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da62b09ab

Denys Vlasenko

2010-03-11

FAILED Duration: 29s

Subject

awk: be more paranoid when freeing loop variable; make code less obfuscated

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

editors/awk.c +49 -21

editors/awk.c+49 -21

@@ -14,6 +14,16 @@
	/* This is a NOEXEC applet. Be very careful! */


+	/* If you comment out one of these below, it will be #defined later
+	* to perform debug printfs to stderr: */
+	#define debug_printf_walker(...) do {} while (0)
+
+	#ifndef debug_printf_walker
+	# define debug_printf_walker(...) (fprintf(stderr, __VA_ARGS__))
+	#endif
+
+
+
	#define MAXVARFMT 240
	#define MINNVBLOCK 64

@@ -32,6 +42,13 @@
	/* these flags are static, don't change them when value is changed */
	#define VF_DONTTOUCH (VF_ARRAY \| VF_SPECIAL \| VF_WALK \| VF_CHILD \| VF_DIRTY)

+	typedef struct walker_list {
+	char *end;
+	char *cur;
+	struct walker_list *prev;
+	char wbuf[1];
+	} walker_list;
+
	/* Variable */
	typedef struct var_s {
	unsigned type; /* flags */
@@ -41,7 +58,7 @@ typedef struct var_s {
	int aidx; /* func arg idx (for compilation stage) */
	struct xhash_s array; / array ptr */
	struct var_s parent; / for func args, ptr to actual parameter */
-	char *walker; / list of array elements (for..in) */
+	walker_list walker; / list of array elements (for..in) */
	} x;
	} var;

@@ -913,10 +930,17 @@ static void nvfree(var *v)
	free(p->x.array);
	}
	if (p->type & VF_WALK) {
-	//bb_error_msg("free(walker@%p:%p) #1", &p->x.walker, p->x.walker);
-	free(p->x.walker);
+	walker_list *n;
+	walker_list *w = p->x.walker;
+	debug_printf_walker("nvfree: freeing walker @%p\n", &p->x.walker);
+	p->x.walker = NULL;
+	while (w) {
+	n = w->prev;
+	debug_printf_walker(" free(%p)\n", w);
+	free(w);
+	w = n;
+	}
	}
-
	clrvar(p);
	}

@@ -1724,23 +1748,28 @@ static node nextarg(node *pn)

	static void hashwalk_init(var v, xhash array)
	{
-	char **w;
	hash_item *hi;
	unsigned i;
-	char **prev_walker = (v->type & VF_WALK) ? v->x.walker : NULL;
+	walker_list *w;
+	walker_list *prev_walker;

-	v->type \|= VF_WALK;
+	if (v->type & VF_WALK) {
+	prev_walker = v->x.walker;
+	} else {
+	v->type \|= VF_WALK;
+	prev_walker = NULL;
+	}
+	debug_printf_walker("hashwalk_init: prev_walker:%p\n", prev_walker);

-	/* walker structure is: "[ptr2end][ptr2start][prev]<word1>NUL<word2>NUL" */
-	w = v->x.walker = xzalloc(2 + 3sizeof(char ) + array->glen);
-	//bb_error_msg("walker@%p=%p", &v->x.walker, v->x.walker);
-	w[0] = w[1] = (char *)(w + 3);
-	w[2] = (char *)prev_walker;
+	w = v->x.walker = xzalloc(sizeof(w) + array->glen + 1); / why + 1? */
+	debug_printf_walker(" walker@%p=%p\n", &v->x.walker, w);
+	w->cur = w->end = w->wbuf;
+	w->prev = prev_walker;
	for (i = 0; i < array->csize; i++) {
	hi = array->items[i];
	while (hi) {
-	strcpy(w[0], hi->name);
-	nextword(&w[0]);
+	strcpy(w->end, hi->name);
+	nextword(&w->end);
	hi = hi->next;
	}
	}
@@ -1748,19 +1777,18 @@ static void hashwalk_init(var v, xhash array)

	static int hashwalk_next(var *v)
	{
-	char **w;
+	walker_list *w = v->x.walker;

-	w = v->x.walker;
-	if (w[1] == w[0]) {
-	char prev_walker = (char)w[2];
+	if (w->cur >= w->end) {
+	walker_list *prev_walker = w->prev;

-	//bb_error_msg("free(walker@%p:%p) #3, restoring to %p", &v->x.walker, v->x.walker, prev_walker);
-	free(v->x.walker);
+	debug_printf_walker("end of iteration, free(walker@%p:%p), prev_walker:%p\n", &v->x.walker, w, prev_walker);
+	free(w);
	v->x.walker = prev_walker;
	return FALSE;
	}

-	setvar_s(v, nextword(&w[1]));
+	setvar_s(v, nextword(&w->cur));
	return TRUE;
	}