filehdr(4)                       UNIX System V                       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  fmagic ;   /* magic number */
         unsigned short  fnscns ;   /* number of sections */
         long            ftimdat ;  /* time & date stamp */
         long            fsymptr ;  /* file ptr to symtab */
         long            fnsyms ;   /* number of symtab entries */
         unsigned short  fopthdr ;  /* sizeof(opt and header) */
         unsigned short  fflags ;   /* flags */
      } ;

      fsymptr 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 UNIX system optional header is 28
      bytes.  The valid magic numbers are given below:

      #define I386MAGIC  0514   /* i386 Computer */
      #define WE32MAGIC  0560   /* 3B2, 3B5, and 3B15 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 ftimdat is obtained from the time(2) system call.  Flag
      bits currently defined are:

      #define FRELFLG  0000001   /* relocation entries stripped */
      #define FEXEC    0000002   /* file is executable */
      #define FLNNO    0000004   /* line numbers stripped */
      #define FLSYMS   0000010   /* local symbols stripped */
      #define FAR16WR  0000200   /* 16-bit DEC host */
      #define FAR32WR  0000400   /* 32-bit DEC host */
      #define FAR32W   0001000   /* non-DEC host */
      #define FBM32ID  0160000   /* WE32000 family ID field */
      #define FBM32B   0020000   /* file contains WE 32100 code */
      #define FBM32MAU 0040000   /* file reqs MAU to execute */
      #define FBM32RST 0010000   /* this object file contains restore
                                     work around [3B5/3B2 only] */




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filehdr(4)                       UNIX System V                       filehdr(4)


SEE ALSO
      time(2), fseek(3S), a.out(4)

      The ``Common Object File Format (COFF)'' chapter in the Programmer's
      Guide

















































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