[Mach-O] Add -headerpad_max_install_names

macho/cmdline.cc

@@ -33,6 +33,8 @@ Options:
   -framework <NAME>,[,<SUFFIX>]
                               Search for a given framework
   -headerpad <SIZE>           Allocate the size of padding after load commands
+  -headerpad_max_install_names
+                              Allocate MAXPATHLEN byte padding after load commands
   -help                       Report usage information
   -l<LIB>                     Search for a given library
   -lto_library <FILE>         Ignored
@@ -200,6 +202,8 @@ void parse_nonpositional_args(Context<E> &ctx,
       ctx.arg.headerpad = std::stol(std::string(arg), &pos, 16);
       if (pos != arg.size())
         Fatal(ctx) << "malformed -headerpad: " << arg;
+    } else if (read_flag("-headerpad_max_install_names")) {
+      ctx.arg.headerpad = 1024;
     } else if (read_flag("-dynamic")) {
       ctx.arg.dynamic = true;
     } else if (read_arg("-e")) {

test/macho/headerpad-max-install-names.sh

@@ -0,0 +1,16 @@
+#!/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,-headerpad_max_install_names
+otool -l $t/exe | grep -A5 'sectname __text' | grep -q 'addr 0x0000000100000978'
+
+echo OK