2021-12-09 12:22:14 +01:00
|
|
|
<!-- Creator : groff version 1.22.4 -->
|
|
|
|
|
<!-- CreationDate: Sun Aug 22 23:03:27 2021 -->
|
2020-03-04 16:55:40 +01:00
|
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
|
|
|
|
|
"http://www.w3.org/TR/html4/loose.dtd">
|
|
|
|
|
<html>
|
|
|
|
|
<head>
|
|
|
|
|
<meta name="generator" content="groff -Thtml, see www.gnu.org">
|
|
|
|
|
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
|
|
|
|
|
<meta name="Content-Style" content="text/css">
|
|
|
|
|
<style type="text/css">
|
|
|
|
|
p { margin-top: 0; margin-bottom: 0; vertical-align: top }
|
|
|
|
|
pre { margin-top: 0; margin-bottom: 0; vertical-align: top }
|
|
|
|
|
table { margin-top: 0; margin-bottom: 0; vertical-align: top }
|
|
|
|
|
h1 { text-align: center }
|
|
|
|
|
</style>
|
|
|
|
|
<title></title>
|
|
|
|
|
</head>
|
|
|
|
|
<body>
|
|
|
|
|
|
|
|
|
|
<hr>
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
<p>CPIO(5) BSD File Formats Manual CPIO(5)</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>NAME</b></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%;"><b>cpio</b> — format of
|
|
|
|
|
cpio archive files</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>DESCRIPTION</b></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%;">The <b>cpio</b> archive format
|
|
|
|
|
collects any number of files, directories, and other file
|
|
|
|
|
system objects (symbolic links, device nodes, etc.) into a
|
|
|
|
|
single stream of bytes.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>General
|
|
|
|
|
Format</b> <br>
|
|
|
|
|
Each file system object in a <b>cpio</b> archive comprises a
|
|
|
|
|
header record with basic numeric metadata followed by the
|
|
|
|
|
full pathname of the entry and the file data. The header
|
|
|
|
|
record stores a series of integer values that generally
|
|
|
|
|
follow the fields in <i>struct stat</i>. (See stat(2) for
|
|
|
|
|
details.) The variants differ primarily in how they store
|
|
|
|
|
those integers (binary, octal, or hexadecimal). The header
|
|
|
|
|
is followed by the pathname of the entry (the length of the
|
|
|
|
|
pathname is stored in the header) and any file data. The end
|
|
|
|
|
of the archive is indicated by a special record with the
|
2021-12-09 12:22:14 +01:00
|
|
|
pathname “TRAILER!!!”.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>PWB
|
|
|
|
|
format</b> <br>
|
2021-12-09 12:22:14 +01:00
|
|
|
The PWB binary <b>cpio</b> format is the original format,
|
|
|
|
|
when cpio was introduced as part of the Programmer’s
|
|
|
|
|
Work Bench system, a variant of 6th Edition UNIX. It stores
|
|
|
|
|
numbers as 2-byte and 4-byte binary values. Each entry
|
|
|
|
|
begins with a header in the following format:</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:14%; margin-top: 1em">struct
|
2021-12-09 12:22:14 +01:00
|
|
|
header_pwb_cpio { <br>
|
|
|
|
|
short h_magic; <br>
|
|
|
|
|
short h_dev; <br>
|
|
|
|
|
short h_ino; <br>
|
|
|
|
|
short h_mode; <br>
|
|
|
|
|
short h_uid; <br>
|
|
|
|
|
short h_gid; <br>
|
|
|
|
|
short h_nlink; <br>
|
|
|
|
|
short h_majmin; <br>
|
|
|
|
|
long h_mtime; <br>
|
|
|
|
|
short h_namesize; <br>
|
|
|
|
|
long h_filesize; <br>
|
|
|
|
|
};</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:6%; margin-top: 1em">The <i>short</i>
|
|
|
|
|
fields here are 16-bit integer values, while the <i>long</i>
|
|
|
|
|
fields are 32 bit integers. Since PWB UNIX, like the 6th
|
|
|
|
|
Edition UNIX it was based on, only ran on PDP-11 computers,
|
|
|
|
|
they are in PDP-endian format, which has little-endian
|
|
|
|
|
shorts, and big-endian longs. That is, the long integer
|
|
|
|
|
whose hexadecimal representation is 0x12345678 would be
|
|
|
|
|
stored in four successive bytes as 0x34, 0x12, 0x78, 0x56.
