/* xsym.c (xsymDec.c)
 *
 * Tom Trebisky  July, 1999
 *
 * given an a.out format file on stdin,
 * copy just the symbol table stuff to standard out.
 */

#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>

#include <a_out.h>

#define BUFSIZE	4096

long long_swap ( long );
void error ( char * );

int fix = 0;
int verbose = 0;

main()
{
	char buf[BUFSIZE];
	struct exec ebuf;
	long magic, syms, extra;
	int n;

	if ( read ( 0, (char *) &ebuf, sizeof(struct exec) ) < 0 )
	    error ("Cannot read file header");

	magic = ebuf.a_magic & 0xffff;
	if ( verbose ) fprintf(stderr,"magic 1 %04x\n",magic);
	if ( magic != OMAGIC ) {
	    fix = 1;
	    magic = long_swap ( ebuf.a_magic ) & 0xffff;
	    if ( verbose ) fprintf(stderr,"magic 2 %04x\n",magic);
	    if ( magic != OMAGIC )
		error ("Unrecognized file format");
	}
	if ( verbose ) {
	    if ( fix )
		fprintf(stderr,"magic number: %08x (swapped)\n",magic);
	    else
		fprintf(stderr,"magic number: %08x\n",magic);
	}

	extra = long_swap(ebuf.a_text) + long_swap(ebuf.a_data) +
	    long_swap(ebuf.a_trsize) + long_swap(ebuf.a_drsize);

	ebuf.a_text = 0;
	ebuf.a_data = 0;
	ebuf.a_bss = 0;
	ebuf.a_entry = 0;
	ebuf.a_trsize = 0;
	ebuf.a_drsize = 0;
	write ( 1, (char *) &ebuf, sizeof(struct exec) );

	if ( lseek ( 0, extra, SEEK_CUR ) < 0 )
	    error ("Cannot seek");

	for ( ;; ) {
	    if ( (n = read ( 0, buf, BUFSIZE )) < 0 )
		error ("File read error");
	    if ( n == 0 )
		break;
	    if ( write ( 1, buf, n ) < 0 )
		error ("Cannot write syms");
	}

	exit ( 0 );
}

void
error ( char * msg )
{
	fprintf(stderr,"%s\n",msg);
	exit ( 1 );
}

#ifdef notdef
long
short_swap ( long num )
{
	int b1, b2;
	long rv;

	if ( ! fix )
	    return num;

	b1 = num & 0xff;
	num >>= 8;
	b2 = num & 0xff;

	return b1<<8 | b2;
}
#endif

long
long_swap ( long num )
{
	int b1, b2, b3, b4;
	long rv;

	if ( ! fix )
	    return num;
	b1 = num & 0xff;
	num >>= 8;
	b2 = num & 0xff;
	num >>= 8;
	b3 = num & 0xff;
	num >>= 8;
	b4 = num & 0xff;

	rv = b1;
	rv <<= 8;
	rv |= b2;
	rv <<= 8;
	rv |= b3;
	rv <<= 8;
	rv |= b4;
	return rv;
}