Write files atomically

Signed-off-by: Graham <gpe@openrs2.dev>

asm/src/main/java/dev/openrs2/asm/classpath/Library.kt

@@ -3,6 +3,7 @@ package dev.openrs2.asm.classpath
 import com.github.michaelbull.logging.InlineLogger
 import dev.openrs2.asm.io.LibraryReader
 import dev.openrs2.asm.io.LibraryWriter
+import dev.openrs2.util.io.useAtomicOutputStream
 import org.objectweb.asm.tree.ClassNode
 import java.nio.file.Files
 import java.nio.file.Path
@@ -47,7 +48,7 @@ class Library(val name: String) : Iterable<ClassNode> {
     fun write(path: Path, writer: LibraryWriter, classPath: ClassPath) {
         logger.info { "Writing library $path" }
 
-        Files.newOutputStream(path).use { output ->
+        path.useAtomicOutputStream { output ->
             writer.write(output, classPath, classes.values)
         }
     }

crypto/build.gradle.kts

@@ -9,6 +9,8 @@ dependencies {
     api("org.bouncycastle:bcpkix-jdk15on:${Versions.bouncyCastlePkix}")
     api("org.bouncycastle:bcprov-jdk15on:${Versions.bouncyCastleProvider}")
 
+    implementation(project(":util"))
+
     testImplementation("com.google.jimfs:jimfs:${Versions.jimfs}")
 }
 

crypto/src/main/java/dev/openrs2/crypto/Pkcs12KeyStore.kt

@@ -1,5 +1,6 @@
 package dev.openrs2.crypto
 
+import dev.openrs2.util.io.useAtomicOutputStream
 import jdk.security.jarsigner.JarSigner
 import org.bouncycastle.asn1.nist.NISTObjectIdentifiers
 import org.bouncycastle.asn1.pkcs.PKCSObjectIdentifiers
@@ -66,7 +67,7 @@ class Pkcs12KeyStore private constructor(privateKeyEntry: KeyStore.PrivateKeyEnt
                 val entry = createPrivateKeyEntry(signerName)
                 keyStore.setEntry(ALIAS, entry, PASSWORD_PARAMETER)
 
-                Files.newOutputStream(path).use { output ->
+                path.useAtomicOutputStream { output ->
                     keyStore.store(output, PASSWORD_CHARS)
                 }
 

crypto/src/main/java/dev/openrs2/crypto/Rsa.kt

@@ -1,5 +1,6 @@
 package dev.openrs2.crypto
 
+import dev.openrs2.util.io.useAtomicBufferedWriter
 import io.netty.buffer.ByteBuf
 import io.netty.buffer.ByteBufUtil
 import io.netty.buffer.Unpooled
@@ -201,8 +202,10 @@ object Rsa {
     }
 
     private fun writeSinglePemObject(path: Path, type: String, content: ByteArray) {
-        PemWriter(Files.newBufferedWriter(path)).use {
+        path.useAtomicBufferedWriter { writer ->
+            PemWriter(writer).use {
                 it.writeObject(PemObject(type, content))
             }
         }
+    }
 }

decompiler/src/main/java/dev/openrs2/decompiler/DecompilerIo.kt

@@ -1,5 +1,6 @@
 package dev.openrs2.decompiler
 
+import dev.openrs2.util.io.useAtomicBufferedWriter
 import org.jetbrains.java.decompiler.main.extern.IBytecodeProvider
 import org.jetbrains.java.decompiler.main.extern.IResultSaver
 import java.io.Closeable
@@ -64,7 +65,7 @@ class DecompilerIo(private val destination: Path) : IBytecodeProvider, IResultSa
     ) {
         val p = destination.resolve(entryName)
         Files.createDirectories(p.parent)
-        Files.newBufferedWriter(p).use {
+        p.useAtomicBufferedWriter {
             it.write(content)
         }
     }

deob-processor/src/main/java/dev/openrs2/deob/processor/NameMapProcessor.kt

@@ -11,6 +11,7 @@ import dev.openrs2.deob.annotation.OriginalMember
 import dev.openrs2.deob.map.Field
 import dev.openrs2.deob.map.Method
 import dev.openrs2.deob.map.NameMap
+import dev.openrs2.util.io.useAtomicBufferedWriter
 import java.nio.file.Files
 import java.nio.file.Path
 import java.nio.file.Paths
@@ -106,7 +107,7 @@ class NameMapProcessor : AbstractProcessor() {
                 combinedMap = map
             }
 
-            Files.newBufferedWriter(mapPath).use { writer ->
+            mapPath.useAtomicBufferedWriter { writer ->
                 mapper.writeValue(writer, combinedMap)
             }
         }

util/src/main/java/dev/openrs2/util/io/PathExtensions.kt

@@ -0,0 +1,44 @@
+package dev.openrs2.util.io
+
+import java.io.BufferedWriter
+import java.io.OutputStream
+import java.nio.charset.Charset
+import java.nio.file.Files
+import java.nio.file.OpenOption
+import java.nio.file.Path
+import java.nio.file.StandardCopyOption
+
+inline fun <T> Path.atomicWrite(f: (Path) -> T): T {
+    val tempFile = Files.createTempFile(parent, ".$fileName", ".tmp")
+    try {
+        val result = f(tempFile)
+        Files.move(tempFile, this, StandardCopyOption.ATOMIC_MOVE, StandardCopyOption.REPLACE_EXISTING)
+        return result
+    } finally {
+        Files.deleteIfExists(tempFile)
+    }
+}
+
+inline fun <T> Path.useAtomicBufferedWriter(vararg options: OpenOption, f: (BufferedWriter) -> T): T {
+    return atomicWrite { path ->
+        Files.newBufferedWriter(path, *options).use { writer ->
+            f(writer)
+        }
+    }
+}
+
+inline fun <T> Path.useAtomicBufferedWriter(cs: Charset, vararg options: OpenOption, f: (BufferedWriter) -> T): T {
+    return atomicWrite { path ->
+        Files.newBufferedWriter(path, cs, *options).use { writer ->
+            f(writer)
+        }
+    }
+}
+
+inline fun <T> Path.useAtomicOutputStream(vararg options: OpenOption, f: (OutputStream) -> T): T {
+    return atomicWrite { path ->
+        Files.newOutputStream(path, *options).use { output ->
+            f(output)
+        }
+    }
+}