Difference between pages "Chrome Disk Cache Format" and "Mac OS X"

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(Data block file format (data_#))
 
 
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== Cache files ==
+
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 cache is stored in multiple:
+
{| class="wikitable"
+
|-
+
! Filename
+
! Description
+
|-
+
| index
+
| The index file
+
|-
+
| data_#
+
| Data block files
+
|-
+
| f_######
+
| (Separate) data stream file
+
|}
+
  
== Cache address ==
+
== EFI boot ==
The cache address is 4 bytes in size and consists of:
+
The firmware is responsible for initializing the hardware and performing a POST (Power-On Self Test).
{| class="wikitable"
+
|-
+
! offset
+
! size
+
! value
+
! description
+
|-
+
| <i>If file type is 0 (Separate file)</i>
+
|
+
|
+
|
+
|-
+
| 0.0
+
| 28 bits
+
|
+
| File number <br> The value represents the value of # in f_######
+
|-
+
| <i>Else</i>
+
|
+
|
+
|
+
|-
+
| 0.0
+
| 16 bits
+
|
+
| Block number
+
|-
+
| 2.0
+
| 8 bits
+
|
+
| File number (or file selector) <br> The value represents the value of # in data_#
+
|-
+
| 3.0
+
| 2 bits
+
|
+
| Block size <br> The number of contiguous blocks where 0 represents 1 block and 3 represents 4 blocks.
+
|-
+
| 3.2
+
| 2 bits
+
|
+
| Reserved
+
|-
+
| <i>Common</i>
+
|
+
|
+
|
+
|-
+
| 3.4
+
| 3 bits
+
|
+
| File type
+
|-
+
| 3.7
+
| 1 bit
+
|
+
| Initialized flag
+
|}
+
  
=== File types ===
+
The default boot volume is stored in NVRAM and can be configured through the "Startup Disk" preference pane or the nvram command line utility [https://developer.apple.com/library/mac/documentation/Darwin/Reference/Manpages/man8/nvram.8.html]. E.g. to print all of the firmware variables.
{| class="wikitable"
+
<pre>
|-
+
nvram -p
! Value
+
</pre>
! Description
+
|-
+
| 0
+
| (Separate) data stream file
+
|-
+
| 1
+
| (Rankings) block data file (36 byte block data file)
+
|-
+
| 2
+
| 256 byte block data file
+
|-
+
| 3
+
| 1024 byte block data file
+
|-
+
| 4
+
| 4096 byte block data file
+
|-
+
|
+
|
+
|-
+
| 6
+
| Unknown; seen on Mac OS  X 0x6f430074
+
|}
+
  
==== Examples ====
+
Additional boot arguments can be provided via the "boot-args" value [http://www.cnet.com/news/boot-argument-options-in-os-x/].
{| class="wikitable"
+
|-
+
! Value
+
! Description
+
|-
+
| 0x00000000
+
| Not initialized
+
|-
+
| 0x8000002a
+
| Data stream file: f_00002a
+
|-
+
| 0xa0010003
+
| Block data file: data_1, block number 3, 1 block of size
+
|}
+
  
== Index file format (index) ==
+
Mac OS X extends EFI with a read-only HFS+ driver. According to [http://refit.sourceforge.net/info/boot_process.html] HFS+ volume header fields are used to point to a "blessed file" to be loaded as an EFI application. Though it is not clear which header field the source is referring to but likely related to the "bless" utility [https://developer.apple.com/library/mac/documentation/Darwin/Reference/Manpages/man8/bless.8.html].
Overview:
+
* File header
+
* least recently used (LRU) data (or eviction control data)
+
* index table
+
  
=== File header ===
+
The firmware start the Mac OS X boot loader (boot.efi). The bootloader displays a dark grey Apple logo on the screen and loads the Darwin kernel from disk, as well as the essential driver extensions.
*TODO*
+
  
== Data block file format (data_#) ==
+
The bootloader can be eithe a MZ-PE/COFF or EFI fat binary type [[Executable|executables]] and is commonly stored in:
Overview:
+
<pre>
* File header
+
/com.apple.recovery.boot/boot.efi
* array of blocks
+
/System/Library/CoreServices/boot.efi
 +
/usr/standalone/i386/boot.efi
 +
</pre>
  
