node-tar

Fast and full-featured Tar for Node.js

The API is designed to mimic the behavior of tar(1) on unix systems.
If you are familiar with how tar works, most of this will hopefully be
straightforward for you. If not, then hopefully this module can teach
you useful unix skills that may come in handy someday :)

Background

A "tar file" or "tarball" is an archive of file system entries
(directories, files, links, etc.) The name comes from "tape archive".
If you run man tar on almost any Unix command line, you'll learn
quite a bit about what it can do, and its history.

Tar has 5 main top-level commands:

c Create an archive
r Replace entries within an archive
u Update entries within an archive (ie, replace if they're newer)
t List out the contents of an archive
x Extract an archive to disk

The other flags and options modify how this top level function works.

High-Level API

These 5 functions are the high-level API. All of them have a
single-character name (for unix nerds familiar with tar(1)) as well
as a long name (for everyone else).

All the high-level functions take the following arguments, all three
of which are optional and may be omitted.

options - An optional object specifying various options
paths - An array of paths to add or extract
callback - Called when the command is completed, if async. (If
sync or no file specified, providing a callback throws a
TypeError.)

If the command is sync (ie, if options.sync=true), then the
callback is not allowed, since the action will be completed immediately.

If a file argument is specified, and the command is async, then a
Promise is returned. In this case, if async, a callback may be
provided which is called when the command is completed.

If a file option is not specified, then a stream is returned. For
create, this is a readable stream of the generated archive. For
list and extract this is a writable stream that an archive should
be written into. If a file is not specified, then a callback is not
allowed, because you're already getting a stream to work with.

replace and update only work on existing archives, and so require
a file argument.

Sync commands without a file argument return a stream that acts on its
input immediately in the same tick. For readable streams, this means
that all of the data is immediately available by calling
stream.read(). For writable streams, it will be acted upon as soon
as it is provided, but this can be at any time.

Warnings

Some things cause tar to emit a warning, but should usually not cause
the entire operation to fail. There are three ways to handle
warnings:

Ignore them (default) Invalid entries won't be put in the
archive, and invalid entries won't be unpacked. This is usually
fine, but can hide failures that you might care about.
Notice them Add an onwarn function to the options, or listen
to the 'warn' event on any tar stream. The function will get
called as onwarn(message, data). Handle as appropriate.
Explode them. Set strict: true in the options object, and
warn messages will be emitted as 'error' events instead. If
there's no error handler, this causes the program to crash. If
used with a promise-returning/callback-taking method, then it'll
send the error to the promise/callback.

Examples

The API mimics the tar(1) command line functionality, with aliases
for more human-readable option and function names. The goal is that
if you know how to use tar(1) in Unix, then you know how to use
require('tar') in JavaScript.

To replicate tar czf my-tarball.tgz files and folders, you'd do:

tar.c(
  {
    gzip: <true|gzip options>,
    file: 'my-tarball.tgz'
  },
  ['some', 'files', 'and', 'folders']
).then(_ => { .. tarball has been created .. })

To replicate tar cz files and folders > my-tarball.tgz, you'd do:

tar.c( // or tar.create
  {
    gzip: <true|gzip options>
  },
  ['some', 'files', 'and', 'folders']
).pipe(fs.createWriteStream('my-tarball.tgz'))

To replicate tar xf my-tarball.tgz you'd do:

tar.x(  // or tar.extract(
  {
    file: 'my-tarball.tgz'
  }
).then(_=> { .. tarball has been dumped in cwd .. })

To replicate cat my-tarball.tgz | tar x -C some-dir --strip=1:

fs.createReadStream('my-tarball.tgz').pipe(
  tar.x({
    strip: 1,
    C: 'some-dir' // alias for cwd:'some-dir', also ok
  })
)

To replicate tar tf my-tarball.tgz, do this:

tar.t({
  file: 'my-tarball.tgz',
  onentry: entry => { .. do whatever with it .. }
})

To replicate cat my-tarball.tgz | tar t do:

fs.createReadStream('my-tarball.tgz')
  .pipe(tar.t())
  .on('entry', entry => { .. do whatever with it .. })

To do anything synchronous, add sync: true to the options. Note
that sync functions don't take a callback and don't return a promise.
When the function returns, it's already done. Sync methods without a
file argument return a sync stream, which flushes immediately. But,
of course, it still won't be done until you .end() it.

