X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Fauto_decoder.c;fp=lzma%2Fcommon%2Fauto_decoder.c;h=bf3550701fe6612d9fe3de3450fca07c9d424a84;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage

diff --git a/lzma/common/auto_decoder.c b/lzma/common/auto_decoder.c
new file mode 100644
index 0000000..bf35507
--- /dev/null
+++ b/lzma/common/auto_decoder.c
@@ -0,0 +1,186 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       auto_decoder.c
+/// \brief      Autodetect between .xz Stream and .lzma (LZMA_Alone) formats
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "stream_decoder.h"
+#include "alone_decoder.h"
+
+
+struct lzma_coder_s {
+	/// Stream decoder or LZMA_Alone decoder
+	lzma_next_coder next;
+
+	uint64_t memlimit;
+	uint32_t flags;
+
+	enum {
+		SEQ_INIT,
+		SEQ_CODE,
+		SEQ_FINISH,
+	} sequence;
+};
+
+
+static lzma_ret
+auto_decode(lzma_coder *coder, const lzma_allocator *allocator,
+		const uint8_t *restrict in, size_t *restrict in_pos,
+		size_t in_size, uint8_t *restrict out,
+		size_t *restrict out_pos, size_t out_size, lzma_action action)
+{
+	switch (coder->sequence) {
+	case SEQ_INIT:
+		if (*in_pos >= in_size)
+			return LZMA_OK;
+
+		// Update the sequence now, because we want to continue from
+		// SEQ_CODE even if we return some LZMA_*_CHECK.
+		coder->sequence = SEQ_CODE;
+
+		// Detect the file format. For now this is simple, since if
+		// it doesn't start with 0xFD (the first magic byte of the
+		// new format), it has to be LZMA_Alone, or something that
+		// we don't support at all.
+		if (in[*in_pos] == 0xFD) {
+			return_if_error(lzma_stream_decoder_init(
+					&coder->next, allocator,
+					coder->memlimit, coder->flags));
+		} else {
+			return_if_error(lzma_alone_decoder_init(&coder->next,
+					allocator, coder->memlimit, true));
+
+			// If the application wants to know about missing
+			// integrity check or about the check in general, we
+			// need to handle it here, because LZMA_Alone decoder
+			// doesn't accept any flags.
+			if (coder->flags & LZMA_TELL_NO_CHECK)
+				return LZMA_NO_CHECK;
+
+			if (coder->flags & LZMA_TELL_ANY_CHECK)
+				return LZMA_GET_CHECK;
+		}
+
+	// Fall through
+
+	case SEQ_CODE: {
+		const lzma_ret ret = coder->next.code(
+				coder->next.coder, allocator,
+				in, in_pos, in_size,
+				out, out_pos, out_size, action);
+		if (ret != LZMA_STREAM_END
+				|| (coder->flags & LZMA_CONCATENATED) == 0)
+			return ret;
+
+		coder->sequence = SEQ_FINISH;
+	}
+
+	// Fall through
+
+	case SEQ_FINISH:
+		// When LZMA_DECODE_CONCATENATED was used and we were decoding
+		// LZMA_Alone file, we need to check check that there is no
+		// trailing garbage and wait for LZMA_FINISH.
+		if (*in_pos < in_size)
+			return LZMA_DATA_ERROR;
+
+		return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK;
+
+	default:
+		assert(0);
+		return LZMA_PROG_ERROR;
+	}
+}
+
+
+static void
+auto_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
+{
+	lzma_next_end(&coder->next, allocator);
+	lzma_free(coder, allocator);
+	return;
+}
+
+
+static lzma_check
+auto_decoder_get_check(const lzma_coder *coder)
+{
+	// It is LZMA_Alone if get_check is NULL.
+	return coder->next.get_check == NULL ? LZMA_CHECK_NONE
+			: coder->next.get_check(coder->next.coder);
+}
+
+
+static lzma_ret
+auto_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
+		uint64_t *old_memlimit, uint64_t new_memlimit)
+{
+	lzma_ret ret;
+
+	if (coder->next.memconfig != NULL) {
+		ret = coder->next.memconfig(coder->next.coder,
+				memusage, old_memlimit, new_memlimit);
+		assert(*old_memlimit == coder->memlimit);
+	} else {
+		// No coder is configured yet. Use the base value as
+		// the current memory usage.
+		*memusage = LZMA_MEMUSAGE_BASE;
+		*old_memlimit = coder->memlimit;
+		ret = LZMA_OK;
+	}
+
+	if (ret == LZMA_OK && new_memlimit != 0)
+		coder->memlimit = new_memlimit;
+
+	return ret;
+}
+
+
+static lzma_ret
+auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+		uint64_t memlimit, uint32_t flags)
+{
+	lzma_next_coder_init(&auto_decoder_init, next, allocator);
+
+	if (memlimit == 0)
+		return LZMA_PROG_ERROR;
+
+	if (flags & ~LZMA_SUPPORTED_FLAGS)
+		return LZMA_OPTIONS_ERROR;
+
+	if (next->coder == NULL) {
+		next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+		if (next->coder == NULL)
+			return LZMA_MEM_ERROR;
+
+		next->code = &auto_decode;
+		next->end = &auto_decoder_end;
+		next->get_check = &auto_decoder_get_check;
+		next->memconfig = &auto_decoder_memconfig;
+		next->coder->next = LZMA_NEXT_CODER_INIT;
+	}
+
+	next->coder->memlimit = memlimit;
+	next->coder->flags = flags;
+	next->coder->sequence = SEQ_INIT;
+
+	return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
+{
+	lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags);
+
+	strm->internal->supported_actions[LZMA_RUN] = true;
+	strm->internal->supported_actions[LZMA_FINISH] = true;
+
+	return LZMA_OK;
+}