|
|
|
|
|
The fields are as follows:</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_magic</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:17%;">The integer value octal
|
|
|
|
|
070707.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_dev</i>, <i>h_ino</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:17%;">The device and inode numbers
|
|
|
|
|
from the disk. These are used by programs that read
|
|
|
|
|
<b>cpio</b> archives to determine when two entries refer to
|
|
|
|
|
the same file. Programs that synthesize <b>cpio</b> archives
|
|
|
|
|
should be careful to set these to distinct values for each
|
|
|
|
|
entry.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_mode</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:17%; margin-top: 1em">The mode
|
2021-12-09 12:22:14 +01:00
|
|
|
specifies both the regular permissions and the file type,
|
|
|
|
|
and it also holds a couple of bits that are irrelevant to
|
|
|
|
|
the cpio format, because the field is actually a raw copy of
|
|
|
|
|
the mode field in the inode representing the file. These are
|
|
|
|
|
the IALLOC flag, which shows that the inode entry is in use,
|
|
|
|
|
and the ILARG flag, which shows that the file it represents
|
|
|
|
|
is large enough to have indirect blocks pointers in the
|
|
|
|
|
inode. The mode is decoded as follows:</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em">0100000</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:28%; margin-top: 1em">IALLOC flag -
|
|
|
|
|
irrelevant to cpio.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p>0060000</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:28%; margin-top: 1em">This masks the
|
|
|
|
|
file type bits.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p>0040000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">File type value
|
|
|
|
|
for directories.</p>
|
|
|
|
|
|
|
|
|
|
<p>0020000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">File type value
|
|
|
|
|
for character special devices.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p>0060000</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">File type value
|
2021-12-09 12:22:14 +01:00
|
|
|
for block special devices.</p>
|
|
|
|
|
|
|
|
|
|
<p>0010000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">ILARG flag -
|
|
|
|
|
irrelevant to cpio.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p>0004000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">SUID bit.</p>
|
|
|
|
|
|
|
|
|
|
<p>0002000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">SGID bit.</p>
|
|
|
|
|
|
|
|
|
|
<p>0001000</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:28%; margin-top: 1em">Sticky bit.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p>0000777</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:28%; margin-top: 1em">The lower 9
|
|
|
|
|
bits specify read/write/execute permissions for world,
|
|
|
|
|
group, and user following standard POSIX conventions.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_uid</i>, <i>h_gid</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:17%;">The numeric user id and group
|
|
|
|
|
id of the owner.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_nlink</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:17%;">The number of links to this
|
|
|
|
|
file. Directories always have a value of at least two here.
|
|
|
|
|
Note that hardlinked files include file data with every copy
|
|
|
|
|
in the archive.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_majmin</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:17%;">For block special and character
|
|
|
|
|
special entries, this field contains the associated device
|
|
|
|
|
number, with the major number in the high byte, and the
|
|
|
|
|
minor number in the low byte. For all other entry types, it
|
2020-03-04 16:55:40 +01:00
|
|
|
should be set to zero by writers and ignored by readers.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_mtime</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:17%;">Modification time of the file,
|
|
|
|
|
indicated as the number of seconds since the start of the
|
|
|
|
|
epoch, 00:00:00 UTC January 1, 1970.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_namesize</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:17%;">The number of bytes in the
|
|
|
|
|
pathname that follows the header. This count includes the
|
|
|
|
|
trailing NUL byte.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-top: 1em"><i>h_filesize</i></p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:17%;">The size of the file. Note that
|
2021-12-09 12:22:14 +01:00
|
|
|
this archive format is limited to 16 megabyte file sizes,
|
|
|
|
|
because PWB UNIX, like 6th Edition, only used an unsigned 24
|
|
|
|
|
bit integer for the file size internally.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">The pathname
|
2021-12-09 12:22:14 +01:00
|
|
|
immediately follows the fixed header. If <b>h_namesize</b>
|
2020-03-04 16:55:40 +01:00
|
|
|
is odd, an additional NUL byte is added after the pathname.
