example to dump sections name using gelf(3) api on FreeBSD

list-sections.c

#include <err.h>
#include <fcntl.h>
#include <gelf.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <unistd.h>

static void
dump_sections_name(Elf *e) {
        Elf_Scn *scn=NULL;
        GElf_Shdr shdr;
        size_t n, shstrndx, sz;
        char *name;

        if (elf_getshdrstrndx(e, &shstrndx) != 0)
                errx(EX_SOFTWARE, "elf_getshdrstrndx() failed : %s . " , elf_errmsg(-1));

        while ((scn = elf_nextscn(e, scn)) != NULL) {
                gelf_getshdr(scn, &shdr);

                name = elf_strptr(e, shstrndx, shdr.sh_name);

                printf("Section %-4.4jd %s\n", (uintmax_t) elf_ndxscn(scn), name);
        }
}

int main(int argc, char *argv[]) {
        int fd, rc;
        Elf *e;

        if (elf_version(EV_CURRENT) == EV_NONE )
                errx(EX_SOFTWARE, "ELF library initialization failed : %s ", elf_errmsg(-1));

        if ((fd =open(argv [1], O_RDONLY , 0)) < 0)
                err(EX_NOINPUT,"open \% s \" failed ", argv [1]);
        if ((e = elf_begin(fd, ELF_C_READ , NULL)) == NULL)
                errx(EX_SOFTWARE, "elf_begin () failed : %s . ", elf_errmsg(-1));
        if (elf_kind(e) != ELF_K_ELF)
                errx(EX_DATAERR, "%s is not an ELF object . ", argv[1]);

        dump_sections_name(e);

	rc=close(fd);
	rc=elf_end(e);

	return (rc);
}

Compile it with

gcc -o list-sections list-sections.c -lelf

Run it:

list-sections /boot/kernel/kernel Section 0001 .interp Section 0002 .hash Section 0003 .dynsym Section 0004 .dynstr Section 0005 .text Section 0006 .rodata Section 0007 set_sysctl_set Section 0008 set_sysinit_set Section 0009 set_sysuninit_set Section 0010 set_modmetadata_set Section 0011 set_ah_chips Section 0012 set_ah_rfs Section 0013 set_cons_set Section 0014 set_kbddriver_set Section 0015 usb_host_id Section 0016 usb_dual_id Section 0017 set_kdb_dbbe_set Section 0018 set_ratectl_set Section 0019 set_crypto_set Section 0020 set_ieee80211_ioctl_setset Section 0021 set_ieee80211_ioctl_getset Section 0022 set_scanner_set Section 0023 set_videodriver_set Section 0024 set_scterm_set Section 0025 set_vga_set Section 0026 set_scrndr_set Section 0027 kern_conf Section 0028 .eh_frame Section 0029 .dynamic Section 0030 .got.plt Section 0031 .data Section 0032 set_pcpu Section 0033 .bss Section 0034 .comment Section 0035 .gnu_debuglink Section 0036 .shstrtab Section 0037 .symtab Section 0038 .strtab