Android中类似Linux下ldd分析可执行文件和动态库对库的依赖
１. Android下面并没有Linux中的ldd工具，但是它也提供了一个类似的工具，路径如下：
prebuilts/gcc/linux-x86/arm/arm-linux-androideabi-4.9/bin/arm-linux-androideabi-readelf
对的，就是arm-linux-androideabi-readelf这个工具
２. 如何使用：
[email protected]:/home/jon/code/V2_PRO# ./arm-linux-androideabi-readelf -d out/target/product/zqp1659_v2/symbols/system/bin/mm-qcamera-app
Dynamic section at offset 0x14d64 contains 32 entries:
Tag Type Name/Value
0x00000003 (PLTGOT) 0x15f30
0x00000002 (PLTRELSZ) 392 (bytes)
0x00000017 (JMPREL) 0x10b8
0x00000014 (PLTREL) REL
0x00000011 (REL) 0xba0
0x00000012 (RELSZ) 1304 (bytes)
0x00000013 (RELENT) 8 (bytes)
0x6ffffffa (RELCOUNT) 158
0x00000015 (DEBUG) 0x0
0x00000006 (SYMTAB) 0x1a0
0x0000000b (SYMENT) 16 (bytes)
0x00000005 (STRTAB) 0x6b0
0x0000000a (STRSZ) 946 (bytes)
0x6ffffef5 (GNU_HASH) 0xa64
0x00000001 (NEEDED) Shared library: [libcutils.so]
0x00000001 (NEEDED) Shared library: [libdl.so]
0x00000001 (NEEDED) Shared library: [libmmcamera_interface.so]
0x00000001 (NEEDED) Shared library: [libc++.so]
0x00000001 (NEEDED) Shared library: [libc.so]
0x00000001 (NEEDED) Shared library: [libm.so]
0x00000019 (INIT_ARRAY) 0x15a28
0x0000001b (INIT_ARRAYSZ) 12 (bytes)
0x00000020 (PREINIT_ARRAY) 0x15a34
0x00000021 (PREINIT_ARRAYSZ) 0x8
0x0000001a (FINI_ARRAY) 0x15a3c
0x0000001c (FINI_ARRAYSZ) 8 (bytes)
0x0000001e (FLAGS) BIND_NOW
0x6ffffffb (FLAGS_1) Flags: NOW
0x6ffffff0 (VERSYM) 0xaac
0x6ffffffe (VERNEED) 0xb50
0x6fffffff (VERNEEDNUM) 2
0x00000000 (NULL) 0x0
如上可以分析出该可执行文件或者动态库对其他动态库的依赖
３. 分析Android的healthd进程无法打印堆栈的原因
首先分析healthd,这个可执行文件中是否含有打印堆栈需要的动态库
[email protected]:/home/jon/code/V2_PRO# ./arm-linux-androideabi-readelf -d out/target/product/zqp1659_v2/root/sbin/healthd
There is no dynamic section in this file.
嗒嗒嗒，悲剧发生了，这个进程居然不含有任何的动态库，为什么呢
我们分析它的Android.mk文件
就是上图高亮的位置搞的鬼， LOCAL_FORCE_STATIC_EXECUTABLE将其标志该模块需要强制静态链接,从而导致加入的动态链接库失效。将其去除后再试下
编译之后，再看下其包含的动态库
[email protected]:/home/jon/code/V2_PRO# ./arm-linux-androideabi-readelf -d out/target/product/zqp1659_v2/root/sbin/healthd
Dynamic section at offset 0x42a70 contains 32 entries:
Tag Type Name/Value
0x00000003 (PLTGOT) 0x43d68
0x00000002 (PLTRELSZ) 1304 (bytes)
0x00000017 (JMPREL) 0xa738
0x00000014 (PLTREL) REL
0x00000011 (REL) 0x7110
0x00000012 (RELSZ) 13864 (bytes)
0x00000013 (RELENT) 8 (bytes)
0x6ffffffa (RELCOUNT) 1553
0x00000015 (DEBUG) 0x0
0x00000006 (SYMTAB) 0x1c0
0x0000000b (SYMENT) 16 (bytes)
0x00000005 (STRTAB) 0x25c0
0x0000000a (STRSZ) 15260 (bytes)
0x6ffffef5 (GNU_HASH) 0x615c
0x00000001 (NEEDED) Shared library: [libutils.so]
0x00000001 (NEEDED) Shared library: [libbacktrace.so]
0x00000001 (NEEDED) Shared library: [libc++.so]
0x00000001 (NEEDED) Shared library: [libdl.so]
0x00000001 (NEEDED) Shared library: [libc.so]
0x00000001 (NEEDED) Shared library: [libm.so]
0x00000020 (PREINIT_ARRAY) 0x41270
0x00000021 (PREINIT_ARRAYSZ) 0x8
0x00000019 (INIT_ARRAY) 0x41278
0x0000001b (INIT_ARRAYSZ) 56 (bytes)
0x0000001a (FINI_ARRAY) 0x412b0
0x0000001c (FINI_ARRAYSZ) 8 (bytes)
0x0000001e (FLAGS) BIND_NOW
0x6ffffffb (FLAGS_1) Flags: NOW
0x6ffffff0 (VERSYM) 0x6c40
0x6ffffffe (VERNEED) 0x70c0
0x6fffffff (VERNEEDNUM) 2
0x00000000 (NULL) 0x0
OK,现在可以打印堆栈了