/*

 * input.c - low-level input for libelf.

 * Copyright (C) 1995 - 2001, 2005 Michael Riepe

 *

 * This library is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Library General Public

 * License as published by the Free Software Foundation; either

 * version 2 of the License, or (at your option) any later version.

 *

 * This library is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Library General Public License for more details.

 *

 * You should have received a copy of the GNU Library General Public

 * License along with this library; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

 */

#include <private.h>

#ifndef lint

static const char rcsid[] = "@(#) $Id: input.c,v 1.10 2005/10/20 21:08:02 michael Exp $";

#endif /* lint */

#include <errno.h>

#if HAVE_MMAP

#include <sys/mman.h>

#endif /* HAVE_MMAP */

static int

xread(int fd, char *buffer, size_t len) {

    size_t done = 0;

    size_t n;

    while (done < len) {

	n = read(fd, buffer + done, len - done);

	if (n == 0) {

	    /* premature end of file */

	    return -1;

	}

	else if (n != (size_t)-1) {

	    /* some bytes read, continue */

	    done += n;

	}

	else if (errno != EAGAIN && errno != EINTR) {

	    /* real error */

	    return -1;

	}

    }

    return 0;

}

void*

_elf_read(Elf *elf, void *buffer, size_t off, size_t len) {

    void *tmp;

    elf_assert(elf);

    elf_assert(elf->e_magic == ELF_MAGIC);

    elf_assert(off >= 0 && off + len <= elf->e_size);

    if (elf->e_disabled) {

	seterr(ERROR_FDDISABLED);

    }

    else if (len) {

	off += elf->e_base;

	if (lseek(elf->e_fd, (off_t)off, SEEK_SET) != (off_t)off) {

	    seterr(ERROR_IO_SEEK);

	}

	else if (!(tmp = buffer) && !(tmp = malloc(len))) {

	    seterr(ERROR_IO_2BIG);

	}

	else if (xread(elf->e_fd, tmp, len)) {

	    seterr(ERROR_IO_READ);

	    if (tmp != buffer) {

		free(tmp);

	    }

	}

	else {

	    return tmp;

	}

    }

    return NULL;

}

void*

_elf_mmap(Elf *elf) {

#if HAVE_MMAP

    void *tmp;

    elf_assert(elf);

    elf_assert(elf->e_magic == ELF_MAGIC);

    elf_assert(elf->e_base == 0);

    if (elf->e_disabled) {

	seterr(ERROR_FDDISABLED);

    }

    else if (elf->e_size) {

	tmp = (void*)mmap(0, elf->e_size, PROT_READ | PROT_WRITE,

			  MAP_PRIVATE, elf->e_fd, 0);

	if (tmp != (void*)-1) {

	    return tmp;

	}

    }

#endif /* HAVE_MMAP */

    return NULL;

}