run on win32 using the clang wrapper

fuzzers/libfuzzer_libpng/src/bin/cc.rs

@@ -1,4 +1,4 @@
-use libafl_cc::{ClangWrapper, CompilerWrapper};
+use libafl_cc::{ClangWrapper, CompilerWrapper, LIB_EXT, LIB_PREFIX};
 use std::env;
 
 fn main() {
@@ -11,7 +11,11 @@ fn main() {
             .unwrap()
             .add_arg("-fsanitize-coverage=trace-pc-guard".into())
             .unwrap()
-            .add_link_arg(dir.join("liblibfuzzer_libpng.a").display().to_string())
+            .add_link_arg(
+                dir.join(format!("{}libfuzzer_libpng.{}", LIB_PREFIX, LIB_EXT))
+                    .display()
+                    .to_string(),
+            )
             .unwrap()
             .run()
             .unwrap();

fuzzers/libfuzzer_libpng/src/bin/cxx.rs

@@ -1,4 +1,4 @@
-use libafl_cc::{ClangWrapper, CompilerWrapper};
+use libafl_cc::{ClangWrapper, CompilerWrapper, LIB_EXT, LIB_PREFIX};
 use std::env;
 
 fn main() {
@@ -12,7 +12,11 @@ fn main() {
             .unwrap()
             .add_arg("-fsanitize-coverage=trace-pc-guard".into())
             .unwrap()
-            .add_link_arg(dir.join("liblibfuzzer_libpng.a").display().to_string())
+            .add_link_arg(
+                dir.join(format!("{}libfuzzer_libpng.{}", LIB_PREFIX, LIB_EXT))
+                    .display()
+                    .to_string(),
+            )
             .unwrap()
             .run()
             .unwrap();

fuzzers/libfuzzer_libpng/src/lib.rs

@@ -131,7 +131,7 @@ fn fuzz(corpus_dirs: Vec<PathBuf>, objective_dir: PathBuf, broker_port: u16) ->
 
     // The actual target run starts here.
     // Call LLVMFUzzerInitialize() if present.
-	let args: Vec<String> = env::args().collect();
+    let args: Vec<String> = env::args().collect();
     if libfuzzer_initialize(&args) == -1 {
         println!("Warning: LLVMFuzzerInitialize failed with -1")
     }

libafl_cc/src/lib.rs

@@ -7,6 +7,17 @@ pub enum Error {
     Unknown(String),
 }
 
+// TODO macOS
+#[cfg(windows)]
+pub const LIB_EXT: &'static str = "lib";
+#[cfg(not(windows))]
+pub const LIB_EXT: &'static str = "a";
+
+#[cfg(windows)]
+pub const LIB_PREFIX: &'static str = "";
+#[cfg(not(windows))]
+pub const LIB_PREFIX: &'static str = "lib";
+
 /// Wrap a compiler hijacking its arguments
 pub trait CompilerWrapper {
     /// Set the wrapper arguments parsing a command line set of arguments

libafl_targets/libfuzzer_compatibility.c

@@ -31,6 +31,8 @@
 #define EXTERNAL_FUNC(Name, Default)                                   \
   __pragma(comment(linker, "/alternatename:" WIN_SYM_PREFIX STRINGIFY( \
                                Name) "=" WIN_SYM_PREFIX STRINGIFY(Default)))
+
+#define CHECK_WEAK_FN(Name) (Name != &Name##Def)
 #else
 // Declare external functions as weak to allow them to default to a specified
 // function if not defined explicitly. We must use weak symbols because clang's
@@ -38,21 +40,20 @@
 // https://bugs.llvm.org/show_bug.cgi?id=40218 for more details.
 #define EXTERNAL_FUNC(Name, Default) \
   __attribute__((weak, alias(STRINGIFY(Default))))
+
+#define CHECK_WEAK_FN(Name) (Name != NULL)
 #endif  // LIBFUZZER_MSVC
 
 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)         \
-  RETURN_TYPE NAME##Def FUNC_SIG {                          \
+  RETURN_TYPE (*NAME##Def) FUNC_SIG = NULL;                 \
-    printf("ERROR: Function \"%s\" not defined.\n", #NAME); \
-    exit(1);                                                \
-  }                                                         \
   EXTERNAL_FUNC(NAME, NAME##Def) RETURN_TYPE NAME FUNC_SIG
-
 #else
 
 // Declare these symbols as weak to allow them to be optionally defined.
 #define EXT_FUNC(NAME, RETURN_TYPE, FUNC_SIG, WARN)                            \
   __attribute__((weak, visibility("default"))) RETURN_TYPE NAME FUNC_SIG
 
+#define CHECK_WEAK_FN(Name) (Name != NULL)
 #endif
 
 EXT_FUNC(LLVMFuzzerInitialize, int, (int *argc, char ***argv), false);
@@ -68,13 +69,13 @@ EXT_FUNC(LLVMFuzzerCustomCrossOver, size_t,
 #undef EXT_FUNC
 
 int libafl_targets_has_libfuzzer_init() {
-  return LLVMFuzzerInitialize != NULL;
+  return CHECK_WEAK_FN(LLVMFuzzerInitialize);
 }
 
 int libafl_targets_libfuzzer_init(int *argc, char ***argv) {
-  if (LLVMFuzzerInitialize) {
+  if (libafl_targets_has_libfuzzer_init()) {
     return LLVMFuzzerInitialize(argc, argv);
   } else {
    return 0;
   }
-}
+}