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/**
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* Copyright (c) 2017-present, Gregory Szorc
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* All rights reserved.
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*
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* This software may be modified and distributed under the terms
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* of the BSD license. See the LICENSE file for details.
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*/
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#include "python-zstandard.h"
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extern PyObject* ZstdError;
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static void set_unsupported_operation(void) {
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PyObject* iomod;
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PyObject* exc;
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iomod = PyImport_ImportModule("io");
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if (NULL == iomod) {
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return;
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}
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exc = PyObject_GetAttrString(iomod, "UnsupportedOperation");
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if (NULL == exc) {
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Py_DECREF(iomod);
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return;
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}
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PyErr_SetNone(exc);
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Py_DECREF(exc);
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Py_DECREF(iomod);
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}
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static void reader_dealloc(ZstdDecompressionReader* self) {
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Py_XDECREF(self->decompressor);
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Py_XDECREF(self->reader);
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if (self->buffer.buf) {
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PyBuffer_Release(&self->buffer);
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}
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PyObject_Del(self);
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}
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static ZstdDecompressionReader* reader_enter(ZstdDecompressionReader* self) {
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if (self->entered) {
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PyErr_SetString(PyExc_ValueError, "cannot __enter__ multiple times");
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return NULL;
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}
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if (ensure_dctx(self->decompressor, 1)) {
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return NULL;
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}
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self->entered = 1;
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Py_INCREF(self);
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return self;
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}
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static PyObject* reader_exit(ZstdDecompressionReader* self, PyObject* args) {
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PyObject* exc_type;
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PyObject* exc_value;
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PyObject* exc_tb;
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if (!PyArg_ParseTuple(args, "OOO:__exit__", &exc_type, &exc_value, &exc_tb)) {
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return NULL;
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}
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self->entered = 0;
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self->closed = 1;
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/* Release resources. */
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Py_CLEAR(self->reader);
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if (self->buffer.buf) {
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PyBuffer_Release(&self->buffer);
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memset(&self->buffer, 0, sizeof(self->buffer));
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}
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Py_CLEAR(self->decompressor);
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Py_RETURN_FALSE;
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}
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static PyObject* reader_readable(PyObject* self) {
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Py_RETURN_TRUE;
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}
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static PyObject* reader_writable(PyObject* self) {
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Py_RETURN_FALSE;
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}
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static PyObject* reader_seekable(PyObject* self) {
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Py_RETURN_TRUE;
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}
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static PyObject* reader_close(ZstdDecompressionReader* self) {
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self->closed = 1;
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Py_RETURN_NONE;
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}
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static PyObject* reader_closed(ZstdDecompressionReader* self) {
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if (self->closed) {
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Py_RETURN_TRUE;
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}
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else {
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Py_RETURN_FALSE;
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}
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}
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static PyObject* reader_flush(PyObject* self) {
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Py_RETURN_NONE;
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}
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static PyObject* reader_isatty(PyObject* self) {
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Py_RETURN_FALSE;
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}
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static PyObject* reader_read(ZstdDecompressionReader* self, PyObject* args, PyObject* kwargs) {
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static char* kwlist[] = {
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"size",
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NULL
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};
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Py_ssize_t size = -1;
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PyObject* result = NULL;
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char* resultBuffer;
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Py_ssize_t resultSize;
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ZSTD_outBuffer output;
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size_t zresult;
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if (!self->entered) {
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PyErr_SetString(ZstdError, "read() must be called from an active context manager");
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return NULL;
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}
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if (self->closed) {
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PyErr_SetString(PyExc_ValueError, "stream is closed");
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return NULL;
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}
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if (self->finishedOutput) {
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return PyBytes_FromStringAndSize("", 0);
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}
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if (!PyArg_ParseTupleAndKeywords(args, kwargs, "n", kwlist, &size)) {
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return NULL;
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}
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if (size < 1) {
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PyErr_SetString(PyExc_ValueError, "cannot read negative or size 0 amounts");
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return NULL;
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}
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result = PyBytes_FromStringAndSize(NULL, size);
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if (NULL == result) {
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return NULL;
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}
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PyBytes_AsStringAndSize(result, &resultBuffer, &resultSize);
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output.dst = resultBuffer;
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output.size = resultSize;
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output.pos = 0;
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readinput:
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/* Consume input data left over from last time. */
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if (self->input.pos < self->input.size) {
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Py_BEGIN_ALLOW_THREADS
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zresult = ZSTD_decompress_generic(self->decompressor->dctx,
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&output, &self->input);
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Py_END_ALLOW_THREADS
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/* Input exhausted. Clear our state tracking. */
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if (self->input.pos == self->input.size) {
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memset(&self->input, 0, sizeof(self->input));
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Py_CLEAR(self->readResult);
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if (self->buffer.buf) {
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self->finishedInput = 1;
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}
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}
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if (ZSTD_isError(zresult)) {
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PyErr_Format(ZstdError, "zstd decompress error: %s", ZSTD_getErrorName(zresult));
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return NULL;
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}
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else if (0 == zresult) {
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self->finishedOutput = 1;
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}
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/* We fulfilled the full read request. Emit it. */
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if (output.pos && output.pos == output.size) {
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self->bytesDecompressed += output.size;
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return result;
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}
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/*
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* There is more room in the output. Fall through to try to collect
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* more data so we can try to fill the output.