|
2021-12-09 12:22:14 +01:00
|
|
|
The file data is then appended, again with an additional NUL
|
|
|
|
|
appended if needed to get the next header at an even
|
|
|
|
|
offset.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Hardlinked files
|
|
|
|
|
are not given special treatment; the full file contents are
|
|
|
|
|
included with each copy of the file.</p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>New Binary
|
|
|
|
|
Format</b> <br>
|
|
|
|
|
The new binary <b>cpio</b> format showed up when cpio was
|
|
|
|
|
adopted into late 7th Edition UNIX. It is exactly like the
|
|
|
|
|
PWB binary format, described above, except for three
|
|
|
|
|
changes:</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">First, UNIX now
|
|
|
|
|
ran on more than one hardware type, so the endianness of 16
|
|
|
|
|
bit integers must be determined by observing the magic
|
|
|
|
|
number at the start of the header. The 32 bit integers are
|
|
|
|
|
still always stored with the most significant word first,
|
|
|
|
|
though, so each of those two, in the struct shown above, was
|
|
|
|
|
stored as an array of two 16 bit integers, in the
|
|
|
|
|
traditional order. Those 16 bit integers, like all the
|
|
|
|
|
others in the struct, were accessed using a macro that byte
|
|
|
|
|
swapped them if necessary.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Next, 7th
|
|
|
|
|
Edition had more file types to store, and the IALLOC and
|
|
|
|
|
ILARG flag bits were re-purposed to accommodate these. The
|
|
|
|
|
revised use of the various bits is as follows:</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em">0170000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">This masks the
|
|
|
|
|
file type bits.</p>
|
|
|
|
|
|
|
|
|
|
<p>0140000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for sockets.</p>
|
|
|
|
|
|
|
|
|
|
<p>0120000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for symbolic links. For symbolic links, the link body is
|
|
|
|
|
stored as file data.</p>
|
|
|
|
|
|
|
|
|
|
<p>0100000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for regular files.</p>
|
|
|
|
|
|
|
|
|
|
<p>0060000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for block special devices.</p>
|
|
|
|
|
|
|
|
|
|
<p>0040000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for directories.</p>
|
|
|
|
|
|
|
|
|
|
<p>0020000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for character special devices.</p>
|
|
|
|
|
|
|
|
|
|
<p>0010000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">File type value
|
|
|
|
|
for named pipes or FIFOs.</p>
|
|
|
|
|
|
|
|
|
|
<p>0004000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">SUID bit.</p>
|
|
|
|
|
|
|
|
|
|
<p>0002000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">SGID bit.</p>
|
|
|
|
|
|
|
|
|
|
<p>0001000</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">Sticky bit.</p>
|
|
|
|
|
|
|
|
|
|
<p>0000777</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:18%; margin-top: 1em">The lower 9
|
|
|
|
|
bits specify read/write/execute permissions for world,
|
|
|
|
|
group, and user following standard POSIX conventions.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Finally, the
|
|
|
|
|
file size field now represents a signed 32 bit integer in
|
|
|
|
|
the underlying file system, so the maximum file size has
|
|
|
|
|
increased to 2 gigabytes.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Note that there
|
|
|
|
|
is no obvious way to tell which of the two binary formats an
|
|
|
|
|
archive uses, other than to see which one makes more sense.
