Add an unpatched version of xz, XZ Utils, to /trunk/deps/third_party

xz/src/liblzma/common/index_encoder.c

+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file       index_encoder.c
+/// \brief      Encodes the Index field
+//
+//  Author:     Lasse Collin
+//
+//  This file has been put into the public domain.
+//  You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "index_encoder.h"
+#include "index.h"
+#include "check.h"
+
+
+struct lzma_coder_s {
+        enum {
+                SEQ_INDICATOR,
+                SEQ_COUNT,
+                SEQ_UNPADDED,
+                SEQ_UNCOMPRESSED,
+                SEQ_NEXT,
+                SEQ_PADDING,
+                SEQ_CRC32,
+        } sequence;
+
+        /// Index being encoded
+        const lzma_index *index;
+
+        /// Iterator for the Index being encoded
+        lzma_index_iter iter;
+
+        /// Position in integers
+        size_t pos;
+
+        /// CRC32 of the List of Records field
+        uint32_t crc32;
+};
+
+
+static lzma_ret
+index_encode(lzma_coder *coder,
+                lzma_allocator *allocator lzma_attribute((unused)),
+                const uint8_t *restrict in lzma_attribute((unused)),
+                size_t *restrict in_pos lzma_attribute((unused)),
+                size_t in_size lzma_attribute((unused)),
+                uint8_t *restrict out, size_t *restrict out_pos,
+                size_t out_size, lzma_action action lzma_attribute((unused)))
+{
+        // Position where to start calculating CRC32. The idea is that we
+        // need to call lzma_crc32() only once per call to index_encode().
+        const size_t out_start = *out_pos;
+
+        // Return value to use if we return at the end of this function.
+        // We use "goto out" to jump out of the while-switch construct
+        // instead of returning directly, because that way we don't need
+        // to copypaste the lzma_crc32() call to many places.
+        lzma_ret ret = LZMA_OK;
+
+        while (*out_pos < out_size)
+        switch (coder->sequence) {
+        case SEQ_INDICATOR:
+                out[*out_pos] = 0x00;
+                ++*out_pos;
+                coder->sequence = SEQ_COUNT;
+                break;
+
+        case SEQ_COUNT: {
+                const lzma_vli count = lzma_index_block_count(coder->index);
+                ret = lzma_vli_encode(count, &coder->pos,
+                                out, out_pos, out_size);
+                if (ret != LZMA_STREAM_END)
+                        goto out;
+
+                ret = LZMA_OK;
+                coder->pos = 0;
+                coder->sequence = SEQ_NEXT;
+                break;
+        }
+
+        case SEQ_NEXT:
+                if (lzma_index_iter_next(
+                                &coder->iter, LZMA_INDEX_ITER_BLOCK)) {
+                        // Get the size of the Index Padding field.
+                        coder->pos = lzma_index_padding_size(coder->index);
+                        assert(coder->pos <= 3);
+                        coder->sequence = SEQ_PADDING;
+                        break;
+                }
+
+                coder->sequence = SEQ_UNPADDED;
+
+        // Fall through
+
+        case SEQ_UNPADDED:
+        case SEQ_UNCOMPRESSED: {
+                const lzma_vli size = coder->sequence == SEQ_UNPADDED
+                                ? coder->iter.block.unpadded_size
+                                : coder->iter.block.uncompressed_size;
+
+                ret = lzma_vli_encode(size, &coder->pos,
+                                out, out_pos, out_size);
+                if (ret != LZMA_STREAM_END)
+                        goto out;
+
+                ret = LZMA_OK;
+                coder->pos = 0;
+
+                // Advance to SEQ_UNCOMPRESSED or SEQ_NEXT.
+                ++coder->sequence;
+                break;
+        }
+
+        case SEQ_PADDING:
+                if (coder->pos > 0) {
+                        --coder->pos;
+                        out[(*out_pos)++] = 0x00;
+                        break;
+                }
+
+                // Finish the CRC32 calculation.
+                coder->crc32 = lzma_crc32(out + out_start,
+                                *out_pos - out_start, coder->crc32);
+
+                coder->sequence = SEQ_CRC32;
+
+        // Fall through
+
+        case SEQ_CRC32:
+                // We don't use the main loop, because we don't want
+                // coder->crc32 to be touched anymore.
+                do {
+                        if (*out_pos == out_size)
+                                return LZMA_OK;
+
+                        out[*out_pos] = (coder->crc32 >> (coder->pos * 8))
+                                        & 0xFF;
+                        ++*out_pos;
+
+                } while (++coder->pos < 4);
+
+                return LZMA_STREAM_END;
+
+        default:
+                assert(0);
+                return LZMA_PROG_ERROR;
+        }
+
+out:
+        // Update the CRC32.
+        coder->crc32 = lzma_crc32(out + out_start,
+                        *out_pos - out_start, coder->crc32);
+
+        return ret;
+}
+
+
+static void
+index_encoder_end(lzma_coder *coder, lzma_allocator *allocator)
+{
+        lzma_free(coder, allocator);
+        return;
+}
+
+
+static void
+index_encoder_reset(lzma_coder *coder, const lzma_index *i)
+{
+        lzma_index_iter_init(&coder->iter, i);
+
+        coder->sequence = SEQ_INDICATOR;
+        coder->index = i;
+        coder->pos = 0;
+        coder->crc32 = 0;
+
+        return;
+}
+
+
+extern lzma_ret
+lzma_index_encoder_init(lzma_next_coder *next, lzma_allocator *allocator,
+                const lzma_index *i)
+{
+        lzma_next_coder_init(&lzma_index_encoder_init, next, allocator);
+
+        if (i == NULL)
+                return LZMA_PROG_ERROR;
+
+        if (next->coder == NULL) {
+                next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+                if (next->coder == NULL)
+                        return LZMA_MEM_ERROR;
+
+                next->code = &index_encode;
+                next->end = &index_encoder_end;
+        }
+
+        index_encoder_reset(next->coder, i);
+
+        return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_index_encoder(lzma_stream *strm, const lzma_index *i)
+{
+        lzma_next_strm_init(lzma_index_encoder_init, strm, i);
+
+        strm->internal->supported_actions[LZMA_RUN] = true;
+
+        return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_index_buffer_encode(const lzma_index *i,
+                uint8_t *out, size_t *out_pos, size_t out_size)
+{
+        // Validate the arguments.
+        if (i == NULL || out == NULL || out_pos == NULL || *out_pos > out_size)
+                return LZMA_PROG_ERROR;
+
+        // Don't try to encode if there's not enough output space.
+        if (out_size - *out_pos < lzma_index_size(i))
+                return LZMA_BUF_ERROR;
+
+        // The Index encoder needs just one small data structure so we can
+        // allocate it on stack.
+        lzma_coder coder;
+        index_encoder_reset(&coder, i);
+
+        // Do the actual encoding. This should never fail, but store
+        // the original *out_pos just in case.
+        const size_t out_start = *out_pos;
+        lzma_ret ret = index_encode(&coder, NULL, NULL, NULL, 0,
+                        out, out_pos, out_size, LZMA_RUN);
+
+        if (ret == LZMA_STREAM_END) {
+                ret = LZMA_OK;
+        } else {
+                // We should never get here, but just in case, restore the
+                // output position and set the error accordingly if something
+                // goes wrong and debugging isn't enabled.
+                assert(0);
+                *out_pos = out_start;
+                ret = LZMA_PROG_ERROR;
+        }
+
+        return ret;
+}