It does not feel "right" from a dependency perspective.
ZSTD_initDCtx_internal() is triggered once, on DCtx creation,
while ZSTD_decompressBegin() is invoked at the beginning of each new frame,
and is also a user-facing prototype.
Downside : a DCtx must be init before first usage !
This was always the intention by the way, and is documented as such.
This stage is automatically done within ZSTD_decompress() and variants,
and also within ZSTD_decompressStream().
Only ZSTD_decompressContinue() is impacted,
it must be preceded by a ZSTD_decompressBegin(), as detailed in doc.
A test has been fixed, to no longer rely on undocumented assumption that ZSTD_decompressBegin() is invoked during init.
decoder output buffer would receive a wrong size.
In previous version, ZSTD_decompressStream() would blindly trust the caller that pos <= size.
In this version, this condition is actively checked,
and the function returns an error code if this condition is not respected.
This check could also be done with an assert(),
but since this is a user-facing interface, it seems better to keep this check at runtime.
adding check at end of single-pass ZSTD_decompressFrame().
Check within ZSTD_decompressContinue() was already added in a previous patch : b3f33ccfb3b4fcc73df82126fd5ecfb751268fc6
supporting function for bufferless streaming API (ZSTD_decompressContinue())
makes it possible to correctly size a round buffer for decoding using this API.
also : added field blockSizeMax within ZSTD_frameHeader,
as it's a necessary information to know when to restart at beginning of decoding buffer.
Note : all error codes are changed by this new version,
but it's expected to be the last change for existing codes.
Codes are now grouped by category, and receive a manually attributed value.
The objective is to guarantee that
error code values will not change in the future
when introducing new codes.
Intentionnal empty spaces and ranges are defined
in order to keep room for potential new codes.
Makes frame type (zstd,skippable) detection more straighforward.
ZSTD_getFrameHeader set frameContentSize=ZSTD_CONTENTSIZE_UNKNOWN to mean "field not present"
* `ZSTD_decompressStream_generic()` `ip` may be `NULL` for one of the calls
to `memcpy()`
* Assert the source is not `NULL` for calls to `memcpy()` where I believe
the source should not be `NULL`.
