Difference between pages "Gzip" and "Mac OS X"

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== File format ==
+
Apple Inc.'s Macintosh OS X (pronounced "'''OS Ten'''") is the operating system distributed with Apple computers. It includes heavily used several programs by default, including [[Apple Mail]], a web browser called [[Apple Safari | Safari]], and an [[Apple Address Book]], and [[iCal]].
The gzip file (.gz) format consists of:
+
* a file header
+
* optional headers
+
** extra fields
+
** original file name
+
** comment
+
** header checksum
+
* compressed data (commonly used compression method DEFLATE, without zlib header)
+
* a file footer
+
  
{| class="wikitable"
+
== EFI boot ==
! align="left"| Characteristics
+
* Configuration in nvram
! Description
+
|-
+
| Byte order
+
| little-endian
+
|-
+
| Date and time values
+
| POSIX timestamp <br> Number of seconds since January 1, 1970 00:00:00 UTC
+
|-
+
| Character strings
+
| ISO 8859-1 (LATIN-1)
+
|}
+
  
=== File header ===
+
The firmware looks for the boot partition in nvram.
The file header is 10 bytes in size and contains:
+
{| class="wikitable"
+
! align="left"| Offset
+
! Size
+
! Value
+
! Description
+
|-
+
| 0
+
| 2
+
| 0x1f 0x8b
+
| Signature (or identification byte 1 and 2)
+
|-
+
| 2
+
| 1
+
|
+
| Compression Method
+
|-
+
| 3
+
| 1
+
|
+
| Flags
+
|-
+
| 4
+
| 4
+
|
+
| Last modification time <br> Contains a POSIX timestamp.
+
|-
+
| 8
+
| 1
+
|
+
| Compression flags (or extra flags)
+
|-
+
| 9
+
| 1
+
|
+
| Operating system <br> Value that indicates on which operating system the gzip file was created.
+
|}
+
  
==== Compression method ====
+
Mac OS X EFI boot process supports both MZ-PE/COFF and EFI fat binary type [[Executable executables]].
 +
<pre>
 +
/com.apple.recovery.boot/boot.efi
 +
/System/Library/CoreServices/boot.efi
 +
/usr/standalone/i386/boot.efi
 +
</pre>
  
{| class="wikitable"
+
== Disk image types ==
! align="left"| Value
+
! Identifier
+
! Description
+
|-
+
| 0 - 7
+
|
+
| Reserved
+
|-
+
| 8
+
| deflate
+
| deflate compressed data
+
|}
+
  
==== Flags ====
+
Mac OS X has support for various disk image types build-in, some of which are:
 +
* read-write disk image (.dmg) some of which use the [[Raw Image Format]]
 +
* [[Sparse Image format|Sparse disk image (.spareimage)]]
 +
* [[Sparse Bundle Image format|Sparse bundle disk image (.sparsebundle)]]
  
{| class="wikitable"
+
== Burn Folder ==
! align="left"| Value
+
! Identifier
+
! Description
+
|-
+
| 0x01
+
| FTEXT
+
| If set the uncompressed data needs to be treated as text instead of binary data. <br> This flag hints end-of-line conversion for cross-platform text files but does not enforce it.
+
|-
+
| 0x02
+
| FHCRC
+
| The file contains a header checksum (CRC-16)
+
|-
+
| 0x04
+
| FEXTRA
+
| The file contains extra fields
+
|-
+
| 0x08
+
| FNAME
+
| The file contains an original file name string
+
|-
+
| 0x10
+
| FCOMMENT
+
| The file contains comment
+
|-
+
| 0x20
+
|
+
| Reserved
+
|-
+
| 0x40
+
|
+
| Reserved
+
|-
+
| 0x80
+
|
+
| Reserved
+
|}
+
  
<b>Notes:</b>
+
Mac OS X Burn Folder:
* Reserved flags bits must be zero.
+
<pre>
* The FHCRC bit was never set by versions of gzip up to 1.2.4, even though it was documented with a different meaning in gzip 1.2.4.
+
$NAME.fpbf
 +
</pre>
  
==== Compression flags ====
+
This folder normally contains [[Mac OS X Alias Files|alias files]] (similar to LNK files under Windows). Which should have the following signature.
This value contains flags specific to the compression method.
+
<pre>
 +
00000000  62 6f 6f 6b 00 00 00 00  6d 61 72 6b 00 00 00 00  |book....mark....|
 +
</pre>
  
===== Compression flags - deflate =====
+
These [[Mac OS X Alias Files|alias files]] contain additional date and time values.
If compression method value is 8 (deflate) the following compression flags can be used:
+
{| class="wikitable"
+
! align="left"| Value
+
! Identifier
+
! Description
+
|-
+
| 0x02
+
|
+
| compressor used maximum compression, slowest algorithm
+
|-
+
| 0x04
+
|
+
| compressor used fastest algorithm
+
|}
+
  
