1 files changed, 30 insertions, 0 deletions
diff --git a/src/lib-compression/iostream-lz4.h b/src/lib-compression/iostream-lz4.h
new file mode 100644
index 0000000..a0897f5
--- /dev/null
+++ b/src/lib-compression/iostream-lz4.h
@@ -0,0 +1,30 @@
+#ifndef IOSTREAM_LZ4_H
+#define IOSTREAM_LZ4_H
+
+/*
+   Dovecot's LZ4 compressed files contain:
+
+   IOSTREAM_LZ4_HEADER
+   n x (4 byte big-endian: compressed chunk length, compressed chunk)
+*/
+
+#define IOSTREAM_LZ4_MAGIC "Dovecot-LZ4\x0d\x2a\x9b\xc5"
+#define IOSTREAM_LZ4_MAGIC_LEN (sizeof(IOSTREAM_LZ4_MAGIC)-1)
+
+struct iostream_lz4_header {
+	unsigned char magic[IOSTREAM_LZ4_MAGIC_LEN];
+	/* OSTREAM_LZ4_CHUNK_SIZE in big-endian */
+	unsigned char max_uncompressed_chunk_size[4];
+};
+
+/* How large chunks we're buffering into memory before compressing them */
+#define OSTREAM_LZ4_CHUNK_SIZE (1024*64)
+/* How large chunks we allow in input data before returning a failure.
+   This must be at least OSTREAM_LZ4_CHUNK_SIZE, but for future compatibility
+   should be somewhat higher (but not too high to avoid wasting memory for
+   corrupted files). */
+#define ISTREAM_LZ4_CHUNK_SIZE (1024*1024)
+
+#define IOSTREAM_LZ4_CHUNK_PREFIX_LEN 4 /* big-endian size of chunk */
+
+#endif