[2.0.x] fix: Ensure resources are copied atomically (#9234)

Bumps io to released 1.12.0 which contains the atomic-write changes
to IO.copyFile, IO.transfer(InputStream, File), and IO.jar/zip.
ActionCacheStore.putBlob now uses IO.transfer instead of duplicating
staging logic.

Co-authored-by: Anatolii Kmetiuk <anatoliykmetyuk@gmail.com>

main-actions/src/main/scala/sbt/Pkg.scala

@@ -226,9 +226,7 @@ object Pkg:
     val path = jar.getAbsolutePath
     log.debug("Packaging " + path + " ...")
     if (jar.exists)
-      if (jar.isFile)
-        IO.delete(jar)
-      else
+      if (!jar.isFile)
         sys.error(path + " exists, but is not a regular file")
     log.debug(sourcesDebugString(sources))
     IO.jar(sources, jar, manifest, time)

util-cache/src/main/scala/sbt/util/ActionCacheStore.scala

@@ -1,6 +1,6 @@
 package sbt.util
 
-import java.io.{ IOException, RandomAccessFile }
+import java.io.{ ByteArrayInputStream, IOException }
 import java.nio.ByteBuffer
 import java.nio.file.{
   Files,
@@ -240,23 +240,30 @@ class DiskActionCacheStore(base: Path, converter: FileConverter) extends Abstrac
 
   def putBlob(input: InputStream, digest: Digest): Path =
     val casFile = toCasFile(digest)
-    IO.transfer(input, casFile.toFile())
-    casFile
+    if isCompleteBlob(casFile, digest) then casFile
+    else
+      IO.transfer(input, casFile.toFile())
+      casFile
 
   def putBlob(input: ByteBuffer, digest: Digest): Path =
     val casFile = toCasFile(digest)
-    input.flip()
-    val file = RandomAccessFile(casFile.toFile(), "rw")
-    try
-      file.getChannel().write(input)
+    if isCompleteBlob(casFile, digest) then casFile
+    else
+      input.flip()
+      val bytes = new Array[Byte](input.remaining())
+      input.get(bytes)
+      IO.transfer(new ByteArrayInputStream(bytes), casFile.toFile())
       casFile
-    finally file.close()
+
+  private def isCompleteBlob(casFile: Path, digest: Digest): Boolean =
+    try Files.exists(casFile) && Digest.sameDigest(casFile, digest)
+    catch case _: NoSuchFileException => false
 
   private def getBlobs(refs: Seq[HashedVirtualFileRef]): Seq[VirtualFile] =
     refs.flatMap: r =>
       try
         val casFile = toCasFile(Digest(r))
-        if casFile.toFile().exists then
+        if isCompleteBlob(casFile, Digest(r)) then
           r match
             case p: PathBasedFile => Some(p)
             case _ =>
@@ -270,7 +277,7 @@ class DiskActionCacheStore(base: Path, converter: FileConverter) extends Abstrac
     refs.flatMap: r =>
       try
         val casFile = toCasFile(Digest(r))
-        if casFile.toFile().exists then
+        if isCompleteBlob(casFile, Digest(r)) then
           // println(s"syncBlobs: $casFile exists for $r")
           Some(syncFile(r, casFile, outputDirectory))
         else None
@@ -384,7 +391,7 @@ class DiskActionCacheStore(base: Path, converter: FileConverter) extends Abstrac
     refs.flatMap: r =>
       try
         val casFile = toCasFile(Digest(r))
-        if casFile.toFile().exists then Some(r)
+        if isCompleteBlob(casFile, Digest(r)) then Some(r)
         else None
       // Digest(r) can throw NoSuchFileException
       catch case _: NoSuchFileException => None

util-cache/src/test/scala/sbt/util/ActionCacheTest.scala

@@ -1,5 +1,8 @@
 package sbt.util
 
+import java.io.{ IOException, InputStream }
+import java.nio.charset.StandardCharsets
+
 import sbt.internal.util.CacheEventLog
 import sbt.internal.util.StringVirtualFile1
 import sbt.io.IO
@@ -27,6 +30,32 @@ object ActionCacheTest extends BasicTestSuite:
   test("Disk cache can hold a blob"):
     withDiskCache(testHoldBlob)
 
+  test("Disk cache rejects truncated blobs"):
+    withDiskCache: cache =>
+      val blob = StringVirtualFile1("a.txt", "hello")
+      val digest = Digest(blob)
+      val ref: HashedVirtualFileRef = blob
+      val casFile = cache.toCasFile(digest)
+      Files.writeString(casFile, "he", StandardCharsets.UTF_8)
+
+      assert(cache.findBlobs(Seq(ref)).isEmpty)
+      cache.putBlobs(Seq(blob))
+      assert(cache.findBlobs(Seq(ref)) == Seq(ref))
+      assert(Files.readString(casFile, StandardCharsets.UTF_8) == "hello")
+
+  test("Disk cache removes staged blobs when writes fail"):
+    withDiskCache: cache =>
+      val blob = StringVirtualFile1("a.txt", "hello")
+      val digest = Digest(blob)
+      val casFile = cache.toCasFile(digest)
+      try
+        cache.putBlob(FailingInputStream("hello".getBytes(StandardCharsets.UTF_8), 2), digest)
+        assert(false, "expected blob write to fail")
+      catch case _: IOException => ()
+
+      assert(!Files.exists(casFile))
+      assert(Files.list(cache.casBase).toArray.isEmpty)
+
   def testHoldBlob(cache: ActionCacheStore): Unit =
     IO.withTemporaryDirectory: tempDir =>
       val in = StringVirtualFile1(s"$tempDir/a.txt", "foo")
@@ -35,6 +64,16 @@ object ActionCacheTest extends BasicTestSuite:
       val actual = cache.syncBlobs(hashRefs, tempDir.toPath()).head
       assert(actual.getFileName().toString() == "a.txt")
 
+  final class FailingInputStream(bytes: Array[Byte], failAt: Int) extends InputStream:
+    private var index = 0
+    override def read(): Int =
+      if index == failAt then throw IOException("simulated interrupted write")
+      else if index >= bytes.length then -1
+      else
+        val b = bytes(index) & 0xff
+        index += 1
+        b
+
   test("In-memory cache can hold action value"):
     withInMemoryCache(testActionCacheBasic)