yasm/modules/objfmts/bin/bin-objfmt.c

/*
 * Flat-format binary object format
 *
 *  Copyright (C) 2002-2007  Peter Johnson
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND OTHER CONTRIBUTORS ``AS IS''
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR OTHER CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <util.h>
/*@unused@*/ RCSID("$Id$");

#define YASM_LIB_INTERNAL
#define YASM_BC_INTERNAL
#define YASM_EXPR_INTERNAL
#include <libyasm.h>


#define REGULAR_OUTBUF_SIZE	1024

typedef struct yasm_objfmt_bin {
    yasm_objfmt_base objfmt;		/* base structure */
} yasm_objfmt_bin;

yasm_objfmt_module yasm_bin_LTX_objfmt;


static yasm_objfmt *
bin_objfmt_create(yasm_object *object)
{
    yasm_objfmt_bin *objfmt_bin = yasm_xmalloc(sizeof(yasm_objfmt_bin));
    objfmt_bin->objfmt.module = &yasm_bin_LTX_objfmt;
    return (yasm_objfmt *)objfmt_bin;
}

/* Aligns sect to either its specified alignment.  Uses prevsect and base to
 * both determine the new starting address (returned) and the total length of
 * prevsect after sect has been aligned.
 */
static unsigned long
bin_objfmt_align_section(yasm_section *sect, yasm_section *prevsect,
			 unsigned long base,
			 /*@out@*/ unsigned long *prevsectlen,
			 /*@out@*/ unsigned long *padamt)
{
    unsigned long start;
    unsigned long align;

    /* Figure out the size of .text by looking at the last bytecode's offset
     * plus its length.  Add the start and size together to get the new start.
     */
    *prevsectlen = yasm_bc_next_offset(yasm_section_bcs_last(prevsect));
    start = base + *prevsectlen;

    /* Round new start up to alignment of .data section, and adjust textlen to
     * indicate padded size.  Because aignment is always a power of two, we
     * can use some bit trickery to do this easily.
     */
    align = yasm_section_get_align(sect);

    if (start & (align-1))
	start = (start & ~(align-1)) + align;

    *padamt = start - (base + *prevsectlen);

    return start;
}

typedef struct bin_objfmt_output_info {
    yasm_object *object;
    yasm_errwarns *errwarns;
    /*@dependent@*/ FILE *f;
    /*@only@*/ unsigned char *buf;
    /*@observer@*/ const yasm_section *sect;
    unsigned long start;	/* what normal variables go against */
    unsigned long abs_start;	/* what absolutes go against */
} bin_objfmt_output_info;

static /*@only@*/ yasm_expr *
bin_objfmt_expr_xform(/*@returned@*/ /*@only@*/ yasm_expr *e,
		      /*@unused@*/ /*@null@*/ void *d)
{
    int i;
    /*@dependent@*/ yasm_section *sect;
    /*@dependent@*/ /*@null@*/ yasm_bytecode *precbc;
    /*@null@*/ yasm_intnum *dist;

    for (i=0; i<e->numterms; i++) {
        /* Transform symrecs or precbcs that reference sections into
	 * start expr + intnum(dist).
	 */
        if (((e->terms[i].type == YASM_EXPR_SYM &&
             yasm_symrec_get_label(e->terms[i].data.sym, &precbc)) ||
            (e->terms[i].type == YASM_EXPR_PRECBC &&
             (precbc = e->terms[i].data.precbc))) &&
	    (sect = yasm_bc_get_section(precbc)) &&
	    (dist = yasm_calc_bc_dist(yasm_section_bcs_first(sect), precbc))) {
	    const yasm_expr *start = yasm_section_get_start(sect);
	    e->terms[i].type = YASM_EXPR_EXPR;
	    e->terms[i].data.expn =
		yasm_expr_create(YASM_EXPR_ADD,
				 yasm_expr_expr(yasm_expr_copy(start)),
				 yasm_expr_int(dist), e->line);
	}
    }

    return e;
}

static int
bin_objfmt_output_value(yasm_value *value, unsigned char *buf,
			unsigned int destsize,
			/*@unused@*/ unsigned long offset, yasm_bytecode *bc,
			int warn, /*@null@*/ void *d)
{
    /*@null@*/ bin_objfmt_output_info *info = (bin_objfmt_output_info *)d;
    /*@dependent@*/ /*@null@*/ yasm_bytecode *precbc;
    /*@dependent@*/ yasm_section *sect;

    assert(info != NULL);

