From ca54ca7422ae51a10c284c977f9e0f2582d93977 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <alexis.engelke@googlemail.com>
Date: Tue, 25 Dec 2018 17:06:47 +0100
Subject: [PATCH] Add compile-time option for architecture mode

This allows to decode x86-32 machine code on a 64-bit platform (but
not vice versa). As a side-effect, we also get rid of pointer-size
detection for architecture selection.
---
 decode.h          | 4 ++++
 meson.build       | 9 ++++-----
 meson_options.txt | 1 +
 tests/meson.build | 2 +-
 4 files changed, 10 insertions(+), 6 deletions(-)
 create mode 100644 meson_options.txt

diff --git a/decode.h b/decode.h
index 6f9abec..a8b3172 100644
--- a/decode.h
+++ b/decode.h
@@ -5,6 +5,10 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#if defined(ARCH_X86_64) && __SIZEOF_POINTER__ < 8
+#error "Decoding x86-64 requires a 64-bit architecture"
+#endif
+
 #ifndef ssize_t
 #define ssize_t intptr_t
 #endif
diff --git a/meson.build b/meson.build
index d23c1b1..bf3c7ae 100644
--- a/meson.build
+++ b/meson.build
@@ -29,14 +29,13 @@ if get_option('warning_level').to_int() >= 3
                         language: 'c')
 endif
 
-c_compiler = meson.get_compiler('c')
-pointer_size = c_compiler.sizeof('void*')
-if pointer_size == 4
+archmode = get_option('archmode')
+if archmode == '32'
   add_project_arguments(['-DARCH_386'], language: 'c')
-elif pointer_size == 8
+elif archmode == '64'
   add_project_arguments(['-DARCH_X86_64'], language: 'c')
 else
-  error('Invalid pointer size')
+  error('Invalid architecture mode')
 endif
 
 instr_data = custom_target('tables',
diff --git a/meson_options.txt b/meson_options.txt
new file mode 100644
index 0000000..ce5a124
--- /dev/null
+++ b/meson_options.txt
@@ -0,0 +1 @@
+option('archmode', type: 'combo', choices: ['32', '64'])
diff --git a/tests/meson.build b/tests/meson.build
index de7edb9..199a9cb 100644
--- a/tests/meson.build
+++ b/tests/meson.build
@@ -15,7 +15,7 @@ cases = [
 test_driver = executable('test_driver', 'driver.c',
                          dependencies: libx86decode,
                          c_args: ['-D_GNU_SOURCE'])
-test_args = files('common.sh') + [test_driver.full_path(), '@0@'.format(pointer_size * 8)]
+test_args = files('common.sh') + [test_driver.full_path(), get_option('archmode')]
 
 foreach case : cases
   test(case[0], sh, args: test_args + files(case[1]))