API clean up and require strings to be malloced.

10 files changed, 284 insertions, 111 deletions

diff --git a/ChangeLog b/ChangeLog
index 759daaa8..2429bd8b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,30 @@
+2012-07-11         Arnold D. Robbins     <arnold@skeeve.com>
+
+	Lots of API work.
+
+	* gawkapi.h: Function pointer members renamed api_XXXX and
+	macros adjusted. More documentation.
+	(awk_valtype_t): New AWK_SCALAR enum for scalar cookies.
+	(awk_scalar_t): New type.
+	(awk_value_t): New member scalar_cookie.
+	(api_sym_update_scalar): New API function.
+	(erealloc): New macro.
+	(make_const_string): New macro, renamed from dup_string.
+	(make_malloced_string): New macro, renamed from make_string.
+	(make_null_string): New inline function.
+
+	* gawkapi.c (awk_value_to_node): Assume that string values came
+	from malloc.
+	(node_to_awk_value): Handle AWK_SCALAR.
+	(api_sym_update): Ditto.
+	(api_sym_update_scalar): New routine.
+	(api_get_array_element): Return false if the element doesn't exist.
+	Always unref the subscript.
+	(remove_element): New helper routine.
+	(api_del_array_element): Use it.
+	(api_release_flattened_array): Ditto.
+	(api_impl): Add the new routine.
+
 2012-07-11         Andrew J. Schorr     <aschorr@telemetry-investments.com>
 
 	* gawkapi.c (api_sym_update): Allow val_type to be AWK_UNDEFINED
diff --git a/extension/ChangeLog b/extension/ChangeLog
index 7e61fc54..be315619 100644
--- a/extension/ChangeLog
+++ b/extension/ChangeLog
@@ -1,3 +1,14 @@
+2012-07-11         Arnold D. Robbins     <arnold@skeeve.com>
+
+	* filefuncs.c (array_set, do_stat): Use make_const_string.
+	* fork.c (array_set_numeric): Ditto.
+	* ordchr.c (do_chr): Ditto.
+	* readfile.c (do_readfile): Use make_null_string, make_malloced_string.
+	* rwarray.c (read_elem): Ditto.
+	* testext.c (valrep2str): Add case for AWK_SCALAR.
+	(test_array_elem): Duplicate strings coming from gawk before passing
+	them back in.
+
 2012-07-09         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* filefuncs.c (do_readfile): Return "" and set ERRNO on error
diff --git a/extension/filefuncs.c b/extension/filefuncs.c
index 32a3cee6..74af8b1b 100644
--- a/extension/filefuncs.c
+++ b/extension/filefuncs.c
@@ -214,7 +214,7 @@ array_set(awk_array_t array, const char *sub, awk_value_t *value)
 	awk_value_t index;
 
 	set_array_element(array,
-			make_string(sub, strlen(sub), & index),
+			make_const_string(sub, strlen(sub), & index),
 			value);
 
 }
@@ -292,7 +292,7 @@ do_stat(int nargs, awk_value_t *result)
 	}
 
 	/* fill in the array */
-	array_set(array, "name", make_string(name, file_param.str_value.len, &tmp));
+	array_set(array, "name", make_const_string(name, file_param.str_value.len, &tmp));
 	array_set_numeric(array, "dev", sbuf.st_dev);
 	array_set_numeric(array, "ino", sbuf.st_ino);
 	array_set_numeric(array, "mode", sbuf.st_mode);
@@ -317,7 +317,7 @@ do_stat(int nargs, awk_value_t *result)
 #endif /* HAVE_ST_BLKSIZE */
 
 	pmode = format_mode(sbuf.st_mode);
-	array_set(array, "pmode", make_string(pmode, strlen(pmode), & tmp));
+	array_set(array, "pmode", make_const_string(pmode, strlen(pmode), & tmp));
 
 	/* for symbolic links, add a linkval field */
 	if (S_ISLNK(sbuf.st_mode)) {
@@ -326,7 +326,7 @@ do_stat(int nargs, awk_value_t *result)
 
 		if ((buf = read_symlink(name, sbuf.st_size,
 					& linksize)) != NULL)
-			array_set(array, "linkval", make_string(buf, linksize, & tmp));
+			array_set(array, "linkval", make_malloced_string(buf, linksize, & tmp));
 		else
 			warning(ext_id, "stat: unable to read symbolic link `%s'", name);
 	}
@@ -340,7 +340,7 @@ do_stat(int nargs, awk_value_t *result)
 		}
 	}
 
