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diff --git a/libarchive/libarchive-2.8.0/doc/man/cpio.5 b/libarchive/libarchive-2.8.0/doc/man/cpio.5 new file mode 100644 index 0000000..922df01 --- /dev/null +++ b/libarchive/libarchive-2.8.0/doc/man/cpio.5 @@ -0,0 +1,329 @@ +.TH CPIO 5 "October 5, 2007" "" +.SH NAME +.ad l +\fB\%cpio\fP +\- format of cpio archive files +.SH DESCRIPTION +.ad l +The +\fB\%cpio\fP +archive format collects any number of files, directories, and other +file system objects (symbolic links, device nodes, etc.) into a single +stream of bytes. +.SS General Format +Each file system object in a +\fB\%cpio\fP +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 +\fIstruct\fP stat. +(See +\fBstat\fP(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!!!''. +.SS PWB format +XXX Any documentation of the original PWB/UNIX 1.0 format? XXX +.SS Old Binary Format +The old binary +\fB\%cpio\fP +format stores numbers as 2-byte and 4-byte binary values. +Each entry begins with a header in the following format: +.RS 4 +.nf +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]; +}; +.RE +.PP +The +\fIunsigned\fP short +fields here are 16-bit integer values; the +\fIunsigned\fP int +fields are 32-bit integer values. +The fields are as follows +.RS 5 +.TP +\fImagic\fP +The integer value octal 070707. +This value can be used to determine whether this archive is +written with little-endian or big-endian integers. +.TP +\fIdev\fP, \fIino\fP +The device and inode numbers from the disk. +These are used by programs that read +\fB\%cpio\fP +archives to determine when two entries refer to the same file. +Programs that synthesize +\fB\%cpio\fP +archives should be careful to set these to distinct values for each entry. +.TP +\fImode\fP +The mode specifies both the regular permissions and the file type. +It consists of several bit fields as follows: +.RS 5 +.TP +0170000 +This masks the file type bits. +.TP +0140000 +File type value for sockets. +.TP +0120000 +File type value for symbolic links. +For symbolic links, the link body is stored as file data. +.TP +0100000 +File type value for regular files. +.TP +0060000 +File type value for block special devices. +.TP +0040000 +File type value for directories. +.TP +0020000 +File type value for character special devices. +.TP +0010000 +File type value for named pipes or FIFOs. +.TP +0004000 +SUID bit. +.TP +0002000 +SGID bit. +.TP +0001000 +Sticky bit. +On some systems, this modifies the behavior of executables and/or directories. +.TP +0000777 +The lower 9 bits specify read/write/execute permissions +for world, group, and user following standard POSIX conventions. +.RE +.TP +\fIuid\fP, \fIgid\fP +The numeric user id and group id of the owner. +.TP +\fInlink\fP +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. +.TP +\fIrdev\fP +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. +.TP +\fImtime\fP +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. +.TP +\fInamesize\fP +The number of bytes in the pathname that follows the header. +This count includes the trailing NUL byte. +.TP +\fIfilesize\fP +The size of the file. +Note that this archive format is limited to +four gigabyte file sizes. +See +\fImtime\fP +above for a description of the storage of four-byte integers. +.RE +.PP +The pathname immediately follows the fixed header. +If the +\fBnamesize\fP +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. +.PP +Hardlinked files are not given special treatment; +the full file contents are included with each copy of the +file. +.SS 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. +.RS 4 +.nf +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]; +}; +.RE +.PP +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. +.SS 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. +.RS 4 +.nf +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]; +}; +.RE +.PP +Except as specified below, the fields here match those specified +for the old binary format above. +.RS 5 +.TP +\fImagic\fP +The string +``070701''. +.TP +\fIcheck\fP +This field is always set to zero by writers and ignored by readers. +See the next section for more details. +.RE +.PP +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). +.PP +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. +.SS 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 +\fIcheck\fP +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. +.SS HP variants +The +\fB\%cpio\fP +implementation distributed with HPUX used XXXX but stored +device numbers differently XXX. +.SS 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. +.PP +XXX Others? XXX +.SH BUGS +.ad l +The +``CRC'' +format is mis-named, as it uses a simple checksum and +not a cyclic redundancy check. +.PP +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. +.PP +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. +.PP +The new ASCII format is limited to 4 gigabyte file sizes. +.PP +None of the cpio formats store user or group names, +which are essential when moving files between systems with +dissimilar user or group numbering. +.PP +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. +.SH SEE ALSO +.ad l +\fBcpio\fP(1), +\fBtar\fP(5) +.SH STANDARDS +.ad l +The +\fB\%cpio\fP +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 +\fBpax\fP(1). +The portable ASCII format is currently part of the specification for the +\fBpax\fP(1) +utility. +.SH HISTORY +.ad l +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 |