wireshark-dissector-sys: Use raw-dylib on Windows

Fixes #62.

wireshark-dissector/build.rs

@@ -1,48 +1,9 @@
 use std::env;
-use std::path::PathBuf;
 
 fn non_windows_msvc() {
     println!("cargo:rustc-cdylib-link-arg=-Wl,-undefined,dynamic_lookup");
 }
 
-fn windows_msvc() {
-    let top_level =
-        PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").expect("missing CARGO_MANIFEST_DIR"));
-    let out_dir = PathBuf::from(env::var_os("OUT_DIR").expect("missing OUT_DIR"));
-    let target = env::var_os("TARGET")
-        .expect("missing TARGET")
-        .into_string()
-        .expect("invalid TARGET");
-
-    let lib = cc::windows_registry::find_tool(&target, "lib.exe").expect("lib.exe not found");
-    let build_and_link_lib = |def_filename: &str, lib_filename: &str| {
-        let def_file = top_level.join(def_filename);
-        let def_file = def_file
-            .into_os_string()
-            .into_string()
-            .expect("invalid CARGO_MANIFEST_DIR");
-
-        let lib_file = out_dir.join(lib_filename);
-        let lib_file = lib_file
-            .into_os_string()
-            .into_string()
-            .expect("invalid OUT_DIR");
-
-        let result = lib
-            .to_command()
-            .arg(format!("/def:{}", def_file))
-            .arg(format!("/out:{}", lib_file))
-            .status()
-            .expect("failed to execute lib.exe");
-        assert!(result.success());
-
-        println!("cargo:rustc-cdylib-link-arg={}", lib_file);
-    };
-
-    build_and_link_lib("sys\\src\\libwireshark.def", "libwireshark.lib");
-    build_and_link_lib("sys\\src\\libwsutil.def", "libwsutil.lib");
-}
-
 fn main() {
     let msvc = env::var_os("CARGO_CFG_TARGET_VENDOR")
         .map(|v| v == "pc")
@@ -53,9 +14,7 @@ fn main() {
         && env::var_os("CARGO_CFG_TARGET_ENV")
             .map(|v| v == "msvc")
             .unwrap_or(false);
-    if msvc {
-        windows_msvc();
-    } else {
+    if !msvc {
         non_windows_msvc();
     }
 }

wireshark-dissector/sys/fix.py

@@ -1,4 +1,7 @@
+import os.path
 import re
+import subprocess
+import sys
 
 def rindex(l, element):
     return len(l) - 1 - l[::-1].index(element)
@@ -26,19 +29,68 @@ def replace_types(line):
         return TYPE_REPLACEMENTS[line[:17]]
     return line
 
-def do(filename):
+def extract_exported_functions(library):
+    """
+    Returns the list of all exported functions from the shared object specified
+    by the file path `library`.
+    """
+    output = subprocess.check_output(["nm", "-D", library], encoding="utf8")
+    symbols = [line.split() for line in output.splitlines()]
+    return [name for (*_, type_, name) in symbols if type_ == "T"]
+
+RE_FUNCTION_NAME=re.compile(r'^    pub fn (?P<name>[A-Za-z0-9_]+).*$')
+def annotate_imported_functions(lines, exported_functions):
+    result = []
+    extern_c = []
+    library = None
+    for line in lines:
+        if not extern_c:
+            if line == 'extern "C" {\n':
+                extern_c.append(line)
+            else:
+                result.append(line)
+        else:
+            m = RE_FUNCTION_NAME.match(line)
+            extern_c.append(line)
+            if line == "}\n":
+                result.append("#[cfg_attr(windows, link(name = \"lib{}.dll\", kind = \"raw-dylib\"))]\n".format(library))
+                result += extern_c
+                extern_c = []
+                library = None
+            elif m:
+                function = m.group("name")
+                if library is None:
+                    library = exported_functions[function]
+                elif library != exported_functions[function]:
+                    raise RuntimeError("extern \"C\" block has functions from two different libraries, can't annotate")
+    return result
+
+def do(filename, libs_path, libraries):
     with open(filename) as f:
         input = list(f)
     input = [replace_types(line) for line in input]
+
+    exported_functions_by_library = [(library, extract_exported_functions(os.path.join(libs_path, "lib{}.so".format(library)))) for library in libraries]
+    exported_functions = {}
+    for library, functions in exported_functions_by_library:
+        for function in functions:
+            if function in exported_functions:
+                print("Found symbol {} in two different libraries: {} and {}".format(function, exported_functions[function], library), file=sys.stderr)
+                return 1
+            exported_functions[function] = library
+
+    input = annotate_imported_functions(input, exported_functions)
     with open(filename, "w") as f:
         f.write("".join(input))
 
 def main():
     import argparse
-    p = argparse.ArgumentParser(description="Post-process a bindgen-generated Wireshark binding")
+    p = argparse.ArgumentParser(description="Post-process a bindgen-generated Wireshark binding. Only works on Linux and requires the `nm` tool.")
     p.add_argument("filename", metavar="FILENAME", help="File to post-process")
+    p.add_argument("libs_path", metavar="LIBS_PATH", help="Path to the libraries to take the symbols from")
+    p.add_argument("libraries", metavar="LIBRARY", nargs="+", help="Library names (without lib prefix and without .so suffix)")
     args = p.parse_args()
-    do(args.filename)
+    sys.exit(do(args.filename, args.libs_path, args.libraries))
 
 if __name__ == '__main__':
     main()

wireshark-dissector/sys/generate

@@ -60,8 +60,7 @@ bindgen \
 	$(pkg-config wireshark --cflags)
 echo
 ) > src/lib.rs
-python3 fix.py src/lib.rs
-python3 extract_def_file.py src/lib.rs /usr/lib src/ wireshark wsutil
+python3 fix.py src/lib.rs /usr/lib wireshark wsutil
 cargo fmt
 
 # These makes the resulting source contain errors.