NAME
cpio — format of cpio archive
DESCRIPTION
The
header
structure, when the
-c
option of
cpio
is not used (see
cpio(1)),
is:
struct {
short c_magic,
c_dev;
ushort c_ino,
c_mode,
c_uid,
c_gid;
short c_nlink,
c_rdev,
c_mtime[2],
c_namesize,
c_filesize[2];
char c_name[c_namesize rounded to word];
} Hdr;
When the
cpio -c
option is used, the
header
information is described by:
sscanf(Chdr,"%6ho%6ho%6ho%6ho%6ho%6ho%6ho%6ho%11lo%6ho%11lo",
&Hdr.c_magic,&Hdr.c_dev,&Hdr.c_ino,&Hdr.c_mode,
&Hdr.c_uid,&Hdr.c_gid,&Hdr.c_nlink,&Hdr.c_rdev,
&Longtime,&Hdr.c_namesize,&Longfile);
Longtime
and
Longfile
are equivalent to
Hdr.c_mtime
and
Hdr.c_filesize,
respectively.
The contents of each file are recorded
together with other items describing the file.
Every instance of
c_magic
contains the constant 070707 (octal).
The items
c_dev
through
c_mtime
have meanings explained in
stat(2).
The length of the null-terminated path name
c_name,
including the null byte, is given by
c_namesize.
The last record of the
archive
always contains the name
TRAILER!!!.
Directories and the trailer are recorded with
c_filesize
equal to zero.
It will not always be the case that
c_dev
and
c_ino
correspond to the results of
stat(),
but the values are always sufficient
to tell whether two files in the archive are linked to each other.
When a device special file is archived by
HP-UX
cpio
(using the
-x
option),
c_rdev
contains a magic constant
which is dependent upon the implementation doing the writing.
H_rdev
flags the device file as an
HP-UX
32-bit device specifier, and
c_filesize
contains the 32-bit device specifier (see
stat(2)).
If the
-x
option is not present,
special files are not archived or restored.
Non-HPUX
device special files are never restored.
STANDARDS CONFORMANCE
cpio: XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1
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