Skip sections which are not PROGBITS

[elfdbg/.git] / elf.c

#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

#include "elf.h"


Elf_Obj *
elf_init(const char *filename)
{
    int fd;
    struct stat sb;
    Elf_Obj *e = NULL;

    if ((fd = open(filename, O_RDONLY)) == -1)
        errx(1, "open");

    e = (Elf_Obj *)malloc(sizeof(Elf_Obj));
    if (e == NULL)
        errx(1, "malloc");

    e->fd = fd;

    if (fstat(fd, &sb) == -1)
        errx(1, "fstat");

    e->sb = sb;

    e->mm = mmap(NULL, sb.st_size, PROT_READ,  MAP_SHARED, fd, 0);
    if (e->mm == MAP_FAILED)
        errx(1, "mmap");

    e->ehdr = (Elf_Ehdr *) e->mm;
    e->ehdr_size = e->ehdr->e_ehsize;

    if (e->sb.st_size < sizeof(Elf_Ehdr))
        errx(1, "not a ELF object");

    if (memcmp(e->ehdr->e_ident, ELFMAG, sizeof(ELFMAG) -1) != 0)
        errx(1, "not a ELF object");

    e->shdr = (Elf_Shdr *) (e->mm + e->ehdr->e_shoff);
    e->shdr_size = e->ehdr->e_shnum;

    e->strtab = NULL;
    e->strtab_size = 0;

    return (e);
}

Elf_Shdr *
elf_strtab(Elf_Obj *e)
{
    Elf_Shdr *ptr;

    ptr = &e->shdr[e->ehdr->e_shstrndx];
    e->strtab = malloc(ptr->sh_size);
    if (e->strtab == NULL)
        errx(1, "malloc %s:%d", __func__, __LINE__);

    e->strtab_size = ptr->sh_size;

    memcpy(e->strtab, (e->mm + ptr->sh_offset), ptr->sh_size);

    return (ptr);
}

int
elf_destroy(Elf_Obj *e)
{
    if (e == NULL)
        return (1);

    if (e->mm != NULL)
        if (munmap(e->mm, e->sb.st_size) == -1)
            return (1);

    close(e->fd);

    if (e->strtab != NULL)
        free(e->strtab);

    free(e);

    return (0);
}

char *
elf_str_get(Elf_Obj *e, int index) {
    if (e == NULL || index > e->strtab_size)
        return (NULL);

    return (&e->strtab[e->shdr[index].sh_name]);
}

int
elf_debug(Elf_Obj *e) 
{
    int i, has_debug = 0;
    char *debug_prefix = ".debug_";
    char *section_name = NULL;

    for (i=0; i < e->shdr_size; i++) {
        section_name = elf_str_get(e, i);
        if (strnstr(section_name, debug_prefix, strlen(debug_prefix))) {
            has_debug++;
        }
    }

    return (has_debug);
}

void
elf_debug_print(Elf_Obj *e)
{
    int i;
    char *debug_prefix = ".debug_";
    char *section_name = NULL;

    printf("%d ELF debug sections:\n", elf_debug(e));

    for (i=0; i < e->shdr_size; i++) {
        if (e->shdr[i].sh_type != SHT_PROGBITS)
            continue;

        section_name = elf_str_get(e, i);
        if (strnstr(section_name, debug_prefix, strlen(debug_prefix))) {
            printf("%s\n", section_name);
        }
    }
}