init_decompression(struct archive_read *a, struct _7zip *zip,
    const struct _7z_coder *coder1, const struct _7z_coder *coder2)
{
	int r;

	zip->codec = coder1->codec;
	zip->codec2 = -1;

	switch (zip->codec) {
	case _7Z_COPY:
	case _7Z_BZ2:
	case _7Z_DEFLATE:
	case _7Z_PPMD:
		if (coder2 != NULL) {
			if (coder2->codec != _7Z_X86 &&
			    coder2->codec != _7Z_X86_BCJ2) {
				archive_set_error(&a->archive,
				    ARCHIVE_ERRNO_MISC,
				    "Unsupported filter %lx for %lx",
				    coder2->codec, coder1->codec);
				return (ARCHIVE_FAILED);
			}
			zip->codec2 = coder2->codec;
			zip->bcj_state = 0;
			if (coder2->codec == _7Z_X86)
				x86_Init(zip);
		}
		break;
	default:
		break;
	}

	switch (zip->codec) {
	case _7Z_COPY:
		break;

	case _7Z_LZMA: case _7Z_LZMA2:
#ifdef HAVE_LZMA_H
#if LZMA_VERSION_MAJOR >= 5
/* Effectively disable the limiter. */
#define LZMA_MEMLIMIT   UINT64_MAX
#else
/* NOTE: This needs to check memory size which running system has. */
#define LZMA_MEMLIMIT   (1U << 30)
#endif
	{
		lzma_options_delta delta_opt;
		lzma_filter filters[LZMA_FILTERS_MAX];
#if LZMA_VERSION < 50010000
		lzma_filter *ff;
#endif
		int fi = 0;

		if (zip->lzstream_valid) {
			lzma_end(&(zip->lzstream));
			zip->lzstream_valid = 0;
		}

		/*
		 * NOTE: liblzma incompletely handle the BCJ+LZMA compressed
		 * data made by 7-Zip because 7-Zip does not add End-Of-
		 * Payload Marker(EOPM) at the end of LZMA compressed data,
		 * and so liblzma cannot know the end of the compressed data
		 * without EOPM. So consequently liblzma will not return last
		 * three or four bytes of uncompressed data because
		 * LZMA_FILTER_X86 filter does not handle input data if its
		 * data size is less than five bytes. If liblzma detect EOPM
		 * or know the uncompressed data size, liblzma will flush out
		 * the remaining that three or four bytes of uncompressed
		 * data. That is why we have to use our converting program
		 * for BCJ+LZMA. If we were able to tell the uncompressed
		 * size to liblzma when using lzma_raw_decoder() liblzma
		 * could correctly deal with BCJ+LZMA. But unfortunately
		 * there is no way to do that.
		 * Discussion about this can be found at XZ Utils forum.
		 */
		if (coder2 != NULL) {
			zip->codec2 = coder2->codec;

			filters[fi].options = NULL;
			switch (zip->codec2) {
			case _7Z_X86:
				if (zip->codec == _7Z_LZMA2) {
					filters[fi].id = LZMA_FILTER_X86;
					fi++;
				} else
					/* Use our filter. */
					x86_Init(zip);
				break;
			case _7Z_X86_BCJ2:
				/* Use our filter. */
				zip->bcj_state = 0;
				break;
			case _7Z_DELTA:
				filters[fi].id = LZMA_FILTER_DELTA;
				memset(&delta_opt, 0, sizeof(delta_opt));
				delta_opt.type = LZMA_DELTA_TYPE_BYTE;
				delta_opt.dist = 1;
				filters[fi].options = &delta_opt;
				fi++;
				break;
			/* Following filters have not been tested yet. */
			case _7Z_POWERPC:
				filters[fi].id = LZMA_FILTER_POWERPC;
				fi++;
				break;
			case _7Z_IA64:
				filters[fi].id = LZMA_FILTER_IA64;
				fi++;
				break;
			case _7Z_ARM:
				filters[fi].id = LZMA_FILTER_ARM;
				fi++;
				break;
			case _7Z_ARMTHUMB:
				filters[fi].id = LZMA_FILTER_ARMTHUMB;
				fi++;
				break;
			case _7Z_SPARC:
				filters[fi].id = LZMA_FILTER_SPARC;
				fi++;
				break;
			default:
				archive_set_error(&a->archive,
				    ARCHIVE_ERRNO_MISC,
				    "Unexpected codec ID: %lX", zip->codec2);
				return (ARCHIVE_FAILED);
			}
		}

		if (zip->codec == _7Z_LZMA2)
			filters[fi].id = LZMA_FILTER_LZMA2;
		else
			filters[fi].id = LZMA_FILTER_LZMA1;
		filters[fi].options = NULL;
#if LZMA_VERSION < 50010000
		ff = &filters[fi];
#endif
		r = lzma_properties_decode(&filters[fi], NULL,
		    coder1->properties, (size_t)coder1->propertiesSize);
		if (r != LZMA_OK) {
			set_error(a, r);
			return (ARCHIVE_FAILED);
		}
		fi++;