-	array_set(array, "type", make_string(type, strlen(type), &tmp));
+	array_set(array, "type", make_const_string(type, strlen(type), &tmp));
 
 	ret = 1;	/* success */
 
diff --git a/extension/fork.c b/extension/fork.c
index efad17eb..84232663 100644
--- a/extension/fork.c
+++ b/extension/fork.c
@@ -53,7 +53,7 @@ array_set_numeric(awk_array_t array, const char *sub, double num)
 	awk_value_t index, value;
 
 	set_array_element(array,
-		make_string(sub, strlen(sub), & index),
+		make_const_string(sub, strlen(sub), & index),
 		make_number(num, & value));
 
 }
diff --git a/extension/ordchr.c b/extension/ordchr.c
index 8d7eac8f..3ab0f872 100644
--- a/extension/ordchr.c
+++ b/extension/ordchr.c
@@ -103,7 +103,7 @@ do_chr(int nargs, awk_value_t *result)
 	}
 
 	/* Set the return value */
-	return dup_string(str, 1, result);
+	return make_const_string(str, 1, result);
 }
 
 static awk_ext_func_t func_table[] = {
diff --git a/extension/readfile.c b/extension/readfile.c
index 56bdcbc3..1b6772fe 100644
--- a/extension/readfile.c
+++ b/extension/readfile.c
@@ -65,7 +65,7 @@ do_readfile(int nargs, awk_value_t *result)
 	int fd;
 
 	assert(result != NULL);
-	make_string("", 0, result);	/* default return value */
+	make_null_string(result);	/* default return value */
 
 	if (do_lint && nargs > 1)
 		lintwarn(ext_id, "readfile: called with too many arguments");
@@ -98,7 +98,7 @@ do_readfile(int nargs, awk_value_t *result)
 		}
 
 		close(fd);
-		make_string(text, sbuf.st_size, result);
+		make_malloced_string(text, sbuf.st_size, result);
 		goto done;
 	} else if (do_lint)
 		lintwarn(ext_id, "readfile: called with no arguments");
diff --git a/extension/rwarray.c b/extension/rwarray.c
index a63fa3d2..64c501dd 100644
--- a/extension/rwarray.c
+++ b/extension/rwarray.c
@@ -394,9 +394,9 @@ read_elem(int fd, awk_element_t *element)
 		if (read(fd, buffer, index_len) != (ssize_t) index_len) {
 			return 0;
 		}
-		make_string(buffer, index_len, & element->index);
+		make_const_string(buffer, index_len, & element->index);
 	} else {
-		make_string("", 0, & element->index);
+		make_null_string(& element->index);
 	}
 
 	if (! read_value(fd, & element->value))
diff --git a/extension/testext.c b/extension/testext.c
index e54055cc..8dac1c2b 100644
--- a/extension/testext.c
+++ b/extension/testext.c
@@ -59,6 +59,9 @@ valrep2str(const awk_value_t *value)
 	case AWK_ARRAY:
 		strcpy(buf, "<array>");
 		break;
+	case AWK_SCALAR:
+		strcpy(buf, "<scalar>");
+		break;
 	case AWK_STRING:
 		if (value->str_value.len < size)
 			size = value->str_value.len;
@@ -334,7 +337,7 @@ BEGIN {
 static awk_value_t *
 test_array_elem(int nargs, awk_value_t *result)
 {
-	awk_value_t array, index, value;
+	awk_value_t array, index, index2, value;
 
 	make_number(0.0, result);	/* default return until full success */
 
@@ -354,7 +357,8 @@ test_array_elem(int nargs, awk_value_t *result)
 		printf("test_array_elem: get_argument 1 (index) failed\n");
 		goto out;
 	}
-	if (! get_array_element(array.array_cookie, & index, AWK_UNDEFINED, & value)) {
+	(void) make_const_string(index.str_value.str, index.str_value.len, & index2);
+	if (! get_array_element(array.array_cookie, & index2, AWK_UNDEFINED, & value)) {
 		printf("test_array_elem: get_array_element failed\n");
 		goto out;
 	}
@@ -365,28 +369,29 @@ test_array_elem(int nargs, awk_value_t *result)
 