    /* Binary objects we need to resolve against object, not against section. */
    if (value->rel) {
	unsigned int rshift = (unsigned int)value->rshift;
	yasm_expr *syme;

        if (yasm_symrec_is_abs(value->rel)) {
            syme = yasm_expr_create_ident(yasm_expr_int(
                yasm_intnum_create_uint(0)), bc->line);
        } else if (yasm_symrec_get_label(value->rel, &precbc)
                   && (sect = yasm_bc_get_section(precbc))) {
            syme = yasm_expr_create_ident(yasm_expr_sym(value->rel), bc->line);
        } else
            goto done;

        /* Handle PC-relative */
        if (value->curpos_rel) {
            yasm_expr *sube;
            sube = yasm_expr_create(YASM_EXPR_SUB, yasm_expr_precbc(bc),
                yasm_expr_int(yasm_intnum_create_uint(bc->len*bc->mult_int)),
                bc->line);
            syme = yasm_expr_create(YASM_EXPR_SUB, yasm_expr_expr(syme),
                                    yasm_expr_expr(sube), bc->line);
            value->curpos_rel = 0;
            value->ip_rel = 0;
        } else

	if (value->rshift > 0)
            syme = yasm_expr_create(YASM_EXPR_SHR, yasm_expr_expr(syme),
		yasm_expr_int(yasm_intnum_create_uint(rshift)), bc->line);

        /* Add into absolute portion */
	if (!value->abs)
	    value->abs = syme;
	else
	    value->abs =
		yasm_expr_create(YASM_EXPR_ADD, yasm_expr_expr(value->abs),
				 yasm_expr_expr(syme), bc->line);
	value->rel = NULL;
	value->rshift = 0;
    }
done:
    /* Simplify absolute portion of value, transforming symrecs */
    if (value->abs)
	value->abs = yasm_expr__level_tree
	    (value->abs, 1, 1, 1, 0, bin_objfmt_expr_xform, NULL);

    /* Output */
    switch (yasm_value_output_basic(value, buf, destsize, bc, warn,
				    info->object->arch)) {
	case -1:
	    return 1;
	case 0:
	    break;
	default:
	    return 0;
    }

    /* Couldn't output, assume it contains an external reference. */
    yasm_error_set(YASM_ERROR_GENERAL,
	N_("binary object format does not support external references"));
    return 1;
}

static int
bin_objfmt_output_bytecode(yasm_bytecode *bc, /*@null@*/ void *d)
{
    /*@null@*/ bin_objfmt_output_info *info = (bin_objfmt_output_info *)d;
    /*@null@*/ /*@only@*/ unsigned char *bigbuf;
    unsigned long size = REGULAR_OUTBUF_SIZE;
    int gap;

    assert(info != NULL);

    bigbuf = yasm_bc_tobytes(bc, info->buf, &size, &gap, info,
			     bin_objfmt_output_value, NULL);

    /* Don't bother doing anything else if size ended up being 0. */
    if (size == 0) {
	if (bigbuf)
	    yasm_xfree(bigbuf);
	return 0;
    }

    /* Warn that gaps are converted to 0 and write out the 0's. */
    if (gap) {
	unsigned long left;
	yasm_warn_set(YASM_WARN_UNINIT_CONTENTS,
	    N_("uninitialized space declared in code/data section: zeroing"));
	/* Write out in chunks */
	memset(info->buf, 0, REGULAR_OUTBUF_SIZE);
	left = size;
	while (left > REGULAR_OUTBUF_SIZE) {
	    fwrite(info->buf, REGULAR_OUTBUF_SIZE, 1, info->f);
	    left -= REGULAR_OUTBUF_SIZE;
	}
	fwrite(info->buf, left, 1, info->f);
    } else {
	/* Output buf (or bigbuf if non-NULL) to file */
	fwrite(bigbuf ? bigbuf : info->buf, (size_t)size, 1, info->f);
    }

    /* If bigbuf was allocated, free it */
    if (bigbuf)
	yasm_xfree(bigbuf);

    return 0;
}

static int
bin_objfmt_check_sym(yasm_symrec *sym, /*@null@*/ void *d)
{
    /*@null@*/ bin_objfmt_output_info *info = (bin_objfmt_output_info *)d;
    yasm_sym_vis vis = yasm_symrec_get_visibility(sym);
    assert(info != NULL);

    if (vis & YASM_SYM_EXTERN) {
	yasm_warn_set(YASM_WARN_GENERAL,
	    N_("binary object format does not support extern variables"));
	yasm_errwarn_propagate(info->errwarns, yasm_symrec_get_decl_line(sym));
    } else if (vis & YASM_SYM_GLOBAL) {
	yasm_warn_set(YASM_WARN_GENERAL,
	    N_("binary object format does not support global variables"));
	yasm_errwarn_propagate(info->errwarns, yasm_symrec_get_decl_line(sym));
    } else if (vis & YASM_SYM_COMMON) {
	yasm_error_set(YASM_ERROR_TYPE,
	    N_("binary object format does not support common variables"));
	yasm_errwarn_propagate(info->errwarns, yasm_symrec_get_decl_line(sym));
    }
    return 0;
}

