FILEHDR(F)                                 UNIX System V



     Name
          filehdr - file header for common object files


     Syntax
          #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(S) 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 I286SMAGIC 0512 /* 80286 computers-small model
                                  programs */
          #define I286LMAGIC 0522 /* 80286 computers-large model
                                  programs */
          #define I386MAGIC  0514 /* 80386 computers */
          #define FBOMAGIC   0560 /* 3B2 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 f_timdat is obtained from  the  time(S)  system
          call.  Flag bits currently defined are:

          #define F_RELFLG  0000001 /* relocation entries stripped */
          #define F_EXEC    0000002 /* file is executable */
          #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_80186   010000  /* contains 80186 instructions */
          #define F_80286   020000  /* contains 80286 instructions */
          #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 [3B15/3B2 only] */


     See Also
          time(S), fseek(S), a.out(F)


     (printed 8/23/89)                                  FILEHDR(F)