 	/* change the element - "3" */
 	(void) make_number(42.0, & value);
-	if (! set_array_element(array.array_cookie, & index, & value)) {
+	(void) make_const_string(index.str_value.str, index.str_value.len, & index2);
+	if (! set_array_element(array.array_cookie, & index2, & value)) {
 		printf("test_array_elem: set_array_element failed\n");
 		goto out;
 	}
 
 	/* delete another element - "5" */
-	(void) make_string("5", 1, & index);
+	(void) make_const_string("5", 1, & index);
 	if (! del_array_element(array.array_cookie, & index)) {
 		printf("test_array_elem: del_array_element failed\n");
 		goto out;
 	}
 
 	/* add a new element - "7" */
-	(void) make_string("7", 1, & index);
-	(void) make_string("seven", 5, & value);
+	(void) make_const_string("7", 1, & index);
+	(void) make_const_string("seven", 5, & value);
 	if (! set_array_element(array.array_cookie, & index, & value)) {
 		printf("test_array_elem: set_array_element failed\n");
 		goto out;
 	}
 
 	/* add a subarray */
-	(void) make_string("subarray", 8, & index);
+	(void) make_const_string("subarray", 8, & index);
 	fill_in_array(& value);
 	if (! set_array_element(array.array_cookie, & index, & value)) {
 		printf("test_array_elem: set_array_element (subarray) failed\n");
@@ -488,14 +493,14 @@ fill_in_array(awk_value_t *new_array)
 
 	a_cookie = create_array();
 
-	(void) make_string("hello", 5, & index);
-	(void) make_string("world", 5, & value);
+	(void) make_const_string("hello", 5, & index);
+	(void) make_const_string("world", 5, & value);
 	if (! set_array_element(a_cookie, & index, & value)) {
 		printf("fill_in_array:%d: set_array_element failed\n", __LINE__);
 		return;
 	}
 
-	(void) make_string("answer", 6, & index);
+	(void) make_const_string("answer", 6, & index);
 	(void) make_number(42.0, & value);
 	if (! set_array_element(a_cookie, & index, & value)) {
 		printf("fill_in_array:%d: set_array_element failed\n", __LINE__);
@@ -620,7 +625,8 @@ BEGIN {
 	if (! sym_update("answer_num", make_number(42, & value)))
 		printf("testext: sym_update(\"answer_num\") failed!\n");
 
-	if (! sym_update("message_string", dup_string(message, strlen(message), & value)))
+	if (! sym_update("message_string",
+			make_const_string(message, strlen(message), & value)))
 		printf("testext: sym_update(\"answer_num\") failed!\n");
 
 	create_new_array();
diff --git a/gawkapi.c b/gawkapi.c
index 3fa3e3ba..c5f8953d 100644
--- a/gawkapi.c
+++ b/gawkapi.c
@@ -140,8 +140,8 @@ awk_value_to_node(const awk_value_t *retval)
 	} else if (retval->val_type == AWK_NUMBER) {
 		ext_ret_val = make_number(retval->num_value);
 	} else {
-		ext_ret_val = make_string(retval->str_value.str,
-				retval->str_value.len);
+		ext_ret_val = make_str_node(retval->str_value.str,
+				retval->str_value.len, ALREADY_MALLOCED);
 	}
 
 	return ext_ret_val;
@@ -317,6 +317,14 @@ node_to_awk_value(NODE *node, awk_value_t *val, awk_valtype_t wanted)
 		break;
 
 	case Node_var:
+		/* a scalar value */
+		if (wanted == AWK_SCALAR) {
+			val->val_type = AWK_SCALAR;
+			val->scalar_cookie = (void *) node;
+			ret = true;
+			break;
+		}
+
 		node = node->var_value;
 		/* FALL THROUGH */
 	case Node_val:
@@ -343,6 +351,16 @@ node_to_awk_value(NODE *node, awk_value_t *val, awk_valtype_t wanted)
 			}
 			break;
 
+		case AWK_SCALAR:
+			if (node->flags & NUMBER) {
+				val->val_type = AWK_NUMBER;
+			} else if (node->flags & STRING) {
+				val->val_type = AWK_STRING;
+			} else
+				val->val_type = AWK_UNDEFINED;
+			ret = false;
+			break;
+
 		case AWK_UNDEFINED:
 			/* return true and actual type for request of undefined */
 			if (node->flags & NUMBER) {
@@ -466,6 +484,9 @@ api_sym_update(awk_ext_id_t id, const char *name, awk_value_t *value)
 
