2 different libelf.h and libdwarf.h in FreeBSD?

Question

In FreeBSD 10.3 there are 2 libelf.h, /usr/include/libelf.h and /usr/local/include/libelf/libelf.h. And they have different defines, such as enum Elf_Cmd.

Also there are 2 libdwarf.h, /usr/include/libdwarf.h and /usr/local/include/libdwarf.h. And they have different defines, such as dwarf_init().

Why? What's the difference? Which one should I use?

=== update ===

Thanks for forquare, now I know that there are 2 libraries both named libelf. I have tried them, and they worked both. However I still have problom with libdwarf.

Code:

#include <stdio.h>
#include <fcntl.h>
#include <libdwarf.h>

int main()
{
    int fd = open("memleax", O_RDONLY);

    Dwarf_Debug dbg;
    Dwarf_Error error;
#if USR_LOCAL
    int res = dwarf_init(fd, DW_DLC_READ, 0, 0, &dbg, &error);
    if(res != DW_DLV_OK) {
            printf("dwarf_init error: %s\n", dwarf_errmsg(error));
            return -1;
    }
#else
    int res = dwarf_init(fd, DW_DLC_READ, &dbg, &error);
    if(res != DW_DLV_OK) {
            printf("dwarf_init error: %s\n", dwarf_errmsg(&error));
            return -1;
    }
#endif

If using system-lib:

cc  debugline.c -o debugline   -lelf -ldwarf

it goes wrong with:

dwarf_init error: ELF error : I/O error [dwarf_init(738)]

If using usr-local-lib:

cc -D USR_LOCAL -I /usr/local/include/ debugline.c -o debugline -L /usr/local/lib/ -lelf -ldwarf

it goes wrong with:

dwarf_init error: DW_DLE_ELF_BEGIN_ERROR 27 a call to elf_begin(... ELF_C_READ_MMAP... ) failed

How should I use libdwarf?

=== update

Ok, I know....

There are 2 libdwarf. I should ignore system-lib, and install the non-system-lib by pkg, and use it.

There are 2 libelf. I should use the system-lib, and can't install the non-system-lib by pkg.

Answer 1

The one located in /usr/include/libelf.h is included with FreeBSD while /usr/local/include/libelf/libelf.h has been installed by you/the system admin most likely as part of a dependency for another package—perhaps the one included in base wasn't at the correct version, or maybe the one installed is from a difference source altogether.

You can use either, but if you move to a system that doesn't have /usr/local/include/libelf/libelf.h you will need to install it via ports or pkg.