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Fix expansions that start from the end of another expansion (#839)

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Do not free an expansion until its offset is *past* its size.
This means potentially freeing a nested stack of expansions
all at once.

Fixes #696
This commit is contained in:
Rangi
2021-04-17 13:14:40 -04:00
committed by GitHub
parent 750e93be3d
commit 9923fa3eee
9 changed files with 94 additions and 91 deletions
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17
src/asm/lexer.c
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@@ -736,7 +736,11 @@ static char const *readMacroArg(char name)
static int peekInternal(uint8_t distance)
{
for (struct Expansion *exp = lexerState->expansions; exp; exp = exp->parent) {
assert(exp->offset < exp->size);
/*
* An expansion that has reached its end will have `exp->offset` == `exp->size`,
* and `peekInternal` will continue with its parent
*/
assert(exp->offset <= exp->size);
if (distance < exp->size - exp->offset)
return exp->contents.unowned[exp->offset + distance];
distance -= exp->size - exp->offset;
@@ -870,16 +874,21 @@ static void shiftChar(void)
lexerState->macroArgScanDistance--;
restart:
if (lexerState->expansions) {
/* Advance within the current expansion */
assert(lexerState->expansions->offset < lexerState->expansions->size);
assert(lexerState->expansions->offset <= lexerState->expansions->size);
lexerState->expansions->offset++;
if (lexerState->expansions->offset == lexerState->expansions->size) {
/* When an expansion is done, free it and move up to its parent */
if (lexerState->expansions->offset > lexerState->expansions->size) {
/*
* When advancing would go past an expansion's end, free it,
* move up to its parent, and try again to advance
*/
struct Expansion *exp = lexerState->expansions;
lexerState->expansions = lexerState->expansions->parent;
freeExpansion(exp);
goto restart;
}
} else {
/* Advance within the file contents */