freebsd-src/gnu/usr.bin/cpio

This is GNU cpio, a program to manage archives of files.
As of version 2.0, it supports the features of the System V release 4
cpio, including support for tar archives.

The main advantages of GNU cpio over Unix versions are:

* It can access tape drives on other hosts using TCP/IP.

* `-o' and `-p' can copy symbolic links either as symbolic links or,
with `-L', as the files they point to.

* `-i' automatically recognizes the archive format and tries to
recover from corrupted archives.

* The output of '-itv' looks like 'ls -l'.

* It accepts long-named options as well as traditional
single-character options.

A few features of other versions of cpio are missing from GNU cpio, including:

* The `-6' option to support Sixth Edition Unix cpio archives with `-i'.

* An option to limit volume size, like afio -s.


GNU cpio supports the POSIX.1 "ustar" tar format.  GNU tar supports a
somewhat different, early draft of that format.  That draft format has
a slightly different magic number in the tar header and doesn't
include the path prefix part of the header, which allows storing file
names that are longer than 100 characters.  GNU cpio knows to
recognize the nonstandard GNU tar "ustar" archives.

The following patch to GNU tar 1.11.1 makes GNU tar recognize standard
"ustar" archives, such as GNU cpio produces, except that it won't use
the path prefix.  Without this patch, GNU tar thinks that standard
"ustar" archives are old-format tar archives and can not use the extra
information that "ustar" format contains.  If you use this patch,
remember that you will lose the beginnings of paths that are longer
than 100 characters.  That's why it's not an official part of GNU tar.
(Adding support for the path prefix to GNU tar is not trivial.)

--- list.c.orig Mon Sep 14 17:04:03 1992
+++ list.c      Wed Oct 14 14:02:28 1992
@@ -439,7 +439,7 @@
                st->st_ctime = from_oct(1+12, header->header.ctime);
        }
 
-       if (0==strcmp(header->header.magic, TMAGIC)) {
+       if (0==strncmp(header->header.magic, TMAGIC, 5)) {
                /* Unix Standard tar archive */
                *stdp = 1;
                if (wantug) {

Mail suggestions and bug reports for GNU cpio to
bug-gnu-utils@prep.ai.mit.edu.