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• Does this have anything to do with endian-ness?

  - by eSKay

  This piece of code: #include<stdio.h> void hello() { printf("hello\n"); } void bye() { printf("bye\n"); } int main() { printf("%p\n", hello); printf("%p\n", bye); return 0; } output on my machine: 0x80483f4 0x8048408 [second address is bigger in value] on Codepad 0x8048541 0x8048511 [second address is smaller in value] Does this have anything to do with endian-ness of the machines? If not, Why the difference in the ordering of the addresses? Also, Why the difference in the difference? 0x8048541 - 0x8048511 = 0x30 0x8048408 - 0x80483f4 = 0x14 Btw, I just checked. This code (taken from here) says that both the machines are Little-Endian #include<stdio.h> int main() { int num = 1; if(*(char *)&num == 1) printf("Little-Endian\n"); else printf("Big-Endian\n"); return 0; }

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• Git Shell in Windows: patch's default character encoding is UCS-2 Little Endian - how to change this to ANSI or UTF-8 without BOM?

  - by Sk8erPeter

  When creating a diff patch with Git Shell in Windows (when using GitHub for Windows), the character encoding of the patch will be UCS-2 Little Endian according to Notepad++ (see the screenshots below). How can I change this behavior, and force git to create patches with ANSI or UTF-8 without BOM character encoding? It causes a problem because UCS-2 Little Endian encoded patches can not be applied, I have to manually convert it to ANSI.

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• Endianness inside CPU registers

  - by Abhishek Tamhane

  I need help understanding endianness inside CPU registers of x86 processors. I wrote this small assembly program: section .data section .bss section .text global _start _start: nop mov eax, 0x78FF5ABC mov ebx,'WXYZ' nop ; GDB breakpoint here. mov eax, 1 mov ebx, 0 int 0x80 I ran this program in GDB with a breakpoint on line number 10 (commented in the source above). At this breakpoint, info registers shows the value of eax=0x78ff5abc and ebx=0x5a595857. Since the ASCII codes for W, X, Y, Z are 57, 58, 59, 5A respectively; and intel is little endian, 0x5a595857 seems like the correct byte order (least significant byte first). Why isn't then the output for eax register 0xbc5aff78 (least significant byte of the number 0x78ff5abc first) instead of 0x78ff5abc?

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• How to test your code on a machine with big-endian architecture?

  - by eSKay

  Both ideone.com and codepad.org have Little endian architechtures. I want to test my code on some machine with big-endian architechture (for example - Solaris - which I don't have). Is there some way that you know about?

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• Can someone explain this "endian-ness" function for me?

  - by Mike

  Write a program to determine whether a computer is big-endian or little-endian. bool endianness() { int i = 1; char *ptr; ptr = (char*) &i; return (*ptr); } So I have the above function. I don't really get it. ptr = (char*) &i, which I think means a pointer to a character at address of where i is sitting, so if an int is 4 bytes, say ABCD, are we talking about A or D when you call char* on that? and why? Would some one please explain this in more detail? Thanks. So specifically, ptr = (char*) &i; when you cast it to char*, what part of &i do I get?

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• How to convert Big Endian and how to flip the highest bit?

  - by Robert Frank

  I am using a TStream to read binary data (thanks to this post: http://stackoverflow.com/questions/2878180/how-to-use-a-tfilestream-to-read-2d-matrices-into-dynamic-array). My next problem is that the data is Big Endian. From my reading, the Swap() method is seemingly deprecated. How would I swap the types below? 16-bit two's complement binary integer 32-bit two's complement binary integer 64-bit two's complement binary integer IEEE single precision floating-point - Are IEEE affected by Big Endian? And, finally, since the data is unsigned, the creators of this dataset have stored the unsigned values as signed integers (excluding the IEEE). They instruct that one need only add an offset (2^15, 2^31, and 2^63) to recover the unsigned data. But, they note that flipping the most significant bit is the fastest way to do that. How does one efficiently flip the most significant bit of a 16, 32, or 64-bit integer? So, if the data on disk (16-bit) is "85 FB" - the desired result after reading the data and swapping and bit flipping would be 1531. Is there a way to accomplish the swapping and bit flipping with generics so it fits into the generic answer at the link above? Yes, kids, THIS is how scientific astronomical data is stored by NASA, ESO, and all professional astronomers. This FITS standard is considered by some to be one of the most successful standards ever created in its proliferation and flexibility!

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• Modify this code to read bytes in the reverse endian?

  - by ibiza

  Hi, I have this bit of code which reads an 8 bytes array and converts it to a int64. I would like to know how to tweak this code so it would work when receiving data represented with the reverse endian... protected static long getLong(byte[] b, int off) { return ((b[off + 7] & 0xFFL) >> 0) + ((b[off + 6] & 0xFFL) << 8) + ((b[off + 5] & 0xFFL) << 16) + ((b[off + 4] & 0xFFL) << 24) + ((b[off + 3] & 0xFFL) << 32) + ((b[off + 2] & 0xFFL) << 40) + ((b[off + 1] & 0xFFL) << 48) + (((long) b[off + 0]) << 56); } Thanks for the help!