To filter entries, add filter: <function> to the options.
Tar-creating methods call the filter with filter(path, stat).
Tar-reading methods (including extraction) call the filter with
filter(path, entry). The filter is called in the this-context of
the Pack or Unpack stream object.

The arguments list to tar t and tar x specify a list of filenames
to extract or list, so they're equivalent to a filter that tests if
the file is in the list.

For those who aren't fans of tar's single-character command names:

tar.c === tar.create
tar.r === tar.replace (appends to archive, file is required)
tar.u === tar.update (appends if newer, file is required)
tar.x === tar.extract
tar.t === tar.list

Keep reading for all the command descriptions and options, as well as
the low-level API that they are built on.

tar.c(options, fileList, callback) [alias: tar.create]

Create a tarball archive.

The fileList is an array of paths to add to the tarball. Adding a
directory also adds its children recursively.

An entry in fileList that starts with an @ symbol is a tar archive
whose entries will be added. To add a file that starts with @,
prepend it with ./.

The following options are supported:

file Write the tarball archive to the specified filename. If this
is specified, then the callback will be fired when the file has been
written, and a promise will be returned that resolves when the file
is written. If a filename is not specified, then a Readable Stream
will be returned which will emit the file data. [Alias: f]
sync Act synchronously. If this is set, then any provided file
will be fully written after the call to tar.c. If this is set,
and a file is not provided, then the resulting stream will already
have the data ready to read or emit('data') as soon as you
request it.
onwarn A function that will get called with (message, data) for
any warnings encountered.
strict Treat warnings as crash-worthy errors. Default false.
cwd The current working directory for creating the archive.
Defaults to process.cwd(). [Alias: C]
prefix A path portion to prefix onto the entries in the archive.
gzip Set to any truthy value to create a gzipped archive, or an
object with settings for zlib.Gzip() [Alias: z]
filter A function that gets called with (path, stat) for each
entry being added. Return true to add the entry to the archive,
or false to omit it.
portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths. [Alias: P]
mode The mode to set on the created file archive
noDirRecurse Do not recursively archive the contents of
directories. [Alias: n]
follow Set to true to pack the targets of symbolic links. Without
this option, symbolic links are archived as such. [Alias: L, h]
noPax Suppress pax extended headers. Note that this means that
long paths and linkpaths will be truncated, and large or negative
numeric values may be interpreted incorrectly.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.
[Alias: m, no-mtime]
mtime Set to a Date object to force a specific mtime for
everything added to the archive. Overridden by noMtime.

The following options are mostly internal, but can be modified in some
advanced use cases, such as re-using caches between runs.

linkCache A Map object containing the device and inode value for
any file whose nlink is > 1, to identify hard links.
statCache A Map object that caches calls lstat.
readdirCache A Map object that caches calls to readdir.
jobs A number specifying how many concurrent jobs to run.
Defaults to 4.
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.

tar.x(options, fileList, callback) [alias: tar.extract]

Extract a tarball archive.

The fileList is an array of paths to extract from the tarball. If
no paths are provided, then all the entries are extracted.

If the archive is gzipped, then tar will detect this and unzip it.

Note that all directories that are created will be forced to be
writable, readable, and listable by their owner, to avoid cases where
a directory prevents extraction of child entries by virtue of its
mode.

Most extraction errors will cause a warn event to be emitted. If
the cwd is missing, or not a directory, then the extraction will
fail completely.

