deny(unused_results)

- Add LLVM error check.
- Add read length checks.

src/lib.rs

@@ -1,4 +1,5 @@
 #![deny(clippy::all)]
+#![deny(unused_results)]
 
 mod linker;
 mod llvm;

src/linker.rs

@@ -49,6 +49,10 @@ pub enum LinkerError {
     #[error("failure linking module {1} from {0}")]
     LinkArchiveModuleError(PathBuf, PathBuf),
 
+    /// Optimizing the BPF code failed.
+    #[error("LLVMRunPasses failed: {0}")]
+    OptimizeError(String),
+
     /// Generating the BPF code failed.
     #[error("LLVMTargetMachineEmitToFile failed: {0}")]
     EmitCodeError(String),
@@ -255,7 +259,7 @@ impl Linker {
 
             // determine whether the input is bitcode, ELF with embedded bitcode, an archive file
             // or an invalid file
-            file.read(&mut buf)
+            file.read_exact(&mut buf)
                 .map_err(|e| LinkerError::IoError(path.clone(), e))?;
             file.rewind()
                 .map_err(|e| LinkerError::IoError(path.clone(), e))?;
@@ -321,7 +325,7 @@ impl Linker {
         in_type: Option<InputType>,
     ) -> Result<(), LinkerError> {
         let mut data = Vec::new();
-        reader
+        let _: usize = reader
             .read_to_end(&mut data)
             .map_err(|e| LinkerError::IoError(path.to_owned(), e))?;
         // in_type is unknown when we're linking an item from an archive file
@@ -437,9 +441,8 @@ impl Linker {
                 self.options.ignore_inline_never,
                 &self.options.export_symbols,
             )
-        };
-
-        Ok(())
+        }
+        .map_err(LinkerError::OptimizeError)
     }
 
     fn codegen(&mut self) -> Result<(), LinkerError> {

src/llvm/mod.rs

@@ -12,6 +12,7 @@ use libc::c_char as libc_char;
 use llvm_sys::bit_reader::*;
 use llvm_sys::core::*;
 use llvm_sys::debuginfo::LLVMStripModuleDebugInfo;
+use llvm_sys::error::*;
 use llvm_sys::linker::LLVMLinkModules2;
 use llvm_sys::object::*;
 use llvm_sys::prelude::*;
@@ -170,7 +171,7 @@ pub unsafe fn optimize(
     opt_level: OptLevel,
     ignore_inline_never: bool,
     export_symbols: &HashSet<Cow<'static, str>>,
-) {
+) -> Result<(), String> {
     if module_asm_is_probestack(module) {
         LLVMSetModuleInlineAsm2(module, ptr::null_mut(), 0);
     }
@@ -192,8 +193,6 @@ pub unsafe fn optimize(
         }
     }
 
-    let options = LLVMCreatePassBuilderOptions();
-
     let passes = [
         // NB: "default<_>" must be the first pass in the list, otherwise it will be ignored.
         match opt_level {
@@ -214,13 +213,25 @@ pub unsafe fn optimize(
     let passes = passes.join(",");
     debug!("running passes: {passes}");
     let passes = CString::new(passes).unwrap();
-    LLVMRunPasses(module, passes.as_ptr(), tm, options);
-
+    let options = LLVMCreatePassBuilderOptions();
+    let error = LLVMRunPasses(module, passes.as_ptr(), tm, options);
     LLVMDisposePassBuilderOptions(options);
+    // Handle the error and print it to stderr.
+    if !error.is_null() {
+        let error_type_id = LLVMGetErrorTypeId(error);
+        // This is the only error type that exists currently, but there might be more in the future.
+        assert_eq!(error_type_id, LLVMGetStringErrorTypeId());
+        let error_message = LLVMGetErrorMessage(error);
+        let error_string = CStr::from_ptr(error_message).to_str().unwrap().to_owned();
+        LLVMDisposeErrorMessage(error_message);
+        return Err(error_string);
+    }
 
     // Some debug info generated by rustc seems to trigger a segfault in the
     // BTF code in llvm, so strip it until that is fixed
-    LLVMStripModuleDebugInfo(module);
+    let _modified = LLVMStripModuleDebugInfo(module) != 0;
+
+    Ok(())
 }
 
 unsafe fn module_asm_is_probestack(module: LLVMModuleRef) -> bool {