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diff --git a/libarchive/libarchive-2.8.0/doc/wiki/ManPageCpio5.wiki b/libarchive/libarchive-2.8.0/doc/wiki/ManPageCpio5.wiki new file mode 100644 index 0000000..f39f64f --- /dev/null +++ b/libarchive/libarchive-2.8.0/doc/wiki/ManPageCpio5.wiki @@ -0,0 +1,297 @@ +#summary CPIO 5 manual page +== NAME == +*cpio* +- format of cpio archive files +== DESCRIPTION == +The +*cpio* +archive format collects any number of files, directories, and other +file system objects (symbolic links, device nodes, etc.) into a single +stream of bytes. +=== General Format=== +Each file system object in a +*cpio* +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 +_struct_ stat. +(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 pathname +"TRAILER!!!". +=== PWB format=== +XXX Any documentation of the original PWB/UNIX 1.0 format? XXX +=== Old Binary Format=== +The old binary +*cpio* +format stores numbers as 2-byte and 4-byte binary values. +Each entry begins with a header in the following format: +{{{ +struct header_old_cpio { + unsigned short c_magic; + unsigned short c_dev; + unsigned short c_ino; + unsigned short c_mode; + unsigned short c_uid; + unsigned short c_gid; + unsigned short c_nlink; + unsigned short c_rdev; + unsigned short c_mtime[2]; + unsigned short c_namesize; + unsigned short c_filesize[2]; +}; +}}} + +The +_unsigned_ short +fields here are 16-bit integer values; the +_unsigned_ int +fields are 32-bit integer values. +The fields are as follows +<dl> +<dt>_magic_</dt><dd> +The integer value octal 070707. +This value can be used to determine whether this archive is +written with little-endian or big-endian integers. +</dd><dt>_dev_, _ino_</dt><dd> +The device and inode numbers from the disk. +These are used by programs that read +*cpio* +archives to determine when two entries refer to the same file. +Programs that synthesize +*cpio* +archives should be careful to set these to distinct values for each entry. +</dd><dt>_mode_</dt><dd> +The mode specifies both the regular permissions and the file type. +It consists of several bit fields as follows: +<dl> +<dt>0170000</dt><dd> +This masks the file type bits. +</dd><dt>0140000</dt><dd> +File type value for sockets. +</dd><dt>0120000</dt><dd> +File type value for symbolic links. +For symbolic links, the link body is stored as file data. +</dd><dt>0100000</dt><dd> +File type value for regular files. +</dd><dt>0060000</dt><dd> +File type value for block special devices. +</dd><dt>0040000</dt><dd> +File type value for directories. +</dd><dt>0020000</dt><dd> +File type value for character special devices. +</dd><dt>0010000</dt><dd> +File type value for named pipes or FIFOs. +</dd><dt>0004000</dt><dd> +SUID bit. +</dd><dt>0002000</dt><dd> +SGID bit. +</dd><dt>0001000</dt><dd> +Sticky bit. +On some systems, this modifies the behavior of executables and/or directories. +</dd><dt>0000777</dt><dd> +The lower 9 bits specify read/write/execute permissions +for world, group, and user following standard POSIX conventions. +</dd></dl> +</dd><dt>_uid_, _gid_</dt><dd> +The numeric user id and group id of the owner. +</dd><dt>_nlink_</dt><dd> +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. +</dd><dt>_rdev_</dt><dd> +For block special and character special entries, +this field contains the associated device number. +For all other entry types, it should be set to zero by writers +and ignored by readers. +</dd><dt>_mtime_</dt><dd> +Modification time of the file, indicated as the number +of seconds since the start of the epoch, +00:00:00 UTC January 1, 1970. +The four-byte integer is stored with the most-significant 16 bits first +followed by the least-significant 16 bits. +Each of the two 16 bit values are stored in machine-native byte order. +</dd><dt>_namesize_</dt><dd> +The number of bytes in the pathname that follows the header. +This count includes the trailing NUL byte. +</dd><dt>_filesize_</dt><dd> +The size of the file. +Note that this archive format is limited to +four gigabyte file sizes. +See +_mtime_ +above for a description of the storage of four-byte integers. +</dd></dl> + +The pathname immediately follows the fixed header. +If the +*namesize* +is odd, an additional NUL byte is added after the pathname. +The file data is then appended, padded with NUL +bytes to an even length. + +Hardlinked files are not given special treatment; +the full file contents are included with each copy of the +file. +=== Portable ASCII Format=== +Version 2 of the Single UNIX Specification (``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. +{{{ +struct cpio_odc_header { + char c_magic[6]; + char c_dev[6]; + char c_ino[6]; + char c_mode[6]; + char c_uid[6]; + char c_gid[6]; + char c_nlink[6]; + char c_rdev[6]; + char c_mtime[11]; + char c_namesize[6]; + char c_filesize[11]; +}; +}}} + +The fields are identical to those in the old binary format. +The name and file body follow the fixed header. +Unlike the old binary format, there is no additional padding +after the pathname or file contents. +If the files being archived are themselves entirely ASCII, then +the resulting archive will be entirely ASCII, except for the +NUL byte that terminates the name field. +=== New ASCII Format=== +The "new" ASCII format uses 8-byte hexadecimal fields for +all numbers and separates device numbers into separate fields +for major and minor numbers. +{{{ +struct cpio_newc_header { + char c_magic[6]; + char c_ino[8]; + char c_mode[8]; + char c_uid[8]; + char c_gid[8]; + char c_nlink[8]; + char c_mtime[8]; + char c_filesize[8]; + char c_devmajor[8]; + char c_devminor[8]; + char c_rdevmajor[8]; + char c_rdevminor[8]; + char c_namesize[8]; + char c_check[8]; +}; +}}} + +Except as specified below, the fields here match those specified +for the old binary format above. +<dl> +<dt>_magic_</dt><dd> +The string +"070701". +</dd><dt>_check_</dt><dd> +This field is always set to zero by writers and ignored by readers. +See the next section for more details. +</dd></dl> + +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). + +In this format, hardlinked files are handled by setting the +filesize to zero for each entry except the last one that +appears in the archive. +=== New CRC Format=== +The CRC format is identical to the new ASCII format described +in the previous section except that the magic field is set +to +"070702" +and the +_check_ +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. +=== HP variants=== +The +*cpio* +implementation distributed with HPUX used XXXX but stored +device numbers differently XXX. +=== Other Extensions and Variants=== +Sun Solaris uses additional file types to store extended file +data, including ACLs and extended attributes, as special +entries in cpio archives. + +XXX Others? XXX +== BUGS == +The +"CRC" +format is mis-named, as it uses a simple checksum and +not a cyclic redundancy check. + +The old binary format is limited to 16 bits for user id, +group id, device, and inode numbers. +It is limited to 4 gigabyte file sizes. + +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. + +The new ASCII format is limited to 4 gigabyte file sizes. + +None of the cpio formats store user or group names, +which are essential when moving files between systems with +dissimilar user or group numbering. + +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. +== SEE ALSO == +*cpio*(1), +*tar*(5) +== STANDARDS == +The +*cpio* +utility is no longer a part of POSIX or the Single Unix Standard. +It last appeared in +Version 2 of the Single UNIX Specification (``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. +== HISTORY == +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 1.0, the +"Programmer's Work Bench" +derived from +At v6 +that was used internally at AT&T. +Both the old 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 "newc" appear? Who invented it? When did HP come out with their variant? When did Sun introduce ACLs and extended attributes? XXX |