sbase/tar.1

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Audit tar(1), add DIRFIRST-flag to recurse() I've been wanting to do this for a while now, as tar(1) used to be one of messiest and cruftiest tools. First off, before walking through the audit, I'll talk about what the DIRFIRST-flag for recurse() does. It basically calls fn() on the first-level-dir before calling it's subentries. It's necessary here, because else the order of the tar-files would've been wrong (it would try to create dir/file before creating dir/). Now, to the audit: 1) Update manpage, fix mistake that compression is also available for compressing. It's only available for extracting. 2) Define the major, minor and makedev macros from glibc by ourselves. No need to rely on them, as they are common sense. decomp() 3) Simple refactorization. putoctal() 4) Add a truncation check for snprintf(). archive() 5) BUGFIX: Add checks to any checkable function, don't blindly call them, this is harmful and there are 100 ways to exploit that. 6) Use estrlcpy() instead of snprintf() wherever possible, fix alignment. 7) BUGFIX: Terminate the result-buffer of readlink(), check if it even succeeded. 8) Fix sizeof()-formatting. unarchive() 9) BUGFIX: Add checks to any checkable function, don't blindly call them, this is harmful and there are 100 ways to exploit that. 10) BUGFIX: strtoul can happily return negative numbers. Add checks for that and also if the full string has been processed. 11) Remove calls to perror(). We have eprintf, use it. 12) BUGFIX: "minor = strtoul(h->mode, 0, 8);". We need h->minor of course. 13) Fix typo "usupported", remove fprintf-call. print() 14) Check fread(). xt() 15) Get rid of snprintf-magic. Use estrlcat(). 16) BUGFIX: check for ferror() on the tarfile. usage() 17) Update it. The old usage() was like 1000 years old. main() 18) Add DIRFIRST-flag to the recursor. 19) Don't print usage() when a mode is re-set. We allow this in general. 20) Add function checks and fix error messages. 21) Add tarfilename-global for proper error-messages.
2015-03-21 00:03:35 +00:00
.Dd March 21, 2015
.Dt TAR 1
.Os sbase
.Sh NAME
.Nm tar
.Nd create, list or extract a tape archive
.Sh SYNOPSIS
.Nm
.Op Fl C Ar dir
.Op Fl j | Fl z
.Fl x Op Fl m | Fl t
.Op Fl f Ar file
.Nm
.Op Fl C Ar dir
.Op Fl h
.Fl c Ar dir
.Op Fl f Ar file
.Sh DESCRIPTION
.Nm
is the standard file archiver.
.Sh OPTIONS
.Bl -tag -width Ds
.It Fl c Ar path
Create archive from
.Ar path .
.It Fl C Ar dir
Change directory to
.Ar dir
before beginning.
.It Fl f Ar file
Set
.Ar file
as input | output archive instead of stdin | stdout.
.It Fl m
Do not preserve modification time.
.It Fl t
List all files in the archive.
.It Fl x
Extract archive.
.It Fl h
Always dereference symbolic links while recursively traversing directories.
.It Fl j | Fl z
Audit tar(1), add DIRFIRST-flag to recurse() I've been wanting to do this for a while now, as tar(1) used to be one of messiest and cruftiest tools. First off, before walking through the audit, I'll talk about what the DIRFIRST-flag for recurse() does. It basically calls fn() on the first-level-dir before calling it's subentries. It's necessary here, because else the order of the tar-files would've been wrong (it would try to create dir/file before creating dir/). Now, to the audit: 1) Update manpage, fix mistake that compression is also available for compressing. It's only available for extracting. 2) Define the major, minor and makedev macros from glibc by ourselves. No need to rely on them, as they are common sense. decomp() 3) Simple refactorization. putoctal() 4) Add a truncation check for snprintf(). archive() 5) BUGFIX: Add checks to any checkable function, don't blindly call them, this is harmful and there are 100 ways to exploit that. 6) Use estrlcpy() instead of snprintf() wherever possible, fix alignment. 7) BUGFIX: Terminate the result-buffer of readlink(), check if it even succeeded. 8) Fix sizeof()-formatting. unarchive() 9) BUGFIX: Add checks to any checkable function, don't blindly call them, this is harmful and there are 100 ways to exploit that. 10) BUGFIX: strtoul can happily return negative numbers. Add checks for that and also if the full string has been processed. 11) Remove calls to perror(). We have eprintf, use it. 12) BUGFIX: "minor = strtoul(h->mode, 0, 8);". We need h->minor of course. 13) Fix typo "usupported", remove fprintf-call. print() 14) Check fread(). xt() 15) Get rid of snprintf-magic. Use estrlcat(). 16) BUGFIX: check for ferror() on the tarfile. usage() 17) Update it. The old usage() was like 1000 years old. main() 18) Add DIRFIRST-flag to the recursor. 19) Don't print usage() when a mode is re-set. We allow this in general. 20) Add function checks and fix error messages. 21) Add tarfilename-global for proper error-messages.
2015-03-21 00:03:35 +00:00
Use bzip2 | gzip decompression. The
.Xr bzip2 1 |
.Xr gzip 1
utilities must be installed separately.
Using these flags is discouraged in favour of the flexibility
and clarity of pipes:
.Bd -literal -offset indent
$ bzcat archive.tar.bz2 | tar -x
$ zcat archive.tar.gz | tar -x
.Ed
.Bd -literal -offset indent
$ tar -c file ... | bzip2 > archive.tar.bz2
$ tar -c file ... | gzip2 > archive.tar.gz
.Ed
.El
.Sh SEE ALSO
.Xr ar 1 ,
.Xr bzip2 1 ,
.Xr gzip 1
.Sh STANDARDS
The
.Nm
utility is compliant with the UStar (Uniform Standard Tape ARchive)
format defined in the
.St -p1003.1-88
specification.