ZSTD_findDecompressedSize is ZSTDLIB_STATIC_API

[mkitti]

Here is the declaration of ZSTD_findDecompressedSize which is to used to implement TranscodingStreams.expectedsize:

ZSTDLIB_STATIC_API unsigned long long ZSTD_findDecompressedSize(const void* src, size_t srcSize);

https://github.com/facebook/zstd/blob/78955f5f9ddb3601566884ce217d91c132f5edc1/lib/zstd.h#L1455

This appears to come with the following warning.

/****************************************************************************************
 *   experimental API (static linking only)
 ****************************************************************************************
 * The following symbols and constants
 * are not planned to join "stable API" status in the near future.
 * They can still change in future versions.
 * Some of them are planned to remain in the static_only section indefinitely.
 * Some of them might be removed in the future (especially when redundant with existing stable functions)
 * ***************************************************************************************/

https://github.com/facebook/zstd/blob/78955f5f9ddb3601566884ce217d91c132f5edc1/lib/zstd.h#L1193-L1200

An implementation that uses ZSTD_getFrameContentSize may be more stable directly. ZSTD_getFrameContentSize only obtains the size of the first frame while ZSTD_findDecompressedSize appears to iterate over many frames, using ZSTD_getFrameContentSize for each frame, accumulating the total. In theory, we could write the equivalent function if needed.

This is only going to be a problem if someone ever tries to use CodecZstd.jl with libzstd built with ZSTDLIB_STATIC_API set to something that hides the static symbols.

[nhz2]

Fixed by #63