1 // Copyright 2014 The Android Open Source Project
2 //
3 // This software is licensed under the terms of the GNU General Public
4 // License version 2, as published by the Free Software Foundation, and
5 // may be copied, distributed, and modified under those terms.
6 //
7 // This program is distributed in the hope that it will be useful,
8 // but WITHOUT ANY WARRANTY; without even the implied warranty of
9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 // GNU General Public License for more details.
11
12 #include "android/utils/host_bitness.h"
13
14 #ifdef _WIN32
15 #include <windows.h>
16 #else
17 #include <stdlib.h>
18 #endif
19
android_getHostBitness(void)20 int android_getHostBitness(void) {
21 #ifdef _WIN32
22 char directory[900];
23
24 // Retrieves the path of the WOW64 system directory, which doesn't
25 // exist on 32-bit systems.
26 unsigned len = GetSystemWow64Directory(directory, sizeof(directory));
27 if (len == 0) {
28 return 32;
29 } else {
30 return 64;
31 }
32 #else // !_WIN32
33 /*
34 This function returns 64 if host is running 64-bit OS, or 32 otherwise.
35
36 It uses the same technique in ndk/build/core/ndk-common.sh.
37 Here are comments from there:
38
39 ## On Linux or Darwin, a 64-bit kernel (*) doesn't mean that the user-land
40 ## is always 32-bit, so use "file" to determine the bitness of the shell
41 ## that invoked us. The -L option is used to de-reference symlinks.
42 ##
43 ## Note that on Darwin, a single executable can contain both x86 and
44 ## x86_64 machine code, so just look for x86_64 (darwin) or x86-64 (Linux)
45 ## in the output.
46
47 (*) ie. The following code doesn't always work:
48 struct utsname u;
49 int host_runs_64bit_OS = (uname(&u) == 0 && strcmp(u.machine, "x86_64") == 0);
50 */
51 return system("file -L \"$SHELL\" | grep -q \"x86[_-]64\"") == 0 ? 64 : 32;
52 #endif // !_WIN32
53 }
54