Android NDK for x86_64 has no reference for bcopy and index

Question

I am trying to compile Lame sound library with Android NDK for x86_64 architecture. I am getting the below link error for undefined references to bcopy and index:

jni/libmp3lame/encoder.c:471: error: undefined reference to 'bcopy'
jni/libmp3lame/encoder.c:476: error: undefined reference to 'bcopy'
jni/libmp3lame/id3tag.c:1125: error: undefined reference to 'index'
jni/libmp3lame/newmdct.c:1036: error: undefined reference to 'bcopy'
jni/libmp3lame/util.c:685: error: undefined reference to 'bcopy'

The code successfully compiles for x86 and arm architectures.

So I digged through NDK's libs a bit and noticed that bcopy and index are both exported in libc.so for x86 and arm platforms but not for x86_64 (see below objdump outputs).

$> objdump -d android-ndk-r10d/platforms/android-21/arch-arm/usr/lib/libc.so | grep bcopy -A 6
0000b000 <bcopy>:
    b000:   e52db004 push   {fp}    ; (str fp, [sp, #-4]!)
    b004:   e28db000 add    fp, sp, #0
    b008:   e28bd000 add    sp, fp, #0
    b00c:   e8bd0800 ldmfd  sp!, {fp}
    b010:   e12fff1e bx lr


$> objdump -d android-ndk-r10d/platforms/android-21/arch-x86/usr/lib/libc.so | grep -A 6 bcopy
00009fb0 <bcopy>:
    9fb0:   55                   push   %ebp
    9fb1:   89 e5                   mov    %esp,%ebp
    9fb3:   5d                   pop    %ebp
    9fb4:   c3                   ret


$>  objdump -d android-ndk-r10d/platforms/android-21/arch-x86_64/usr/lib/libc.so | grep -A 6 bcopy
<<NOTHING FOUND>>

Any thoughts? Below are my Android.mk and Application.mk files.

Application.mk:

APP_ABI:=x86_64
APP_PLATFORM := android-21

Android.mk:

LOCAL_PATH := $(call my-dir)

APP_PLATFORM := android-21

include $(CLEAR_VARS)

LOCAL_MODULE        := libmp3lame

LOCAL_SRC_FILES     := \
...<list-of-.c-files>...

LOCAL_LDLIBS += -llog

include $(BUILD_SHARED_LIBRARY)

Answer 1

You can fix this cleanly with a single line in Application.mk (docs):

APP_CFLAGS += -DSTDC_HEADERS

Why?

LAME assumes that certain symbols will be accessible without explicit inclusion via #include. However, it also provides a way to signal that explicit inclusion is necessary.

In my distribution, the conflictive files (machine.h and id3tag.c) have something like this:

#ifdef STDC_HEADERS
# include <stdlib.h>
# include <string.h>
#endif

This is the block you need to trigger, by setting the STDC_HEADERS preprocessor variable. The line above, with the -D flag, tells the C compiler to create it.

Answer 2

To fix bcopy issue, I added #include <strings.h> in machine.h and id3tag.h.

To fix index issue, I ended up commenting out the #define strchar index line in both machine.h and id3tag.c:

#ifdef STDC_HEADERS
# include <stdlib.h>
# include <string.h>
#else
# ifndef HAVE_STRCHR
//#  define strchr index
#  define strrchr rindex
# endif
char   *strchr(), *strrchr();
# ifndef HAVE_MEMCPY
#  define memcpy(d, s, n) bcopy ((s), (d), (n))
#  define memmove(d, s, n) bcopy ((s), (d), (n))
# endif
#endif

Answer 3

I have it in strings.h, but its a #define:

$ cd /opt/android-ndk-r10d
$ grep -R bcopy * | grep x86_64
platforms/android-21/arch-x86_64/usr/include/linux/mroute6.h:#define IF_COPY(f, t) bcopy(f, t, sizeof(*(f)))
platforms/android-21/arch-x86_64/usr/include/strings.h:#define bcopy(b1, b2, len) \
platforms/android-21/arch-x86_64/usr/include/strings.h:#define bcopy(b1, b2, len) (void)(__builtin_memmove((b2), (b1), (len)))

Here's what it looks like (taken from the header strings.h):

#if defined(__BIONIC_FORTIFY)
#  define bcopy(b1, b2, len) \
    (void)(__builtin___memmove_chk((b2), (b1), (len), __bos0(b2)))
#  define bzero(b, len) \
    (void)(__builtin___memset_chk((b), '\0', (len), __bos0(b)))
#else
# define bcopy(b1, b2, len) (void)(__builtin_memmove((b2), (b1), (len)))
# define bzero(b, len) (void)(__builtin_memset((b), '\0', (len)))
#endif

Earlier version of the Android runtime provided it as a library call. See, for example, How to understand this code snippet in the bcopy.c of bionic?.

It sounds like its another case of the headers changing at android-21. That is, its a function that used to present as an export in a library, but now available in a headers. See, for example, Cannot load library: reloc_library[1285]: cannot locate 'rand'.

I think the workaround is to re-compile the Lame sound library with android-21, and not an earlier version of the toolchain.

Also, there are various config.h that have the following comment:

/* HAS_BCOPY:
 *  This symbol is defined if the bcopy() routine is available to
 *  copy blocks of memory.
 */
#define HAS_BCOPY   /**/

You can find the config.h at, for example, android-ndk-r10d/prebuilt/darwin-x86_64/lib/perl5/5.16.2/darwin-2level/CORE/config.h.

If its not something obvious (like you already are compiling under android-21 and arch is correct), then we'll need to see how your project is setup (like what does Application.mk look like, or what --sysroot is being used).