=== File header ===
+
The behavior of the bootloader can be configured in the com.apple.Boot.plist [https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man5/com.apple.Boot.plist.5.html] which can be found in:
The index file header (struct BlockFileHeader) is 8192 bytes in size and consists of:
+
<pre>
{| class="wikitable"
+
/Library/Preferences/SystemConfiguration/
|-
+
</pre>
! offset
+
! size
+
! value
+
! description
+
|-
+
| 0
+
| 4
+
| "\xc3\xca\x04\xc1"
+
| Signature
+
|-
+
| 4
+
| 2
+
|
+
| Minor version
+
|-
+
| 6
+
| 2
+
|
+
| Major version
+
|-
+
| 8
+
| 2
+
|
+
| File number (or file index) <br> The value represents the value of # in data_#
+
|-
+
| 10
+
| 2
+
|
+
| Next file number (or next file index) <br> The value represents the value of # in data_#
+
|-
+
| 12
+
| 4
+
|
+
| Block size (or cache entry) size
+
|-
+
| 16
+
| 4
+
|
+
| Number of entries
+
|-
+
| 20
+
| 4
+
|
+
| Maximum number of entries
+
|-
+
| 24
+
| 4 x 4 = 16
+
|
+
| Array of empty entry counters <br> The counters of empty entries for each type
+
|-
+
| 40
+
| 4 x 4 = 16
+
|
+
| Array of last used position (hints) <br> The last used position for each type
+
|-
+
| 56
+
| 4
+
|
+
| Updating <br> Value to keep track of updates to the header
+
|-
+
| 60
+
| 5 x 4 = 20
+
|
+
| User
+
|-
+
| 80
+
| 2028 x 4 = 8112
+
|
+
| Block allocation bitmap
+
|}
+
  
==== Format versions ====
+
== Disk image types ==
{| class="wikitable"
+
|-
+
! Value
+
! Description
+
|-
+
| 2.0
+
|
+
|-
+
| 2.1
+
|
+
|}
+
  
=== Cache entry ===
+
Mac OS X has support for various disk image types build-in, some of which are:
The cache entry (struct EntryStore) is 256 bytes in size and consists of:
+
* read-write disk image (.dmg) some of which use the [[Raw Image Format]]
{| class="wikitable"
+
* [[Sparse Image format|Sparse disk image (.spareimage)]]
|-
+
* [[Sparse Bundle Image format|Sparse bundle disk image (.sparsebundle)]]
! offset
+
! size
+
! value
+
! description
+
|-
+
| 0
+
| 4
+
|
+
| Hash <br> The hash of the key
+
|-
+
| 4
+
| 4
+
|
+
| Next entry cache address <br> The next entry with the same hash or bucket
+
|-
+
| 8
+
| 4
+
|
+
| Rankings node cache address
+
|-
+
| 12
+
| 4
+
|
+
| Reuse count <br> Value that indicates how often this entry was (re-)used
+
|-
+
| 16
+
| 4
+
|
+
| Refetch count <br> Value that indicates how often this entry was (re-)fetched (or downloaded)
+
|-
+
| 20
+
| 4
+
|
+
| Cache entry state
+
|-
+
| 24
+
| 8
+
|
+
| Creation time
+
|-
+
| 32
+
| 4
+
|
+
| Key data size
+
|-
+
| 36
+
| 4
+
|
+
| Long key data cache address <br> The value is 0 if no long key data is present
+
|-
+
| 40
+
| 4 x 4 = 16
+
|
+
| Array of data stream sizes
+
|-
+
| 56
+
| 4 x 4 = 16
+
|
+
| Array of data stream cache addresses
+
|-
+
| 72
+
| 4
+
|
+
| Cache entry flags
+
|-
+
| 76
+
| 4 x 4 = 16
+
|
+
| Padding
+
|-
+
| 92
+
| 4
+
|
+
| Self hash <br> The hash of the first 92 bytes of the cache entry is this used as a checksum?
+
|-
+
| 96
+
| 160
+
|
+
| Key data <br> Contains an UTF-8 encoded string with an end-of-string character with the original URL
+
|}
+
  
==== Array indexes ====
+
== Burn Folder ==
The data stream array indexes correspond to:
+
{| class="wikitable"
+
|-
+
! Value
+
! Description
+
|-
+
| 0
+
| HTTP response headers
+
|-
+
| 1
+
| Page contents (Payload)
+
|-
+
| 2
+
|
+
|-
+
| 3
+
|
+
|}
+
  
==== Cache entry state ====
+
Mac OS X Burn Folder:
{| class="wikitable"
+
<pre>
|-
+
$NAME.fpbf
! Value
+
</pre>
! Identifier
+
! Description
+
|-
+
| 0
+
| ENTRY_NORMAL
+
| Normal cache entry
+
|-
+
| 1
+
| ENTRY_EVICTED
+
| The cache entry was recently evicted
+
|-
+
| 2
+
| ENTRY_DOOMED
+
| The cache entry was doomed
+
|}
+
  
==== Cache entry flags ====
+
This folder normally contains [[Mac OS X Alias Files|alias files]] (similar to LNK files under Windows). Which should have the following signature.
{| class="wikitable"
+
<pre>
|-
+
00000000  62 6f 6f 6b 00 00 00 00  6d 61 72 6b 00 00 00 00  |book....mark....|
! Value
+
</pre>
! Identifier
+
! Description
+
|-
+
| 0x00000001
+
| PARENT_ENTRY
+
| Parent cache entry
+
|-
+
| 0x00000002
+
| CHILD_ENTRY
+
| Child cache entry
+
|}
+
  
