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authorDenys Vlasenko2021-07-01 17:50:26 +0200
committerDenys Vlasenko2021-07-01 17:50:26 +0200
commit8b4c429025c233640bd5c5838552f34683a06fc0 (patch)
tree385135c4fd35dbfd8f4e682c3819c0d46dc4770b /editors
parent1573487e2100892d06e3628828690692313a48d5 (diff)
downloadbusybox-8b4c429025c233640bd5c5838552f34683a06fc0.zip
busybox-8b4c429025c233640bd5c5838552f34683a06fc0.tar.gz
awk: use static tmpvars instead of nvalloc(1)ed ones
ptest() was using this idea already. As far as I can see, this is safe. Ttestsuite passes. One downside is that a temporary from e.g. printf invocation won't be freed until the next printf call. function old new delta awk_printf 481 468 -13 as_regex 137 111 -26 ------------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-39) Total: -39 bytes Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Diffstat (limited to 'editors')
-rw-r--r--editors/awk.c49
1 files changed, 34 insertions, 15 deletions
diff --git a/editors/awk.c b/editors/awk.c
index 2c2cb74..0be044e 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -559,7 +559,9 @@ struct globals2 {
unsigned evaluate__seed;
regex_t evaluate__sreg;
- var ptest__v;
+ var ptest__tmpvar;
+ var awk_printf__tmpvar;
+ var as_regex__tmpvar;
tsplitter exec_builtin__tspl;
@@ -1775,14 +1777,19 @@ static node *mk_splitter(const char *s, tsplitter *spl)
static regex_t *as_regex(node *op, regex_t *preg)
{
int cflags;
- var *tmpvar;
const char *s;
if ((op->info & OPCLSMASK) == OC_REGEXP) {
return icase ? op->r.ire : op->l.re;
}
- tmpvar = nvalloc(1);
- s = getvar_s(evaluate(op, tmpvar));
+
+#define TMPVAR (&G.as_regex__tmpvar)
+ //tmpvar = nvalloc(1);
+ // We use a single "static" tmpvar (instead of on-stack or malloced one)
+ // to decrease memory consumption in deeply-recursive awk programs.
+ // The rule to work safely is to never call evaluate() while our static
+ // TMPVAR's value is still needed.
+ s = getvar_s(evaluate(op, TMPVAR));
cflags = icase ? REG_EXTENDED | REG_ICASE : REG_EXTENDED;
/* Testcase where REG_EXTENDED fails (unpaired '{'):
@@ -1794,7 +1801,8 @@ static regex_t *as_regex(node *op, regex_t *preg)
cflags &= ~REG_EXTENDED;
xregcomp(preg, s, cflags);
}
- nvfree(tmpvar, 1);
+ //nvfree(tmpvar, 1);
+#undef TMPVAR
return preg;
}
@@ -2105,8 +2113,11 @@ static int hashwalk_next(var *v)
/* evaluate node, return 1 when result is true, 0 otherwise */
static int ptest(node *pattern)
{
- /* ptest__v is "static": to save stack space? */
- return istrue(evaluate(pattern, &G.ptest__v));
+ // We use a single "static" tmpvar (instead of on-stack or malloced one)
+ // to decrease memory consumption in deeply-recursive awk programs.
+ // The rule to work safely is to never call evaluate() while our static
+ // TMPVAR's value is still needed.
+ return istrue(evaluate(pattern, &G.ptest__tmpvar));
}
/* read next record from stream rsm into a variable v */
@@ -2243,12 +2254,18 @@ static char *awk_printf(node *n, int *len)
const char *s1;
int i, j, incr, bsize;
char c, c1;
- var *tmpvar, *arg;
-
- tmpvar = nvalloc(1);
-//TODO: above, to avoid allocating a single temporary var, take a pointer
-//to a temporary that our caller (evaluate()) already has?
- fmt = f = xstrdup(getvar_s(evaluate(nextarg(&n), tmpvar)));
+ var *arg;
+
+ //tmpvar = nvalloc(1);
+#define TMPVAR (&G.awk_printf__tmpvar)
+ // We use a single "static" tmpvar (instead of on-stack or malloced one)
+ // to decrease memory consumption in deeply-recursive awk programs.
+ // The rule to work safely is to never call evaluate() while our static
+ // TMPVAR's value is still needed.
+ fmt = f = xstrdup(getvar_s(evaluate(nextarg(&n), TMPVAR)));
+ // ^^^^^^^^^ here we immediately strdup() the value, so the later call
+ // to evaluate() potentially recursing into another awk_printf() can't
+ // mangle the value.
i = 0;
while (*f) {
@@ -2268,7 +2285,7 @@ static char *awk_printf(node *n, int *len)
f++;
c1 = *f;
*f = '\0';
- arg = evaluate(nextarg(&n), tmpvar);
+ arg = evaluate(nextarg(&n), TMPVAR);
j = i;
if (c == 'c' || !c) {
@@ -2289,7 +2306,9 @@ static char *awk_printf(node *n, int *len)
}
free(fmt);
- nvfree(tmpvar, 1);
+// nvfree(tmpvar, 1);
+#undef TMPVAR
+
b = xrealloc(b, i + 1);
b[i] = '\0';
#if ENABLE_FEATURE_AWK_GNU_EXTENSIONS