fn dav1d_decode_frame_exit: Cleanup and make mostly safe (#422)

src/decode.rs

@@ -1,5 +1,8 @@
-use std::ptr::{self, addr_of_mut};
-use std::sync::atomic::{AtomicI32, Ordering};
+use std::ptr;
+use std::ptr::addr_of_mut;
+use std::slice;
+use std::sync::atomic::AtomicI32;
+use std::sync::atomic::Ordering;
 
 #[cfg(feature = "bitdepth_16")]
 use crate::include::common::bitdepth::BitDepth16;
@@ -6311,57 +6314,49 @@ pub unsafe extern "C" fn dav1d_decode_frame_main(f: *mut Dav1dFrameContext) -> l
     }
     return retval;
 }
+
 #[no_mangle]
 pub unsafe extern "C" fn dav1d_decode_frame_exit(f: *mut Dav1dFrameContext, retval: libc::c_int) {
-    let c: *const Dav1dContext = (*f).c;
-    if !((*f).sr_cur.p.data[0]).is_null() {
-        *&mut (*f).task_thread.error = 0 as libc::c_int;
+    let f = &mut *f; // TODO(kkysen) propagate to arg once we deduplicate the fn decl
+    let c = &*f.c;
+    if !f.sr_cur.p.data[0].is_null() {
+        f.task_thread.error = 0;
     }
-    if (*c).n_fc > 1 as libc::c_uint && retval != 0 && !((*f).frame_thread.cf).is_null() {
-        memset(
-            (*f).frame_thread.cf,
-            0 as libc::c_int,
-            ((*f).frame_thread.cf_sz as size_t)
-                .wrapping_mul(128)
-                .wrapping_mul(128)
-                .wrapping_div(2),
-        );
+    if c.n_fc > 1 && retval != 0 && !f.frame_thread.cf.is_null() {
+        slice::from_raw_parts_mut(
+            f.frame_thread.cf.cast::<u8>(),
+            usize::try_from(f.frame_thread.cf_sz).unwrap() * 128 * 128 / 2,
+        )
+        .fill(0);
     }
-    let mut i = 0;
-    while i < 7 {
-        if !((*f).refp[i as usize].p.frame_hdr).is_null() {
-            dav1d_thread_picture_unref(&mut *((*f).refp).as_mut_ptr().offset(i as isize));
+    // TODO(kkysen) use array::zip when stable
+    for i in 0..7 {
+        if !f.refp[i].p.frame_hdr.is_null() {
+            dav1d_thread_picture_unref(&mut f.refp[i]);
         }
-        dav1d_ref_dec(&mut *((*f).ref_mvs_ref).as_mut_ptr().offset(i as isize));
-        i += 1;
+        dav1d_ref_dec(&mut f.ref_mvs_ref[i]);
     }
-    dav1d_picture_unref_internal(&mut (*f).cur);
-    dav1d_thread_picture_unref(&mut (*f).sr_cur);
-    dav1d_cdf_thread_unref(&mut (*f).in_cdf);
-    if !((*f).frame_hdr).is_null() && (*(*f).frame_hdr).refresh_context != 0 {
-        if !((*f).out_cdf.progress).is_null() {
+    dav1d_picture_unref_internal(&mut f.cur);
+    dav1d_thread_picture_unref(&mut f.sr_cur);
+    dav1d_cdf_thread_unref(&mut f.in_cdf);
+    if !f.frame_hdr.is_null() && (*f.frame_hdr).refresh_context != 0 {
+        if !f.out_cdf.progress.is_null() {
             ::core::intrinsics::atomic_store_seqcst(
-                (*f).out_cdf.progress,
-                (if retval == 0 {
-                    1 as libc::c_int
-                } else {
-                    2147483647 - 1
-                }) as libc::c_uint,
+                f.out_cdf.progress,
+                if retval == 0 { 1 } else { 2147483647 - 1 },
             );
         }
-        dav1d_cdf_thread_unref(&mut (*f).out_cdf);
+        dav1d_cdf_thread_unref(&mut f.out_cdf);
     }
-    dav1d_ref_dec(&mut (*f).cur_segmap_ref);
-    dav1d_ref_dec(&mut (*f).prev_segmap_ref);
-    dav1d_ref_dec(&mut (*f).mvs_ref);
-    dav1d_ref_dec(&mut (*f).seq_hdr_ref);
-    dav1d_ref_dec(&mut (*f).frame_hdr_ref);
-    let mut i_0 = 0;
-    while i_0 < (*f).n_tile_data {
-        dav1d_data_unref_internal(&mut (*((*f).tile).offset(i_0 as isize)).data);
-        i_0 += 1;
+    dav1d_ref_dec(&mut f.cur_segmap_ref);
+    dav1d_ref_dec(&mut f.prev_segmap_ref);
+    dav1d_ref_dec(&mut f.mvs_ref);
+    dav1d_ref_dec(&mut f.seq_hdr_ref);
+    dav1d_ref_dec(&mut f.frame_hdr_ref);
+    for tile in slice::from_raw_parts_mut(f.tile, f.n_tile_data.try_into().unwrap()) {
+        dav1d_data_unref_internal(&mut tile.data);
     }
-    (*f).task_thread.retval = retval;
+    f.task_thread.retval = retval;
 }
 
 pub unsafe fn dav1d_decode_frame(f: &mut Dav1dFrameContext) -> libc::c_int {