static void
bin_objfmt_output(yasm_object *object, FILE *f, /*@unused@*/ int all_syms,
		  yasm_errwarns *errwarns)
{
    /*@observer@*/ /*@null@*/ yasm_section *text, *data, *bss, *prevsect;
    /*@null@*/ yasm_expr *startexpr;
    /*@dependent@*/ /*@null@*/ const yasm_intnum *startnum;
    unsigned long start = 0, textstart = 0, datastart = 0;
    unsigned long textlen = 0, textpad = 0, datalen = 0, datapad = 0;
    unsigned long *prevsectlenptr, *prevsectpadptr;
    unsigned long i;
    bin_objfmt_output_info info;

    info.object = object;
    info.errwarns = errwarns;
    info.f = f;
    info.buf = yasm_xmalloc(REGULAR_OUTBUF_SIZE);

    /* Check symbol table */
    yasm_symtab_traverse(object->symtab, &info, bin_objfmt_check_sym);

    text = yasm_object_find_general(object, ".text");
    data = yasm_object_find_general(object, ".data");
    bss = yasm_object_find_general(object, ".bss");

    if (!text)
	yasm_internal_error(N_("No `.text' section in bin objfmt output"));

    /* First determine the actual starting offsets for .data and .bss.
     * As the order in the file is .text -> .data -> .bss (not present),
     * use the last bytecode in .text (and the .text section start) to
     * determine the starting offset in .data, and likewise for .bss.
     * Also compensate properly for alignment.
     */

    /* Find out the start of .text */
    startexpr = yasm_expr_copy(yasm_section_get_start(text));
    assert(startexpr != NULL);
    startnum = yasm_expr_get_intnum(&startexpr, 0);
    if (!startnum) {
	yasm_error_set(YASM_ERROR_TOO_COMPLEX,
		       N_("ORG expression too complex"));
	yasm_errwarn_propagate(errwarns, startexpr->line);
	return;
    }
    start = yasm_intnum_get_uint(startnum);
    yasm_expr_destroy(startexpr);
    info.abs_start = start;
    textstart = start;

    /* Align .data and .bss (if present) by adjusting their starts. */
    prevsect = text;
    prevsectlenptr = &textlen;
    prevsectpadptr = &textpad;
    if (data) {
	start = bin_objfmt_align_section(data, prevsect, start,
					 prevsectlenptr, prevsectpadptr);
	yasm_section_set_start(data, yasm_expr_create_ident(
	    yasm_expr_int(yasm_intnum_create_uint(start)), 0), 0);
	datastart = start;
	prevsect = data;
	prevsectlenptr = &datalen;
	prevsectpadptr = &datapad;
    }
    if (bss) {
	start = bin_objfmt_align_section(bss, prevsect, start,
					 prevsectlenptr, prevsectpadptr);
	yasm_section_set_start(bss, yasm_expr_create_ident(
	    yasm_expr_int(yasm_intnum_create_uint(start)), 0), 0);
    }

    /* Output .text first. */
    info.sect = text;
    info.start = textstart;
    yasm_section_bcs_traverse(text, errwarns, &info,
			      bin_objfmt_output_bytecode);

    /* If .data is present, output it */
    if (data) {
	/* Add padding to align .data.  Just use a for loop, as this will
	 * seldom be very many bytes.
	 */
	for (i=0; i<textpad; i++)
	    fputc(0, f);

	/* Output .data bytecodes */
	info.sect = data;
	info.start = datastart;
	yasm_section_bcs_traverse(data, errwarns,
				  &info, bin_objfmt_output_bytecode);
    }

    /* If .bss is present, check it for non-reserve bytecodes */


    yasm_xfree(info.buf);
}

static void
bin_objfmt_destroy(yasm_objfmt *objfmt)
{
    yasm_xfree(objfmt);
}

static void
bin_objfmt_init_new_section(yasm_object *object, yasm_section *sect,
			    const char *sectname, unsigned long line)
{
    yasm_symtab_define_label(object->symtab, sectname,
			     yasm_section_bcs_first(sect), 1, line);
}

static yasm_section *
bin_objfmt_add_default_section(yasm_object *object)
{
    yasm_section *retval;
    int isnew;

