FILEHDR(4) — Silicon Graphics not on PDP-11
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:
structfilehdr
{
unsigned shortf_magic ;/∗ magic number ∗/
unsigned shortf_nscns ;/∗ number of sections ∗/
longf_timdat ;/∗ time & date stamp ∗/
longf_symptr ;/∗ file ptr to symtab ∗/
longf_nsyms ;/∗ # symtab entries ∗/
unsigned shortf_opthdr ;/∗ sizeof(opt hdr) ∗/
unsigned shortf_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(3S) to position an I/O stream to the symbol table. The UNIX System optional header is always 36 bytes. The valid magic numbers are given below:
| #define | N3BMAGIC | 0550 | /∗ 3B20S ∗/ |
| #define | NTVMAGIC | 0551 | /∗ 3B20S ∗/ |
| #define | VAXWRMAGIC | 0570 | /∗ VAX writable text segments ∗/ |
| #define | VAXROMAGIC | 0575 | /∗ VAX readonly sharable text segments ∗/ |
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 ∗/ |
SEE ALSO
Version 2.1 — January 02, 1985