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b3c91a127

Denys Vlasenko

2021-06-29

SUCCESS Duration: 153s

Subject

awk: free unused parsing structures after parse is done

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Architecture & Compiler Flags

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

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Commit Diff GitHub →

editors/awk.c +47 -27

editors/awk.c+47 -27

@@ -530,7 +530,8 @@ struct globals {
	xhash ahash; / argument names, used only while parsing function bodies */
	xhash fnhash; / function names, used only in parsing stage */
	xhash vhash; / variables and arrays */
-	xhash fdhash; / file objects, used only in execution stage */
+	//xhash fdhash; / file objects, used only in execution stage */
+	//we are reusing ahash as fdhash, via define (see later)
	const char *g_progname;
	int g_lineno;
	int nfields;
@@ -592,10 +593,13 @@ struct globals2 {
	#define break_ptr (G1.break_ptr )
	#define continue_ptr (G1.continue_ptr)
	#define iF (G1.iF )
-	#define vhash (G1.vhash )
	#define ahash (G1.ahash )
-	#define fdhash (G1.fdhash )
	#define fnhash (G1.fnhash )
+	#define vhash (G1.vhash )
+	#define fdhash ahash
+	//^^^^^^^^^^^^^^^^^^ ahash is cleared after every function parsing,
+	// and ends up empty after parsing phase. Thus, we can simply reuse it
+	// for fdhash in execution stage.
	#define g_progname (G1.g_progname )
	#define g_lineno (G1.g_lineno )
	#define nfields (G1.nfields )
@@ -682,6 +686,33 @@ static xhash *hash_init(void)
	return newhash;
	}

+	static void hash_clear(xhash *hash)
+	{
+	unsigned i;
+	hash_item hi, thi;
+
+	for (i = 0; i < hash->csize; i++) {
+	hi = hash->items[i];
+	while (hi) {
+	thi = hi;
+	hi = hi->next;
+	free(thi->data.v.string);
+	free(thi);
+	}
+	hash->items[i] = NULL;
+	}
+	hash->glen = hash->nel = 0;
+	}
+
+	#if 0 //UNUSED
+	static void hash_free(xhash *hash)
+	{
+	hash_clear(hash);
+	free(hash->items);
+	free(hash);
+	}
+	#endif
+
	/* find item in hash, return ptr to data, NULL if not found */
	static void hash_search(xhash hash, const char *name)
	{
@@ -869,23 +900,7 @@ static xhash iamarray(var v)
	return a->x.array;
	}

-	static void clear_array(xhash *array)
-	{
-	unsigned i;
-	hash_item hi, thi;
-
-	for (i = 0; i < array->csize; i++) {
-	hi = array->items[i];
-	while (hi) {
-	thi = hi;
-	hi = hi->next;
-	free(thi->data.v.string);
-	free(thi);
-	}
-	array->items[i] = NULL;
-	}
-	array->glen = array->nel = 0;
-	}
+	#define clear_array(array) hash_clear(array)

	/* clear a variable */
	static var clrvar(var v)
@@ -1742,7 +1757,7 @@ static void parse_program(char *p)
	}
	seq = &f->body;
	chain_group();
-	clear_array(ahash);
+	hash_clear(ahash);
	} else if (tclass & TS_OPSEQ) {
	debug_printf_parse("%s: TS_OPSEQ\n", __func__);
	rollback_token();
@@ -3471,11 +3486,16 @@ int awk_main(int argc UNUSED_PARAM, char **argv)
	bb_show_usage();
	parse_program(*argv++);
	}
-	//free_hash(ahash) // ~250 bytes, arg names, used only during parse of function bodies
-	//ahash = NULL; // debug
-	//free_hash(fnhash) // ~250 bytes, used only for function names
-	//fnhash = NULL; // debug
-	/* parsing done, on to executing */
+	/* Free unused parse structures */
+	//hash_free(fnhash); // ~250 bytes when empty, used only for function names
+	//^^^^^^^^^^^^^^^^^ does not work, hash_clear() inside SEGVs
+	// (IOW: hash_clear() assumes it's a hash of variables. fnhash is not).
+	free(fnhash->items);
+	free(fnhash);
+	fnhash = NULL; // debug
+	//hash_free(ahash); // empty after parsing, will reuse as fdhash instead of freeing
+
+	/* Parsing done, on to executing */

	/* fill in ARGV array */
	setari_u(intvar[ARGV], 0, "awk");
@@ -3484,7 +3504,7 @@ int awk_main(int argc UNUSED_PARAM, char **argv)
	setari_u(intvar[ARGV], ++i, *argv++);
	setvar_i(intvar[ARGC], i + 1);

-	fdhash = hash_init();
+	//fdhash = ahash - done via define
	newfile("/dev/stdin")->F = stdin;
	newfile("/dev/stdout")->F = stdout;
	newfile("/dev/stderr")->F = stderr;