==== Operating System ====
+
Also check the following files for references to deleted .fpbf paths:
{| class="wikitable"
+
<pre>
! align="left"| Value
+
/Users/$USERNAME/Library/Preferences/com.apple.finder.plist
! Identifier
+
/Users/$USERNAME/Library/Preferences/com.apple.sidebarlists.plist
! Description
+
</pre>
|-
+
| 0
+
|
+
| FAT filesystem (MS-DOS, OS/2, NT/Win32)
+
|-
+
| 1
+
|
+
| Amiga
+
|-
+
| 2
+
|
+
| VMS (or OpenVMS)
+
|-
+
| 3
+
|
+
| Unix
+
|-
+
| 4
+
|
+
| VM/CMS
+
|-
+
| 5
+
|
+
| Atari TOS
+
|-
+
| 6
+
|
+
| HPFS filesystem (OS/2, NT)
+
|-
+
| 7
+
|
+
| Macintosh
+
|-
+
| 8
+
|
+
| Z-System
+
|-
+
| 9
+
|
+
| CP/M
+
|-
+
| 10
+
|
+
| TOPS-20
+
|-
+
| 11
+
|
+
| NTFS filesystem (NT)
+
|-
+
| 12
+
|
+
| QDOS
+
|-
+
| 13
+
|
+
| Acorn RISCOS
+
|-
+
| 255
+
|
+
| unknown
+
|}
+
  
=== Optional headers ===
+
Actual burning of optical media is logged in:
==== Extra fields ====
+
<pre>
This value is present in the file if the FEXTRA flag is set in the file header flags.
+
/var/log/system.log
 +
/Users/$USERNAME/Library/Logs/DiscRecording.log
 +
/private/var/.logs_exporter/cache/Users/$USERNAME/Library/Logs/DiscRecording.log
 +
</pre>
  
The extra field are variable of size and contains:
+
== HFS/HFS+ date and time values ==
{| class="wikitable"
+
! align="left"| Offset
+
! Size
+
! Value
+
! Description
+
|-
+
| 0
+
| 2
+
|
+
| Extra field data size <br> Value in bytes.
+
|-
+
| 2
+
| ...
+
|
+
| Extra field data
+
|}
+
  
==== Original file name ====
+
In HFS+ date and time values are stored in an unsigned 32-bit integer containing the number of seconds since January 1, 1904 at 00:00:00 (midnight) UTC (GMT). This is slightly different from HFS where the date and time value are stored using the local time. The maximum representable date is February 6, 2040 at 06:28:15 UTC (GMT). The date values do not account for leap seconds. They do include a leap day in every year that is evenly divisible by four. This is sufficient given that the range of representable dates does not contain 1900 or 2100, neither of which have leap days. Also see: [http://web.archive.org/web/20090214212148/http://developer.apple.com/technotes/tn/tn1150.html Technical Note TN1150 - HFS Plus Volume Format]
This value is present in the file if the FNAME flag is set in the file header flags.
+
  
This is the original name of the file being compressed, with any directory components removed, and, if the file being compressed is on a file system with case insensitive names, forced to lower case.
+
Converting HFS/HFS+ date and time values with Python:
 +
<pre>
 +
import datetime
  
Contains an ISO 8859-1 (LATIN-1) string with end-of-string character.
+
print datetime.datetime( 1904, 1, 1 ) + datetime.timedelta( seconds=0xCBDAF25B )
 +
</pre>
  
==== Comment ====
+
== Launch Agents ==
This value is present in the file if the FCOMMENT flag is set in the file header flags.
+
System-wide:
 +
<pre>
 +
/Library/LaunchAgents
 +
/System/Library/LaunchAgents
 +
</pre>
  
Contains an ISO 8859-1 (LATIN-1) string with end-of-string character. Line breaks should be denoted by a single line feed character.
+
Per user:
 +
<pre>
 +
/Users/$USERNAME/Library/LaunchAgents
 +
</pre>
  
==== Header checksum ====
+
These directories contain [[Property list (plist)]] files.
The header checksum contain a CRC-16 that consists of the two least significant bytes of the CRC-32 for all bytes of the gzip header up to and not including the CRC-16.
+
  
=== File footer ===
+
== Launch Daemons ==
The file footer is 8 bytes in size and contains:
+
System-wide:
{| class="wikitable"
+
<pre>
! align="left"| Offset
+
/Library/LaunchDaemons
! Size
+
/System/Library/LaunchDaemons
! Value
+
</pre>
! Description
+
|-
+
| 0
+
| 4
+
|
+
| Checksum (CRC-32)
+
|-
+
| 4
+
| 4
+
|
+
| Uncompressed data size <br> Value in bytes.
+
|}
+
  
== See Also ==
+
These directories contain [[Property list (plist)]] files.
* [[bzip2]]
+
 
