Linux 应用调试技术/动态链接器

依赖项

• ldd -d -r /path/to/binary
• 一个用于可视化库及其依赖关系的脚本。
• 二进制文件分析工具
• tldd

解析的符号

找出哪个动态库来自符号

$ LD_DEBUG_OUTPUT=sym.log LD_DEBUG=bindings /bin/ls

$ cat sym.log.7688 | grep malloc
      7688:     binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `__malloc_initialize_hook' [GLIBC_2.0]
      7688:     binding file /lib/i686/cmov/libc.so.6 [0] to /bin/ls [0]: normal symbol `malloc' [GLIBC_2.0]
      7688:     binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `__malloc_hook' [GLIBC_2.0]
      7688:     binding file /lib/ld-linux.so.2 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0]
      7688:     binding file /lib/i686/cmov/libc.so.6 [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0]
      7688:     binding file /bin/ls [0] to /lib/i686/cmov/libc.so.6 [0]: normal symbol `malloc' [GLIBC_2.0]

$ LD_DEBUG=help /bin/ls
Valid options for the LD_DEBUG environment variable are:

  libs        display library search paths
  reloc       display relocation processing
  files       display progress for input file
  symbols     display symbol table processing
  bindings    display information about symbol binding
  versions    display version dependencies
  all         all previous options combined
  statistics  display relocation statistics
  unused      determined unused DSOs
  help        display this help message and exit

To direct the debugging output into a file instead of standard output
a filename can be specified using the LD_DEBUG_OUTPUT environment variable.

参考资料

• man 8 ld.so
• libc 符号可见性和链接

备注

• 它在授予应用程序程序的任何凭据下运行；因此，例如，如果正在执行一个 set-user-ID-root 程序，动态链接器将以 root 的有效用户 ID 运行。

杂项

• 动态链接概述