The following options are supported:

cwd Extract files relative to the specified directory. Defaults
to process.cwd(). If provided, this must exist and must be a
directory. [Alias: C]
file The archive file to extract. If not specified, then a
Writable stream is returned where the archive data should be
written. [Alias: f]
sync Create files and directories synchronously.
strict Treat warnings as crash-worthy errors. Default false.
filter A function that gets called with (path, entry) for each
entry being unpacked. Return true to unpack the entry from the
archive, or false to skip it.
newer Set to true to keep the existing file on disk if it's newer
than the file in the archive. [Alias: keep-newer,
keep-newer-files]
keep Do not overwrite existing files. In particular, if a file
appears more than once in an archive, later copies will not
overwrite earlier copies. [Alias: k, keep-existing]
preservePaths Allow absolute paths, paths containing .., and
extracting through symbolic links. By default, / is stripped from
absolute paths, .. paths are not extracted, and any file whose
location would be modified by a symbolic link is not extracted.
[Alias: P]
unlink Unlink files before creating them. Without this option,
tar overwrites existing files, which preserves existing hardlinks.
With this option, existing hardlinks will be broken, as will any
symlink that would affect the location of an extracted file. [Alias:
U]
strip Remove the specified number of leading path elements.
Pathnames with fewer elements will be silently skipped. Note that
the pathname is edited after applying the filter, but before
security checks. [Alias: strip-components, stripComponents]
onwarn A function that will get called with (message, data) for
any warnings encountered.
preserveOwner If true, tar will set the uid and gid of
extracted entries to the uid and gid fields in the archive.
This defaults to true when run as root, and false otherwise. If
false, then files and directories will be set with the owner and
group of the user running the process. This is similar to -p in
tar(1), but ACLs and other system-specific data is never unpacked
in this implementation, and modes are set by default already.
[Alias: p]
uid Set to a number to force ownership of all extracted files and
folders, and all implicitly created directories, to be owned by the
specified user id, regardless of the uid field in the archive.
Cannot be used along with preserveOwner. Requires also setting a
gid option.
gid Set to a number to force ownership of all extracted files and
folders, and all implicitly created directories, to be owned by the
specified group id, regardless of the gid field in the archive.
Cannot be used along with preserveOwner. Requires also setting a
uid option.
noMtime Set to true to omit writing mtime value for extracted
entries. [Alias: m, no-mtime]
transform Provide a function that takes an entry object, and
returns a stream, or any falsey value. If a stream is provided,
then that stream's data will be written instead of the contents of
the archive entry. If a falsey value is provided, then the entry is
written to disk as normal. (To exclude items from extraction, use
the filter option described above.)
onentry A function that gets called with (entry) for each entry
that passes the filter.

The following options are mostly internal, but can be modified in some
advanced use cases, such as re-using caches between runs.

maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.
umask Filter the modes of entries like process.umask().
dmode Default mode for directories
fmode Default mode for files
dirCache A Map object of which directories exist.
maxMetaEntrySize The maximum size of meta entries that is
supported. Defaults to 1 MB.

Note that using an asynchronous stream type with the transform
option will cause undefined behavior in sync extractions.
MiniPass-based streams are designed for this
use case.

tar.t(options, fileList, callback) [alias: tar.list]

List the contents of a tarball archive.

The fileList is an array of paths to list from the tarball. If
no paths are provided, then all the entries are listed.

If the archive is gzipped, then tar will detect this and unzip it.

Returns an event emitter that emits entry events with
tar.ReadEntry objects. However, they don't emit 'data' or 'end'
events. (If you want to get actual readable entries, use the
tar.Parse class instead.)

The following options are supported:

cwd Extract files relative to the specified directory. Defaults
to process.cwd(). [Alias: C]
file The archive file to list. If not specified, then a
Writable stream is returned where the archive data should be
written. [Alias: f]
sync Read the specified file synchronously. (This has no effect
when a file option isn't specified, because entries are emitted as
fast as they are parsed from the stream anyway.)
strict Treat warnings as crash-worthy errors. Default false.
filter A function that gets called with (path, entry) for each
entry being listed. Return true to emit the entry from the
archive, or false to skip it.
onentry A function that gets called with (entry) for each entry
that passes the filter. This is important for when both file and
sync are set, because it will be called synchronously.
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.
noResume By default, entry streams are resumed immediately after
the call to onentry. Set noResume: true to suppress this
behavior. Note that by opting into this, the stream will never
complete until the entry data is consumed.

tar.u(options, fileList, callback) [alias: tar.update]

Add files to an archive if they are newer than the entry already in
the tarball archive.