|
|
|
|
|
The typical error scenario is that a PWB format archive
|
|
|
|
|
unpacked as if it were in the new format will create named
|
|
|
|
|
sockets instead of directories, and then fail to unpack
|
|
|
|
|
files that should go in those directories. Running
|
|
|
|
|
<i>bsdcpio -itv</i> on an unknown archive will make it
|
|
|
|
|
obvious which it is: if it’s PWB format, directories
|
|
|
|
|
will be listed with an ’s’ instead of a
|
|
|
|
|
’d’ as the first character of the mode string,
|
|
|
|
|
and the larger files will have a ’?’ in that
|
|
|
|
|
position.</p>
|
|
|
|
|
|
2020-03-04 16:55:40 +01:00
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>Portable
|
|
|
|
|
ASCII Format</b> <br>
|
|
|
|
|
Version 2 of the Single UNIX Specification
|
2021-12-09 12:22:14 +01:00
|
|
|
(“SUSv2”) standardized an ASCII variant that is
|
|
|
|
|
portable across all platforms. It is commonly known as the
|
|
|
|
|
“old character” format or as the
|
|
|
|
|
“odc” format. It stores the same numeric fields
|
|
|
|
|
as the old binary format, but represents them as 6-character
|
|
|
|
|
or 11-character octal values.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:14%; margin-top: 1em">struct
|
|
|
|
|
cpio_odc_header { <br>
|
|
|
|
|
char c_magic[6]; <br>
|
|
|
|
|
char c_dev[6]; <br>
|
|
|
|
|
char c_ino[6]; <br>
|
|
|
|
|
char c_mode[6]; <br>
|
|
|
|
|
char c_uid[6]; <br>
|
|
|
|
|
char c_gid[6]; <br>
|
|
|
|
|
char c_nlink[6]; <br>
|
|
|
|
|
char c_rdev[6]; <br>
|
|
|
|
|
char c_mtime[11]; <br>
|
|
|
|
|
char c_namesize[6]; <br>
|
|
|
|
|
char c_filesize[11]; <br>
|
|
|
|
|
};</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">The fields are
|
2021-12-09 12:22:14 +01:00
|
|
|
identical to those in the new binary format. The name and
|
|
|
|
|
file body follow the fixed header. Unlike the binary
|
|
|
|
|
formats, there is no additional padding after the pathname
|
|
|
|
|
or file contents. If the files being archived are themselves
|
2020-03-04 16:55:40 +01:00
|
|
|
entirely ASCII, then the resulting archive will be entirely
|
|
|
|
|
ASCII, except for the NUL byte that terminates the name
|
|
|
|
|
field.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>New ASCII
|
|
|
|
|
Format</b> <br>
|
|
|
|
|
The "new" ASCII format uses 8-byte hexadecimal
|
|
|
|
|
fields for all numbers and separates device numbers into
|
|
|
|
|
separate fields for major and minor numbers.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:14%; margin-top: 1em">struct
|
|
|
|
|
cpio_newc_header { <br>
|
|
|
|
|
char c_magic[6]; <br>
|
|
|
|
|
char c_ino[8]; <br>
|
|
|
|
|
char c_mode[8]; <br>
|
|
|
|
|
char c_uid[8]; <br>
|
|
|
|
|
char c_gid[8]; <br>
|
|
|
|
|
char c_nlink[8]; <br>
|
|
|
|
|
char c_mtime[8]; <br>
|
|
|
|
|
char c_filesize[8]; <br>
|
|
|
|
|
char c_devmajor[8]; <br>
|
|
|
|
|
char c_devminor[8]; <br>
|
|
|
|
|
char c_rdevmajor[8]; <br>
|
|
|
|
|
char c_rdevminor[8]; <br>
|
|
|
|
|
char c_namesize[8]; <br>
|
|
|
|
|
char c_check[8]; <br>
|
|
|
|
|
};</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Except as
|
|
|
|
|
specified below, the fields here match those specified for
|
2021-12-09 12:22:14 +01:00
|
|
|
the new binary format above.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><i>magic</i></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:17%; margin-top: 1em">The string
|
2021-12-09 12:22:14 +01:00
|
|
|
“070701”.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><i>check</i></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:17%; margin-top: 1em">This field is
|
|
|
|
|
always set to zero by writers and ignored by readers. See
|
|
|
|
|
the next section for more details.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">The pathname is
|
|
|
|
|
followed by NUL bytes so that the total size of the fixed
|
|
|
|
|
header plus pathname is a multiple of four. Likewise, the
|
|
|
|
|
file data is padded to a multiple of four bytes. Note that
|
|
|
|
|
this format supports only 4 gigabyte files (unlike the older
|
|
|
|
|
ASCII format, which supports 8 gigabyte files).</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">In this format,
|
|
|
|
|
hardlinked files are handled by setting the filesize to zero
|
2021-12-09 12:22:14 +01:00
|
|
|
for each entry except the first one that appears in the
|
2020-03-04 16:55:40 +01:00
|
|
|
archive.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>New CRC
|
|
|
|
|
Format</b> <br>
|
|
|
|
|
The CRC format is identical to the new ASCII format
|
|
|
|
|
described in the previous section except that the magic
|
2021-12-09 12:22:14 +01:00
|
|
|
field is set to “070702” and the <i>check</i>
|
|
|
|
|
field is set to the sum of all bytes in the file data. This
|
|
|
|
|
sum is computed treating all bytes as unsigned values and
|
|
|
|
|
using unsigned arithmetic. Only the least-significant 32
|
|
|
|
|
bits of the sum are stored.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>HP
|
|
|
|
|
variants</b> <br>
|
|
|
|
|
The <b>cpio</b> implementation distributed with HPUX used
|
|
|
|
|
XXXX but stored device numbers differently XXX.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em"><b>Other
|
|
|
|
|
Extensions and Variants</b> <br>
|
|
|
|
|
Sun Solaris uses additional file types to store extended
|
|
|
|
|
file data, including ACLs and extended attributes, as
|
|
|
|
|
special entries in cpio archives.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">XXX Others?
