from cinap acid: fix memory corruption due to gc we cannot call gc() in execute() because it will gc anonyous intermediate results which happens when we construct a list and the elements are calculated by calling a function thru ocall() which calls execute(). also, the _thiscmd symbol; which is used to keep a reference to a statement so it wont get garbage collected; does not work as yyparse() is recursive (include statements). we add execrec() function which *only* gets called from yyparse() when evaluating a statement. it will keep a stack on the _thiscmd symbol handling the yyparse() recursion. we also only call gc() in execrec() before calling execute(). so execute() will never gc() while evaluating a statement which prevents the intermediate results from getting collected. Reference: /n/atom/patch/applied/acidgc Date: Fri Feb 14 03:11:45 CET 2014 Signed-off-by: quanstro@quanstro.net --- /sys/src/cmd/acid/lex.c Fri Feb 14 03:04:10 2014 +++ /sys/src/cmd/acid/lex.c Fri Feb 14 03:04:11 2014 @@ -580,11 +580,12 @@ s->lexval = t; v = gmalloc(sizeof(Value)); - s->v = v; + memset(v, 0, sizeof(Value)); v->fmt = 'X'; v->type = TINT; - memset(v, 0, sizeof(Value)); + + s->v = v; return s; } --- /sys/src/cmd/acid/exec.c Fri Feb 14 03:04:13 2014 +++ /sys/src/cmd/acid/exec.c Fri Feb 14 03:04:14 2014 @@ -57,6 +57,32 @@ } void +execrec(Node *n) +{ + Value *v; + Lsym *s; + + /* make node a root so it isn't collected! */ + s = mkvar("_thiscmd"); + + v = gmalloc(sizeof(Value)); + memset(v, 0, sizeof(Value)); + v->type = TCODE; + v->cc = n; + v->pop = s->v; + + s->v = v; + s->proc = n; + + gc(); + execute(n); + + s->proc = s->v->cc; + s->v = v->pop; + free(v); +} + +void execute(Node *n) { Value *v; @@ -66,7 +92,6 @@ Node res, xx; static int stmnt; - gc(); if(gotint) error("interrupted"); --- /sys/src/cmd/acid/dbg.y Fri Feb 14 03:04:16 2014 +++ /sys/src/cmd/acid/dbg.y Fri Feb 14 03:04:17 2014 @@ -50,11 +50,7 @@ bigstmnt : stmnt { - /* make stmnt a root so it isn't collected! */ - mkvar("_thiscmd")->proc = $1; - execute($1); - mkvar("_thiscmd")->proc = nil; - gc(); + execrec($1); if(interactive && needprompt){ Bprint(bout, "acid; "); needprompt = 0; --- /sys/src/cmd/acid/acid.h Fri Feb 14 03:04:18 2014 +++ /sys/src/cmd/acid/acid.h Fri Feb 14 03:04:19 2014 @@ -194,6 +194,7 @@ Lsym* enter(char*, int); void error(char*, ...); void execute(Node*); +void execrec(Node*); void fatal(char*, ...); void flatten(Node**, Node*); void gc(void);