655b4c7 · Idris-dev · git.iko.soy

git.iko.soy/Idris-dev

Fix potential memory allocation problem

If we allocate space for a substring, and that triggers a gc, the original string won't be in the same place, so we need to account for this in idris_substr.

commit655b4c7f3d5b12f51a3bcf235c345506eaec6e78 authorEdwin Brady <ecb10@st-andrews.ac.uk> dateThu 13 Sep 2018, 23:00 (8 years ago) parent51d3888

1 file changed+19−4

compare with master

unifiedsplit

rts/idris_rts.c+19−4

rts/idris_rts.c+19−4

@@ -697,10 +697,25 @@ VAL idris_substr(VM* vm, VAL offset, VAL length, VAL str) {

697697 char *start = idris_utf8_advance(str_val, offset_val);

698698 char *end = idris_utf8_advance(start, length_val);

699699 size_t sz = end - start;

700− String * newstr = allocStr(vm, sz, 0);

701− memcpy(newstr->str, start, sz);

702− newstr->str[sz] = '\0';

703− return (VAL)newstr;

700+

701+ if (space(vm, sz)) {

702+ String * newstr = allocStr(vm, sz, 0);

703+ memcpy(newstr->str, start, sz);

704+ newstr->str[sz] = '\0';

705+ return (VAL)newstr;

706+ } else {

707+ // Need to copy into an intermediate string before allocating,

708+ // because if there's no enough space then allocating will move the

709+ // original string!

710+ char* cpystr = malloc(sz);

711+ memcpy(cpystr, start, sz);

712+

713+ String * newstr = allocStr(vm, sz, 0);

714+ memcpy(newstr->str, cpystr, sz);

715+ newstr->str[sz] = '\0';

716+ free(cpystr);

717+ return (VAL)newstr;

718+ }

704719 }

705720}

706721