The fileList is an array of paths to add to the tarball. Adding a
directory also adds its children recursively.

An entry in fileList that starts with an @ symbol is a tar archive
whose entries will be added. To add a file that starts with @,
prepend it with ./.

The following options are supported:

file Required. Write the tarball archive to the specified
filename. [Alias: f]
sync Act synchronously. If this is set, then any provided file
will be fully written after the call to tar.c.
onwarn A function that will get called with (message, data) for
any warnings encountered.
strict Treat warnings as crash-worthy errors. Default false.
cwd The current working directory for adding entries to the
archive. Defaults to process.cwd(). [Alias: C]
prefix A path portion to prefix onto the entries in the archive.
gzip Set to any truthy value to create a gzipped archive, or an
object with settings for zlib.Gzip() [Alias: z]
filter A function that gets called with (path, stat) for each
entry being added. Return true to add the entry to the archive,
or false to omit it.
portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths. [Alias: P]
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.
noDirRecurse Do not recursively archive the contents of
directories. [Alias: n]
follow Set to true to pack the targets of symbolic links. Without
this option, symbolic links are archived as such. [Alias: L, h]
noPax Suppress pax extended headers. Note that this means that
long paths and linkpaths will be truncated, and large or negative
numeric values may be interpreted incorrectly.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.
[Alias: m, no-mtime]
mtime Set to a Date object to force a specific mtime for
everything added to the archive. Overridden by noMtime.

tar.r(options, fileList, callback) [alias: tar.replace]

Add files to an existing archive. Because later entries override
earlier entries, this effectively replaces any existing entries.

The fileList is an array of paths to add to the tarball. Adding a
directory also adds its children recursively.

An entry in fileList that starts with an @ symbol is a tar archive
whose entries will be added. To add a file that starts with @,
prepend it with ./.

The following options are supported:

file Required. Write the tarball archive to the specified
filename. [Alias: f]
sync Act synchronously. If this is set, then any provided file
will be fully written after the call to tar.c.
onwarn A function that will get called with (message, data) for
any warnings encountered.
strict Treat warnings as crash-worthy errors. Default false.
cwd The current working directory for adding entries to the
archive. Defaults to process.cwd(). [Alias: C]
prefix A path portion to prefix onto the entries in the archive.
gzip Set to any truthy value to create a gzipped archive, or an
object with settings for zlib.Gzip() [Alias: z]
filter A function that gets called with (path, stat) for each
entry being added. Return true to add the entry to the archive,
or false to omit it.
portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths. [Alias: P]
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.
noDirRecurse Do not recursively archive the contents of
directories. [Alias: n]
follow Set to true to pack the targets of symbolic links. Without
this option, symbolic links are archived as such. [Alias: L, h]
noPax Suppress pax extended headers. Note that this means that
long paths and linkpaths will be truncated, and large or negative
numeric values may be interpreted incorrectly.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.
[Alias: m, no-mtime]
mtime Set to a Date object to force a specific mtime for
everything added to the archive. Overridden by noMtime.

Low-Level API

class tar.Pack

A readable tar stream.

Has all the standard readable stream interface stuff. 'data' and
'end' events, read() method, pause() and resume(), etc.

constructor(options)