 	/* if we get here, then it exists already */
 	switch (value->val_type) {
+	case AWK_SCALAR:
+		return false;
+
 	case AWK_STRING:
 	case AWK_NUMBER:
 	case AWK_UNDEFINED:
@@ -484,6 +505,33 @@ api_sym_update(awk_ext_id_t id, const char *name, awk_value_t *value)
 	return true;
 }
 
+/* api_sym_update_scalar --- update a scalar cookie */
+
+static awk_bool_t
+api_sym_update_scalar(awk_ext_id_t id,
+			awk_scalar_t cookie,
+			awk_value_t *value)
+{
+	NODE *node = (NODE *) cookie;
+	NODE *new_value;
+
+	if (value == NULL
+	    || node == NULL
+	    || node->type != Node_var)
+		return false;
+
+	new_value = awk_value_to_node(value);
+	if (new_value->type != Node_val) {
+		unref(new_value);
+		return false;
+	}
+
+	unref(node->var_value);
+	node->var_value = new_value;
+
+	return true;
+}
+
 /* Array management */
 /*
  * Return the value of an element - read only!
@@ -510,10 +558,21 @@ api_get_array_element(awk_ext_id_t id,
 		return false;
 
 	subscript = awk_value_to_node(index);
+
+	/* if it doesn't exist, return false */
+	if (in_array(array, subscript) == NULL) {
+		unref(subscript);
+		return false;
+	}
+
 	aptr = assoc_lookup(array, subscript);
-	unref(subscript);
-	if (aptr == NULL)
+
+	if (aptr == NULL) {	/* can't happen */
+		unref(subscript);
 		return false;
+	}
+
+	unref(subscript);
 
 	return node_to_awk_value(*aptr, result, wanted);
 }
@@ -556,6 +615,32 @@ api_set_array_element(awk_ext_id_t id, awk_array_t a_cookie,
 }
 
 /*
+ * remove_element --- remove an array element 
+ *		common code used by multiple functions
+ */
+
+static void
+remove_element(NODE *array, NODE *subscript)
+{
+	NODE *val;
+
+	val = in_array(array, subscript);
+
+	if (val == NULL)
+		return;
+
+	if (val->type == Node_var_array) {
+		assoc_clear(val);
+		/* cleared a sub-array, free Node_var_array */
+		efree(val->vname);
+		freenode(val);
+	} else
+		unref(val);
+
+	(void) assoc_remove(array, subscript);
+}
+
+/*
  * Remove the element with the given index.
  * Returns success if removed or if element did not exist.
  */
@@ -563,7 +648,7 @@ static awk_bool_t
 api_del_array_element(awk_ext_id_t id,
 		awk_array_t a_cookie, const awk_value_t* const index)
 {
-	NODE *array, *sub, *val;
+	NODE *array, *sub;
 
 	array = (NODE *) a_cookie;
 	if (   array == NULL
@@ -573,20 +658,7 @@ api_del_array_element(awk_ext_id_t id,
 		return false;
 
 	sub = awk_value_to_node(index);
-	val = in_array(array, sub);
-
-	if (val == NULL)
-		return false;
-
-	if (val->type == Node_var_array) {
-		assoc_clear(val);
-		/* cleared a sub-array, free Node_var_array */
-		efree(val->vname);
-		freenode(val);
-	} else
-		unref(val);
-
-	(void) assoc_remove(array, sub);
+	remove_element(array, sub);
 	unref(sub);
 
 	return true;
@@ -698,7 +770,7 @@ api_release_flattened_array(awk_ext_id_t id,
 {
 	NODE *array = a_cookie;
 	NODE **list;
-	size_t i;
+	size_t i, j, k;
 
 	if (   array == NULL
 	    || array->type != Node_var_array
@@ -710,17 +782,12 @@ api_release_flattened_array(awk_ext_id_t id,
 
 	list = (NODE **) data->opaque2;
 
