c++cgccsymbolsname-mangling

How do I list the symbols in a .so file


How do I list the symbols being exported from a .so file? If possible, I'd also like to know their source (e.g. if they are pulled in from a static library).

I'm using gcc 4.0.2, if that makes a difference.


Solution

  • The standard tool for listing symbols is nm, you can use it simply like this:

    nm -gD yourLib.so
    

    If you want to see symbols of a C++ library, add the "-C" option which demangle the symbols (it's far more readable demangled).

    nm -gDC yourLib.so
    

    If your .so file is in elf format, you have two options:

    Either objdump (-C is also useful for demangling C++):

    $ objdump -TC libz.so
    
    libz.so:     file format elf64-x86-64
    
    DYNAMIC SYMBOL TABLE:
    0000000000002010 l    d  .init  0000000000000000              .init
    0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 free
    0000000000000000      DF *UND*  0000000000000000  GLIBC_2.2.5 __errno_location
    0000000000000000  w   D  *UND*  0000000000000000              _ITM_deregisterTMCloneTable
    

    Or use readelf:

    $ readelf -Ws libz.so
    Symbol table '.dynsym' contains 112 entries:
       Num:    Value          Size Type    Bind   Vis      Ndx Name
         0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
         1: 0000000000002010     0 SECTION LOCAL  DEFAULT   10
         2: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND free@GLIBC_2.2.5 (14)
         3: 0000000000000000     0 FUNC    GLOBAL DEFAULT  UND __errno_location@GLIBC_2.2.5 (14)
         4: 0000000000000000     0 NOTYPE  WEAK   DEFAULT  UND _ITM_deregisterTMCloneTable