object.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

/*#@(#)object.c	4.1	Ultrix	7/17/90*/
/* Copyright (c) 1982 Regents of the University of California */

static char sccsid[] = "@(#)object.c 1.14 10/22/83";

static char rcsid[] = "$Header: object.c,v 1.4 84/03/27 10:22:25 linton Exp $";

/*
 * Object code interface, mainly for extraction of symbolic information.
 */

#include "defs.h"
#include "object.h"
#include "stabstring.h"
#include "main.h"
#include "symbols.h"
#include "names.h"
#include "languages.h"
#include "mappings.h"
#include "lists.h"
#include <a.out.h>
#include <stab.h>
#include <ctype.h>

#ifndef public

struct {
    unsigned int stringsize;	/* size of the dumped string table */
    unsigned int nsyms;		/* number of symbols */
    unsigned int nfiles;	/* number of files */
    unsigned int nlines;	/* number of lines */
} nlhdr;

#include "languages.h"
#include "symbols.h"

#endif

#ifndef N_MOD2
#    define N_MOD2 0x50
#endif

public String objname = "a.out";
public integer objsize;

public Language curlang;
public Symbol curmodule;
public Symbol curparam;
public Symbol curcomm;
public Symbol commchain;

private char *stringtab;
private struct nlist *curnp;
private Boolean warned;
private Boolean strip_ = false;

private Filetab *filep;
private Linetab *linep, *prevlinep;

public String curfilename ()
{
    return ((filep-1)->filename);
}

/*
 * Blocks are figured out on the fly while reading the symbol table.
 */

#define MAXBLKDEPTH 25

public Symbol curblock;

private Symbol blkstack[MAXBLKDEPTH];
private integer curlevel;
private integer bnum, nesting;
private Address addrstk[MAXBLKDEPTH];

public pushBlock (b)
Symbol b;
{
    if (curlevel >= MAXBLKDEPTH) {
	fatal("nesting depth too large (%d)", curlevel);
    }
    blkstack[curlevel] = curblock;
    ++curlevel;
    curblock = b;
    if (traceblocks) {
	printf("entering block %s\n", symname(b));
    }
}

public enterblock (b)
Symbol b;
{
    if (curblock == nil) {
	b->level = 1;
    } else {
	b->level = curblock->level + 1;
    }
    b->block = curblock;
    pushBlock(b);
}

public exitblock ()
{
    if (curblock->class == FUNC or curblock->class == PROC) {
	if (prevlinep != linep) {
	    curblock->symvalue.funcv.src = true;
	}
    }
    if (curlevel <= 0) {
	panic("nesting depth underflow (%d)", curlevel);
    }
    --curlevel;
    if (traceblocks) {
	printf("exiting block %s\n", symname(curblock));
    }
    curblock = blkstack[curlevel];
}

/*
 * Enter a source line or file name reference into the appropriate table.
 * Expanded inline to reduce procedure calls.
 *
 * private enterline (linenumber, address)
 * Lineno linenumber;
 * Address address;
 *  ...
 */

#define enterline(linenumber, address) \
{ \
    register Linetab *lp; \
 \
    lp = linep - 1; \
    if (linenumber != lp->line) { \
	if (address != lp->addr) { \
	    ++lp; \
	} \
	lp->line = linenumber; \
	lp->addr = address; \
	linep = lp + 1; \
    } \
}

/*
 * Read in the namelist from the obj file.
 *
 * Reads and seeks are used instead of fread's and fseek's
 * for efficiency sake; there's a lot of data being read here.
 */

public readobj (file)
String file;
{
    Fileid f;
    struct exec hdr;
    struct nlist nlist;

    f = open(file, 0);
    if (f < 0) {
	fatal("can't open %s", file);
    }
    read(f, &hdr, sizeof(hdr));
    objsize = hdr.a_text;
    nlhdr.nsyms = hdr.a_syms / sizeof(nlist);
    nlhdr.nfiles = nlhdr.nsyms;
    nlhdr.nlines = nlhdr.nsyms;
    if (nlhdr.nsyms > 0) {
	lseek(f, (long) N_STROFF(hdr), 0);
	read(f, &(nlhdr.stringsize), sizeof(nlhdr.stringsize));
	nlhdr.stringsize -= 4;
	stringtab = newarr(char, nlhdr.stringsize);
	read(f, stringtab, nlhdr.stringsize);
	allocmaps(nlhdr.nfiles, nlhdr.nlines);
	lseek(f, (long) N_SYMOFF(hdr), 0);
	readsyms(f);
	ordfunctab();
	setnlines();
	setnfiles();
    }
    close(f);
}

