fixes #684 [tx] -cff2 blend/path optimization should respect stack limit #697
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cjchapman
suggested changes
Dec 17, 2018
| cstr_saveop(h, op); | ||
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| h->pendop = tx_noop; /* Clear pending op */ | ||
| } | ||
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| /* Returns 1 if argcnt maybe blended args may overflow the operand stack */ |
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This comment is not clear to me. Did you mean "...argcnt plus blended args will overflow..."?
| @@ -484,11 +505,18 @@ static void pushBlendDeltas(cstrCtx h, abfBlendArg *blendArg) { | |||
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| static void flushBlends(cstrCtx h) { | |||
| int i; | |||
| if ((h->deltaStack.cnt + h->stack.cnt) > 513) { | |||
| if ((h->deltaStack.cnt + 1 + h->stack.cnt + h->flushed_cnt | |||
| + ((h->g->flags & CFW_SUBRIZE) ? 1 : 0)) > CFF2_MAX_OP_STACK) { | |||
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Why not use checkOverflow(h) here?
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Because checkOverflow() is used to check against overflow before pushing numRegions+1 of arguments onto stack. The condition here is to detect if overflow actually happened, and it shouldn't happen.
readroberts
approved these changes
Dec 18, 2018
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Fixes tx issue #684 [tx] -cff2 blend/path optimization should respect stack limit
The charstring optimization enabled by default (disabled with -no_opt) is supposed to generate charstrings that would not overflow the standard operand stack size (48 for CFF1, 513 for CFF2), but the limit check was not correctly calculated with CFF2 variable font blending charstrings.
Also added a test case that used to break the limit, and is now fixed along with its expected result.