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*/
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}
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if (!self->finishedInput) {
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if (self->reader) {
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Py_buffer buffer;
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assert(self->readResult == NULL);
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self->readResult = PyObject_CallMethod(self->reader, "read",
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"k", self->readSize);
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if (NULL == self->readResult) {
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return NULL;
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}
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memset(&buffer, 0, sizeof(buffer));
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if (0 != PyObject_GetBuffer(self->readResult, &buffer, PyBUF_CONTIG_RO)) {
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return NULL;
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}
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/* EOF */
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if (0 == buffer.len) {
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self->finishedInput = 1;
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Py_CLEAR(self->readResult);
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}
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else {
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self->input.src = buffer.buf;
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self->input.size = buffer.len;
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self->input.pos = 0;
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}
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PyBuffer_Release(&buffer);
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}
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else {
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assert(self->buffer.buf);
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/*
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* We should only get here once since above block will exhaust
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* source buffer until finishedInput is set.
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*/
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assert(self->input.src == NULL);
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self->input.src = self->buffer.buf;
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self->input.size = self->buffer.len;
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self->input.pos = 0;
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}
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}
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if (self->input.size) {
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goto readinput;
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}
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/* EOF */
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self->bytesDecompressed += output.pos;
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if (safe_pybytes_resize(&result, output.pos)) {
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Py_XDECREF(result);
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return NULL;
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}
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return result;
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}
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static PyObject* reader_readall(PyObject* self) {
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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}
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static PyObject* reader_readline(PyObject* self) {
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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}
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static PyObject* reader_readlines(PyObject* self) {
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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}
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static PyObject* reader_seek(ZstdDecompressionReader* self, PyObject* args) {
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Py_ssize_t pos;
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int whence = 0;
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unsigned long long readAmount = 0;
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size_t defaultOutSize = ZSTD_DStreamOutSize();
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if (!self->entered) {
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PyErr_SetString(ZstdError, "seek() must be called from an active context manager");
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return NULL;
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}
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if (self->closed) {
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PyErr_SetString(PyExc_ValueError, "stream is closed");
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return NULL;
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}
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if (!PyArg_ParseTuple(args, "n|i:seek", &pos, &whence)) {
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return NULL;
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}
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if (whence == SEEK_SET) {
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if (pos < 0) {
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PyErr_SetString(PyExc_ValueError,
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"cannot seek to negative position with SEEK_SET");
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return NULL;
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}
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if ((unsigned long long)pos < self->bytesDecompressed) {
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PyErr_SetString(PyExc_ValueError,
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"cannot seek zstd decompression stream backwards");
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return NULL;
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}
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readAmount = pos - self->bytesDecompressed;
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}
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else if (whence == SEEK_CUR) {
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if (pos < 0) {
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PyErr_SetString(PyExc_ValueError,
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"cannot seek zstd decompression stream backwards");
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return NULL;
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}
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readAmount = pos;
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}
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else if (whence == SEEK_END) {
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/* We /could/ support this with pos==0. But let's not do that until someone
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needs it. */
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PyErr_SetString(PyExc_ValueError,
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"zstd decompression streams cannot be seeked with SEEK_END");
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return NULL;
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}
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/* It is a bit inefficient to do this via the Python API. But since there
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is a bit of state tracking involved to read from this type, it is the
