Make all callbacks optional in libgit2-sys

Appease the nightly compiler's checks for undefinededness and reflect
how this is actually what the typedef is in C, a nullable function
pointer.

src/blob.rs

@@ -124,19 +124,27 @@ impl<'repo> Drop for BlobWriter<'repo> {
     fn drop(&mut self) {
         // We need cleanup in case the stream has not been committed
         if self.need_cleanup {
-            unsafe { ((*self.raw).free)(self.raw) }
+            unsafe {
+                if let Some(f) = (*self.raw).free {
+                    f(self.raw)
+                }
+            }
         }
     }
 }
 
 impl<'repo> io::Write for BlobWriter<'repo> {
     fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
         unsafe {
-            let res = ((*self.raw).write)(self.raw, buf.as_ptr() as *const _, buf.len());
-            if res < 0 {
-                Err(io::Error::new(io::ErrorKind::Other, "Write error"))
+            if let Some(f) = (*self.raw).write {
+                let res = f(self.raw, buf.as_ptr() as *const _, buf.len());
+                if res < 0 {
+                    Err(io::Error::new(io::ErrorKind::Other, "Write error"))
+                } else {
+                    Ok(buf.len())
+                }
             } else {
-                Ok(buf.len())
+                Err(io::Error::new(io::ErrorKind::Other, "no write callback"))
             }
         }
     }

src/build.rs

@@ -589,13 +589,11 @@ impl<'cb> CheckoutBuilder<'cb> {
             opts.their_label = c.as_ptr();
         }
         if self.progress.is_some() {
-            let f: raw::git_checkout_progress_cb = progress_cb;
-            opts.progress_cb = Some(f);
+            opts.progress_cb = Some(progress_cb);
             opts.progress_payload = self as *mut _ as *mut _;
         }
         if self.notify.is_some() {
-            let f: raw::git_checkout_notify_cb = notify_cb;
-            opts.notify_cb = Some(f);
+            opts.notify_cb = Some(notify_cb);
             opts.notify_payload = self as *mut _ as *mut _;
             opts.notify_flags = self.notify_flags.bits() as c_uint;
         }

src/cred.rs

@@ -179,7 +179,11 @@ impl Binding for Cred {
 impl Drop for Cred {
     fn drop(&mut self) {
         if !self.raw.is_null() {
-            unsafe { ((*self.raw).free)(self.raw) }
+            unsafe {
+                if let Some(f) = (*self.raw).free {
+                    f(self.raw)
+                }
+            }
         }
     }
 }

src/diff.rs

@@ -164,13 +164,9 @@ impl<'repo> Diff<'repo> {
     {
         let mut cb: &mut PrintCb<'_> = &mut cb;
         let ptr = &mut cb as *mut _;
+        let print: raw::git_diff_line_cb = Some(print_cb);
         unsafe {
-            try_call!(raw::git_diff_print(
-                self.raw,
-                format,
-                print_cb,
-                ptr as *mut _
-            ));
+            try_call!(raw::git_diff_print(self.raw, format, print, ptr as *mut _));
             Ok(())
         }
     }
@@ -194,24 +190,25 @@ impl<'repo> Diff<'repo> {
         };
         let ptr = &mut cbs as *mut _;
         unsafe {
-            let binary_cb_c = if cbs.binary.is_some() {
-                Some(binary_cb_c as raw::git_diff_binary_cb)
+            let binary_cb_c: raw::git_diff_binary_cb = if cbs.binary.is_some() {
+                Some(binary_cb_c)
             } else {
                 None
             };
-            let hunk_cb_c = if cbs.hunk.is_some() {
-                Some(hunk_cb_c as raw::git_diff_hunk_cb)
+            let hunk_cb_c: raw::git_diff_hunk_cb = if cbs.hunk.is_some() {
+                Some(hunk_cb_c)
             } else {
                 None
             };
-            let line_cb_c = if cbs.line.is_some() {
-                Some(line_cb_c as raw::git_diff_line_cb)
+            let line_cb_c: raw::git_diff_line_cb = if cbs.line.is_some() {
+                Some(line_cb_c)
             } else {
                 None
             };
+            let file_cb: raw::git_diff_file_cb = Some(file_cb_c);
             try_call!(raw::git_diff_foreach(
                 self.raw,
-                file_cb_c,
+                file_cb,
                 binary_cb_c,
                 hunk_cb_c,
                 line_cb_c,

