elfload.h

/*
 * Copyright © 2018, M4xw
 * Copyright © 2014, Owen Shepherd
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

#ifndef ELFLOAD_H
#define ELFLOAD_H
#include <stddef.h>

#include "elfarch.h"
#include "elf.h"

#ifdef DEBUG
#include <gfx_utils.h>
#define EL_DEBUG(format, ...) \
	gfx_printf(format __VA_OPT__(, ) __VA_ARGS__)
#else
#define EL_DEBUG(...) \
	do                \
	{                 \
	} while (0)
#endif

typedef enum
{
	EL_OK = 0,

	EL_EIO,
	EL_ENOMEM,

	EL_NOTELF,
	EL_WRONGBITS,
	EL_WRONGENDIAN,
	EL_WRONGARCH,
	EL_WRONGOS,
	EL_NOTEXEC,
	EL_NODYN,
	EL_BADREL,

} el_status;

typedef struct el_ctx
{
	el_status (*pread)(struct el_ctx *ctx, void *dest, size_t nb, size_t offset);

	/* base_load_* -> address we are actually going to load at
	 */
	Elf_Addr
		base_load_paddr,
		base_load_vaddr;

	/* original memory of binary */
	Elf_Addr eaddr;

	/* size in memory of binary */
	Elf_Addr memsz;

	/* required alignment */
	Elf_Addr align;

	/* ELF header */
	Elf_Ehdr ehdr;

	// Section Header Str Table
	Elf_Shdr shstr;
	Elf_Shdr symtab;

	/* Offset of dynamic table (0 if not ET_DYN) */
	Elf_Off dynoff;
	/* Size of dynamic table (0 if not ET_DYN) */
	Elf_Addr dynsize;
} el_ctx;

el_status el_pread(el_ctx *ctx, void *def, size_t nb, size_t offset);

el_status el_init(el_ctx *ctx);
typedef void *(*el_alloc_cb)(
	el_ctx *ctx,
	Elf_Addr phys,
	Elf_Addr virt,
	Elf_Addr size);

el_status el_load(el_ctx *ctx, el_alloc_cb alloccb);

/* find the next phdr of type \p type, starting at \p *i.
 * On success, returns EL_OK with *i set to the phdr number, and the phdr loaded
 * in *phdr.
 *
 * If the end of the phdrs table was reached, *i is set to -1 and the contents
 * of *phdr are undefined
 */
el_status el_findphdr(el_ctx *ctx, Elf_Phdr *phdr, u32 type, unsigned *i);

/* Relocate the loaded executable */
el_status el_relocate(el_ctx *ctx);

/* find a dynamic table entry
 * returns the entry on success, dyn->d_tag = DT_NULL on failure
 */
el_status el_finddyn(el_ctx *ctx, Elf_Dyn *dyn, u32 type);

typedef struct
{
	Elf_Off tableoff;
	Elf_Addr tablesize;
	Elf_Addr entrysize;
} el_relocinfo;

/* find all information regarding relocations of a specific type.
 *
 * pass DT_REL or DT_RELA for type
 * sets ri->entrysize = 0 if not found
 */
el_status el_findrelocs(el_ctx *ctx, el_relocinfo *ri, u32 type);

#endif