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easiest to implement. */
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while (readAmount) {
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Py_ssize_t readSize;
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PyObject* readResult = PyObject_CallMethod((PyObject*)self, "read", "K",
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readAmount < defaultOutSize ? readAmount : defaultOutSize);
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if (!readResult) {
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return NULL;
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}
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readSize = PyBytes_GET_SIZE(readResult);
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/* Empty read means EOF. */
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if (!readSize) {
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break;
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}
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readAmount -= readSize;
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}
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return PyLong_FromUnsignedLongLong(self->bytesDecompressed);
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}
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static PyObject* reader_tell(ZstdDecompressionReader* self) {
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/* TODO should this raise OSError since stream isn't seekable? */
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return PyLong_FromUnsignedLongLong(self->bytesDecompressed);
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}
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static PyObject* reader_write(PyObject* self, PyObject* args) {
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set_unsupported_operation();
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return NULL;
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}
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static PyObject* reader_writelines(PyObject* self, PyObject* args) {
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set_unsupported_operation();
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return NULL;
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}
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static PyObject* reader_iter(PyObject* self) {
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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}
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static PyObject* reader_iternext(PyObject* self) {
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PyErr_SetNone(PyExc_NotImplementedError);
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return NULL;
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}
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static PyMethodDef reader_methods[] = {
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{ "__enter__", (PyCFunction)reader_enter, METH_NOARGS,
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PyDoc_STR("Enter a compression context") },
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{ "__exit__", (PyCFunction)reader_exit, METH_VARARGS,
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PyDoc_STR("Exit a compression context") },
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{ "close", (PyCFunction)reader_close, METH_NOARGS,
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PyDoc_STR("Close the stream so it cannot perform any more operations") },
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{ "closed", (PyCFunction)reader_closed, METH_NOARGS,
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PyDoc_STR("Whether stream is closed") },
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{ "flush", (PyCFunction)reader_flush, METH_NOARGS, PyDoc_STR("no-ops") },
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{ "isatty", (PyCFunction)reader_isatty, METH_NOARGS, PyDoc_STR("Returns False") },
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{ "readable", (PyCFunction)reader_readable, METH_NOARGS,
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PyDoc_STR("Returns True") },
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{ "read", (PyCFunction)reader_read, METH_VARARGS | METH_KEYWORDS,
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PyDoc_STR("read compressed data") },
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{ "readall", (PyCFunction)reader_readall, METH_NOARGS, PyDoc_STR("Not implemented") },
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{ "readline", (PyCFunction)reader_readline, METH_NOARGS, PyDoc_STR("Not implemented") },
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{ "readlines", (PyCFunction)reader_readlines, METH_NOARGS, PyDoc_STR("Not implemented") },
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{ "seek", (PyCFunction)reader_seek, METH_VARARGS, PyDoc_STR("Seek the stream") },
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{ "seekable", (PyCFunction)reader_seekable, METH_NOARGS,
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PyDoc_STR("Returns True") },
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{ "tell", (PyCFunction)reader_tell, METH_NOARGS,
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PyDoc_STR("Returns current number of bytes compressed") },
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{ "writable", (PyCFunction)reader_writable, METH_NOARGS,
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PyDoc_STR("Returns False") },
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{ "write", (PyCFunction)reader_write, METH_VARARGS, PyDoc_STR("unsupported operation") },
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{ "writelines", (PyCFunction)reader_writelines, METH_VARARGS, PyDoc_STR("unsupported operation") },
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{ NULL, NULL }
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};
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PyTypeObject ZstdDecompressionReaderType = {
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PyVarObject_HEAD_INIT(NULL, 0)
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"zstd.ZstdDecompressionReader", /* tp_name */
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sizeof(ZstdDecompressionReader), /* tp_basicsize */
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0, /* tp_itemsize */
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(destructor)reader_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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0, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT, /* tp_flags */
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0, /* tp_doc */
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0, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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0, /* tp_weaklistoffset */
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reader_iter, /* tp_iter */
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reader_iternext, /* tp_iternext */
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reader_methods, /* tp_methods */
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0, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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0, /* tp_init */
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0, /* tp_alloc */
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PyType_GenericNew, /* tp_new */
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};
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void decompressionreader_module_init(PyObject* mod) {
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/* TODO make reader a sub-class of io.RawIOBase */
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|
|
Py_TYPE(&ZstdDecompressionReaderType) = &PyType_Type;
|
|
|
if (PyType_Ready(&ZstdDecompressionReaderType) < 0) {
|
|
|
return;
|
|
|
}
|
|
|
}
|
|
|
|
