add QID class

1 files changed, 95 insertions, 0 deletions

diff --git a/src/main/kotlin/QID.kt b/src/main/kotlin/QID.kt
new file mode 100644
index 0000000..93f9f68
--- /dev/null
+++ b/src/main/kotlin/QID.kt
@@ -0,0 +1,95 @@
+/**
+ * This class holds information about a single QID.
+ */
+class QID {
+    /**
+     * Does the QID represent a directory?
+     */
+    val isDirectory get() = getIsDirectory()
+
+    /**
+     * Does the QID represent an append-only file?
+     */
+    val isAppendOnly get() = getIsAppendOnly()
+
+    /**
+     * Does the QID represent an exclusive-use file?
+     */
+    val isExclusive get() = getIsExclusive()
+
+    /**
+     * Does the QID represent a temporary file?
+     */
+    val isTemporary get() = getIsTemporary()
+
+    /**
+     * The QID type.
+     */
+    val type: UByte
+
+    /**
+     * The QID file version.
+     */
+    val version: UInt
+
+    /**
+     * The QID path.
+     */
+    val path: ULong
+
+    /**
+     * Constructor for a QID with separate fields. See the `stat(5)` manual page for more information about [type],
+     * [version], and [path].
+     *
+     * @param type The QID type.
+     * @param version The QID file version.
+     * @param path The QID path.
+     */
+    constructor(type: UByte, version: UInt, path: ULong) {
+        this.type = type
+        this.version = version
+        this.path = path
+    }
+
+    /**
+     * Constructor for raw QID data. Only the first 13 elements are read.
+     *
+     * @param raw The raw QID data.
+     * @throws IllegalArgumentException if [raw] does not have at least 13 elements.
+     */
+    constructor(raw: Array<UByte>) {
+        require(raw.size >= 13)
+        this.type = raw.first()
+        val rawVersion = raw.slice(1..4)
+        val rawPath = raw.slice(5..12)
+
+        // TODO: find a way to use InMessage's convInteger method here
+        var version = 0u
+        for (i in 0..rawVersion.size) {
+            version += rawVersion[i].toUInt().shl(i*8)
+        }
+        this.version = version
+
+        var path: ULong = 0u
+        for (i in 0..rawPath.size) {
+            path += rawPath[i].toULong().shl(i*8)
+        }
+        this.path = path
+    }
+
+    private fun getIsDirectory(): Boolean {
+        return this.type.and(0x80.toUByte()) != 0u.toUByte()
+    }
+
+    private fun getIsAppendOnly(): Boolean {
+        return this.type.and(0x40.toUByte()) != 0u.toUByte()
+    }
+
+    private fun getIsExclusive(): Boolean {
+        return this.type.and(0x20.toUByte()) != 0u.toUByte()
+    }
+
+    private fun getIsTemporary(): Boolean {
+        return this.type.and(0x04.toUByte()) != 0u.toUByte()
+    }
+}
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