FIX: Failure when system/script/args > 1022 bytes

Fixes: metaeducation/rebol-issues#2140

(cherry picked from commit 33da799)
(cherry picked from commit d637340)
(cherry picked from commit cf99471)

Author: Oldes

src/os/host-args.c

@@ -45,8 +45,6 @@
 #include "reb-c.h"
 #include "reb-args.h"
 
-#define ARG_BUF_SIZE 1024
-
 extern int OS_Get_Current_Dir(REBCHR **lp);
 
 // REBOL Option --Words:
@@ -201,14 +199,16 @@ const struct arg_chr arg_chars2[] = {
 **
 ***********************************************************************/
 {
+	int arg_buf_size=128;
+
 	REBCHR *arg;
 	REBCHR *args = 0; // holds trailing args
 	int flag;
 	int i;
 
 	CLEARS(rargs);
 
-	// First arg is path to execuable (on most systems):
+	// First arg is path to executable (on most systems):
 	if (argc > 0) rargs->exe_path = *argv;
 
 	OS_Get_Current_Dir(&rargs->home_dir);
@@ -262,11 +262,23 @@ const struct arg_chr arg_chars2[] = {
 				rargs->script = arg;
 			else {
 				int len;
+				int size;
+				REBCHR *tmp;
 				if (!args) {
-					args = MAKE_STR(ARG_BUF_SIZE);
+					args = MAKE_STR(arg_buf_size);
 					args[0] = 0;
 				}
-				len = ARG_BUF_SIZE - LEN_STR(args) - 2; // space remaining
+				len = LEN_STR(arg) + LEN_STR(args) + 2;
+				size = arg_buf_size;
+				while (size < len) size *= 2;
+				if (size > arg_buf_size) {
+					tmp = args;
+					args = MAKE_STR(size);
+					memcpy(args, tmp, arg_buf_size);
+					arg_buf_size = size;
+					free(tmp);
+				}
+				len = arg_buf_size - LEN_STR(args) - 2; // space remaining
 				JOIN_STR(args, arg, len);
 				JOIN_STR(args, TXT(" "), 1);
 			}