NAME

filehdr − File header for object files

SYNOPSIS

#include < filehdr.h>

DESCRIPTION

Every object file begins with a header.  The following C struct declaration is used:

struct filehdr
{
    unsigned short f_magic; /∗ magic number ∗/
    unsigned short f_nscns; /∗ number of sections ∗/
    int f_timdat; /∗ time & date stamp ∗/
    long f_symptr; /∗ file pointer to symbolic header ∗/
    int  f_nsyms; /∗ sizeof(symbolic header) ∗/
    unsigned short f_opthdr; /∗ sizeof(optional header) ∗/
    unsigned short f_flags; /∗ flags ∗/
};

f_symptr is the byte offset into the file at which the symbolic header can be found.  Its value can be used as the offset in fseek(3) to position an I/O stream to the symbolic header. f_nsyms contains the size of the symbolic header.  The valid magic numbers are given below:

#define ALPHAMAGIC0603    /∗ object file ∗/
#define ALPHAMAGICZ     0610    /∗ compressed object file ∗/
#define ALPHAUMAGIC0617/∗ ucode object file ∗/

The value in f_timdat is obtained from the times(3) system call.  Flag bits used in objects 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 ∗/

RELATED INFORMATION

times(3), fseek(3), a.out(4).