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/*
* Copyright 2001-2024 Petter Reinholdtsen
*
* This program is free software: you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation, either version 2 of the
* License, or (at your option) any later version.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <elf.h>
#if defined(HAVE_SYS_LINK_H)
# include <sys/link.h> /* Find DT_RPATH on Solaris 2.6 */
#endif /* HAVE_SYS_LINK_H */
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include "protos.h"
#define EHDR_PWS(x) (is_e32() ? DO_SWAPS32(ehdr->e32.x) : DO_SWAPS64(ehdr->e64.x))
#define EHDR_PHS(x) (is_e32() ? DO_SWAPS16(ehdr->e32.x) : DO_SWAPS16(ehdr->e64.x))
#define PHDR_PWS(x) (is_e32() ? DO_SWAPS32(phdr->e32.x) : DO_SWAPS64(phdr->e64.x))
#define EHDR_PWU(x) (is_e32() ? DO_SWAPU32(ehdr->e32.x) : DO_SWAPU64(ehdr->e64.x))
#define EHDR_PHU(x) (is_e32() ? DO_SWAPU16(ehdr->e32.x) : DO_SWAPU16(ehdr->e64.x))
#define PHDR_PWU(x) (is_e32() ? DO_SWAPU32(phdr->e32.x) : DO_SWAPU32(phdr->e64.x))
#define PHDR_POU(x) (is_e32() ? DO_SWAPU32(phdr->e32.x) : DO_SWAPU64(phdr->e64.x))
static int is_e32_flag;
static int swap_bytes_flag;
int
is_e32(void)
{
return is_e32_flag;
}
int
swap_bytes(void)
{
return swap_bytes_flag;
}
int
elf_open(const char *filename, int flags, Elf_Ehdr *ehdr)
{
int fd;
size_t sz_ehdr;
size_t sz_phdr;
fd = open(filename, flags);
if (fd == -1)
{
perror ("open");
return -1;
}
if (read(fd, ehdr, EI_NIDENT) != EI_NIDENT)
{
perror ("reading header (e_ident)");
close(fd);
return -1;
}
if (0 != memcmp(ehdr->e_ident, ELFMAG, SELFMAG) ||
(ehdr->e_ident[EI_CLASS] != ELFCLASS32 &&
ehdr->e_ident[EI_CLASS] != ELFCLASS64) ||
(ehdr->e_ident[EI_DATA] != ELFDATA2LSB &&
ehdr->e_ident[EI_DATA] != ELFDATA2MSB) ||
ehdr->e_ident[EI_VERSION] != EV_CURRENT)
{
fprintf(stderr, "`%s' probably isn't an ELF file.\n", filename);
close(fd);
errno = ENOEXEC; /* Hm, is this the best errno code to use? */
return -1;
}
is_e32_flag = ehdr->e_ident[EI_CLASS] == ELFCLASS32;
swap_bytes_flag = ehdr->e_ident[EI_DATA] != ELFDATA2;
sz_ehdr = is_e32() ? sizeof(Elf32_Ehdr) : sizeof(Elf64_Ehdr);
if (read(fd, ((char *)ehdr) + EI_NIDENT, sz_ehdr - EI_NIDENT)
!= (ssize_t)(sz_ehdr - EI_NIDENT))
{
perror ("reading header");
close(fd);
return -1;
}
sz_phdr = is_e32() ? sizeof(Elf32_Phdr) : sizeof(Elf64_Phdr);
if ((size_t)EHDR_PHS(e_phentsize) != sz_phdr)
{
fprintf(stderr, "section size was read as %zd, not %zd!\n",
(size_t)EHDR_PHS(e_phentsize), sz_phdr);
close(fd);
return -1;
}
return fd;
}
int
elf_find_dynamic_section(int fd, Elf_Ehdr *ehdr, Elf_Phdr *phdr)
{
int i;
if (lseek(fd, EHDR_PWU(e_phoff), SEEK_SET) == -1)
{
perror ("positioning for sections");
return 1;
}
for (i = 0; i < EHDR_PHS(e_phnum); i++)
{
const size_t sz_phdr = is_e32() ? sizeof(Elf32_Phdr) : sizeof(Elf64_Phdr);
if (read(fd, phdr, sz_phdr) != (ssize_t)sz_phdr)
{
perror ("reading section header");
return 1;
}
if (PHDR_PWU(p_type) == PT_DYNAMIC)
break;
}
if (i == EHDR_PHS(e_phnum))
{
fprintf (stderr, "No dynamic section found.\n");
return 2;
}
if (0 == PHDR_POU(p_filesz))
{
fprintf (stderr, "Length of dynamic section is zero.\n");
return 3;
}
return 0;
}
void
elf_close(int fd)
{
close(fd);
}
const char *
elf_tagname(int tag)
{
switch (tag) {
case DT_RPATH:
return "RPATH";
break;
#if defined(DT_RUNPATH)
case DT_RUNPATH:
return "RUNPATH";
break;
#endif /* DT_RUNPATH */
}
return "UNKNOWN";
}
int
elf_dynpath_tag(int tag)
{
return ( tag == DT_RPATH
#if defined(DT_RUNPATH)
|| tag == DT_RUNPATH
#endif /* DT_RUNPATH */
);
}
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