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

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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>
This commit is contained in:
Denys Vlasenko 2010-03-11 12:13:18 +01:00
parent 90f19fa468
commit da62b09ab1
1 changed files with 49 additions and 21 deletions
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70
editors/awk.c
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@ -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;
}