standard library replacements are incompatible with Android

[jzern]

ld.lld: error: undefined symbol: __read
>>> referenced by nalloc.h:277 (external/libvpx/third_party/nalloc/nalloc.h:277)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(read)
                                                                                                                                                                                                                     
ld.lld: error: undefined symbol: __write                                                                                                                                                                             
>>> referenced by nalloc.h:285 (external/libvpx/third_party/nalloc/nalloc.h:285)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(write)                                                      
                                                                                                                                                                                                                     
ld.lld: error: undefined symbol: __recv                                                                                                                                                                              
>>> referenced by nalloc.h:293 (external/libvpx/third_party/nalloc/nalloc.h:293)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(recv)                                                       
                                                                                                                                                                                                                     
ld.lld: error: undefined symbol: __send
>>> referenced by nalloc.h:301 (external/libvpx/third_party/nalloc/nalloc.h:301)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(send)

ld.lld: error: undefined symbol: __libc_calloc
>>> referenced by nalloc.h:309 (external/libvpx/third_party/nalloc/nalloc.h:309)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(calloc)                                                     
>>> referenced by nalloc.h:309 (external/libvpx/third_party/nalloc/nalloc.h:309)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(calloc)                                                     

ld.lld: error: undefined symbol: __libc_malloc
>>> referenced by nalloc.h:317 (external/libvpx/third_party/nalloc/nalloc.h:317)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(malloc)                                                     
>>> referenced by nalloc.h:317 (external/libvpx/third_party/nalloc/nalloc.h:317)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(malloc)

ld.lld: error: undefined symbol: __libc_realloc
>>> referenced by nalloc.h:325 (external/libvpx/third_party/nalloc/nalloc.h:325)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(realloc)                                                    
>>> referenced by nalloc.h:325 (external/libvpx/third_party/nalloc/nalloc.h:325)                                                                                                                                     
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(realloc)

ld.lld: error: undefined symbol: __libc_reallocarray
>>> referenced by nalloc.h:333 (external/libvpx/third_party/nalloc/nalloc.h:333)
>>>               out/soong/.intermediates/external/libvpx/vp8_dec_fuzzer/android_arm_armv7-a-neon_fuzzer/obj/external/libvpx/examples/vpx_dec_fuzzer.o:(reallocarray)  

[jzern]

cc: @wantehchang

[jzern]

This isn't a major issue as in libvpx we can define FUZZER_DISABLE_NALLOC.

[catenacyber]

Thanks for the report, do you have a fix on how to detect Android and what names it uses for its routines ?

[jzern]

A quick workaround would be to check for __BIONIC__ and disable nalloc by default like what is done with MSan. As for making it work, https://android.googlesource.com/platform/bionic/+/main/libc/malloc_hooks/README.md might be a starting point for the allocation functions at least.

[wantehchang]

In addition, the current code is likely to be specific to glibc. If so, it should be guarded with #if defined(__GLIBC__).