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authorDenys Vlasenko <vda.linux@googlemail.com>2010-03-11 11:13:18 (GMT)
committer Denys Vlasenko <vda.linux@googlemail.com>2010-03-11 11:13:18 (GMT)
commitda62b09ab1def06ed8844c4df7b7eacf05474284 (patch)
tree5555dcabc789f27d026adc0fac2c39274e938b3c
parent90f19fa468d5b9f6374a62343e98066be8169140 (diff)
downloadbusybox-da62b09ab1def06ed8844c4df7b7eacf05474284.tar.gz
busybox-da62b09ab1def06ed8844c4df7b7eacf05474284.tar.bz2
awk: be more paranoid when freeing loop variable; make code less obfuscated
function old new delta nvfree 149 170 +21 next_token 928 932 +4 getvar_i 95 94 -1 skip_spaces 51 45 -6 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 2/2 up/down: 25/-7) Total: 18 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--editors/awk.c70
1 files changed, 49 insertions, 21 deletions
diff --git a/editors/awk.c b/editors/awk.c
index 1d704e8..397d70f 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -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 + 3*sizeof(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;
}