AR(4) DOMAIN/IX Reference Manual (SYS5) AR(4)
NAME
ar - common archive file format
DESCRIPTION
The archive command ar(1) is used to combine several files
into one. Archives are used mainly as libraries for the
link editor ld(1) to search.
Each archive begins with the archive magic string.
#define ARMAG "!<arch>\n" /* magic string */
#define SARMAG 8 /* length of magic string */
Each archive that contains common object files (see
a.out(4)) includes an archive symbol table. This symbol
table is used by the link editor ld(1) 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 it is never listed) and is automat-
ically created and/or updated by ar.
Following the archive magic string are the archive file
members. Each file member is preceded by a file member
header which has the following 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 in the form of decimal numbers (except for ar_mode
which is in octal). Thus, if the archive contains printable
files, the archive itself is printable.
The ar_name field is blank-padded and ends with a slash (/).
The ar_date field is the file's last modification date (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(1) is used. Conversion tools
like arcv(1) and convert(1) help to transport archives in
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AR(4) DOMAIN/IX Reference Manual (SYS5) AR(4)
different formats to this format.
Each member file of an archive file begins on an even byte
boundary. A newline is inserted between member files, if
necessary. Nevertheless, the size given reflects the actual
size of the file, exclusive of padding.
There is no provision for empty areas in an archive file.
If the archive symbol table exists, the first file in the
archive has a zero length name (i.e., ar_name[0] == '/').
The contents of this file are as follows:
⊕ The number of symbols. Length: 4 bytes.
⊕ The array of offsets into the archive file. Length: 4
bytes * ``the number of symbols''.
⊕ The name string table. Length: ar_size - (4 bytes *
(``the number of symbols'' + 1)).
The number of symbols and the array of offsets are managed
with sgetl and sputl. The string table contains exactly as
many null terminated strings as there are elements in the
array of offsets. Each offset from the array is associated
with the corresponding name from the string table (in
order). 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 location of the archive header
for the associated symbol.
NOTES
Strip(1) will remove all archive symbol entries from the
header. The archive symbol entries must be restored with
the ts option of the ar(1) command before the archive can be
used with the link editor ld(1).
RELATED INFORMATION
ar(1), arcv(1), convert(1), ld(1), strip(1), sputl(3X)
AR-2 Printed 5/13/85