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 in 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.
     See aouthdr(4) for the structure of the optional a.out
     header.  The valid magic number is

        #define   MC68MAGIC   0520    /* magic number */

     The value in f_timdat is obtained from the time(2) system
     call.  Flag bits currently defined are

        #define F_RELFLG  00001 /* relocation entries stripped */
        #define F_EXEC    00002 /* file is executable */
        #define F_LNNO    00004 /* line numbers stripped */
        #define F_LSYMS   00010 /* local symbols stripped */
        #define F_MINMAL  00020 /* minimal object file */
        #define F_UPDATE  00040 /* update file, ogen produced */
        #define F_SWABD   00100 /* file is "pre-swabbed" */
        #define F_AR16WR  00200 /* 16-bit DEC host */
        #define F_AR32WR  00400 /* 32-bit DEC host */
        #define F_AR32W   01000 /* non-DEC host */
        #define F_PATCH   02000 /* "patch" list in opt hdr */
        #define F_NODF    02000 /* "patch" list in opt hdr */


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







January 1992                                                    1