src/index.rs

@@ -295,7 +295,7 @@ impl Index {
         let ptr = cb.as_mut();
         let callback = ptr
             .as_ref()
-            .map(|_| index_matched_path_cb as raw::git_index_matched_path_cb);
+            .map(|_| index_matched_path_cb as extern "C" fn(_, _, _) -> _);
         unsafe {
             try_call!(raw::git_index_add_all(
                 self.raw,
@@ -473,7 +473,7 @@ impl Index {
         let ptr = cb.as_mut();
         let callback = ptr
             .as_ref()
-            .map(|_| index_matched_path_cb as raw::git_index_matched_path_cb);
+            .map(|_| index_matched_path_cb as extern "C" fn(_, _, _) -> _);
         unsafe {
             try_call!(raw::git_index_remove_all(
                 self.raw,
@@ -511,7 +511,7 @@ impl Index {
         let ptr = cb.as_mut();
         let callback = ptr
             .as_ref()
-            .map(|_| index_matched_path_cb as raw::git_index_matched_path_cb);
+            .map(|_| index_matched_path_cb as extern "C" fn(_, _, _) -> _);
         unsafe {
             try_call!(raw::git_index_update_all(
                 self.raw,

src/odb.rs

@@ -98,9 +98,10 @@ impl<'repo> Odb<'repo> {
             let mut data = ForeachCbData {
                 callback: &mut callback,
             };
+            let cb: raw::git_odb_foreach_cb = Some(foreach_cb);
             try_call!(raw::git_odb_foreach(
                 self.raw(),
-                foreach_cb,
+                cb,
                 &mut data as *mut _ as *mut _
             ));
             Ok(())
@@ -155,7 +156,7 @@ impl<'repo> Odb<'repo> {
     pub fn packwriter(&self) -> Result<OdbPackwriter<'_>, Error> {
         let mut out = ptr::null_mut();
         let progress = MaybeUninit::uninit();
-        let progress_cb = write_pack_progress_cb;
+        let progress_cb: raw::git_indexer_progress_cb = Some(write_pack_progress_cb);
         let progress_payload = Box::new(OdbPackwriterCb { cb: None });
         let progress_payload_ptr = Box::into_raw(progress_payload);
 

src/packbuilder.rs

@@ -89,10 +89,11 @@ impl<'repo> PackBuilder<'repo> {
     {
         let mut cb = &mut cb as &mut ForEachCb<'_>;
         let ptr = &mut cb as *mut _;
+        let foreach: raw::git_packbuilder_foreach_cb = Some(foreach_c);
         unsafe {
             try_call!(raw::git_packbuilder_foreach(
                 self.raw,
-                foreach_c,
+                foreach,
                 ptr as *mut _
             ));
         }
@@ -112,7 +113,7 @@ impl<'repo> PackBuilder<'repo> {
     {
         let mut progress = Box::new(Box::new(progress) as Box<ProgressCb<'_>>);
         let ptr = &mut *progress as *mut _;
-        let progress_c = Some(progress_c as raw::git_packbuilder_progress);
+        let progress_c: raw::git_packbuilder_progress = Some(progress_c);
         unsafe {
             try_call!(raw::git_packbuilder_set_callbacks(
                 self.raw,

src/patch.rs

@@ -206,7 +206,8 @@ impl<'buffers> Patch<'buffers> {
     pub fn print(&mut self, mut line_cb: &mut LineCb<'_>) -> Result<(), Error> {
         let ptr = &mut line_cb as *mut _ as *mut c_void;
         unsafe {
-            try_call!(raw::git_patch_print(self.raw, print_cb, ptr));
+            let cb: raw::git_diff_line_cb = Some(print_cb);
+            try_call!(raw::git_patch_print(self.raw, cb, ptr));
             Ok(())
         }
     }

