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ar.h(3HEAD)			    Headers			   ar.h(3HEAD)

NAME
       ar.h, ar	- archive file format

SYNOPSIS
       #include	<ar.h>

DESCRIPTION
       The  archive  command ar	is used	to combine several files into one. Ar-
       chives are used mainly as libraries to be searched by the  link	editor
       ld.

       Each archive begins with	the archive magic string.

       #define	ARMAG	"!<arch>\n"    /* magic	string */
       #define	SARMAG	 8	       /* length of magic string */

       Following  the  archive magic string are	the archive file members. Each
       file member is preceded by a file member	header which is	of the follow-
       ing format:

       #define	ARFMAG	 "`\n"	       /* header trailer string	*/

       struct  ar_hdr		       /* file member header */
       {
	   char	   ar_name[16];	       /* '/' terminated file member name */
	   char	   ar_date[12];	       /* file member date */
	   char	   ar_uid[6]	       /* file member user identification */
	   char	   ar_gid[6]	       /* file member group identification */
	   char	   ar_mode[8]	       /* file member mode (octal) */
	   char	   ar_size[10];	       /* file member size */
	   char	   ar_fmag[2];	       /* header trailer string	*/
       };

       All  information	 in the	file member headers is in printable ASCII. The
       numeric information contained in	the headers is stored as decimal  num-
       bers  (except for ar_mode which is in octal). Thus, if the archive con-
       tains printable files, the archive itself is printable.

       If the file member name fits, the ar_name field contains	the  name  di-
       rectly,	and is terminated by a slash (/) and padded with blanks	on the
       right. If the member's name does	not fit, ar_name contains a slash  (/)
       followed	 by  a	decimal	representation of the name's offset in the ar-
       chive string table described below.

       The ar_date field is the	modification date of the file at the  time  of
       its  insertion  into  the  archive. Common format archives can be moved
       from system to system as	long as	the portable  archive  command	ar  is
       used.

       Each  archive file member begins	on an even byte	boundary; a newline is
       inserted	between	files if necessary. Nevertheless, the size  given  re-
       flects the actual size of the file exclusive of padding.

       Notice there is no provision for	empty areas in an archive file.

       Each archive that contains object files (see  a.out(4)) includes	an ar-
       chive symbol table. This	symbol table is	used by	the link editor	 ld to
       determine  which	 archive  members  must	be loaded during the link edit
       process.	The archive symbol table (if it	exists)	is  always  the	 first
       file  in	the archive (but is never listed) and is automatically created
       and/or updated by  ar.

       The archive symbol table	has a zero length name (that  is,   ar_name[0]
       is  '/'),   ar_name[1]=='  ', etc.). All	``words'' in this symbol table
       have four bytes,	using the machine-independent  encoding	 shown	below.
       All machines use	the encoding described here for	the symbol table, even
       if the machine's	``natural'' byte order is different.

			0	1	2	3
       0x01020304	01	02	03	04

       The contents of this file are as	follows:

       1.  The number of symbols.  Length: 4 bytes.

       2.  The array of	offsets	into the archive  file.	  Length:  4  bytes  *
	   ``the number	of symbols''.

       3.  The	name  string table.  Length: ar_size - 4 bytes * (``the	number
	   of symbols''	+ 1).

       As an example, the following symbol table defines 4  symbols.  The  ar-
       chive  member  at  file	offset 114 defines name. The archive member at
       file offset 122 defines object. The archive member at file  offset  426
       defines	function  and  the  archive  member at file offset 434 defines
       name2.

   Example Symbol Table
       Offset	  +0   +1   +2	 +3
		 ___________________
	0	|	  4	    | 4	offset entries
		|___________________|
	4	|	114	    | name
		|___________________|
	8	|	122	    | object
		|___________________|
       12	|	426	    | function
		|___________________|
       16	|	434	    | name2
		|___________________|
       20	|  n | a  | m  | e  |
		|____|____|____|____|
       24	| \0 | o  | b  | j  |
		|____|____|____|____|
       28	|  e | c  | t  | \0 |
		|____|____|____|____|
       32	|  f | u  | n  | c  |
		|____|____|____|____|
       36	|  t | i  | o  | n  |
		|____|____|____|____|
       40	| \0 | n  | a  | m  |
		|____|____|____|____|
       44	|  e | 2  | \0 |    |
		|____|____|____|____|

       The string table	contains exactly as many null  terminated  strings  as
       there  are elements in the offsets array. Each offset from the array is
       associated with the corresponding name from the string  table  (in  or-
       der).  The names	in the string table are	all the	defined	global symbols
       found in	the common object files	in the archive.	Each offset is the lo-
       cation of the archive header for	the associated symbol.

       If some archive member's	name is	more than 15 bytes long, a special ar-
       chive member contains a table of	file names, each followed by  a	 slash
       and  a new-line.	This string table member, if present, will precede all
       ``normal'' archive members. The special archive symbol table is	not  a
       ``normal'' member, and must be first if it exists. The ar_name entry of
       the  string  table's  member  header   holds   a	  zero	 length	  name
       ar_name[0]=='/',	followed by one	trailing slash (ar_name[1]=='/'), fol-
       lowed by	blanks (ar_name[2]==' ', etc.).	 Offsets into the string table
       begin at	zero. Example ar_name values for short and long	file names ap-
       pear below.

       Offset	+0   +1	  +2   +3   +4	 +5   +6   +7	+8   +9
	      __________________________________________________
	0     |	f  | i	| l  | e  | _  | n  | a	 | m  |	e  | _	|
	      |____|____|____|____|____|____|____|____|____|____|
       10     |	s  | a	| m  | p  | l  | e  | /	 | \n |	l  | o	|
	      |____|____|____|____|____|____|____|____|____|____|
       20     |	n  | g	| e  | r  | f  | i  | l	 | e  |	n  | a	|
	      |____|____|____|____|____|____|____|____|____|____|
       30     |	m  | e	| x  | a  | m  | p  | l	 | e  |	/  | \n	|
	      |____|____|____|____|____|____|____|____|____|____|

	  Member Name				 ar_name
       _______________________________________________________________
       short-name	    | short-name/  | Not in string table
			    |		   |
       file_name_sample	    | /0	   | Offset 0 in string	table
			    |		   |
       longerfilenamexample | /18	   | Offset 18 in string table
       _____________________|______________|___________________________

SEE ALSO
       ar(1), ld(1), strip(1), a.out(4)

NOTES
       The strip utility will remove  all  archive  symbol  entries  from  the
       header.	 The  archive symbol entries must be restored with the -ts op-
       tions of	the ar command before the archive can be used  with  the  link
       editor ld.

SunOS 5.10			  1 Jul	1998			   ar.h(3HEAD)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | NOTES

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