[Mach-O] Add -rpath

macho/cmdline.cc

@@ -29,6 +29,7 @@ Options:
   -pagezero_size <SIZE>       Specify the size of the __PAGEZERO segment
   -platform_version <PLATFORM> <MIN_VERSION> <SDK_VERSION>
                               Set platform, platform version and SDK version
+  -rpath <PATH>               Add PATH to the runpath search path list
   -syslibroot <DIR>           Prepend DIR to library search paths
   -t                          Print out each file the linker loads
   -v                          Report version information)";
@@ -174,6 +175,8 @@ void parse_nonpositional_args(Context &ctx,
       ctx.arg.platform = parse_platform(ctx, arg);
       ctx.arg.platform_min_version = parse_version(ctx, arg2);
       ctx.arg.platform_sdk_version = parse_version(ctx, arg3);
+    } else if (read_arg("-rpath")) {
+      ctx.arg.rpath.push_back(std::string(arg));
     } else if (read_arg("-syslibroot")) {
       ctx.arg.syslibroot.push_back(std::string(arg));
     } else if (read_flag("-t")) {

macho/macho.h

@@ -475,6 +475,12 @@ struct UUIDCommand {
   u8 uuid[16];
 };
 
+struct RpathCommand {
+  u32 cmd;
+  u32 cmdsize;
+  u32 path_off;
+};
+
 struct LinkEditDataCommand {
   u32 cmd;
   u32 cmdsize;

macho/mold.h

@@ -733,8 +733,9 @@ struct Context {
     std::string entry = "_main";
     std::string map;
     std::string output;
-    std::vector<std::string> syslibroot;
     std::vector<std::string> library_paths;
+    std::vector<std::string> rpath;
+    std::vector<std::string> syslibroot;
   } arg;
 
   std::vector<std::string_view> cmdline_args;

macho/output-chunks.cc

@@ -159,6 +159,18 @@ static std::vector<u8> create_load_dylib_cmd(Context &ctx, std::string_view name
   return buf;
 }
 
+static std::vector<u8> create_rpath_cmd(Context &ctx, std::string_view name) {
+  i64 size = sizeof(RpathCommand) + name.size() + 1; // +1 for NUL
+  std::vector<u8> buf(align_to(size, 8));
+  RpathCommand &cmd = *(RpathCommand *)buf.data();
+
+  cmd.cmd = LC_RPATH;
+  cmd.cmdsize = buf.size();
+  cmd.path_off = sizeof(cmd);
+  write_string(buf.data() + sizeof(cmd), name);
+  return buf;
+}
+
 static std::vector<u8> create_function_starts_cmd(Context &ctx) {
   std::vector<u8> buf(sizeof(LinkEditDataCommand));
   LinkEditDataCommand &cmd = *(LinkEditDataCommand *)buf.data();
@@ -232,13 +244,20 @@ static std::pair<i64, std::vector<u8>> create_load_commands(Context &ctx) {
   vec.push_back(create_build_version_cmd(ctx));
   vec.push_back(create_source_version_cmd(ctx));
   vec.push_back(create_main_cmd(ctx));
+  vec.push_back(create_function_starts_cmd(ctx));
+
   for (DylibFile *dylib : ctx.dylibs)
     vec.push_back(create_load_dylib_cmd(ctx, dylib->install_name));
-  vec.push_back(create_function_starts_cmd(ctx));
+
+  for (std::string_view rpath : ctx.arg.rpath)
+    vec.push_back(create_rpath_cmd(ctx, rpath));
+
   if (!ctx.data_in_code.contents.empty())
     vec.push_back(create_data_in_code_cmd(ctx));
+
   if (ctx.arg.adhoc_codesign)
     vec.push_back(create_code_signature_cmd(ctx));
+
   return {vec.size(), flatten(vec)};
 }
 

test/macho/rpath.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+set -e
+cd $(dirname $0)
+mold=`pwd`/../../ld64.mold
+echo -n "Testing $(basename -s .sh $0) ... "
+t=$(pwd)/../../out/test/macho/$(basename -s .sh $0)
+mkdir -p $t
+
+cat <<EOF | cc -o $t/a.o -c -xc -
+int main() {}
+EOF
+
+clang -fuse-ld=$mold -o $t/exe $t/a.o -Wl,-rpath,foo -Wl,-rpath,bar
+otool -l $t/exe > $t/log
+
+grep -A3 'cmd LC_RPATH' $t/log | grep -q 'path foo'
+grep -A3 'cmd LC_RPATH' $t/log | grep -q 'path bar'
+
+echo OK