    retval = yasm_object_get_general(object, ".text", 0, 16, 1, 0, &isnew, 0);
    if (isnew) {
	bin_objfmt_init_new_section(object, retval, ".text", 0);
	yasm_section_set_default(retval, 1);
    }
    return retval;
}

static /*@observer@*/ /*@null@*/ yasm_section *
bin_objfmt_section_switch(yasm_object *object, yasm_valparamhead *valparams,
			  /*@unused@*/ /*@null@*/
			  yasm_valparamhead *objext_valparams,
			  unsigned long line)
{
    yasm_valparam *vp;
    yasm_section *retval;
    int isnew;
    unsigned long start;
    const char *sectname;
    int resonly = 0;
    /*@only@*/ /*@null@*/ yasm_intnum *align_intn = NULL;
    unsigned long align = 4;
    int have_align = 0;

    static const yasm_dir_help help[] = {
        { "align", 1, yasm_dir_helper_intn, 0, 0 }
    };

    vp = yasm_vps_first(valparams);
    sectname = yasm_vp_string(vp);
    if (!sectname)
        return NULL;
    vp = yasm_vps_next(vp);

	/* If it's the first section output (.text) start at 0, otherwise
	 * make sure the start is > 128.
	 */
	if (strcmp(sectname, ".text") == 0)
	    start = 0;
	else if (strcmp(sectname, ".data") == 0)
	    start = 200;
	else if (strcmp(sectname, ".bss") == 0) {
	    start = 200;
	    resonly = 1;
	} else {
	    /* other section names not recognized. */
	    yasm_error_set(YASM_ERROR_GENERAL,
			   N_("segment name `%s' not recognized"), sectname);
	    return NULL;
	}

    have_align = yasm_dir_helper(object, vp, line, help, NELEMS(help),
                                 &align_intn, yasm_dir_helper_valparam_warn);
    if (have_align < 0)
        return NULL;    /* error occurred */

    if (align_intn) {
        align = yasm_intnum_get_uint(align_intn);
        yasm_intnum_destroy(align_intn);

		/* Alignments must be a power of two. */
		if (!is_exp2(align)) {
		    yasm_error_set(YASM_ERROR_VALUE,
				N_("argument to `%s' is not a power of two"),
                           "align");
		    return NULL;
		}
	    }

	retval = yasm_object_get_general(object, sectname,
	    yasm_expr_create_ident(
		yasm_expr_int(yasm_intnum_create_uint(start)), line), align,
	    strcmp(sectname, ".text") == 0, resonly, &isnew, line);

	if (isnew)
	    bin_objfmt_init_new_section(object, retval, sectname, line);

	if (isnew || yasm_section_is_default(retval)) {
	    yasm_section_set_default(retval, 0);
	    yasm_section_set_align(retval, align, line);
	} else if (have_align)
	    yasm_warn_set(YASM_WARN_GENERAL,
		N_("alignment value ignored on section redeclaration"));

	return retval;
}

static void
bin_objfmt_dir_org(yasm_object *object,
		   /*@null@*/ yasm_valparamhead *valparams,
		   /*@unused@*/ /*@null@*/
		   yasm_valparamhead *objext_valparams, unsigned long line)
{
    yasm_section *sect;
    yasm_valparam *vp;
    /*@only@*/ /*@null@*/ yasm_expr *start;

    /* ORG takes just a simple integer as param */
    vp = yasm_vps_first(valparams);
    start = yasm_vp_expr(vp, object->symtab, line);
    if (!start) {
	yasm_error_set(YASM_ERROR_SYNTAX,
		       N_("argument to ORG must be expression"));
	return;
    }

    /* ORG changes the start of the .text section */
    sect = yasm_object_find_general(object, ".text");
    if (!sect)
	yasm_internal_error(
	    N_("bin objfmt: .text section does not exist before ORG is called?"));
    yasm_section_set_start(sect, start, line);
}


/* Define valid debug formats to use with this object format */
static const char *bin_objfmt_dbgfmt_keywords[] = {
    "null",
    NULL
};

static const yasm_directive bin_objfmt_directives[] = {
    { "org",	"nasm",	bin_objfmt_dir_org,	YASM_DIR_ARG_REQUIRED },
    { NULL, NULL, NULL, 0 }
};

/* Define objfmt structure -- see objfmt.h for details */
yasm_objfmt_module yasm_bin_LTX_objfmt = {
    "Flat format binary",
    "bin",
    NULL,
    16,
    bin_objfmt_dbgfmt_keywords,
    "null",
    bin_objfmt_directives,
    bin_objfmt_create,
    bin_objfmt_output,
    bin_objfmt_destroy,
    bin_objfmt_add_default_section,
    bin_objfmt_section_switch
};