Using BFD to get debugging information from .elf files

[Rick Mann]

Hi. I'm working on some Mac OS X (Darwin)-based AVR debugging tools.  
I built the avr-gcc toolchain and have used it successfully, even  
with gdb, to build for and debug various AVR microcontrollers. My  
builds produce a .elf file that gdb then uses for debugging.

I figured I should be able to build binutils, enabling all targets,  
and use BFD from my Mac OS X app to get debugging information out of  
the .elf file. So, I wrote code like this:

bfd_init();
bfd* bfdRef = bfd_openr(argv[1], "elf32-avr");
if (bfdRef == NULL)
{
     printf("Failed to open BFD");
     return 1;
}

if (!bfd_check_format(bfdRef, bfd_archive))
{
     printf("Format matches\n");
}

const char** ts = bfd_target_list();
int i = 0;
while (ts[i] != NULL)
{
     const char* t = ts[i];
     printf("Arch: %s\n", t);
     i++;
}

if ((bfd_get_file_flags (bfdRef) & HAS_SYMS) == 0)
{
     printf("NO SYMS\n");
}

long storageNeeded = bfd_get_symtab_upper_bound(bfdRef);
printf("%ld\n", storageNeeded);


This works, up until the call to bfd_get_symtab_upper_bound(), at  
which point I get a bus error. It prints that the format matches,  
"elf32-avr" shows up as one of the available targets, and it shows  
that there are no symbols. Then it waits a long time before Bus  
Erroring.

If I specify NULL for the target to bfd_openr(), I get an assertion  
failure before the crash: "BFD: BFD 2.17 assertion fail ../../bfd/ 
mach-o.c:168"

So, I realize I must be making some rookie mistake, but I'm not sure  
what that is. Can anyone enlighten me? Thanks!


-- 
Rick