Initial implementations

2023-12-29 18:43:54 +06:00
commit 6ebf969d35
24 changed files with 991 additions and 0 deletions
--- a/src/main/kotlin/ziputils/CentralDirectoryFileHeader.kt
+++ b/src/main/kotlin/ziputils/CentralDirectoryFileHeader.kt
@@ -0,0 +1,93 @@
+package ziputils
+
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+
+internal class CentralDirectoryFileHeader(
+    val compressedSize: UInt,
+    val uncompressedSize: UInt,
+    val nameLength: UShort,
+    val extraFieldLength: UShort,
+    val commentLength: UShort,
+    val disk: UShort,
+    val localHeaderOffset: UInt,
+    val fileName: String,
+    val extraFieldRecords: List<ExtraFieldRecord>
+) {
+    val size: Int
+        get() = SIZE + nameLength.toInt() + extraFieldLength.toInt() + commentLength.toInt()
+
+    companion object {
+        const val SIGNATURE = 0x02014b50U
+        const val SIZE = 46
+
+        /**
+         * Create CentralDirectoryFileHeader from raw byte data.
+         * @throws InvalidDataException provided ByteArray is not a supported CEN.
+         */
+        @Throws(InvalidDataException::class)
+        fun fromByteArray(data: ByteArray, offset: Int): CentralDirectoryFileHeader {
+            if (data.size - offset < SIZE) {
+                throw InvalidDataException("CEN must be at least 46 bytes")
+            }
+            val buf = ByteBuffer.wrap(data, offset, 46).order(ByteOrder.LITTLE_ENDIAN)
+            if (buf.getInt().toUInt() != SIGNATURE) {
+                throw InvalidSignatureException("Invalid signature")
+            }
+
+            val extraFieldRecords = mutableListOf<ExtraFieldRecord>()
+            val nameLength = buf.getShort(offset + 28).toUShort()
+            buf.position(offset + 20)
+            val cen = CentralDirectoryFileHeader(
+                compressedSize = buf.getInt().toUInt(),
+                uncompressedSize = buf.getInt().toUInt(),
+                nameLength = nameLength
+                    .also { buf.position(offset + 30) },
+                extraFieldLength = buf.getShort().toUShort(),
+                commentLength = buf.getShort().toUShort(),
+                disk = buf.getShort().toUShort()
+                    .also { buf.position(offset + 42) },
+                localHeaderOffset = buf.getInt().toUInt(),
+                fileName = String(data.sliceArray(offset + SIZE..<offset + SIZE + nameLength.toInt())),
+                extraFieldRecords = extraFieldRecords
+            )
+            if (data.size - offset < cen.size) {
+                throw InvalidDataException("CEN is too short")
+            }
+
+            // Parse extra field records
+            val extraFieldsBuf = ByteBuffer.wrap(
+                data, offset + SIZE + cen.nameLength.toInt(), cen.extraFieldLength.toInt()
+            ).order(ByteOrder.LITTLE_ENDIAN)
+            while (extraFieldsBuf.remaining() > 0) {
+                val id = extraFieldsBuf.getShort().toUShort()
+                val size = extraFieldsBuf.getShort().toUShort()
+                extraFieldRecords.add(when (id) {
+                    Zip64ExtraFieldRecord.ID -> {
+                        Zip64ExtraFieldRecord(
+                            size,
+                            if (cen.uncompressedSize == 0xffffffffU) {
+                                extraFieldsBuf.getLong().toULong()
+                            } else null,
+                            if (cen.compressedSize == 0xffffffffU) {
+                                extraFieldsBuf.getLong().toULong()
+                            } else null,
+                            if (cen.localHeaderOffset == 0xffffffffU) {
+                                extraFieldsBuf.getLong().toULong()
+                            } else null,
+                            if (cen.disk == 0xffffU.toUShort()) {
+                                extraFieldsBuf.getInt().toUInt()
+                            } else null
+                        )
+                    }
+                    else -> {
+                        extraFieldsBuf.position(extraFieldsBuf.position() + size.toInt())
+                        ExtraFieldRecord(id, size)
+                    }
+                })
+            }
+
+            return cen
+        }
+    }
+}