The following options are supported:

onwarn A function that will get called with (message, data) for
any warnings encountered.
strict Treat warnings as crash-worthy errors. Default false.
cwd The current working directory for creating the archive.
Defaults to process.cwd().
prefix A path portion to prefix onto the entries in the archive.
gzip Set to any truthy value to create a gzipped archive, or an
object with settings for zlib.Gzip()
filter A function that gets called with (path, stat) for each
entry being added. Return true to add the entry to the archive,
or false to omit it.
portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths.
linkCache A Map object containing the device and inode value for
any file whose nlink is > 1, to identify hard links.
statCache A Map object that caches calls lstat.
readdirCache A Map object that caches calls to readdir.
jobs A number specifying how many concurrent jobs to run.
Defaults to 4.
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 16 MB.
noDirRecurse Do not recursively archive the contents of
directories.
follow Set to true to pack the targets of symbolic links. Without
this option, symbolic links are archived as such.
noPax Suppress pax extended headers. Note that this means that
long paths and linkpaths will be truncated, and large or negative
numeric values may be interpreted incorrectly.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.
mtime Set to a Date object to force a specific mtime for
everything added to the archive. Overridden by noMtime.

add(path)

Adds an entry to the archive. Returns the Pack stream.

write(path)

Adds an entry to the archive. Returns true if flushed.

end()

Finishes the archive.

class tar.Pack.Sync

Synchronous version of tar.Pack.

class tar.Unpack

A writable stream that unpacks a tar archive onto the file system.

All the normal writable stream stuff is supported. write() and
end() methods, 'drain' events, etc.

'close' is emitted when it's done writing stuff to the file system.

Most unpack errors will cause a warn event to be emitted. If the
cwd is missing, or not a directory, then an error will be emitted.

constructor(options)

cwd Extract files relative to the specified directory. Defaults
to process.cwd(). If provided, this must exist and must be a
directory.
filter A function that gets called with (path, entry) for each
entry being unpacked. Return true to unpack the entry from the
archive, or false to skip it.
newer Set to true to keep the existing file on disk if it's newer
than the file in the archive.
keep Do not overwrite existing files. In particular, if a file
appears more than once in an archive, later copies will not
overwrite earlier copies.
preservePaths Allow absolute paths, paths containing .., and
extracting through symbolic links. By default, / is stripped from
absolute paths, .. paths are not extracted, and any file whose
location would be modified by a symbolic link is not extracted.
unlink Unlink files before creating them. Without this option,
tar overwrites existing files, which preserves existing hardlinks.
With this option, existing hardlinks will be broken, as will any
symlink that would affect the location of an extracted file.
strip Remove the specified number of leading path elements.
Pathnames with fewer elements will be silently skipped. Note that
the pathname is edited after applying the filter, but before
security checks.
onwarn A function that will get called with (message, data) for
any warnings encountered.
umask Filter the modes of entries like process.umask().
dmode Default mode for directories
fmode Default mode for files
dirCache A Map object of which directories exist.
maxMetaEntrySize The maximum size of meta entries that is
supported. Defaults to 1 MB.
preserveOwner If true, tar will set the uid and gid of
extracted entries to the uid and gid fields in the archive.
This defaults to true when run as root, and false otherwise. If
false, then files and directories will be set with the owner and
group of the user running the process. This is similar to -p in
tar(1), but ACLs and other system-specific data is never unpacked
in this implementation, and modes are set by default already.
win32 True if on a windows platform. Causes behavior where
filenames containing <|>? chars are converted to
windows-compatible values while being unpacked.
uid Set to a number to force ownership of all extracted files and
folders, and all implicitly created directories, to be owned by the
specified user id, regardless of the uid field in the archive.
Cannot be used along with preserveOwner. Requires also setting a
gid option.
gid Set to a number to force ownership of all extracted files and
folders, and all implicitly created directories, to be owned by the
specified group id, regardless of the gid field in the archive.
Cannot be used along with preserveOwner. Requires also setting a
uid option.
noMtime Set to true to omit writing mtime value for extracted
entries.
transform Provide a function that takes an entry object, and
returns a stream, or any falsey value. If a stream is provided,
then that stream's data will be written instead of the contents of
the archive entry. If a falsey value is provided, then the entry is
written to disk as normal. (To exclude items from extraction, use
the filter option described above.)
strict Treat warnings as crash-worthy errors. Default false.
onentry A function that gets called with (entry) for each entry
that passes the filter.
onwarn A function that will get called with (message, data) for
any warnings encountered.

class tar.Unpack.Sync

Synchronous version of tar.Unpack.

