Question

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.

Answer 1

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