How do I check if an object file is in COFF or ELF format from within C?

c linux elf coff
Chris picture Chris · Oct 10, 2012 · Viewed 9.5k times · Source

I would like to be able to check the format of an object file from within my C code so that I can use different functions for reading the file based on whether it is COFF or ELF format.

Is this possible, and if so, how would I do it?

This is in Linux btw if that makes any difference.

Answer

nneonneo picture nneonneo · Oct 10, 2012

Read the first four bytes. If they are equal to \x7fELF, it's an ELF file. Otherwise, you should parse it as COFF and see if it makes sense. (Note that COFF magic is a lot more complicated; I get no less than 42 magic entries in /usr/share/file/magic for it).

Related questions

How do I find out which functions of a shared object are used by a program or an other library?

How do I find out which functions of a shared object are used by a program or an other library? In this specific case, I would like to see which functions in /lib/libgcc1_s.so.1 are used by an …

Read More
Adding section to ELF file

I need to be able to add an arbitrary section to an ELF file. I cannot use GPL code in this program, so BFD is out of the question. I can use libelf/gelf to read sections, but the documentation …

Read More
What is the "__gmon_start__" symbol?

I'm compiling this code with gcc hello.c -o hello -O3: #include <stdio.h> int main(void) { printf("Hello world\n"); return 0; } and when I list the relocations I get: test@southpark$ readelf -r hello | grep gmon 080495a4 00000106 …

Read More