Use a two-pass algorithm for COPY-REPLACING and then REPLACE

cobc/cobc.c

@@ -1316,6 +1316,61 @@ cobc_plex_strdup (const char *dupstr)
 	return p;
 }
 
+/* Return a newly allocated string with only the first len chars of the first argument */
+void *
+cobc_plex_strsub (const char *s, const int len)
+{
+	void	*p;
+	int	n;
+
+#ifdef	COB_TREE_DEBUG
+	/* LCOV_EXCL_START */
+	if (unlikely (!s)) {
+		cobc_err_msg (_("call to %s with NULL pointer"),
+			      "cobc_plex_strsub");
+		cobc_abort_terminate (1);
+	}
+	/* LCOV_EXCL_STOP */
+#endif
+	n = strlen (s);
+
+#ifdef	COB_TREE_DEBUG
+	/* LCOV_EXCL_START */
+	if ( len>n ) {
+		cobc_err_msg (_("call to %s with bad argument len=%d>%d=strlen(s)"),
+			      "cobc_plex_strsub", len, n);
+		cobc_abort_terminate (1);
+	}
+	/* LCOV_EXCL_STOP */
+#endif
+
+	p = cobc_plex_malloc (len + 1);
+	memcpy (p, s, len);
+	return p;
+}
+
+char *
+cobc_plex_stradd (const char *str1, const char *str2)
+{
+	char	*p;
+	size_t	m, n;
+
+	/* LCOV_EXCL_START */
+	if (unlikely (!str1 || !str2)) {
+		cobc_err_msg (_("call to %s with NULL pointer"),
+			      "cobc_plex_stradd");
+		cobc_abort_terminate (1);
+	}
+	/* LCOV_EXCL_STOP */
+	m = strlen (str1);
+	n = strlen (str2);
+	p = cobc_plex_malloc (m + n + 1);
+	memcpy (p, str1, m);
+	memcpy (p + m, str2, n);
+	return p;
+}
+
+
 /* variant of strcpy which copies max 'max_size' bytes from 'src' to 'dest',
    if the size of 'src' is too long only its last/last bytes are copied and an
    eliding "..." is placed in front or at end depending on 'elide_at_end' */

cobc/cobc.h

@@ -513,6 +513,8 @@ extern void			cobc_parse_free (void *);
 
 extern void			*cobc_plex_malloc (const size_t);
 extern void			*cobc_plex_strdup (const char *);
+extern void			*cobc_plex_strsub (const char *, const int len);
+extern char                     *cobc_plex_stradd (const char *str1, const char *str2);
 
 extern void			*cobc_check_string (const char *);
 extern void			cobc_err_msg (const char *, ...) COB_A_FORMAT12;