Note that using an asynchronous stream type with the transform
option will cause undefined behavior in sync unpack streams.
MiniPass-based streams are designed for this
use case.

class tar.Parse

A writable stream that parses a tar archive stream. All the standard
writable stream stuff is supported.

If the archive is gzipped, then tar will detect this and unzip it.

Emits 'entry' events with tar.ReadEntry objects, which are
themselves readable streams that you can pipe wherever.

Each entry will not emit until the one before it is flushed through,
so make sure to either consume the data (with on('data', ...) or
.pipe(...)) or throw it away with .resume() to keep the stream
flowing.

constructor(options)

Returns an event emitter that emits entry events with
tar.ReadEntry objects.

The following options are supported:

strict Treat warnings as crash-worthy errors. Default false.
filter A function that gets called with (path, entry) for each
entry being listed. Return true to emit the entry from the
archive, or false to skip it.
onentry A function that gets called with (entry) for each entry
that passes the filter.
onwarn A function that will get called with (message, data) for
any warnings encountered.

abort(message, error)

Stop all parsing activities. This is called when there are zlib
errors. It also emits a warning with the message and error provided.

class tar.ReadEntry extends MiniPass

A representation of an entry that is being read out of a tar archive.

It has the following fields:

extended The extended metadata object provided to the constructor.
globalExtended The global extended metadata object provided to the
constructor.
remain The number of bytes remaining to be written into the
stream.
blockRemain The number of 512-byte blocks remaining to be written
into the stream.
ignore Whether this entry should be ignored.
meta True if this represents metadata about the next entry, false
if it represents a filesystem object.
All the fields from the header, extended header, and global extended
header are added to the ReadEntry object. So it has path, type,
size,mode`, and so on.

constructor(header, extended, globalExtended)

Create a new ReadEntry object with the specified header, extended
header, and global extended header values.

class tar.WriteEntry extends MiniPass

A representation of an entry that is being written from the file
system into a tar archive.

Emits data for the Header, and for the Pax Extended Header if one is
required, as well as any body data.

Creating a WriteEntry for a directory does not also create
WriteEntry objects for all of the directory contents.

It has the following fields:

path The path field that will be written to the archive. By
default, this is also the path from the cwd to the file system
object.
portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
myuid If supported, the uid of the user running the current
process.
myuser The env.USER string if set, or ''. Set as the entry
uname field if the file's uid matches this.myuid.
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 1 MB.
linkCache A Map object containing the device and inode value for
any file whose nlink is > 1, to identify hard links.
statCache A Map object that caches calls lstat.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths.
cwd The current working directory for creating the archive.
Defaults to process.cwd().
absolute The absolute path to the entry on the filesystem. By
default, this is path.resolve(this.cwd, this.path), but it can be
overridden explicitly.
strict Treat warnings as crash-worthy errors. Default false.
win32 True if on a windows platform. Causes behavior where paths
replace \ with / and filenames containing the windows-compatible
forms of <|>?: characters are converted to actual <|>?: characters
in the archive.
noPax Suppress pax extended headers. Note that this means that
long paths and linkpaths will be truncated, and large or negative
numeric values may be interpreted incorrectly.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.

constructor(path, options)

path is the path of the entry as it is written in the archive.

The following options are supported:

portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
maxReadSize The maximum buffer size for fs.read() operations.
Defaults to 1 MB.
linkCache A Map object containing the device and inode value for
any file whose nlink is > 1, to identify hard links.
statCache A Map object that caches calls lstat.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths.
cwd The current working directory for creating the archive.
Defaults to process.cwd().
absolute The absolute path to the entry on the filesystem. By
default, this is path.resolve(this.cwd, this.path), but it can be
overridden explicitly.
strict Treat warnings as crash-worthy errors. Default false.
win32 True if on a windows platform. Causes behavior where paths
replace \ with /.
onwarn A function that will get called with (message, data) for
any warnings encountered.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.
umask Set to restrict the modes on the entries in the archive,
somewhat like how umask works on file creation. Defaults to
process.umask() on unix systems, or 0o22 on Windows.

warn(message, data)

If strict, emit an error with the provided message.