* [[tar]]
+
== Startup Items ==
 +
<pre>
 +
/Library/StartupItems/
 +
/System/Library/StartupItems/
 +
</pre>
 +
 
 +
== Crash Reporter ==
 +
<pre>
 +
/Library/Application Support/CrashReporter
 +
</pre>
 +
 
 +
Contains text files named .crash, .diag, .spin
 +
 
 +
== Diagnostic Reports ==
 +
<pre>
 +
/Library/Logs/DiagnosticReports
 +
</pre>
 +
 
 +
== Internet Plug-Ins ==
 +
System-wide:
 +
<pre>
 +
/Library/Internet Plug-Ins
 +
</pre>
 +
 
 +
Per user:
 +
<pre>
 +
/Users/$USERNAME/Library/Internet Plug-Ins
 +
</pre>
 +
 
 +
== Quarantine event database ==
 +
See [http://menial.co.uk/blog/2011/06/16/mac-quarantine-event-database/]
 +
 
 +
Snow Leopard and earlier
 +
<pre>
 +
/Users/$USER/Library/Preferences/com.apple.LaunchServices.QuarantineEvents
 +
</pre>
 +
 
 +
<pre>
 +
SELECT datetime(LSQuarantineTimeStamp + 978307200, "unixepoch") as LSQuarantineTimeStamp, LSQuarantineAgentName, LSQuarantineOriginURLString, LSQuarantineDataURLString from LSQuarantineEvent;
 +
</pre>
 +
 
 +
Lion and later
 +
<pre>
 +
/Users/$USER/Library/Preferences/com.apple.LaunchServices.QuarantineEventsV2
 +
</pre>
 +
 
 +
== sleepimage ==
 +
This file is similar to the hibernation file on Windows.
 +
<pre>
 +
/private/var/vm/sleepimage
 +
</pre>
 +
 
 +
Also see: [http://osxdaily.com/2010/10/11/sleepimage-mac/]
 +
 
 +
== Last shutdown logs ==
 +
<pre>
 +
/private/var/log/com.apple.launchd/launchd-shutdown.system.log
 +
/private/var/log/com.apple.launchd/launchd-shutdown.system.log.1
 +
</pre>
 +
 
 +
== Package Files (.PKG) ==
 +
Package Files (.PKG) are XAR archives [http://en.wikipedia.org/wiki/Xar_(archiver)] that contain a cpio archive and metadata [http://s.sudre.free.fr/Stuff/Ivanhoe/FLAT.html].
 +
 
 +
== Also see ==
 +
* [[MacOS Process Monitoring]]
 +
* [[Acquiring a MacOS System with Target Disk Mode]]
 +
* [[Converting Binary Plists]]
 +
* [[FileVault Disk Encryption]]
 +
* [[File Vault]]
 +
 
 +
=== Formats ===
 +
* [[Basic Security Module (BSM) file format]]
 +
* [[Property list (plist)]]
  
 
== External Links ==
 
== External Links ==
 +
* [http://www.apple.com/macosx/ Official website]
 +
* [http://en.wikipedia.org/wiki/OS_X Wikipedia entry on OS X]
 +
* [http://menial.co.uk/blog/2011/06/16/mac-quarantine-event-database/ Quarantine event database]
 +
* [http://www2.tech.purdue.edu/cit/Courses/cit556/readings/MacForensicsCraiger.pdf Mac Forensics: Mac OS X and the HFS+ File System] by P. Craiger
 +
* [http://web.me.com/driley/iWeb/Previous_files/Directory_Services_Overview.pdf Mac OS X Directory Services Integration including Active Directory]
 +
* [http://digitalinvestigation.wordpress.com/2012/04/04/geek-post-nskeyedarchiver-files-what-are-they-and-how-can-i-use-them/ NSKeyedArchiver files – what are they, and how can I use them?]
 +
* [http://krypted.com/mac-os-x/command-line-alf-on-mac-os-x/ Command Line ALF on Mac OS X]
 +
* [http://newosxbook.com/DMG.html Demystifying the DMG File Format]
 +
* [https://code.google.com/p/mac-security-tips/wiki/ALL_THE_TIPS mac-security-tips]
 +
 +
=== Apple Examiner ===
 +
* [http://www.appleexaminer.com/ The Apple Examiner]
 +
* [http://www.appleexaminer.com/MacsAndOS/Analysis/USBOSX/USBOSX.html USB Entries on OS X]
 +
* [http://www.appleexaminer.com/Downloads/MacForensics.pdf Macintosh Forensics - A Guide for the Forensically Sound Examination of a Macintosh Computer] by Ryan R. Kubasiak
 +
 +
=== EFI ===
 +
* [http://ho.ax/posts/2012/02/carving-up-efi-fat-binaries/ Carving up EFI fat binaries], by snare, February 24, 2012
  
