From 8b1a5b7dbf993908f24c1a0a1ddebbf2b96c70dd Mon Sep 17 00:00:00 2001
From: "Arnold D. Robbins" <arnold@skeeve.com>
Date: Sun, 14 Jun 2020 11:18:15 +0300
Subject: Check for FUNCTAB and SYMTAB as destination in builtin functions.

---
 ChangeLog | 12 ++++++++++++
 array.c   |  9 +++------
 awk.h     |  1 +
 builtin.c | 14 ++++++++++++++
 field.c   |  8 ++++++++
 5 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 83bf1a00..384bc6b4 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,15 @@
+2020-06-14         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Disallow SYMTAB and FUNCTAB as destination arguments to builtin
+	functions that clear arrays:
+
+	* awk.h (check_symtab_functab): Add declaration.
+	* array.c (asort_actual): Call it in check for second argument.
+	* builtin.c (check_symtab_functab): New function.
+	(do_match): Call it in check for third argument.
+	* field.c (do_patsplit, do_split): Call it in checks for fourth and
+	second arguments.
+
 2020-06-12         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* array.c (asort_actual): If SYMTAB or FUNCTAB is the second argument,
diff --git a/array.c b/array.c
index e3bbc835..c256620b 100644
--- a/array.c
+++ b/array.c
@@ -824,12 +824,9 @@ asort_actual(int nargs, sort_context_t ctxt)
 			fatal(_("%s: second argument is not an array"),
 				ctxt == ASORT ? "asort" : "asorti");
 		}
-		if (dest == symbol_table)
-			fatal(_("%s: SYMTAB cannot be used as second argument"),
-				ctxt == ASORT ? "asort" : "asorti");
-		else if (dest == func_table)
-			fatal(_("%s: FUNCTAB cannot be used as second argument"),
-				ctxt == ASORT ? "asort" : "asorti");
+		check_symtab_functab(dest,
+				ctxt == ASORT ? "asort" : "asorti",
+				_("%s: cannot use %s as second argument"));
 	}
 
 	array = POP_PARAM();
diff --git a/awk.h b/awk.h
index 9005ff34..cccb8ce5 100644
--- a/awk.h
+++ b/awk.h
@@ -1498,6 +1498,7 @@ extern NODE *do_typeof(int nargs);
 extern int strncasecmpmbs(const unsigned char *,
 			  const unsigned char *, size_t);
 extern int sanitize_exit_status(int status);
+extern void check_symtab_functab(NODE *dest, const char *fname, const char *msg);
 /* debug.c */
 extern void init_debug(void);
 extern int debug_prog(INSTRUCTION *pc);
diff --git a/builtin.c b/builtin.c
index 7ef2acd8..9b5609fa 100644
--- a/builtin.c
+++ b/builtin.c
@@ -2678,6 +2678,8 @@ do_match(int nargs)
 		dest = POP_PARAM();
 		if (dest->type != Node_var_array)
 			fatal(_("match: third argument is not an array"));
+		check_symtab_functab(dest, "match", 
+				_("%s: cannot use %s as third argument"));
 		assoc_clear(dest);
 	}
 	tre = POP();
@@ -4328,3 +4330,15 @@ fmt:
 	}
 	return buf;
 }
+
+
+/* check_symtab_functab --- check if dest is SYMTAB or FUNCTAB, fatal if so */
+
+void
+check_symtab_functab(NODE *dest, const char *fname, const char *msg)
+{
+	if (dest == symbol_table)
+		fatal(msg, fname, "SYMTAB");
+	else if (dest == func_table)
+		fatal(msg, fname, "FUNCTAB");
+}
diff --git a/field.c b/field.c
index 45ab9f5f..0e84447a 100644
--- a/field.c
+++ b/field.c
@@ -980,6 +980,8 @@ do_split(int nargs)
 		sep_arr = POP_PARAM();
 		if (sep_arr->type != Node_var_array)
 			fatal(_("split: fourth argument is not an array"));
+		check_symtab_functab(sep_arr, "split",
+				_("%s: cannot use %s as fourth argument"));
 		if ((do_lint_extensions || do_lint_old) && ! warned) {
 			warned = true;
 			lintwarn(_("split: fourth argument is a gawk extension"));
@@ -990,6 +992,8 @@ do_split(int nargs)
 	arr = POP_PARAM();
 	if (arr->type != Node_var_array)
 		fatal(_("split: second argument is not an array"));
+	check_symtab_functab(arr, "split",
+			_("%s: cannot use %s as second argument"));
 
 	if (sep_arr != NULL) {
 		if (sep_arr == arr)
@@ -1073,11 +1077,15 @@ do_patsplit(int nargs)
 		sep_arr = POP_PARAM();
 		if (sep_arr->type != Node_var_array)
 			fatal(_("patsplit: fourth argument is not an array"));
+		check_symtab_functab(sep_arr, "patsplit",
+				_("%s: cannot use %s as fourth argument"));
 	}
 	sep = POP();
 	arr = POP_PARAM();
 	if (arr->type != Node_var_array)
 		fatal(_("patsplit: second argument is not an array"));
+	check_symtab_functab(arr, "patsplit",
+			_("%s: cannot use %s as second argument"));
 
 	src = TOP_STRING();
 
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