rusticl/program: use write_len_only for CL_PROGRAM_BINARIES

This query would simply write back the same content, so skip it.

Reviewed-by: @LingMan
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/32268>

src/gallium/frontends/rusticl/api/program.rs

@@ -28,11 +28,16 @@ unsafe impl CLInfo<cl_program_info> for cl_program {
         match q {
             CL_PROGRAM_BINARIES => {
                 let input = v.input::<*mut u8>()?;
-                // SAFETY: Oer spec it contains an array of pointers to write the binaries to,
-                //         so we can assume the entire slice to be initialized.
-                let input = unsafe { slice_assume_init_ref(input) };
-                let bins = prog.binaries(input)?;
-                v.write::<Vec<*mut u8>>(bins)
+                // This query is a bit weird. At least the CTS is. We need to return the proper size
+                // of the buffer to hold all pointers, but when actually doing the query, we'd just
+                // parse the pointers out and write to them.
+                if !input.is_empty() {
+                    // SAFETY: Per spec it contains an array of pointers to write the binaries to,
+                    //         so we can assume the entire slice to be initialized.
+                    let input = unsafe { slice_assume_init_ref(input) };
+                    prog.binaries(input)?;
+                }
+                v.write_len_only::<&[*mut u8]>(prog.devs.len())
             }
             CL_PROGRAM_BINARY_SIZES => v.write::<Vec<usize>>(prog.bin_sizes()),
             CL_PROGRAM_CONTEXT => {

src/gallium/frontends/rusticl/core/program.rs

@@ -477,12 +477,7 @@ impl Program {
         res
     }
 
-    pub fn binaries(&self, ptrs: &[*mut u8]) -> CLResult<Vec<*mut u8>> {
-        // if the application didn't provide any pointers, just return the length of devices
-        if ptrs.is_empty() {
-            return Ok(vec![std::ptr::null_mut(); self.devs.len()]);
-        }
-
+    pub fn binaries(&self, ptrs: &[*mut u8]) -> CLResult<()> {
         // ptrs is an array of pointers where we should write the device binaries into
         if ptrs.len() < self.devs.len() {
             return Err(CL_INVALID_VALUE);
@@ -531,7 +526,7 @@ impl Program {
             }
         }
 
-        Ok(ptrs.to_vec())
+        Ok(())
     }
 
     // TODO: at the moment we do not support compiling programs with different signatures across