-	/* Delete items flagged for delete. */
-	for (i = 0; i < data->count; i++) {
-		if ((data->elements[i].flags & AWK_ELEMENT_DELETE) != 0) {
-			/* let the other guy do the work */
-			(void) api_del_array_element(id, a_cookie,
-					& data->elements[i].index);
-		}
-	}
-
 	/* free index nodes */
-	for (i = 0; i < 2 * array->table_size; i += 2) {
+	for (i = j = 0, k = 2 * array->table_size; i < k; i += 2, j++) {
+		/* Delete items flagged for delete. */
+		if ((data->elements[j].flags & AWK_ELEMENT_DELETE) != 0) {
+			remove_element(array, list[i]);
+		}
 		unref(list[i]);
 	}
 
@@ -754,6 +821,7 @@ gawk_api_t api_impl = {
 
 	api_sym_lookup,
 	api_sym_update,
+	api_sym_update_scalar,
 
 	api_get_array_element,
 	api_set_array_element,
diff --git a/gawkapi.h b/gawkapi.h
index 5be5ea08..2bef258e 100644
--- a/gawkapi.h
+++ b/gawkapi.h
@@ -42,6 +42,26 @@
  * functions. If your compiler doesn't support it, you should either
  * -Dinline='' on your command line, or use the autotools and include a
  * config.h in your extensions.
+ *
+ * Additional important information:
+ *
+ * 1. ALL string values in awk_value_t objects need to come from malloc().
+ * Gawk will handle releasing the storage if necessary.  This is slightly
+ * awkward, in that you can't take an awk_value_t that you got from gawk
+ * and reuse it directly, even for something that is conceptually pass
+ * by value.
+ *
+ * 2. The correct way to create new arrays is to work "bottom up".
+ *
+ *	new_array = create_array();
+ *	// fill in new array with lots of subscripts and values
+ *	val.val_type = AWK_ARRAY;
+ *	val.array_cookie = new_array;
+ *	sym_update("array", &val);	// install array in the symbol table
+ *
+ * After doing so, do NOT make further use of the new_array variable;
+ * instead use sym_lookup to get the array_cookie if you need to do further
+ * manipulation of the array.
  */
 
 /* Allow use in C++ code.  */
@@ -73,7 +93,8 @@ typedef enum {
 	AWK_UNDEFINED,
 	AWK_NUMBER,
 	AWK_STRING,
-	AWK_ARRAY
+	AWK_ARRAY,
+	AWK_SCALAR,	/* opaque access to a variable */
 } awk_valtype_t;
 
 /*
@@ -88,6 +109,9 @@ typedef struct {
 /* Arrays are represented as an opaque type. */
 typedef void *awk_array_t;
 
+/* Scalars can be represented as an opaque type. */
+typedef void *awk_scalar_t;
+
 /*
  * An awk value. The val_type tag indicates what
  * is in the union.
@@ -98,10 +122,12 @@ typedef struct {
 		awk_string_t	s;
 		double		d;
 		awk_array_t	a;
+		awk_array_t	scl;
 	} u;
 #define str_value	u.s
 #define num_value	u.d
 #define array_cookie	u.a
+#define scalar_cookie	u.scl
 } awk_value_t;
 
 /*
@@ -200,23 +226,23 @@ typedef struct gawk_api {
 
 	Table entry is type returned:
 
-	                      +-----------------------------------------+
-	                      |               Type Requested:           |
-	                      +----------+----------+-------+-----------+
-	                      |  String  |  Number  | Array | Undefined |
-	+---------+-----------+----------+----------+-------+-----------+
-	| Type    | String    |  String  | Number if| false |   String  |
-	|         |           |          | it can be|       |           |
-	|         |           |          |converted,|       |           |
-	|         |           |          |   else   |       |           |
-	|         |           |          |   false  |       |           |
-	| of      +-----------+----------+----------+-------+-----------+
-	| Actual  | Number    |  String  |  Number  | false |   Number  |
-	| Value:  +-----------+----------+----------+-------+-----------+
-	|         | Array     |   false  |   false  | Array |   Array   |
-	|         +-----------+----------+----------+-------+-----------+
-	|         | Undefined |   false  |   false  | false | Undefined |
-	+---------+-----------+----------+----------+-------+-----------+
+	                      +---------------------------------------------------+
+	                      |                    Type Requested:                |
+	                      +----------+----------+-------+---------+-----------+
+	                      |  String  |  Number  | Array | Scalar  | Undefined |
+	+---------+-----------+----------+----------+-------+---------+-----------+
+	| Type    | String    |  String  | Number if| false | Scalar  |   String  |
+	|         |           |          | it can be|       |         |           |
+	|         |           |          |converted,|       |         |           |
+	|         |           |          |   else   |       |         |           |
+	|         |           |          |   false  |       |         |           |
+	| of      +-----------+----------+----------+-------+---------+-----------+
+	| Actual  | Number    |  String  |  Number  | false | Scalar  |  Number   |
+	| Value:  +-----------+----------+----------+-------+---------+-----------+
+	|         | Array     |   false  |   false  | Array | false   |  Array    |
+	|         +-----------+----------+----------+-------+---------+-----------+
+	|         | Undefined |   false  |   false  | false | false   | Undefined |
+	+---------+-----------+----------+----------+-------+---------+-----------+
 	*/
 
