Convert munmap operation to JNI

native/src/nativeMain/kotlin/moe/tarsin/ehviewer/mmap.kt

@@ -15,13 +15,23 @@ import platform.posix.PROT_READ
 import platform.posix.PROT_WRITE
 import platform.posix.errno
 import platform.posix.mmap
-import platform.posix.strerror
+import platform.posix.munmap
 
 @OptIn(UnsafeNumber::class)
 @Suppress("UNUSED_PARAMETER")
 @CName("Java_com_hippo_Native_mapFd")
 fun mapFd(env: CPointer<JNIEnvVar>, clazz: jclass, fd: jint, capability: jlong): jobject {
     val result = mmap(null, capability.tosize_t(), PROT_READ or PROT_WRITE, MAP_PRIVATE, fd, 0)
-    result ?: Warn("mmap call with fd:${fd} capability:${capability} failed!, error:${strerror(errno)}")
+    result ?: Warn("mmap call with fd:${fd} capability:${capability} failed!, errno:${errno}")
     return result?.let { env.newDirectByteBuffer(result, capability) } ?: interpretCPointer(nativeNullPtr)!!
 }
+
+@Suppress("UNUSED_PARAMETER")
+@OptIn(UnsafeNumber::class)
+@CName("Java_com_hippo_Native_unmapDirectByteBuffer")
+fun unmapFd(env: CPointer<JNIEnvVar>, clazz: jclass, buffer: jobject) {
+    val addr = env.getDirectBufferAddress(buffer)
+    val size = env.getDirectBufferCapacity(buffer)
+    val result = munmap(addr, size.tosize_t())
+    if (result != 0) Warn("mmap call with addr:${addr} size:${size} failed!, errno:${errno}")
+}