global: remove check for C contiguous single dimension buffer

The former is redundant with what Python does behind the scenes
and the latter isn't needed in practice.

I believe all removed instances were for PyBuffer obtained via
Python's argument parser using `y*` or `w*`.

Closes #124.

NEWS.rst

@@ -95,6 +95,11 @@ Bug Fixes
 Changes
 -------
 
+* ``PyBuffer`` instances are no longer checked to be C contiguous and
+  have a single dimension. The former was redundant with what
+  ``PyArg_ParseTuple()`` already did and the latter is not necessary
+  in practice because very few extension modules create buffers with
+  more than 1 dimension. (#124)
 * Added Python typing stub file for the ``zstandard`` module. (#120)
 * The ``make_cffi.py`` script should now respect the ``CC`` environment
   variable for locating the compiler. (#103)

c-ext/bufferutil.c

@@ -68,16 +68,6 @@ static int BufferWithSegments_init(ZstdBufferWithSegments* self, PyObject* args,
 		return -1;
 	}
 
-	if (!PyBuffer_IsContiguous(&self->parent, 'C') || self->parent.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError, "data buffer should be contiguous and have a single dimension");
-		goto except;
-	}
-
-	if (!PyBuffer_IsContiguous(&segments, 'C') || segments.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError, "segments buffer should be contiguous and have a single dimension");
-		goto except;
-	}
-
 	if (segments.len % sizeof(BufferSegment)) {
 		PyErr_Format(PyExc_ValueError, "segments array size is not a multiple of %zu",
 			sizeof(BufferSegment));

c-ext/compressionchunker.c

@@ -213,13 +213,6 @@ static ZstdCompressionChunkerIterator* ZstdCompressionChunker_compress(ZstdCompr
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&self->inBuffer, 'C') || self->inBuffer.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		PyBuffer_Release(&self->inBuffer);
-		return NULL;
-	}
-
 	result = (ZstdCompressionChunkerIterator*)PyObject_CallObject((PyObject*)&ZstdCompressionChunkerIteratorType, NULL);
 	if (!result) {
 		PyBuffer_Release(&self->inBuffer);

c-ext/compressiondict.c

@@ -200,12 +200,6 @@ static int ZstdCompressionDict_init(ZstdCompressionDict* self, PyObject* args, P
 		return -1;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	if (dictType != ZSTD_dct_auto && dictType != ZSTD_dct_rawContent
 		&& dictType != ZSTD_dct_fullDict) {
 		PyErr_Format(PyExc_ValueError,

c-ext/compressionreader.c

@@ -532,12 +532,6 @@ static PyObject* compressionreader_readinto(ZstdCompressionReader* self, PyObjec
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&dest, 'C') || dest.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-		    "destination buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	output.dst = dest.buf;
 	output.size = dest.len;
 	output.pos = 0;
@@ -631,12 +625,6 @@ static PyObject* compressionreader_readinto1(ZstdCompressionReader* self, PyObje
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&dest, 'C') || dest.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-		    "destination buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	output.dst = dest.buf;
 	output.size = dest.len;
 	output.pos = 0;

c-ext/compressionwriter.c

@@ -85,12 +85,6 @@ static PyObject* ZstdCompressionWriter_write(ZstdCompressionWriter* self, PyObje
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	if (self->closed) {
 		PyErr_SetString(PyExc_ValueError, "stream is closed");
 		return NULL;

c-ext/compressobj.c

@@ -45,12 +45,6 @@ static PyObject* ZstdCompressionObj_compress(ZstdCompressionObj* self, PyObject*
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	input.src = source.buf;
 	input.size = source.len;
 	input.pos = 0;

c-ext/compressor.c

@@ -562,12 +562,6 @@ static PyObject* ZstdCompressor_compress(ZstdCompressor* self, PyObject* args, P
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	ZSTD_CCtx_reset(self->cctx, ZSTD_reset_session_only);
 
 	destSize = ZSTD_compressBound(source.len);

c-ext/decompressionreader.c

@@ -417,12 +417,6 @@ static PyObject* decompressionreader_readinto(ZstdDecompressionReader* self, PyO
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&dest, 'C') || dest.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"destination buffer should be contiguous and have at most one dimension");
-	    goto finally;
-	}
-
 	output.dst = dest.buf;
 	output.size = dest.len;
 	output.pos = 0;
@@ -487,12 +481,6 @@ static PyObject* decompressionreader_readinto1(ZstdDecompressionReader* self, Py
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&dest, 'C') || dest.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"destination buffer should be contiguous and have at most one dimension");
-	    goto finally;
-	}
-
 	output.dst = dest.buf;
 	output.size = dest.len;
 	output.pos = 0;

c-ext/decompressionwriter.c

@@ -71,12 +71,6 @@ static PyObject* ZstdDecompressionWriter_write(ZstdDecompressionWriter* self, Py
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	if (self->closed) {
 		PyErr_SetString(PyExc_ValueError, "stream is closed");
 		return NULL;

