binary analysis: handle errors and stdout outputs

This is needed to if --emit=obj=- or --emit=obj=/dev/null is used, which is
what rustc-option used to test for option availability.

Author: nbdd0121

src/binary_analysis/mod.rs

@@ -12,6 +12,12 @@ pub(crate) mod stack_size;
 
 pub fn binary_analysis<'tcx>(cx: &AnalysisCtxt<'tcx>, path: &Path) {
     let file = File::open(path).unwrap();
+    let meta = file.metadata().unwrap();
+    if !meta.is_file() {
+        // We cannot handle special devices (this can be e.g. /dev/null).
+        return;
+    }
+
     let mmap = unsafe { rustc_data_structures::memmap::Mmap::map(file) }.unwrap();
     let object = ObjectFile::parse(&*mmap).unwrap();
 

src/main.rs

@@ -159,9 +159,20 @@ impl driver::CallbacksExt for MyCallbacks {
     }
 
     fn after_codegen<'tcx>(&mut self, cx: &'tcx AnalysisCtxt<'tcx>) {
+        // If compilation fails, do not attempt to perform binary analysis, as
+        // binary might not have been generated.
+        if cx.dcx().has_errors().is_some() {
+            return;
+        }
+
         let outputs = cx.output_filenames(());
         if outputs.outputs.contains_key(&OutputType::Object) {
-            binary_analysis::binary_analysis(cx, outputs.path(OutputType::Object).as_path());
+            let file = outputs.path(OutputType::Object);
+            // We cannot retrieve object back from stdout.
+            if file.is_stdout() {
+                return;
+            }
+            binary_analysis::binary_analysis(cx, file.as_path());
         }
     }
 }