src/remote_callbacks.rs

@@ -174,24 +174,19 @@ impl<'a> Binding for RemoteCallbacks<'a> {
                 0
             );
             if self.progress.is_some() {
-                let f: raw::git_indexer_progress_cb = transfer_progress_cb;
-                callbacks.transfer_progress = Some(f);
+                callbacks.transfer_progress = Some(transfer_progress_cb);
             }
             if self.credentials.is_some() {
-                let f: raw::git_cred_acquire_cb = credentials_cb;
-                callbacks.credentials = Some(f);
+                callbacks.credentials = Some(credentials_cb);
             }
             if self.sideband_progress.is_some() {
-                let f: raw::git_transport_message_cb = sideband_progress_cb;
-                callbacks.sideband_progress = Some(f);
+                callbacks.sideband_progress = Some(sideband_progress_cb);
             }
             if self.certificate_check.is_some() {
-                let f: raw::git_transport_certificate_check_cb = certificate_check_cb;
-                callbacks.certificate_check = Some(f);
+                callbacks.certificate_check = Some(certificate_check_cb);
             }
             if self.push_update_reference.is_some() {
-                let f: extern "C" fn(_, _, _) -> c_int = push_update_reference_cb;
-                callbacks.push_update_reference = Some(f);
+                callbacks.push_update_reference = Some(push_update_reference_cb);
             }
             if self.update_tips.is_some() {
                 let f: extern "C" fn(

src/repo.rs

@@ -778,9 +778,10 @@ impl Repository {
                 repo: self,
                 ret: &mut ret,
             };
+            let cb: raw::git_submodule_cb = Some(append);
             try_call!(raw::git_submodule_foreach(
                 self.raw,
-                append,
+                cb,
                 &mut data as *mut _ as *mut c_void
             ));
         }
@@ -2426,9 +2427,10 @@ impl Repository {
             let mut data = StashCbData {
                 callback: &mut callback,
             };
+            let cb: raw::git_stash_cb = Some(stash_cb);
             try_call!(raw::git_stash_foreach(
                 self.raw(),
-                stash_cb,
+                cb,
                 &mut data as *mut _ as *mut _
             ));
             Ok(())

src/transport.rs

@@ -113,11 +113,8 @@ where
     });
     let prefix = CString::new(prefix)?;
     let datap = (&mut *data) as *mut TransportData as *mut c_void;
-    try_call!(raw::git_transport_register(
-        prefix,
-        transport_factory,
-        datap
-    ));
+    let factory: raw::git_transport_cb = Some(transport_factory);
+    try_call!(raw::git_transport_register(prefix, factory, datap));
     mem::forget(data);
     Ok(())
 }
@@ -141,9 +138,9 @@ impl Transport {
 
         let mut raw = Box::new(RawSmartSubtransport {
             raw: raw::git_smart_subtransport {
-                action: subtransport_action,
-                close: subtransport_close,
-                free: subtransport_free,
+                action: Some(subtransport_action),
+                close: Some(subtransport_close),
+                free: Some(subtransport_free),
             },
             obj: Box::new(subtransport),
         });
@@ -257,9 +254,9 @@ extern "C" fn subtransport_action(
         *stream = mem::transmute(Box::new(RawSmartSubtransportStream {
             raw: raw::git_smart_subtransport_stream {
                 subtransport: raw_transport,
-                read: stream_read,
-                write: stream_write,
-                free: stream_free,
+                read: Some(stream_read),
+                write: Some(stream_write),
+                free: Some(stream_free),
             },
             obj: obj,
         }));

src/tree.rs

@@ -132,7 +132,7 @@ impl<'repo> Tree<'repo> {
             raw::git_tree_walk(
                 self.raw(),
                 mode.into(),
-                treewalk_cb::<T>,
+                Some(treewalk_cb::<T>),
                 &mut data as *mut _ as *mut c_void,
             );
             Ok(())

src/treebuilder.rs

@@ -95,12 +95,9 @@ impl<'repo> TreeBuilder<'repo> {
     {
         let mut cb: &mut FilterCb<'_> = &mut filter;
         let ptr = &mut cb as *mut _;
+        let cb: raw::git_treebuilder_filter_cb = Some(filter_cb);
         unsafe {
-            try_call!(raw::git_treebuilder_filter(
-                self.raw,
-                filter_cb,
-                ptr as *mut _
-            ));
+            try_call!(raw::git_treebuilder_filter(self.raw, cb, ptr as *mut _));
             panic::check();
         }
         Ok(())