c-ext/decompressobj.c

@@ -45,12 +45,6 @@ static PyObject* DecompressionObj_decompress(ZstdDecompressionObj* self, PyObjec
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	/* Special case of empty input. Output will always be empty. */
 	if (source.len == 0) {
 		result = PyBytes_FromString("");

c-ext/decompressor.c

@@ -314,12 +314,6 @@ PyObject* Decompressor_decompress(ZstdDecompressor* self, PyObject* args, PyObje
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	if (ensure_dctx(self, 1)) {
 		goto finally;
 	}
@@ -1533,11 +1527,6 @@ static ZstdBufferWithSegmentsCollection* Decompressor_multi_decompress_to_buffer
 	}
 
 	if (frameSizes.buf) {
-		if (!PyBuffer_IsContiguous(&frameSizes, 'C') || frameSizes.ndim > 1) {
-			PyErr_SetString(PyExc_ValueError, "decompressed_sizes buffer should be contiguous and have a single dimension");
-			goto finally;
-		}
-
 		frameSizesP = (unsigned long long*)frameSizes.buf;
 	}
 

c-ext/frameparams.c

@@ -29,12 +29,6 @@ FrameParametersObject* get_frame_parameters(PyObject* self, PyObject* args, PyOb
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	zresult = ZSTD_getFrameHeader(&header, source.buf, source.len);
 
 	if (ZSTD_isError(zresult)) {

docs/concepts.rst

@@ -104,10 +104,6 @@ Many Python types implement the buffer protocol. These include ``bytes``
 (``str`` on Python 2), ``bytearray``, ``array.array``, ``io.BytesIO``,
 ``mmap.mmap``, and ``memoryview``.
 
-``python-zstandard`` APIs that accept objects conforming to the buffer
-protocol require that the buffer is *C contiguous*. This is usually the
-case.
-
 Requiring Output Sizes for Non-Streaming Decompression APIs
 ===========================================================
 

rust-ext/src/compression_dict.rs

@@ -88,13 +88,6 @@ impl ZstdCompressionDict {
     fn new_impl(py: Python, data: PyObject, dict_type: Option<u32>) -> PyResult<PyObject> {
         let buffer = PyBuffer::get(py, &data)?;
 
-        if !buffer.is_c_contiguous() || buffer.dimensions() > 1 {
-            return Err(PyErr::new::<ValueError, _>(
-                py,
-                "data buffer should be contiguous and have at most one dimension",
-            ));
-        }
-
         let dict_type = if dict_type == Some(zstd_sys::ZSTD_dictContentType_e::ZSTD_dct_auto as u32)
         {
             Ok(zstd_sys::ZSTD_dictContentType_e::ZSTD_dct_auto)

rust-ext/src/compressionobj.rs

@@ -55,13 +55,6 @@ impl ZstdCompressionObj {
 
         let buffer = PyBuffer::get(py, &data)?;
 
-        if !buffer.is_c_contiguous() || buffer.dimensions() > 1 {
-            return Err(PyErr::new::<ValueError, _>(
-                py,
-                "data buffer should be contiguous and have at most one dimension",
-            ));
-        }
-
         let mut source = unsafe {
             std::slice::from_raw_parts::<u8>(buffer.buf_ptr() as *const _, buffer.len_bytes())
         };

rust-ext/src/compressor.rs

@@ -363,13 +363,6 @@ impl ZstdCompressor {
 
         let buffer = PyBuffer::get(py, &data)?;
 
-        if !buffer.is_c_contiguous() || buffer.dimensions() > 1 {
-            return Err(ZstdError::from_message(
-                py,
-                "data buffer should be contiguous and have at most one dimension",
-            ));
-        }
-
         let source: &[u8] =
             unsafe { std::slice::from_raw_parts(buffer.buf_ptr() as *const _, buffer.len_bytes()) };
 

zstd.c

@@ -68,12 +68,6 @@ static PyObject* frame_content_size(PyObject* self, PyObject* args, PyObject* kw
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	size = ZSTD_getFrameContentSize(source.buf, source.len);
 
 	if (size == ZSTD_CONTENTSIZE_ERROR) {
@@ -113,12 +107,6 @@ static PyObject* frame_header_size(PyObject* self, PyObject* args, PyObject* kwa
 		return NULL;
 	}
 
-	if (!PyBuffer_IsContiguous(&source, 'C') || source.ndim > 1) {
-		PyErr_SetString(PyExc_ValueError,
-			"data buffer should be contiguous and have at most one dimension");
-		goto finally;
-	}
-
 	zresult = ZSTD_frameHeaderSize(source.buf, source.len);
 	if (ZSTD_isError(zresult)) {
 		PyErr_Format(ZstdError, "could not determine frame header size: %s",