/*
 * Read in symbols from object file.
 */

private readsyms (f)
Fileid f;
{
    struct nlist *namelist;
    register struct nlist *np, *ub;
    register String name;
    register Boolean afterlg;
    integer index;
    char *lastchar;

    initsyms();
    namelist = newarr(struct nlist, nlhdr.nsyms);
    read(f, namelist, nlhdr.nsyms * sizeof(struct nlist));
    afterlg = false;
    ub = &namelist[nlhdr.nsyms];
    curnp = &namelist[0];
    np = curnp;
    while (np < ub) {
	index = np->n_un.n_strx;
	if (index != 0) {
	    name = &stringtab[index - 4];
	    /*
             *  If the program contains any .f files a trailing _ is stripped
       	     *  from the name on the assumption it was added by the compiler.
	     *  This only affects names that follow the sdb N_SO entry with
             *  the .f name. 
             */
            if (strip_ and name[0] != '\0' ) {
		lastchar = &name[strlen(name) - 1];
		if (*lastchar == '_') {
		    *lastchar = '\0';
		}
            }
	} else {
	    name = nil;
	} 

	/*
	 * Assumptions:
	 *	not an N_STAB	==> name != nil
	 *	name[0] == '-'	==> name == "-lg"
	 *	name[0] != '_'	==> filename or invisible
	 *
	 * The "-lg" signals the beginning of global loader symbols.
         *
	 */
	if ((np->n_type&N_STAB) != 0) {
	    enter_nl(name, np);
	} else if (name[0] == '-') {
	    afterlg = true;
	    if (curblock->class != PROG) {
		exitblock();
		if (curblock->class != PROG) {
		    exitblock();
		}
	    }
	    enterline(0, (linep-1)->addr + 1);
	} else if (afterlg) {
	    if (name[0] == '_') {
		check_global(&name[1], np);
	    }
	} else if (name[0] == '_') {
	    check_local(&name[1], np);
	} else if ((np->n_type&N_TEXT) == N_TEXT) {
	    check_filename(name);
	}
	++curnp;
	np = curnp;
    }
    if (not afterlg) {
	fatal("not linked for debugging, use \"cc -g ...\"");
    }
    dispose(namelist);
}

/*
 * Get a continuation entry from the name list.
 * Return the beginning of the name.
 */

public String getcont ()
{
    register integer index;
    register String name;

    ++curnp;
    index = curnp->n_un.n_strx;
    if (index == 0) {
	panic("continuation followed by empty stab");
    }
    name = &stringtab[index - 4];
    return name;
}

/*
 * Initialize symbol information.
 */

private initsyms ()
{
    curblock = nil;
    curlevel = 0;
    nesting = 0;
    program = insert(identname("", true));
    program->class = PROG;
    program->symvalue.funcv.beginaddr = 0;
    program->symvalue.funcv.inline = false;
    newfunc(program, codeloc(program));
    findbeginning(program);
    enterblock(program);
    curmodule = program;
    t_boolean = maketype("$boolean", 0L, 1L);
    t_int = maketype("$integer", 0x80000000L, 0x7fffffffL);
    t_char = maketype("$char", 0L, 255L);
    t_real = maketype("$real", 8L, 0L);
    t_nil = maketype("$nil", 0L, 0L);
    t_open = maketype("integer", 0L, -1L);
}

/*
 * Free all the object file information that's being stored.
 */

public objfree ()
{
    symbol_free();
    keywords_free();
    names_free();
    dispose(stringtab);
    clrfunctab();
}

/*
 * Enter a namelist entry.
 */

private enter_nl (name, np)
String name;
register struct nlist *np;
{
    register Symbol s;
    register Name n;

    s = nil;
    switch (np->n_type) {
	/*
	 * Build a symbol for the FORTRAN common area.  All GSYMS that follow
	 * will be chained in a list with the head kept in common.offset, and
	 * the tail in common.chain.
	 */
	case N_BCOMM:
 	    if (curcomm) {
		curcomm->symvalue.common.chain = commchain;
	    }
	    n = identname(name, true);
	    curcomm = lookup(n);
	    if (curcomm == nil) {
		curcomm = insert(n);
		curcomm->class = COMMON;
		curcomm->block = curblock;
		curcomm->level = program->level;
		curcomm->symvalue.common.chain = nil;
	    }
	    commchain = curcomm->symvalue.common.chain;
	    break;

	case N_ECOMM:
	    if (curcomm) {
		curcomm->symvalue.common.chain = commchain;
		curcomm = nil;
	    }
	    break;

	case N_LBRAC:
	    ++nesting;
	    addrstk[nesting] = (linep - 1)->addr;
	    break;

	case N_RBRAC:
	    --nesting;
	    if (addrstk[nesting] == NOADDR) {
		exitblock();
		newfunc(curblock, (linep - 1)->addr);
		addrstk[nesting] = (linep - 1)->addr;
	    }
	    break;

	case N_SLINE:
	    enterline((Lineno) np->n_desc, (Address) np->n_value);