From cb042b05828c4c89320bc9c7454c04c2761bbb9a Mon Sep 17 00:00:00 2001
From: Denys Vlasenko <vda.linux@googlemail.com>
Date: Sat, 3 Jul 2021 13:29:32 +0200
Subject: awk: restore strdup elision optimization in assignment
function old new delta
evaluate 3339 3387 +48
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
---
editors/awk.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)
diff --git a/editors/awk.c b/editors/awk.c
index 649198d15..20672db9a 100644
--- a/editors/awk.c
+++ b/editors/awk.c
@@ -102,7 +102,7 @@ enum {
#define VF_USER 0x0200 /* 1 = user input (may be numeric string) */
#define VF_SPECIAL 0x0400 /* 1 = requires extra handling when changed */
#define VF_WALK 0x0800 /* 1 = variable has alloc'd x.walker list */
-#define VF_FSTR 0x1000 /* 1 = var::string points to fstring buffer */
+#define VF_FSTR 0x1000 /* 1 = don't free() var::string (not malloced, or is owned by something else) */
#define VF_CHILD 0x2000 /* 1 = function arg; x.parent points to source */
#define VF_DIRTY 0x4000 /* 1 = variable was set explicitly */
@@ -1371,6 +1371,12 @@ static node *parse_expr(uint32_t term_tc)
cn->a.n = vn->a.n;
if (tc & TS_BINOP) {
cn->l.n = vn;
+//FIXME: this is the place to detect and reject assignments to non-lvalues.
+//Currently we allow "assignments" to consts and temporaries, nonsense like this:
+// awk 'BEGIN { "qwe" = 1 }'
+// awk 'BEGIN { 7 *= 7 }'
+// awk 'BEGIN { length("qwe") = 1 }'
+// awk 'BEGIN { (1+1) += 3 }'
expected_tc = TS_OPERAND | TS_UOPPRE | TC_REGEXP;
if ((t_info & OPCLSMASK) == OC_PGETLINE) {
/* it's a pipe */
@@ -3043,14 +3049,17 @@ static var *evaluate(node *op, var *res)
case XC( OC_MOVE ):
debug_printf_eval("MOVE\n");
/* if source is a temporary string, jusk relink it to dest */
-//Disabled: if R.v is numeric but happens to have cached R.v->string,
-//then L.v ends up being a string, which is wrong
-// if (R.v == TMPVAR1 && R.v->string) {
-// res = setvar_p(L.v, R.v->string);
-// R.v->string = NULL;
-// } else {
+ if (R.v == TMPVAR1
+ && !(R.v->type & VF_NUMBER)
+ /* Why check !NUMBER? if R.v is a number but has cached R.v->string,
+ * L.v ends up a string, which is wrong */
+ /*&& R.v->string - always not NULL (right?) */
+ ) {
+ res = setvar_p(L.v, R.v->string); /* avoids strdup */
+ R.v->string = NULL;
+ } else {
res = copyvar(L.v, R.v);
-// }
+ }
break;
case XC( OC_TERNARY ):
--
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