 	/*
@@ -225,7 +251,7 @@ typedef struct gawk_api {
 	 * does not match what is specified in wanted. In that case,
 	 * result->val_type is as described above.
 	 */
-	awk_bool_t (*get_argument)(awk_ext_id_t id, size_t count,
+	awk_bool_t (*api_get_argument)(awk_ext_id_t id, size_t count,
 					  awk_valtype_t wanted,
 					  awk_value_t *result);
 
@@ -235,7 +261,7 @@ typedef struct gawk_api {
 	 * if count is too big, or if the argument's type is
 	 * not undefined.
 	 */
-	awk_bool_t (*set_argument)(awk_ext_id_t id,
+	awk_bool_t (*api_set_argument)(awk_ext_id_t id,
 					size_t count,
 					awk_array_t array);
 
@@ -245,20 +271,20 @@ typedef struct gawk_api {
 	void (*api_lintwarn)(awk_ext_id_t id, const char *format, ...);
 
 	/* Register an open hook; for opening files read-only */
-	void (*register_open_hook)(awk_ext_id_t id, void* (*open_func)(IOBUF_PUBLIC *));
+	void (*api_register_open_hook)(awk_ext_id_t id, void* (*open_func)(IOBUF_PUBLIC *));
 
 	/* Functions to update ERRNO */
-	void (*update_ERRNO_int)(awk_ext_id_t id, int errno_val);
-	void (*update_ERRNO_string)(awk_ext_id_t id, const char *string,
+	void (*api_update_ERRNO_int)(awk_ext_id_t id, int errno_val);
+	void (*api_update_ERRNO_string)(awk_ext_id_t id, const char *string,
 			awk_bool_t translate);
-	void (*unset_ERRNO)(awk_ext_id_t id);
+	void (*api_unset_ERRNO)(awk_ext_id_t id);
 
 	/* Add a function to the interpreter, returns true upon success */
-	awk_bool_t (*add_ext_func)(awk_ext_id_t id, const awk_ext_func_t *func,
+	awk_bool_t (*api_add_ext_func)(awk_ext_id_t id, const awk_ext_func_t *func,
 			const char *namespace);
 
 	/* Add an exit call back, returns true upon success */
-	void (*awk_atexit)(awk_ext_id_t id,
+	void (*api_awk_atexit)(awk_ext_id_t id,
 			void (*funcp)(void *data, int exit_status),
 			void *arg0);
 
@@ -285,7 +311,7 @@ typedef struct gawk_api {
 	 *		// safe to use val
 	 *	}
 	 */
-	awk_bool_t (*sym_lookup)(awk_ext_id_t id,
+	awk_bool_t (*api_sym_lookup)(awk_ext_id_t id,
 				const char *name,
 				awk_valtype_t wanted,
 				awk_value_t *result);
@@ -296,16 +322,32 @@ typedef struct gawk_api {
 	 * In fact, using this to update an array is not allowed, either.
 	 * Such an attempt returns false.
 	 */
-	awk_bool_t (*sym_update)(awk_ext_id_t id, const char *name, awk_value_t *value);
+	awk_bool_t (*api_sym_update)(awk_ext_id_t id, const char *name, awk_value_t *value);
+
+	/*
+	 * Work with a scalar cookie.
+	 * Flow is
+	 * 	sym_lookup with wanted == AWK_SCALAR
+	 * 	if returns false
+	 * 		sym_update with real initial value
+	 * 		sym_lookup again with AWK_SCALAR
+	 *	else
+	 *		use the scalar cookie
+	 *
+	 * Return will be false if the new value is not one of
+	 * AWK_STRING or AWK_NUMBER.
+	 */
+	awk_bool_t (*api_sym_update_scalar)(awk_ext_id_t id,
+				awk_scalar_t cookie, awk_value_t *value);
 
