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gpgscm: Fix copying values.

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* tests/gpgscm/scheme.c (copy_value): New function.
(mk_tagged_value): Use new function.
(opexe_4): Likewise for OP_SAVE_FORCED.
--

Occasionally, we need to copy a value from one location in the storage
to another.  Scheme objects are fine.  Some primitive objects,
however, require finalization, usually to free resources.

For these values, we either make a copy or acquire a reference.

Fixes e.g. a double free if a delayed expression evaluating to a
string is forced.

Signed-off-by: Justus Winter <justus@g10code.com>
This commit is contained in:
Justus Winter 2017-04-04 17:36:45 +02:00
parent a80d4a9b50
commit 6261611d37
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GPG Key ID: DD1A52F9DA8C9020
1 changed files with 52 additions and 2 deletions
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54
tests/gpgscm/scheme.c
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@ -624,6 +624,56 @@ static long binary_decode(const char *s) {
/*
* Copying values.
*
* Occasionally, we need to copy a value from one location in the
* storage to another. Scheme objects are fine. Some primitive
* objects, however, require finalization, usually to free resources.
*
* For these values, we either make a copy or acquire a reference.
*/
/*
* Copy SRC to DST.
*
* Copies the representation of SRC to DST. This makes SRC
* indistinguishable from DST from the perspective of a Scheme
* expression modulo the fact that they reside at a different location
* in the store.
*
* Conditions:
*
* - SRC must not be a vector.
* - Caller must ensure that any resources associated with the
* value currently stored in DST is accounted for.
*/
static void
copy_value(scheme *sc, pointer dst, pointer src)
{
memcpy(dst, src, sizeof *src);
/* We may need to make a copy or acquire a reference. */
if (typeflag(dst) & T_FINALIZE)
switch (type(dst)) {
case T_STRING:
strvalue(dst) = store_string(sc, strlength(dst), strvalue(dst), 0);
break;
case T_PORT:
/* XXX acquire reference */
assert (!"implemented");
break;
case T_FOREIGN_OBJECT:
/* XXX acquire reference */
assert (!"implemented");
break;
case T_VECTOR:
assert (!"vectors cannot be copied");
}
}
/* Tags are like property lists, but can be attached to arbitrary
* values. */
@ -640,7 +690,7 @@ mk_tagged_value(scheme *sc, pointer v, pointer tag_car, pointer tag_cdr)
if (r == sc->sink)
return sc->sink;
memcpy(r, v, sizeof *v);
copy_value(sc, r, v);
typeflag(r) |= T_TAGGED;
t = r + 1;
@ -4603,7 +4653,7 @@ static pointer opexe_4(scheme *sc, enum scheme_opcodes op) {
}
CASE(OP_SAVE_FORCED): /* Save forced value replacing promise */
memcpy(sc->code,sc->value,sizeof(struct cell));
copy_value(sc, sc->code, sc->value);
s_return(sc,sc->value);
CASE(OP_WRITE): /* write */