FILEHDR(4) FILEHDR(4)
NAME
filehdr - file header for common object files
SYNOPSIS
#include <filehdr.h>
DESCRIPTION
Every common object file begins with a 20-byte header. The
following C struct declaration is used:
struct filehdr
{
unsigned short f_magic ; /* magic number */
unsigned short f_nscns ; /* number of sections */
long f_timdat ; /* time & date stamp */
long f_symptr ; /* file ptr to symtab */
long f_nsyms ; /* # symtab entries */
unsigned short f_opthdr ; /* sizeof(opt hdr) */
unsigned short f_flags ; /* flags */
} ;
F_symptr is the byte offset into the file at which the
symbol table can be found. Its value can be used as the
offset in fseek(3S) to position an I/O stream to the symbol
table. The Baker system optional header is 28-bytes. The
valid magic numbers are given below:
#define FBOMAGIC 0560 /* 3B2 and 3B5 computers */
#define N3BMAGIC 0550 /* 3B20 computer */
#define NTVMAGIC 0551 /* 3B20 computer */
#define VAXWRMAGIC 0570 /* VAX writable text segments */
#define VAXROMAGIC 0575 /* VAX read only sharable
text segments */
The value in f_timdat is obtained from the time(2) system
call. Flag bits currently defined are:
#define F_RELFLG 0000001 /* relocation entries stripped */
#define F_EXEC 0000002 /* file is executable */
Page 1 May 1989
FILEHDR(4) FILEHDR(4)
#define F_LNNO 0000004 /* line numbers stripped */
#define F_LSYMS 0000010 /* local symbols stripped */
#define F_MINMAL 0000020 /* minimal object file */
#define F_UPDATE 0000040 /* update file, ogen produced */
#define F_SWABD 0000100 /* file is "pre-swabbed" */
#define F_AR16WR 0000200 /* 16-bit DEC host */
#define F_AR32WR 0000400 /* 32-bit DEC host */
#define F_AR32W 0001000 /* non-DEC host */
#define F_PATCH 0002000 /* "patch" list in opt hdr */
#define F_BM32ID 0160000 /* WE32000 family ID field */
#define F_BM32B 0020000 /* file contains WE 32100 code */
#define F_BM32MAU 0040000 /* file reqs MAU to execute */
#define F_BM32RST 0010000 /* this object file contains restore
work around [3B5/3B2 only] */
SEE ALSO
time(2), fseek(3S), a.out(4).
Page 2 May 1989