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Code Issues 1 Releases Wiki Activity

Fix stack overflow in deeply nested destructuring.

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Instead, do a recursion depth check and give a normal compile error.
This commit is contained in:
Calvin Rose
2026-08-23 13:14:47 -05:00
parent d177131c84
commit 021a17cda1
1 changed files with 15 additions and 2 deletions
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src/core/specials.c
+15 -2
View File
@@ -150,7 +150,7 @@ static JanetSlot janetc_quasiquote(JanetFopts opts, int32_t argn, const Janet *a
janetc_cerror(opts.compiler, "expected 1 argument to quasiquote");
return janetc_cslot(janet_wrap_nil());
}
return quasiquote(opts, argv[0], JANET_RECURSION_GUARD, 0);
return quasiquote(opts, argv[0], opts.compiler->recursion_guard, 0);
}
static JanetSlot janetc_unquote(JanetFopts opts, int32_t argn, const Janet *argv) {
@@ -171,6 +171,10 @@ static int destructure(JanetCompiler *c,
JanetSlot s,
JanetTable *attr),
JanetTable *attr) {
if (c->recursion_guard <= 0) {
janetc_error(c, janet_cstring("C stack recursed too deeply"));
return 1;
}
switch (janet_type(left)) {
default:
janetc_error(c, janet_formatc("unexpected type in destructuring, got %v", left));
@@ -255,8 +259,10 @@ static int destructure(JanetCompiler *c,
JanetSlot k = janetc_cslot(janet_wrap_integer(i));
janetc_emit_sss(c, JOP_IN, nextright, right, k, 1);
}
c->recursion_guard--;
if (destructure(c, subval, nextright, leaf, attr))
janetc_freeslot(c, nextright);
c->recursion_guard++;
}
}
return 1;
@@ -270,8 +276,10 @@ static int destructure(JanetCompiler *c,
JanetSlot nextright = janetc_farslot(c);
JanetSlot k = janetc_value(janetc_fopts_default(c), kvs[i].key);
janetc_emit_sss(c, JOP_IN, nextright, right, k, 1);
c->recursion_guard--;
if (destructure(c, kvs[i].value, nextright, leaf, attr))
janetc_freeslot(c, nextright);
c->recursion_guard++;
}
}
return 1;
@@ -370,7 +378,10 @@ typedef struct SlotHeadPair {
} SlotHeadPair;
SlotHeadPair *dohead_destructure(JanetCompiler *c, SlotHeadPair *into, JanetFopts opts, Janet lhs, Janet rhs) {
if (c->recursion_guard <= 0) {
janetc_error(c, janet_cstring("C stack recursed too deeply"));
return NULL;
}
/* Detect if we can do an optimization to avoid some allocations */
int can_destructure_lhs = janet_checktype(lhs, JANET_TUPLE)
|| janet_checktype(lhs, JANET_ARRAY);
@@ -415,7 +426,9 @@ SlotHeadPair *dohead_destructure(JanetCompiler *c, SlotHeadPair *into, JanetFopt
if (!found_amp && !found_splice) {
for (int32_t i = 0; i < view_lhs.len; i++) {
Janet sub_rhs = view_rhs.len <= i ? janet_wrap_nil() : view_rhs.items[i];
c->recursion_guard--;
into = dohead_destructure(c, into, subopts, view_lhs.items[i], sub_rhs);
c->recursion_guard++;
}
return into;
}