		filters[fi].id = LZMA_VLI_UNKNOWN;
		filters[fi].options = NULL;
		r = lzma_raw_decoder(&(zip->lzstream), filters);
#if LZMA_VERSION < 50010000
		free(ff->options);
#endif
		if (r != LZMA_OK) {
			set_error(a, r);
			return (ARCHIVE_FAILED);
		}
		zip->lzstream_valid = 1;
		zip->lzstream.total_in = 0;
		zip->lzstream.total_out = 0;
		break;
	}
#else
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "LZMA codec is unsupported");
		return (ARCHIVE_FAILED);
#endif
	case _7Z_BZ2:
#if defined(HAVE_BZLIB_H) && defined(BZ_CONFIG_ERROR)
		if (zip->bzstream_valid) {
			BZ2_bzDecompressEnd(&(zip->bzstream));
			zip->bzstream_valid = 0;
		}
		r = BZ2_bzDecompressInit(&(zip->bzstream), 0, 0);
		if (r == BZ_MEM_ERROR)
			r = BZ2_bzDecompressInit(&(zip->bzstream), 0, 1);
		if (r != BZ_OK) {
			int err = ARCHIVE_ERRNO_MISC;
			const char *detail = NULL;
			switch (r) {
			case BZ_PARAM_ERROR:
				detail = "invalid setup parameter";
				break;
			case BZ_MEM_ERROR:
				err = ENOMEM;
				detail = "out of memory";
				break;
			case BZ_CONFIG_ERROR:
				detail = "mis-compiled library";
				break;
			}
			archive_set_error(&a->archive, err,
			    "Internal error initializing decompressor: %s",
			    detail != NULL ? detail : "??");
			zip->bzstream_valid = 0;
			return (ARCHIVE_FAILED);
		}
		zip->bzstream_valid = 1;
		zip->bzstream.total_in_lo32 = 0;
		zip->bzstream.total_in_hi32 = 0;
		zip->bzstream.total_out_lo32 = 0;
		zip->bzstream.total_out_hi32 = 0;
		break;
#else
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "BZ2 codec is unsupported");
		return (ARCHIVE_FAILED);
#endif
	case _7Z_DEFLATE:
#ifdef HAVE_ZLIB_H
		if (zip->stream_valid)
			r = inflateReset(&(zip->stream));
		else
			r = inflateInit2(&(zip->stream),
			    -15 /* Don't check for zlib header */);
		if (r != Z_OK) {
			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
			    "Couldn't initialize zlib stream.");
			return (ARCHIVE_FAILED);
		}
		zip->stream_valid = 1;
		zip->stream.total_in = 0;
		zip->stream.total_out = 0;
		break;
#else
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "DEFLATE codec is unsupported");
		return (ARCHIVE_FAILED);
#endif
	case _7Z_PPMD:
	{
		unsigned order;
		uint32_t msize;

		if (zip->ppmd7_valid) {
			__archive_ppmd7_functions.Ppmd7_Free(
			    &zip->ppmd7_context, &g_szalloc);
			zip->ppmd7_valid = 0;
		}

		if (coder1->propertiesSize < 5) {
			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
			    "Malformed PPMd parameter");
			return (ARCHIVE_FAILED);
		}
		order = coder1->properties[0];
		msize = archive_le32dec(&(coder1->properties[1]));
		if (order < PPMD7_MIN_ORDER || order > PPMD7_MAX_ORDER ||
		    msize < PPMD7_MIN_MEM_SIZE || msize > PPMD7_MAX_MEM_SIZE) {
			archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
			    "Malformed PPMd parameter");
			return (ARCHIVE_FAILED);
		}
		__archive_ppmd7_functions.Ppmd7_Construct(&zip->ppmd7_context);
		r = __archive_ppmd7_functions.Ppmd7_Alloc(
			&zip->ppmd7_context, msize, &g_szalloc);
		if (r == 0) {
			archive_set_error(&a->archive, ENOMEM,
			    "Coludn't allocate memory for PPMd");
			return (ARCHIVE_FATAL);
		}
		__archive_ppmd7_functions.Ppmd7_Init(
			&zip->ppmd7_context, order);
		__archive_ppmd7_functions.Ppmd7z_RangeDec_CreateVTable(
			&zip->range_dec);
		zip->ppmd7_valid = 1;
		zip->ppmd7_stat = 0;
		zip->ppstream.overconsumed = 0;
		zip->ppstream.total_in = 0;
		zip->ppstream.total_out = 0;
		break;
	}
	case _7Z_X86:
	case _7Z_X86_BCJ2:
	case _7Z_POWERPC:
	case _7Z_IA64:
	case _7Z_ARM:
	case _7Z_ARMTHUMB:
	case _7Z_SPARC:
	case _7Z_DELTA:
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "Unexpected codec ID: %lX", zip->codec);
		return (ARCHIVE_FAILED);
	case _7Z_CRYPTO_MAIN_ZIP:
	case _7Z_CRYPTO_RAR_29:
	case _7Z_CRYPTO_AES_256_SHA_256:
		if (a->entry) {
			archive_entry_set_is_metadata_encrypted(a->entry, 1);
			archive_entry_set_is_data_encrypted(a->entry, 1);
			zip->has_encrypted_entries = 1;
		}
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "Crypto codec not supported yet (ID: 0x%lX)", zip->codec);
		return (ARCHIVE_FAILED);
	default:
		archive_set_error(&a->archive, ARCHIVE_ERRNO_MISC,
		    "Unknown codec ID: %lX", zip->codec);
		return (ARCHIVE_FAILED);
	}

	return (ARCHIVE_OK);
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.