
FSFile("hi", "hi"), FSFile("hi", "hi"),
), ),
), ),
FSFolder("another-folder", listOf()), FSFolder("folder", listOf()),
FSFile("1.txt", "One!"), FSFile("1.txt", "One!"),
FSFile("2.txt", "Two!"), FSFile("2.txt", "Two!"),
), ),
@ -95,7 +94,7 @@ class FSCreatorTest {
"folder", "folder",
listOf( listOf(
FSFolder( FSFolder(
"another-folder", "folder",
listOf( listOf(
FSFolder( FSFolder(
"secrets", "secrets",
@ -113,22 +112,36 @@ class FSCreatorTest {
) )
} }
assertEquals("hi", Files.readString(Path.of("_tmp/folder/sub-folder/hi"))) assertEquals("hi", Files.readString(Path.of("_tmp/folder/sub-folder/hi")))
assertEquals("P4ssW0rd", Files.readString(Path.of("_tmp/folder/another-folder/secrets/secret"))) assertEquals("P4ssW0rd", Files.readString(Path.of("_tmp/folder/folder/secrets/secret")))
assertEquals("One is a good number", Files.readString(Path.of("_tmp/folder/1.txt"))) assertEquals("One is a good number", Files.readString(Path.of("_tmp/folder/1.txt")))
assertEquals("Two!", Files.readString(Path.of("_tmp/folder/2.txt"))) assertEquals("Two!", Files.readString(Path.of("_tmp/folder/2.txt")))
assertEquals("Three!", Files.readString(Path.of("_tmp/folder/3.txt"))) assertEquals("Three!", Files.readString(Path.of("_tmp/folder/3.txt")))
} }
@Test @Test
@Timeout(500, unit = TimeUnit.MILLISECONDS) // in case implementation starts trying to handle recursion @Timeout(500, unit = TimeUnit.MILLISECONDS) // in case implementation starts trying to handle cyclic folders
fun `create throws on recursive folder`() { fun `create throws on cyclic folder`() {
val files = mutableListOf<FSEntry>() val files = mutableListOf<FSEntry>()
val folder = FSFolder("folder", files) val folder = FSFolder("folder", files)
files.add(folder) files.add(folder)
assertThrows<FileSystemException> { assertThrows<CyclicFolderException> {
creator.create(folder, "_tmp") creator.create(folder, "_tmp")
} }
} }
@Test
@Timeout(500, unit = TimeUnit.MILLISECONDS)
fun `create throws on long cyclic folder`() {
val files = mutableListOf<FSEntry>()
val folder1 = FSFolder("folder", files)
val folder2 = FSFolder("folder2", listOf(folder1))
val folder3 = FSFolder("folder3", listOf(folder2))
val folder4 = FSFolder("folder4", listOf(folder3))
files.add(folder4)
assertThrows<CyclicFolderException> {
creator.create(folder4, "_tmp")
}
}
} }
fun deleteRecursive(path: Path) { fun deleteRecursive(path: Path) {

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@ -0,0 +1,42 @@
package filesystem
import org.junit.jupiter.api.Test
import kotlin.test.assertFalse
import kotlin.test.assertTrue
class FSEntryTest {
@Test
fun `non-cyclic folder`() {
val folder =
FSFolder(
"folder",
listOf(
FSFolder("folder", listOf()),
FSFile("text.txt", "Hello!"),
),
)
assertFalse(folder.isCyclic())
}
@Test
fun `cyclic folder`() {
val files = mutableListOf<FSEntry>()
val folder = FSFolder("folder", files)
files.add(folder)
assertTrue(folder.isCyclic())
}
@Test
fun `long cyclic folder`() {
val files = mutableListOf<FSEntry>()
val folder1 = FSFolder("folder", files)
val folder2 = FSFolder("folder2", listOf(folder1))
val folder3 = FSFolder("folder3", listOf(folder2))
val folder4 = FSFolder("folder4", listOf(folder3))
files.add(folder4)
assertTrue(folder1.isCyclic())
assertTrue(folder2.isCyclic())
assertTrue(folder3.isCyclic())
assertTrue(folder4.isCyclic())
}
}