=== Rankings node ===
+
These [[Mac OS X Alias Files|alias files]] contain additional date and time values.
The rankings node (struct RankingsNode) is 36 bytes in size and consists of:
+
{| class="wikitable"
+
|-
+
! offset
+
! size
+
! value
+
! description
+
|-
+
| 0
+
| 8
+
|
+
| Last used <br> Contains LRU information?
+
|-
+
| 8
+
| 8
+
|
+
| Last modified <br> Contains LRU information?
+
|-
+
| 16
+
| 4
+
|
+
| Next rankings node cache address
+
|-
+
| 20
+
| 4
+
|
+
| Previous rankings node cache address
+
|-
+
| 24
+
| 4
+
|
+
| Cache entry cache address
+
|-
+
| 28
+
| 4
+
|
+
| Is dirty flag
+
|-
+
| 32
+
| 4
+
|
+
| Self hash <br> The hash of the first 32 bytes of the rankings node is this used as a checksum?
+
|}
+
  
== Data stream ==
+
Also check the following files for references to deleted .fpbf paths:
See: [[gzip]]
+
<pre>
 +
/Users/$USERNAME/Library/Preferences/com.apple.finder.plist
 +
/Users/$USERNAME/Library/Preferences/com.apple.sidebarlists.plist
 +
</pre>
  
== See Also ==
+
Actual burning of optical media is logged in:
* [[Google Chrome]]
+
<pre>
* [[gzip]]
+
/var/log/system.log
 +
/Users/$USERNAME/Library/Logs/DiscRecording.log
 +
/private/var/.logs_exporter/cache/Users/$USERNAME/Library/Logs/DiscRecording.log
 +
</pre>
 +
 
 +
== 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: [http://web.archive.org/web/20090214212148/http://developer.apple.com/technotes/tn/tn1150.html Technical Note TN1150 - HFS Plus Volume Format]
 +
 
 +
Converting HFS/HFS+ date and time values with Python:
 +
<pre>
 +
import datetime
 +
 
 +
print datetime.datetime( 1904, 1, 1 ) + datetime.timedelta( seconds=0xCBDAF25B )
 +
</pre>
 +
 
 +
== Launch Agents ==
 +
System-wide:
 +
<pre>
 +
/Library/LaunchAgents
 +
/System/Library/LaunchAgents
 +
</pre>
 +
 
 +
Per user:
 +
<pre>
 +
/Users/$USERNAME/Library/LaunchAgents
 +
</pre>
 +
 
 +
These directories contain  [[Property list (plist)]] files.
 +
 
 +
== Launch Daemons ==
 +
System-wide:
 +
<pre>
 +
/Library/LaunchDaemons
 +
/System/Library/LaunchDaemons
 +
</pre>
 +
 
 +
These directories contain [[Property list (plist)]] files.
 +
 
 +
== 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.chromium.org/developers/design-documents/network-stack/disk-cache Disk Cache], The Chromium Projects
+
* [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://refit.sourceforge.net/info/boot_process.html The Intel Mac boot process], by the [[rEFIt|rEFIt project]]
 +
* [http://ho.ax/posts/2012/02/carving-up-efi-fat-binaries/ Carving up EFI fat binaries], by snare, February 24, 2012
 +
 
 +
=== iCloud ===
 +
* [http://support.apple.com/kb/HT4865?viewlocale=en_US&locale=en_US iCloud: iCloud security and privacy overview]
  
[[Category:File Formats]]
+
[[Category:Mac OS X]]
 +
[[Category:Operating systems]]

Revision as of 09:07, 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

The firmware is responsible for initializing the hardware and performing a POST (Power-On Self Test).

The default boot volume is stored in NVRAM and can be configured through the "Startup Disk" preference pane or the nvram command line utility [1]. E.g. to print all of the firmware variables.

nvram -p

Additional boot arguments can be provided via the "boot-args" value [2].

Mac OS X extends EFI with a read-only HFS+ driver. According to [3] HFS+ volume header fields are used to point to a "blessed file" to be loaded as an EFI application. Though it is not clear which header field the source is referring to but likely related to the "bless" utility [4].

The firmware start the Mac OS X boot loader (boot.efi). The bootloader displays a dark grey Apple logo on the screen and loads the Darwin kernel from disk, as well as the essential driver extensions.

The bootloader can be eithe a MZ-PE/COFF or EFI fat binary type executables and is commonly stored in:

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

The behavior of the bootloader can be configured in the com.apple.Boot.plist [5] which can be found in:

/Library/Preferences/SystemConfiguration/

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 [6]

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: [7]

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 [8] that contain a cpio archive and metadata [9].

Also see

Formats

External Links

Apple Examiner

EFI

iCloud