 	/* Array management */
 	/*
 	 * Return the value of an element - read only!
 	 * Use set_array_element() to change it.
-	 * Behavior for value and return is same as for get_argument
+	 * Behavior for value and return is same as for api_get_argument
 	 * and sym_lookup.
 	 */
-	awk_bool_t (*get_array_element)(awk_ext_id_t id,
+	awk_bool_t (*api_get_array_element)(awk_ext_id_t id,
 			awk_array_t a_cookie,
 			const awk_value_t *const index,
 			awk_valtype_t wanted,
@@ -315,7 +357,7 @@ typedef struct gawk_api {
 	 * Change (or create) element in existing array with
 	 * element->index and element->value.
 	 */
-	awk_bool_t (*set_array_element)(awk_ext_id_t id, awk_array_t a_cookie,
+	awk_bool_t (*api_set_array_element)(awk_ext_id_t id, awk_array_t a_cookie,
 					const awk_value_t *const index,
 					const awk_value_t *const value);
 
@@ -323,24 +365,24 @@ typedef struct gawk_api {
 	 * Remove the element with the given index.
 	 * Returns success if removed or if element did not exist.
 	 */
-	awk_bool_t (*del_array_element)(awk_ext_id_t id,
+	awk_bool_t (*api_del_array_element)(awk_ext_id_t id,
 			awk_array_t a_cookie, const awk_value_t* const index);
 
 	/*
 	 * Retrieve total number of elements in array.
 	 * Returns false if some kind of error.
 	 */
-	awk_bool_t (*get_element_count)(awk_ext_id_t id,
+	awk_bool_t (*api_get_element_count)(awk_ext_id_t id,
 			awk_array_t a_cookie, size_t *count);
 
 	/* Create a new array cookie to which elements may be added */
-	awk_array_t (*create_array)(awk_ext_id_t id);
+	awk_array_t (*api_create_array)(awk_ext_id_t id);
 
 	/* Clear out an array */
-	awk_bool_t (*clear_array)(awk_ext_id_t id, awk_array_t a_cookie);
+	awk_bool_t (*api_clear_array)(awk_ext_id_t id, awk_array_t a_cookie);
 
 	/* Flatten out an array so that it can be looped over easily. */
-	awk_bool_t (*flatten_array)(awk_ext_id_t id,
+	awk_bool_t (*api_flatten_array)(awk_ext_id_t id,
 			awk_array_t a_cookie,
 			awk_flat_array_t **data);
 
@@ -349,7 +391,7 @@ typedef struct gawk_api {
 	 * Count must match what gawk thinks the size is.
 	 * Otherwise it's a fatal error.
 	 */
-	awk_bool_t (*release_flattened_array)(awk_ext_id_t id,
+	awk_bool_t (*api_release_flattened_array)(awk_ext_id_t id,
 			awk_array_t a_cookie,
 			awk_flat_array_t *data);
 } gawk_api_t;
@@ -367,52 +409,54 @@ typedef struct gawk_api {
 #define do_mpfr		(api->do_flags[gawk_do_mpfr])
 
 #define get_argument(count, wanted, result) \
-	(api->get_argument(ext_id, count, wanted, result))
+	(api->api_get_argument(ext_id, count, wanted, result))
 #define set_argument(count, new_array) \
-	(api->set_argument(ext_id, count, new_array))
+	(api->api_set_argument(ext_id, count, new_array))
 
 #define fatal		api->api_fatal
 #define warning		api->api_warning
 #define lintwarn	api->api_lintwarn
 
-#define register_open_hook(func)	(api->register_open_hook(ext_id, func))
+#define register_open_hook(func)	(api->api_register_open_hook(ext_id, func))
 
-#define update_ERRNO_int(e)	(api->update_ERRNO_int(ext_id, e))
+#define update_ERRNO_int(e)	(api->api_update_ERRNO_int(ext_id, e))
 #define update_ERRNO_string(str, translate) \
-	(api->update_ERRNO_string(ext_id, str, translate))
-#define unset_ERRNO()	(api->unset_ERRNO(ext_id))
+	(api->api_update_ERRNO_string(ext_id, str, translate))
+#define unset_ERRNO()	(api->api_unset_ERRNO(ext_id))
 
