From 0768038c86de589a4128786f60fdd430c21e8610 Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Tue, 1 Mar 2022 02:04:35 +0100
Subject: [PATCH] Filter: Clean up function call instruction

Pass instructions of function call arguments as vararg arguments to
FI_CALL instruction constructor and move necessary magic from parser
code to interpreter / instruction code.
---
 filter/config.Y | 23 +++++++++--------------
 filter/f-inst.c | 24 +++++++++++++++++-------
 2 files changed, 26 insertions(+), 21 deletions(-)

diff --git a/filter/config.Y b/filter/config.Y
index 8916ea97..0ab32a57 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -700,27 +700,22 @@ var_list: /* EMPTY */ { $$ = NULL; }
  | var_list ',' term { $$ = $3; $$->next = $1; }
 
 function_call:
-   CF_SYM_KNOWN '(' var_list ')' {
+   CF_SYM_KNOWN '(' var_list ')'
+   {
      if ($1->class != SYM_FUNCTION)
        cf_error("You can't call something which is not a function. Really.");
 
-     struct f_inst *fc = f_new_inst(FI_CALL, $1);
-     uint args = 0;
+     /* Revert the var_list */
+     struct f_inst *args = NULL;
      while ($3) {
-       args++;
-       struct f_inst *tmp = $3->next;
-       $3->next = fc;
+       struct f_inst *tmp = $3;
+       $3 = $3->next;
 
-       fc = $3;
-       $3 = tmp;
+       tmp->next = args;
+       args = tmp;
      }
 
-     if (args != $1->function->args)
-       cf_error("Function call '%s' got %u arguments, need %u arguments.",
-	   $1->name, args, $1->function->args);
-
-     $$ = f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_VOID });
-     $$->next = fc;
+     $$ = f_new_inst(FI_CALL, args, $1);
    }
  ;
 
diff --git a/filter/f-inst.c b/filter/f-inst.c
index 901d2939..0d935859 100644
--- a/filter/f-inst.c
+++ b/filter/f-inst.c
@@ -1079,8 +1079,22 @@
 
   INST(FI_CALL, 0, 1) {
     NEVER_CONSTANT;
+    VARARG;
     SYMBOL;
 
+    FID_NEW_BODY()
+    ASSERT(sym->class == SYM_FUNCTION);
+
+    if (whati->varcount != sym->function->args)
+      cf_error("Function '%s' expects %u arguments, got %u arguments",
+	       sym->name, sym->function->args, whati->varcount);
+
+    /* Add implicit void slot for the return value */
+    struct f_inst *tmp = f_new_inst(FI_CONSTANT, (struct f_val) { .type = T_VOID });
+    tmp->next = whati->fvar;
+    whati->fvar = tmp;
+    what->size += tmp->size;
+
     FID_SAME_BODY()
       if (!(f1->sym->flags & SYM_FLAG_SAME))
 	return 0;
@@ -1092,15 +1106,11 @@
 
     /* Push the body on stack */
     LINEX(sym->function);
+    curline.vbase = curline.ventry;
     curline.emask |= FE_RETURN;
 
-    /* Before this instruction was called, there was the T_VOID
-     * automatic return value pushed on value stack and also
-     * sym->function->args function arguments. Setting the
-     * vbase to point to first argument. */
-    ASSERT(curline.ventry >= sym->function->args);
-    curline.ventry -= sym->function->args;
-    curline.vbase = curline.ventry;
+    /* Arguments on stack */
+    fstk->vcnt += sym->function->args;
 
     /* Storage for local variables */
     memset(&(fstk->vstk[fstk->vcnt]), 0, sizeof(struct f_val) * sym->function->vars);