Skip to content

compress: avoid using incomplete dictionary FSE tables #4786

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
atharvmantri wants to merge 1 commit into
base: dev
Choose a base branch
from
Open

compress: avoid using incomplete dictionary FSE tables #4786

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 8 additions & 1 deletion lib/compress/zstd_opt.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -155,7 +155,14 @@ ZSTD_rescaleFreqs(optState_t* const optPtr,
}

assert(optPtr->symbolCosts != NULL);
if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid) {
/* The dictionary's FSE tables are only complete when every repeat
* mode is valid. A table with missing symbols returns a fake cost
* of tableLog + 1 from FSE_getMaxNbBits(), which is not a valid input
* to the scaled frequency calculation below. */
if (optPtr->symbolCosts->huf.repeatMode == HUF_repeat_valid &&
optPtr->symbolCosts->fse.litlength_repeatMode == FSE_repeat_valid &&
optPtr->symbolCosts->fse.matchlength_repeatMode == FSE_repeat_valid &&
optPtr->symbolCosts->fse.offcode_repeatMode == FSE_repeat_valid) {

/* huffman stats covering the full value set : table presumed generated by dictionary */
optPtr->priceType = zop_dynamic;
Expand Down