-#define add_ext_func(func, ns)	(api->add_ext_func(ext_id, func, ns))
-#define awk_atexit(funcp, arg0)	(api->awk_atexit(ext_id, funcp, arg0))
+#define add_ext_func(func, ns)	(api->api_add_ext_func(ext_id, func, ns))
+#define awk_atexit(funcp, arg0)	(api->api_awk_atexit(ext_id, funcp, arg0))
 
-#define sym_lookup(name, wanted, result)	(api->sym_lookup(ext_id, name, wanted, result))
+#define sym_lookup(name, wanted, result)	(api->api_sym_lookup(ext_id, name, wanted, result))
 #define sym_update(name, value) \
-	(api->sym_update(ext_id, name, value))
+	(api->api_sym_update(ext_id, name, value))
+#define sym_update_scalar(scalar_cookie, value) \
+	(api->api_sym_update_scalar)(ext_id, scalar_cookie, value)
 
 #define get_array_element(array, index, wanted, result) \
-	(api->get_array_element(ext_id, array, index, wanted, result))
+	(api->api_get_array_element(ext_id, array, index, wanted, result))
 
 #define set_array_element(array, index, value) \
-	(api->set_array_element(ext_id, array, index, value))
+	(api->api_set_array_element(ext_id, array, index, value))
 
 #define set_array_element_by_elem(array, elem) \
-	(set_array_element(array, & (elem)->index, & (elem)->value))
+	(api->api_set_array_element(ext_id, array, & (elem)->index, & (elem)->value))
 
 #define del_array_element(array, index) \
-	(api->del_array_element(ext_id, array, index))
+	(api->api_del_array_element(ext_id, array, index))
 
 #define get_element_count(array, count_p) \
-	(api->get_element_count(ext_id, array, count_p))
+	(api->api_get_element_count(ext_id, array, count_p))
 
-#define create_array()		(api->create_array(ext_id))
+#define create_array()		(api->api_create_array(ext_id))
 
-#define clear_array(array)	(api->clear_array(ext_id, array))
+#define clear_array(array)	(api->api_clear_array(ext_id, array))
 
 #define flatten_array(array, data) \
-	(api->flatten_array(ext_id, array, data))
+	(api->api_flatten_array(ext_id, array, data))
 
 #define release_flattened_array(array, data) \
-	(api->release_flattened_array(ext_id, array, data))
+	(api->api_release_flattened_array(ext_id, array, data))
 
 #define emalloc(pointer, type, size, message) \
 	do { \
@@ -420,6 +464,12 @@ typedef struct gawk_api {
 			fatal(ext_id, "malloc of %d bytes failed\n", size); \
 	} while(0)
 
+#define erealloc(pointer, type, size, message) \
+	do { \
+		if ((pointer = (type) realloc(pointer, size)) == 0) \
+			fatal(ext_id, "realloc of %d bytes failed\n", size); \
+	} while(0)
+
 /* Constructor functions */
 
 /* r_make_string --- make a string value in result from the passed-in string */
@@ -440,7 +490,7 @@ r_make_string(const gawk_api_t *api,	/* needed for emalloc */
 	result->str_value.len = length;
 
 	if (duplicate) {
-		emalloc(cp, char *, length + 2, "make_string");
+		emalloc(cp, char *, length + 2, "r_make_string");
 		memcpy(cp, string, length);
 		cp[length] = '\0';
 		result->str_value.str = cp;
@@ -451,8 +501,19 @@ r_make_string(const gawk_api_t *api,	/* needed for emalloc */
 	return result;
 }
 
-#define make_string(str, len, result)	r_make_string(api, ext_id, str, len, 0, result)
-#define dup_string(str, len, result)	r_make_string(api, ext_id, str, len, 1, result)
+#define make_const_string(str, len, result)	r_make_string(api, ext_id, str, len, 1, result)
+#define make_malloced_string(str, len, result)	r_make_string(api, ext_id, str, len, 0, result)
+
+/* make_null_string --- make a null string value */
+
+static inline awk_value_t *
+make_null_string(awk_value_t *result)
+{
+	memset(result, 0, sizeof(*result));
+	result->val_type = AWK_UNDEFINED;
+
+	return result;
+}
 
 /* make_number --- make a number value in result */