diff options
| -rw-r--r-- | Objects/listobject.c | 24 |
1 files changed, 20 insertions, 4 deletions
diff --git a/Objects/listobject.c b/Objects/listobject.c index f6ae50f..5c3d0ed 100644 --- a/Objects/listobject.c +++ b/Objects/listobject.c @@ -368,6 +368,13 @@ list_ass_slice(a, ilow, ihigh, v) int ilow, ihigh; object *v; { + /* Because [X]DECREF can recursively invoke list operations on + this list, we must postpone all [X]DECREF activity until + after the list is back in its canonical shape. Therefore + we must allocate an additional array, 'recycle', into which + we temporarily copy the items that are deleted from the + list. :-( */ + object **recycle, **p; object **item; int n; /* Size of replacement list */ int d; /* Change in size */ @@ -402,9 +409,13 @@ list_ass_slice(a, ilow, ihigh, v) ihigh = a->ob_size; item = a->ob_item; d = n - (ihigh-ilow); - if (d <= 0) { /* Delete -d items; XDECREF ihigh-ilow items */ + if (ihigh > ilow) + p = recycle = NEW(object *, (ihigh-ilow)); + else + p = recycle = NULL; + if (d <= 0) { /* Delete -d items; recycle ihigh-ilow items */ for (k = ilow; k < ihigh; k++) - XDECREF(item[k]); /* bug: reentrant side effects */ + *p++ = item[k]; if (d < 0) { for (/*k = ihigh*/; k < a->ob_size; k++) item[k+d] = item[k]; @@ -413,7 +424,7 @@ list_ass_slice(a, ilow, ihigh, v) a->ob_item = item; } } - else { /* Insert d items; XDECREF ihigh-ilow items */ + else { /* Insert d items; recycle ihigh-ilow items */ RESIZE(item, object *, a->ob_size + d); if (item == NULL) { err_nomem(); @@ -422,7 +433,7 @@ list_ass_slice(a, ilow, ihigh, v) for (k = a->ob_size; --k >= ihigh; ) item[k+d] = item[k]; for (/*k = ihigh-1*/; k >= ilow; --k) - XDECREF(item[k]); /* bug: side effects :-( */ + *p++ = item[k]; a->ob_item = item; a->ob_size += d; } @@ -431,6 +442,11 @@ list_ass_slice(a, ilow, ihigh, v) XINCREF(w); item[ilow] = w; } + if (recycle) { + while (--p >= recycle) + XDECREF(*p); + DEL(recycle); + } return 0; #undef b } |