Re: [libgpiod][PATCH 04/16] treewide: unify gpiod_line_config/request_get_offsets() functions

[Viresh Kumar <viresh.kumar@xxxxxxxxxx>]

On 18-01-23, 21:51, Bartosz Golaszewski wrote:
> On Tue, Jan 17, 2023 at 6:44 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> >
> > On 16-01-23, 22:39, Bartosz Golaszewski wrote:
> > > On Mon, Jan 16, 2023 at 6:52 AM Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote:
> > > > > +        let mut offsets = vec![0; num_lines as usize];
> > > > > +
> > > > > +        // SAFETY: gpiod_line_config is guaranteed to be valid here.
> > > > > +        unsafe { gpiod::gpiod_line_config_get_configured_offsets(self.config,
> > > > > +                                                                 offsets.as_mut_ptr(),
> > > > > +                                                                 num_lines) };
> > > >
> > > > Can the returned value be < num_lines here ?
> > > >
> > >
> > > Ah, of course it can. Need to add a test case for that. How do I set
> > > the size of offsets to whatever this function returns?
> >
> > Instead of any heavy operation, you can rather do something like this:
> >
> > let num = unsafe { gpiod::gpiod_line_config_get_configured_offsets(self.config,
> >                                         offsets.as_mut_ptr(), num_lines) };
> > for offset in offsets[0..num] {
> >         ...
> > }
> >
> 
> It sees 'offset' becomes an instance of std::ops::Range. Is there
> anything more to add here?

This builds fine.

diff --git a/bindings/rust/libgpiod/src/line_config.rs b/bindings/rust/libgpiod/src/line_config.rs
index b276cf0c4931..e30ef7c35328 100644
--- a/bindings/rust/libgpiod/src/line_config.rs
+++ b/bindings/rust/libgpiod/src/line_config.rs
@@ -106,14 +106,14 @@ impl Config {
         let mut offsets = vec![0; num_lines as usize];
 
         // SAFETY: gpiod_line_config is guaranteed to be valid here.
-        unsafe { gpiod::gpiod_line_config_get_configured_offsets(self.config,
+        let len = unsafe { gpiod::gpiod_line_config_get_configured_offsets(self.config,
                                                                  offsets.as_mut_ptr(),
                                                                  num_lines) };
 
-        for offset in offsets {
+        for offset in &offsets[0..len as usize] {
             // SAFETY: `gpiod_line_config` is guaranteed to be valid here.
             let settings = unsafe { gpiod::gpiod_line_config_get_line_settings(self.config,
-                                                                               offset) };
+                                                                               *offset) };
             if settings.is_null() {
                 return Err(Error::OperationFailed(
                     OperationType::LineConfigGetSettings,
@@ -121,7 +121,7 @@ impl Config {
                 ));
             }
 
-            map.insert(offset, Settings::new_with_settings(settings));
+            map.insert(*offset, Settings::new_with_settings(settings));
         }
 
         Ok(map)

-- 
viresh