chromium/third_party/nasm/output/outaout.c

/* ----------------------------------------------------------------------- *
 *   
 *   Copyright 1996-2013 The NASM Authors - All Rights Reserved
 *   See the file AUTHORS included with the NASM distribution for
 *   the specific copyright holders.
 *
 *   Redistribution and use in source and binary forms, with or without
 *   modification, are permitted provided that the following
 *   conditions are met:
 *
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * 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 COPYRIGHT HOLDERS AND
 *     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 COPYRIGHT OWNER OR
 *     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.
 *
 * ----------------------------------------------------------------------- */

/* 
 * outaout.c	output routines for the Netwide Assembler to produce
 *		Linux a.out object files
 */

#include "compiler.h"

#include "nctype.h"

#include "nasm.h"
#include "nasmlib.h"
#include "error.h"
#include "saa.h"
#include "raa.h"
#include "stdscan.h"
#include "eval.h"
#include "outform.h"
#include "outlib.h"

#if defined OF_AOUT || defined OF_AOUTB

#define RELTYPE_ABSOLUTE …
#define RELTYPE_RELATIVE …
#define RELTYPE_GOTPC …
#define RELTYPE_GOTOFF …
#define RELTYPE_GOT …
#define RELTYPE_PLT …
#define RELTYPE_SYMFLAG …

struct Reloc { … };

struct Symbol { … };

/*
 * Section IDs - used in Reloc.symbol when negative, and in
 * Symbol.type when positive.
 */
#define SECT_ABS …
#define SECT_TEXT …
#define SECT_DATA …
#define SECT_BSS …
#define SECT_MASK …

/*
 * More flags used in Symbol.type.
 */
#define SYM_GLOBAL …
#define SYM_DATA …
#define SYM_FUNCTION …
#define SYM_WITH_SIZE …

/*
 * Bit more explanation of symbol types: SECT_xxx denotes a local
 * symbol. SECT_xxx|SYM_GLOBAL denotes a global symbol, defined in
 * this module. Just SYM_GLOBAL, with zero value, denotes an
 * external symbol referenced in this module. And just SYM_GLOBAL,
 * but with a non-zero value, declares a C `common' variable, of
 * size `value'.
 */

struct Section { … };

static struct Section stext, sdata, sbss;

static struct SAA *syms;
static uint32_t nsyms;

static struct RAA *bsym;

static struct SAA *strs;
static uint32_t strslen;

static struct Symbol *fwds;

static int bsd;
static int is_pic;

static void aout_write(void);
static void aout_write_relocs(struct Reloc *);
static void aout_write_syms(void);
static void aout_sect_write(struct Section *, const uint8_t *,
                            uint32_t);
static void aout_pad_sections(void);
static void aout_fixup_relocs(struct Section *);

/*
 * Special section numbers which are used to define special
 * symbols, which can be used with WRT to provide PIC relocation
 * types.
 */
static int32_t aout_gotpc_sect, aout_gotoff_sect;
static int32_t aout_got_sect, aout_plt_sect;
static int32_t aout_sym_sect;

static void aoutg_init(void)
{ … }

#ifdef OF_AOUT

static void aout_init(void)
{ … }

#endif

#ifdef OF_AOUTB

extern const struct ofmt of_aoutb;

static void aoutb_init(void)
{ … }

#endif

static void aout_cleanup(void)
{ … }

static int32_t aout_section_names(char *name, int *bits)
{ … }

static void aout_deflabel(char *name, int32_t segment, int64_t offset,
                          int is_global, char *special)
{ … }

static void aout_add_reloc(struct Section *sect, int32_t segment,
                           int reltype, int bytes)
{ … }

/*
 * This routine deals with ..got and ..sym relocations: the more
 * complicated kinds. In shared-library writing, some relocations
 * with respect to global symbols must refer to the precise symbol
 * rather than referring to an offset from the base of the section
 * _containing_ the symbol. Such relocations call to this routine,
 * which searches the symbol list for the symbol in question.
 *
 * RELTYPE_GOT references require the _exact_ symbol address to be
 * used; RELTYPE_ABSOLUTE references can be at an offset from the
 * symbol. The boolean argument `exact' tells us this.
 *
 * Return value is the adjusted value of `addr', having become an
 * offset from the symbol rather than the section. Should always be
 * zero when returning from an exact call.
 *
 * Limitation: if you define two symbols at the same place,
 * confusion will occur.
 *
 * Inefficiency: we search, currently, using a linked list which
 * isn't even necessarily sorted.
 */
static int32_t aout_add_gsym_reloc(struct Section *sect,
                                int32_t segment, int32_t offset,
                                int type, int bytes, int exact)
{ … }

/*
 * This routine deals with ..gotoff relocations. These _must_ refer
 * to a symbol, due to a perversity of *BSD's PIC implementation,
 * and it must be a non-global one as well; so we store `asym', the
 * first nonglobal symbol defined in each section, and always work
 * from that. Relocation type is always RELTYPE_GOTOFF.
 *
 * Return value is the adjusted value of `addr', having become an
 * offset from the `asym' symbol rather than the section.
 */
static int32_t aout_add_gotoff_reloc(struct Section *sect, int32_t segment,
                                  int32_t offset, int bytes)
{ … }

static void aout_out(int32_t segto, const void *data,
		     enum out_type type, uint64_t size,
                     int32_t segment, int32_t wrt)
{ … }

static void aout_pad_sections(void)
{ … }

/*
 * a.out files have the curious property that all references to
 * things in the data or bss sections are done by addresses which
 * are actually relative to the start of the _text_ section, in the
 * _file_. (No relation to what happens after linking. No idea why
 * this should be so. It's very strange.) So we have to go through
 * the relocation table, _after_ the final size of each section is
 * known, and fix up the relocations pointed to.
 */
static void aout_fixup_relocs(struct Section *sect)
{ … }

static void aout_write(void)
{ … }

static void aout_write_relocs(struct Reloc *r)
{ … }

static void aout_write_syms(void)
{ … }

static void aout_sect_write(struct Section *sect,
                            const uint8_t *data, uint32_t len)
{ … }

extern macros_t aout_stdmac[];

#endif                          /* OF_AOUT || OF_AOUTB */

#ifdef OF_AOUT

const struct ofmt of_aout = …;

#endif

#ifdef OF_AOUTB

const struct ofmt of_aoutb = …;

#endif