Change uxsel_input_add's return type from int to pointer.

In case a front end needs to store more than an integer id to be
returned to uxsel_input_remove, we now return a pointer to a
frontend-defined structure.

unix/gtkwin.c

@@ -3218,17 +3218,26 @@ int do_cmdline(int argc, char **argv, int do_everything, int *allow_launch,
     return err;
 }
 
-int uxsel_input_add(int fd, int rwx) {
+struct uxsel_id {
+    int id;
+};
+
+uxsel_id *uxsel_input_add(int fd, int rwx) {
+    uxsel_id *id = snew(uxsel_id);
+
     int flags = 0;
     if (rwx & 1) flags |= GDK_INPUT_READ;
     if (rwx & 2) flags |= GDK_INPUT_WRITE;
     if (rwx & 4) flags |= GDK_INPUT_EXCEPTION;
     assert(flags);
-    return gdk_input_add(fd, flags, fd_input_func, NULL);
+    id->id = gdk_input_add(fd, flags, fd_input_func, NULL);
+
+    return id;
 }
 
-void uxsel_input_remove(int id) {
+void uxsel_input_remove(uxsel_id *id) {
-    gdk_input_remove(id);
+    gdk_input_remove(id->id);
+    sfree(id);
 }
 
 char *setup_fonts_ucs(struct gui_data *inst)

unix/unix.h

@@ -118,6 +118,7 @@ void premsg(struct termios *);
 void postmsg(struct termios *);
 
 /* The interface used by uxsel.c */
+typedef struct uxsel_id uxsel_id;
 void uxsel_init(void);
 typedef int (*uxsel_callback_fn)(int fd, int event);
 void uxsel_set(int fd, int rwx, uxsel_callback_fn callback);
@@ -126,8 +127,8 @@ int select_result(int fd, int event);
 int first_fd(int *state, int *rwx);
 int next_fd(int *state, int *rwx);
 /* The following are expected to be provided _to_ uxsel.c by the frontend */
-int uxsel_input_add(int fd, int rwx);  /* returns an id */
+uxsel_id *uxsel_input_add(int fd, int rwx);  /* returns an id */
-void uxsel_input_remove(int id);
+void uxsel_input_remove(uxsel_id *id);
 
 /* uxcfg.c */
 struct controlbox;

unix/uxpgnt.c

@@ -88,8 +88,8 @@ void pageant_log(void *ctx, const char *fmt, va_list ap)
  * In Pageant our selects are synchronous, so these functions are
  * empty stubs.
  */
-int uxsel_input_add(int fd, int rwx) { return 0; }
+uxsel_id *uxsel_input_add(int fd, int rwx) { return NULL; }
-void uxsel_input_remove(int id) { }
+void uxsel_input_remove(uxsel_id *id) { }
 
 /*
  * More stubs.

unix/uxplink.c

@@ -533,8 +533,8 @@ void sigwinch(int signum)
  * In Plink our selects are synchronous, so these functions are
  * empty stubs.
  */
-int uxsel_input_add(int fd, int rwx) { return 0; }
+uxsel_id *uxsel_input_add(int fd, int rwx) { return NULL; }
-void uxsel_input_remove(int id) { }
+void uxsel_input_remove(uxsel_id *id) { }
 
 /*
  * Short description of parameters.

unix/uxsel.c

@@ -19,7 +19,7 @@ struct fd {
     int fd;
     int rwx;			       /* 4=except 2=write 1=read */
     uxsel_callback_fn callback;
-    int id;			       /* for uxsel_input_remove */
+    uxsel_id *id;                      /* for uxsel_input_remove */
 };
 
 static tree234 *fds;
@@ -80,7 +80,8 @@ void uxsel_del(int fd)
 {
     struct fd *oldfd = find234(fds, &fd, uxsel_fd_findcmp);
     if (oldfd) {
-	uxsel_input_remove(oldfd->id);
+	if (oldfd->id)
+            uxsel_input_remove(oldfd->id);
 	del234(fds, oldfd);
 	sfree(oldfd);
     }

unix/uxsftp.c

@@ -26,8 +26,8 @@
  * In PSFTP our selects are synchronous, so these functions are
  * empty stubs.
  */
-int uxsel_input_add(int fd, int rwx) { return 0; }
+uxsel_id *uxsel_input_add(int fd, int rwx) { return NULL; }
-void uxsel_input_remove(int id) { }
+void uxsel_input_remove(uxsel_id *id) { }
 
 char *x_get_default(const char *key)
 {