Othewise, emit a 'warn' event with the provided message and data.

class tar.WriteEntry.Sync

Synchronous version of tar.WriteEntry

class tar.WriteEntry.Tar

A version of tar.WriteEntry that gets its data from a tar.ReadEntry
instead of from the filesystem.

constructor(readEntry, options)

readEntry is the entry being read out of another archive.

The following options are supported:

portable Omit metadata that is system-specific: ctime, atime,
uid, gid, uname, gname, dev, ino, and nlink. Note
that mtime is still included, because this is necessary other
time-based operations.
preservePaths Allow absolute paths. By default, / is stripped
from absolute paths.
strict Treat warnings as crash-worthy errors. Default false.
onwarn A function that will get called with (message, data) for
any warnings encountered.
noMtime Set to true to omit writing mtime values for entries.
Note that this prevents using other mtime-based features like
tar.update or the keepNewer option with the resulting tar archive.

class tar.Header

A class for reading and writing header blocks.

It has the following fields:

nullBlock True if decoding a block which is entirely composed of
0x00 null bytes. (Useful because tar files are terminated by
at least 2 null blocks.)
cksumValid True if the checksum in the header is valid, false
otherwise.
needPax True if the values, as encoded, will require a Pax
extended header.
path The path of the entry.
mode The 4 lowest-order octal digits of the file mode. That is,
read/write/execute permissions for world, group, and owner, and the
setuid, setgid, and sticky bits.
uid Numeric user id of the file owner
gid Numeric group id of the file owner
size Size of the file in bytes
mtime Modified time of the file
cksum The checksum of the header. This is generated by adding all
the bytes of the header block, treating the checksum field itself as
all ascii space characters (that is, 0x20).
type The human-readable name of the type of entry this represents,
or the alphanumeric key if unknown.
typeKey The alphanumeric key for the type of entry this header
represents.
linkpath The target of Link and SymbolicLink entries.
uname Human-readable user name of the file owner
gname Human-readable group name of the file owner
devmaj The major portion of the device number. Always 0 for
files, directories, and links.
devmin The minor portion of the device number. Always 0 for
files, directories, and links.
atime File access time.
ctime File change time.

constructor(data, [offset=0])

data is optional. It is either a Buffer that should be interpreted
as a tar Header starting at the specified offset and continuing for
512 bytes, or a data object of keys and values to set on the header
object, and eventually encode as a tar Header.

decode(block, offset)

Decode the provided buffer starting at the specified offset.

Buffer length must be greater than 512 bytes.

set(data)

Set the fields in the data object.

encode(buffer, offset)

Encode the header fields into the buffer at the specified offset.

Returns this.needPax to indicate whether a Pax Extended Header is
required to properly encode the specified data.

class tar.Pax

An object representing a set of key-value pairs in an Pax extended
header entry.

It has the following fields. Where the same name is used, they have
the same semantics as the tar.Header field of the same name.

global True if this represents a global extended header, or false
if it is for a single entry.
atime
charset
comment
ctime
gid
gname
linkpath
mtime
path
size
uid
uname
dev
ino
nlink

constructor(object, global)

Set the fields set in the object. global is a boolean that defaults
to false.

encode()

Return a Buffer containing the header and body for the Pax extended
header entry, or null if there is nothing to encode.

encodeBody()

Return a string representing the body of the pax extended header
entry.

encodeField(fieldName)

Return a string representing the key/value encoding for the specified
fieldName, or '' if the field is unset.

tar.Pax.parse(string, extended, global)

Return a new Pax object created by parsing the contents of the string
provided.

If the extended object is set, then also add the fields from that
object. (This is necessary because multiple metadata entries can
occur in sequence.)

tar.types

A translation table for the type field in tar headers.

tar.types.name.get(code)

Get the human-readable name for a given alphanumeric code.

tar.types.code.get(name)

Get the alphanumeric code for a given human-readable name.