|
|
|
|
|
XXX</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>SEE ALSO</b></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%;">cpio(1), tar(5)</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>STANDARDS</b></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%;">The <b>cpio</b> utility is no
|
|
|
|
|
longer a part of POSIX or the Single Unix Standard. It last
|
|
|
|
|
appeared in Version 2 of the Single UNIX Specification
|
2021-12-09 12:22:14 +01:00
|
|
|
(“SUSv2”). It has been supplanted in subsequent
|
|
|
|
|
standards by pax(1). The portable ASCII format is currently
|
|
|
|
|
part of the specification for the pax(1) utility.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>HISTORY</b></p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%;">The original cpio utility was
|
|
|
|
|
written by Dick Haight while working in AT&T’s
|
|
|
|
|
Unix Support Group. It appeared in 1977 as part of PWB/UNIX
|
2021-12-09 12:22:14 +01:00
|
|
|
1.0, the “Programmer’s Work Bench” derived
|
|
|
|
|
from AT&T UNIX 6th Edition UNIX that was used internally
|
|
|
|
|
at AT&T. Both the new binary and old character formats
|
|
|
|
|
were in use by 1980, according to the System III source
|
|
|
|
|
released by SCO under their “Ancient Unix”
|
|
|
|
|
license. The character format was adopted as part of IEEE
|
|
|
|
|
Std 1003.1-1988 (“POSIX.1”). XXX when did
|
2020-03-04 16:55:40 +01:00
|
|
|
"newc" appear? Who invented it? When did HP come
|
|
|
|
|
out with their variant? When did Sun introduce ACLs and
|
|
|
|
|
extended attributes? XXX</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-top: 1em"><b>BUGS</b></p>
|
|
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:6%;">The “CRC” format is
|
|
|
|
|
mis-named, as it uses a simple checksum and not a cyclic
|
|
|
|
|
redundancy check.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
2021-12-09 12:22:14 +01:00
|
|
|
<p style="margin-left:6%; margin-top: 1em">The binary
|
|
|
|
|
formats are limited to 16 bits for user id, group id,
|
|
|
|
|
device, and inode numbers. They are limited to 16 megabyte
|
|
|
|
|
and 2 gigabyte file sizes for the older and newer variants,
|
|
|
|
|
respectively.</p>
|
2020-03-04 16:55:40 +01:00
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">The old ASCII
|
|
|
|
|
format is limited to 18 bits for the user id, group id,
|
|
|
|
|
device, and inode numbers. It is limited to 8 gigabyte file
|
|
|
|
|
sizes.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">The new ASCII
|
|
|
|
|
format is limited to 4 gigabyte file sizes.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">None of the cpio
|
|
|
|
|
formats store user or group names, which are essential when
|
|
|
|
|
moving files between systems with dissimilar user or group
|
|
|
|
|
numbering.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">Especially when
|
|
|
|
|
writing older cpio variants, it may be necessary to map
|
|
|
|
|
actual device/inode values to synthesized values that fit
|
|
|
|
|
the available fields. With very large filesystems, this may
|
|
|
|
|
be necessary even for the newer formats.</p>
|
|
|
|
|
|
|
|
|
|
<p style="margin-left:6%; margin-top: 1em">BSD
|
|
|
|
|
December 23, 2011 BSD</p>
|
|
|
|
|
<hr>
|
|
|
|
|
</body>
|
|
|
|
|
</html>
|
