-e / --empty option added

AUTHORS

@@ -12,3 +12,6 @@ Taylan Ulrich B.<taylanbayirli@gmail.com>
 
 Hans de Groede
         - fix overflow of supported_targets array
+
+Nikola Hadzic <nikola.hadzic.000@protonmail.com>
+        - added -e / --empty flag

xsel.1x

@@ -1,4 +1,4 @@
-.TH XSEL 1x "January 2008"
+.TH XSEL 1x "March 2025"
 .SH NAME
 xsel \- manipulate the X selection.
 .SH SYNOPSIS
@@ -78,6 +78,10 @@ options.
 \fB\-x\fR, \fB\-\-exchange\fR
 exchange the PRIMARY and SECONDARY selections. Ignores all \fIinput\fR
 and \fIoutput\fR options.
+.TP
+\fB\-e\fR, \fB\-\-empty\fR
+When used together with \fB-k\fR or \fB-x\fR it will not ignore the PRIMARY
+and SECONDARY selections even if they (both or any one) are empty.
 
 .PP
 \fBX options\fR

xsel.c

@@ -78,6 +78,9 @@ static Bool do_zeroflush = False;
 /* do_follow: Follow mode for output */
 static Bool do_follow = False;
 
+/* do_empty: Operate with empty strings when -k or -x are supplied */
+static Bool do_empty = False;
+
 /* nodaemon: Disable daemon mode if True. */
 static Bool no_daemon = False;
 
@@ -135,7 +138,9 @@ usage (void)
   printf ("  -k, --keep            Do not modify the selections, but make the PRIMARY\n");
   printf ("                        and SECONDARY selections persist even after the\n");
   printf ("                        programs they were selected in exit.\n");
-  printf ("  -x, --exchange        Exchange the PRIMARY and SECONDARY selections\n\n");
+  printf ("  -x, --exchange        Exchange the PRIMARY and SECONDARY selections\n");
+  printf ("  -e, --empty           Keep / exchange the PRIMARY and SECONDARY selections\n");
+  printf ("                        even when they, both or any one, are empty.\n\n");
   printf ("X options\n");
   printf ("  --display displayname\n");
   printf ("                        Specify the connection to the X server\n");
@@ -1877,13 +1882,26 @@ set_selection_pair (unsigned char * sel_p, unsigned char * sel_s)
  * primary and secondary selections with texts 'sel_p' and 'sel_s'
  * respectively.
  *
- * If both 'sel_p' and 'sel_s' are empty strings (NULL or "") then no
- * daemon process is created, and both selections are cleared instead.
+ * If 'do_empty' is set, whichever one of 'sel_p' and 'sel_s' is NULL
+ * is assigned a newly allocated empty string (""); the function then
+ * proceeds normally i.e. as if 'sel_p' and 'sel_s' were passed to it
+ * as non-NULL strings. If 'do_empty' is not set and both 'sel_p' and
+ * 'sel_s' are empty strings (NULL or "") then no daemon process is
+ * created, and both selections are cleared instead.
  */
 static void
 set_selection_pair__daemon (unsigned char * sel_p, unsigned char * sel_s)
 {
-  if (empty_string (sel_p) && empty_string (sel_s)) {
+  if (do_empty) {
+    if (sel_p == NULL) {
+      sel_p = xs_malloc (sizeof(char));
+      sel_p[0] = '\0';
+    }
+    if (sel_s == NULL) {
+      sel_s = xs_malloc (sizeof(char));
+      sel_s[0] = '\0';
+    }
+  } else if (empty_string (sel_p) && empty_string (sel_s)) {
     clear_selection (XA_PRIMARY);
     clear_selection (XA_SECONDARY);
     return;
@@ -2117,6 +2135,8 @@ main(int argc, char *argv[])
       do_keep = True;
     } else if (OPT("--exchange") || OPT("-x")) {
       do_exchange = True;
+    } else if (OPT("--empty") || OPT("-e")) {
+      do_empty = True;
     } else if (OPT("--display")) {
       i++; if (i >= argc) goto usage_err;
       display_name = argv[i];