integrate lzma

[zpackage] / lzma / common / stream_flags_decoder.c

diff --git a/lzma/common/stream_flags_decoder.c b/lzma/common/stream_flags_decoder.c
new file mode 100644 (file)
index 0000000..1bc2f97
--- /dev/null
+++ b/lzma/common/stream_flags_decoder.c
@@ -0,0 +1,82 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       stream_flags_decoder.c
+/// \brief      Decodes Stream Header and Stream Footer from .xz files
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "stream_flags_common.h"
+
+
+static bool
+stream_flags_decode(lzma_stream_flags *options, const uint8_t *in)
+{
+       // Reserved bits must be unset.
+       if (in[0] != 0x00 || (in[1] & 0xF0))
+               return true;
+
+       options->version = 0;
+       options->check = in[1] & 0x0F;
+
+       return false;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_stream_header_decode(lzma_stream_flags *options, const uint8_t *in)
+{
+       // Magic
+       if (memcmp(in, lzma_header_magic, sizeof(lzma_header_magic)) != 0)
+               return LZMA_FORMAT_ERROR;
+
+       // Verify the CRC32 so we can distinguish between corrupt
+       // and unsupported files.
+       const uint32_t crc = lzma_crc32(in + sizeof(lzma_header_magic),
+                       LZMA_STREAM_FLAGS_SIZE, 0);
+       if (crc != unaligned_read32le(in + sizeof(lzma_header_magic)
+                       + LZMA_STREAM_FLAGS_SIZE))
+               return LZMA_DATA_ERROR;
+
+       // Stream Flags
+       if (stream_flags_decode(options, in + sizeof(lzma_header_magic)))
+               return LZMA_OPTIONS_ERROR;
+
+       // Set Backward Size to indicate unknown value. That way
+       // lzma_stream_flags_compare() can be used to compare Stream Header
+       // and Stream Footer while keeping it useful also for comparing
+       // two Stream Footers.
+       options->backward_size = LZMA_VLI_UNKNOWN;
+
+       return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_stream_footer_decode(lzma_stream_flags *options, const uint8_t *in)
+{
+       // Magic
+       if (memcmp(in + sizeof(uint32_t) * 2 + LZMA_STREAM_FLAGS_SIZE,
+                       lzma_footer_magic, sizeof(lzma_footer_magic)) != 0)
+               return LZMA_FORMAT_ERROR;
+
+       // CRC32
+       const uint32_t crc = lzma_crc32(in + sizeof(uint32_t),
+                       sizeof(uint32_t) + LZMA_STREAM_FLAGS_SIZE, 0);
+       if (crc != unaligned_read32le(in))
+               return LZMA_DATA_ERROR;
+
+       // Stream Flags
+       if (stream_flags_decode(options, in + sizeof(uint32_t) * 2))
+               return LZMA_OPTIONS_ERROR;
+
+       // Backward Size
+       options->backward_size = unaligned_read32le(in + sizeof(uint32_t));
+       options->backward_size = (options->backward_size + 1) * 4;
+
+       return LZMA_OK;
+}