Linux 應用除錯技術/動態連結器

依賴項

• ldd -d -r /path/to/binary
• 一個用於視覺化庫及其依賴關係的指令碼。
• 二進位制檔案分析工具
• tldd

解析的符號

找出哪個動態庫來自符號

$ 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.

參考資料

• man 8 ld.so
• libc 符號可見性和連結

備註

• 它在授予應用程式程式的任何憑據下執行；因此，例如，如果正在執行一個 set-user-ID-root 程式，動態連結器將以 root 的有效使用者 ID 執行。

雜項

• 動態連結概述