* [http://www.gzip.org/format.txt The gzip file format], by the [http://www.gzip.org/ gzip project]
+
=== iCloud ===
* [http://www.gzip.org/algorithm.txt The gzip compression algorithm], by the [http://www.gzip.org/ gzip project]
+
* [http://support.apple.com/kb/HT4865?viewlocale=en_US&locale=en_US iCloud: iCloud security and privacy overview]
* [http://tools.ietf.org/html/rfc1952 RFC1952: GZIP file format specification version 4.3], by [[IETF]]
+
* [http://en.wikipedia.org/wiki/Gzip Wikipedia: gzip]
+
  
[[Category:File Formats]]
+
[[Category:Mac OS X]]
 +
[[Category:Operating systems]]

Revision as of 05:03, 25 June 2014

Information icon.png

Please help to improve this article by expanding it.
Further information might be found on the discussion page.

Apple Inc.'s Macintosh OS X (pronounced "OS Ten") is the operating system distributed with Apple computers. It includes heavily used several programs by default, including Apple Mail, a web browser called Safari, and an Apple Address Book, and iCal.

EFI boot

  • Configuration in nvram

The firmware looks for the boot partition in nvram.

Mac OS X EFI boot process supports both MZ-PE/COFF and EFI fat binary type Executable executables.

/com.apple.recovery.boot/boot.efi
/System/Library/CoreServices/boot.efi
/usr/standalone/i386/boot.efi

Disk image types

Mac OS X has support for various disk image types build-in, some of which are:

Burn Folder

Mac OS X Burn Folder:

$NAME.fpbf

This folder normally contains alias files (similar to LNK files under Windows). Which should have the following signature.

00000000  62 6f 6f 6b 00 00 00 00  6d 61 72 6b 00 00 00 00  |book....mark....|

These alias files contain additional date and time values.

Also check the following files for references to deleted .fpbf paths:

/Users/$USERNAME/Library/Preferences/com.apple.finder.plist
/Users/$USERNAME/Library/Preferences/com.apple.sidebarlists.plist

Actual burning of optical media is logged in:

/var/log/system.log
/Users/$USERNAME/Library/Logs/DiscRecording.log
/private/var/.logs_exporter/cache/Users/$USERNAME/Library/Logs/DiscRecording.log

HFS/HFS+ date and time values

In HFS+ date and time values are stored in an unsigned 32-bit integer containing the number of seconds since January 1, 1904 at 00:00:00 (midnight) UTC (GMT). This is slightly different from HFS where the date and time value are stored using the local time. The maximum representable date is February 6, 2040 at 06:28:15 UTC (GMT). The date values do not account for leap seconds. They do include a leap day in every year that is evenly divisible by four. This is sufficient given that the range of representable dates does not contain 1900 or 2100, neither of which have leap days. Also see: Technical Note TN1150 - HFS Plus Volume Format

Converting HFS/HFS+ date and time values with Python:

import datetime

print datetime.datetime( 1904, 1, 1 ) + datetime.timedelta( seconds=0xCBDAF25B )

Launch Agents

System-wide:

/Library/LaunchAgents
/System/Library/LaunchAgents

Per user:

/Users/$USERNAME/Library/LaunchAgents

These directories contain Property list (plist) files.

Launch Daemons

System-wide:

/Library/LaunchDaemons
/System/Library/LaunchDaemons

These directories contain Property list (plist) files.

Startup Items

/Library/StartupItems/
/System/Library/StartupItems/

Crash Reporter

/Library/Application Support/CrashReporter

Contains text files named .crash, .diag, .spin

Diagnostic Reports

/Library/Logs/DiagnosticReports

Internet Plug-Ins

System-wide:

/Library/Internet Plug-Ins

Per user:

/Users/$USERNAME/Library/Internet Plug-Ins

Quarantine event database

See [1]

Snow Leopard and earlier

/Users/$USER/Library/Preferences/com.apple.LaunchServices.QuarantineEvents
SELECT datetime(LSQuarantineTimeStamp + 978307200, "unixepoch") as LSQuarantineTimeStamp, LSQuarantineAgentName, LSQuarantineOriginURLString, LSQuarantineDataURLString from LSQuarantineEvent;

Lion and later

/Users/$USER/Library/Preferences/com.apple.LaunchServices.QuarantineEventsV2

sleepimage

This file is similar to the hibernation file on Windows.

/private/var/vm/sleepimage

Also see: [2]

Last shutdown logs

/private/var/log/com.apple.launchd/launchd-shutdown.system.log
/private/var/log/com.apple.launchd/launchd-shutdown.system.log.1

Package Files (.PKG)

Package Files (.PKG) are XAR archives [3] that contain a cpio archive and metadata [4].

Also see

Formats

External Links

Apple Examiner

EFI

iCloud