Add helper function for building the LD_PRELOAD list for Steam's runtime

Signed-off-by: Ikey Doherty <ikey@solus-project.com>

configure.ac

@@ -10,6 +10,16 @@ AM_SILENT_RULES([yes])
 LT_INIT([disable-static])
 AC_CONFIG_MACRO_DIR([m4])
 
+# emul32 directory. On Solus this is /usr/lib32. multiarch systems are likely
+# using /usr/lib/i386-linux-gnu/
+AC_ARG_WITH([emul32-libdir], AS_HELP_STRING([--with-emul32-libdir],
+        [the path in which 32-bit libraries are stored]), [emul32dir=${withval}],
+        [emul32dir="/usr/lib32"])
+
+AC_SUBST(emul32dir)
+AC_DEFINE_UNQUOTED(EMUL32LIBDIR, "$emul32dir",
+                   [The location of 32-bit libraries in the OS configuration])
+
 
 AC_CONFIG_FILES([Makefile])
 
@@ -26,6 +36,8 @@ AC_MSG_RESULT([
         bindir:                 ${bindir}
         datarootdir:            ${datarootdir}
 
+        emul32-libdir:          ${emul32dir}
+
         compiler:               ${CC}
         cflags:                 ${CFLAGS}
         ldflags:                ${LDFLAGS}

src/shim/lsi.c

@@ -12,6 +12,7 @@
 #include <assert.h>
 #include <stdio.h>
 
+#include "config.h"
 #include "lsi.h"
 
 bool lsi_config_load(__lsi_unused__ LsiConfig *config)
@@ -36,6 +37,11 @@ void lsi_config_load_defaults(LsiConfig *config)
         config->use_native_runtime = true;
 }
 
+const char *lsi_preload_list()
+{
+        return EMUL32LIBDIR "/libx11.so.6:" EMUL32LIBDIR "/libstdc++.so.6";
+}
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *

src/shim/lsi.h

@@ -59,6 +59,12 @@ __lsi_inline__ static inline bool lsi_system_is_64bit(void)
         return false;
 }
 
+/**
+ * Return the required preload list for running Steam via their runtime
+ * This is static .text - do not free
+ */
+const char *lsi_preload_list(void);
+
 /*
  * Editor modelines  -  https://www.wireshark.org/tools/modelines.html
  *

src/shim/shim.c

@@ -29,6 +29,7 @@ int main(__lsi_unused__ int argc, __lsi_unused__ char **argv)
         fprintf(stderr, "emul32? %s\n", config.force_32 ? "yes" : "no");
         fprintf(stderr, "native-runtime? %s\n", config.use_native_runtime ? "yes" : "no");
         fprintf(stderr, "x86-64? %s\n", is_x86_64 ? "yes" : "no");
+        fprintf(stderr, "LD_PRELOAD=\"%s\"\n", lsi_preload_list());
 
         return EXIT_FAILURE;
 }