scnhdr(4)                                               scnhdr(4)



     NAME
          scnhdr - section header for a common object file

     SYNOPSIS
          #include <scnhdr.h>

     DESCRIPTION
          Every common object file has a table of section headers to
          specify the layout of the data within the file.  Each sec-
          tion within an object file has its own header.  The C struc-
          ture appears below.

          struct scnhdr
          {
             char           s_name[SYMNMLEN]; /* section name */
             long           s_paddr;          /* physical address */
             long           s_vaddr;          /* virtual address */
             long           s_size;           /* section size */
             long           s_scnptr;         /* file ptr to
                                                 raw data */
             long           s_relptr;         /* file ptr to
                                                 relocation */
             long           s_lnnoptr;        /* file ptr to
                                                 line numbers */
             unsigned short s_nreloc;         /* # reloc entries */
             unsigned short s_nlnno;          /* # line number
                                                 entries */
             long           s_flags;          /* flags */
          } ;

          File pointers are byte offsets into the file; they can be
          used as the offset in a call to fseek(3S).  If a section is
          initialized, the file contains the actual bytes.  An unini-
          tialized section is somewhat different.  It has a size, sym-
          bols defined in it, and symbols that refer to it, but it can
          have no relocation entries, line numbers, or data.  Conse-
          quently, an uninitialized section has no raw data in the ob-
          ject file, and the values for s_scnptr, s_relptr, s_lnnoptr,
          s_nreloc, and s_nlnno are zero.

     SEE ALSO
          ld(1), fseek(3S), a.out(4).













     April, 1990                                                     1