Object files in an executable in Linux

Question

Is there a way to find the object files from which the current executable is generated in Linux (RHEL to be specific). I understand that one can use "nm" to find the exported symbols, "ldd" to find dependent shared object.

But I could not find command to find out the name of object (.o) files of which executable is composed of. Is it possible?

Answer 1

The original names of the object files are not stored in the DWARF debugging information.

Each object file has a DW_TAG_compile_unit entry in the .debug_info section. This entry contains a reference to the "primary source file from which the compilation unit was derived", but not the name of the object file. The DWARF standard contains a list of the attributes that can be stored for each compilation unit (section 3.1.1, page number 44, pdf page 58).

You can view the information that is stored with the following command:

$ readelf --debug-dump=info --dwarf-depth=1 hw

Output:

Contents of the .debug_info section:
<some compilation units removed>       
  Compilation Unit @ offset 0x133:
   Length:        0x8b (32-bit)
   Version:       4
   Abbrev Offset: 0x64
   Pointer Size:  4
 <0><13e>: Abbrev Number: 1 (DW_TAG_compile_unit)
    <13f>   DW_AT_producer    : (indirect string, offset: 0x131): GNU C11 5.3.0 -mtune=generic -march=pentiumpro -g
    <143>   DW_AT_language    : 12      (ANSI C99)
    <144>   DW_AT_name        : (indirect string, offset: 0x163): hw.c
    <148>   DW_AT_comp_dir    : (indirect string, offset: 0x168): /home/mikel/src/hw
    <14c>   DW_AT_low_pc      : 0x80483db
    <150>   DW_AT_high_pc     : 0x2e
    <154>   DW_AT_stmt_list   : 0xea
 <1><158>: ...
<some compilation units removed>