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• c++ library for endian-aware reading of raw file stream metadata?

  - by Kache4

  I've got raw data streams from image files, like: vector<char> rawData(fileSize); ifstream inFile("image.jpg"); inFile.read(&rawData[0]); I want to parse the headers of different image formats for height and width. Is there a portable library that can can read ints, longs, shorts, etc. from the buffer/stream, converting for endianess as specified? I'd like to be able to do something like: short x = rawData.readLeShort(offset); or long y = rawData.readBeLong(offset) An even better option would be a lightweight & portable image metadata library (without the extra weight of an image manipulation library) that can work on raw image data. I've found that Exif libraries out there don't support png and gif.

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• multiple vlans routed on one nic? trunk?General? or Access?

  - by Aceth

  ok for the last week I've tried racking my head around this... I have a SRW208P with 802.1q support, and a virtual endian appliance. I would like to be able to have 3 vlans having everything routed through the endian appliance.. i.e. The Virtual server has 2 bridged NIC's to the switch. This is where I'm getting confused .. On the 8 port switch I've got the 3 vlans set up ok (all being untagged as they are not going to be vlan aware), it's the port I'm connecting the endian firewall to the switch I'm having trouble with (second nic goes to the adsl modem and NAT'd) Is it meant to be a trunk, "Genereal" or "Access" then untagged or tagged? the end goal is to have vlan traffic routing through the single NIC and have endian route vlan traffic according to the rules. Any one have any ideas on the cisco small business stuff? Thanks

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• Parsing Concerns

  - by Jesse

  If you’ve ever written an application that accepts date and/or time inputs from an external source (a person, an uploaded file, posted XML, etc.) then you’ve no doubt had to deal with parsing some text representing a date into a data structure that a computer can understand. Similarly, you’ve probably also had to take values from those same data structure and turn them back into their original formats. Most (all?) suitably modern development platforms expose some kind of parsing and formatting functionality for turning text into dates and vice versa. In .NET, the DateTime data structure exposes ‘Parse’ and ‘ToString’ methods for this purpose. This post will focus mostly on parsing, though most of the examples and suggestions below can also be applied to the ToString method. The DateTime.Parse method is pretty permissive in the values that it will accept (though apparently not as permissive as some other languages) which makes it pretty easy to take some text provided by a user and turn it into a proper DateTime instance. Here are some examples (note that the resulting DateTime values are shown using the RFC1123 format): DateTime.Parse("3/12/2010"); //Fri, 12 Mar 2010 00:00:00 GMT DateTime.Parse("2:00 AM"); //Sat, 01 Jan 2011 02:00:00 GMT (took today's date as date portion) DateTime.Parse("5-15/2010"); //Sat, 15 May 2010 00:00:00 GMT DateTime.Parse("7/8"); //Fri, 08 Jul 2011 00:00:00 GMT DateTime.Parse("Thursday, July 1, 2010"); //Thu, 01 Jul 2010 00:00:00 GMT Dealing With Inaccuracy While the DateTime struct has the ability to store a date and time value accurate down to the millisecond, most date strings provided by a user are not going to specify values with that much precision. In each of the above examples, the Parse method was provided a partial value from which to construct a proper DateTime. This means it had to go ahead and assume what you meant and fill in the missing parts of the date and time for you. This is a good thing, especially when we’re talking about taking input from a user. We can’t expect that every person using our software to provide a year, day, month, hour, minute, second, and millisecond every time they need to express a date. That said, it’s important for developers to understand what assumptions the software might be making and plan accordingly. I think the assumptions that were made in each of the above examples were pretty reasonable, though if we dig into this method a little bit deeper we’ll find that there are a lot more assumptions being made under the covers than you might have previously known. One of the biggest assumptions that the DateTime.Parse method has to make relates to the format of the date represented by the provided string. Let’s consider this example input string: ‘10-02-15’. To some people. that might look like ‘15-Feb-2010’. To others, it might be ‘02-Oct-2015’. Like many things, it depends on where you’re from. This Is America! Most cultures around the world have adopted a “little-endian” or “big-endian” formats. (Source: Date And Time Notation By Country) In this context,  a “little-endian” date format would list the date parts with the least significant first while the “big-endian” date format would list them with the most significant first. For example, a “little-endian” date would be “day-month-year” and “big-endian” would be “year-month-day”. It’s worth nothing here that ISO 8601 defines a “big-endian” format as the international standard. While I personally prefer “big-endian” style date formats, I think both styles make sense in that they follow some logical standard with respect to ordering the date parts by their significance. Here in the United States, however, we buck that trend by using what is, in comparison, a completely nonsensical format of “month/day/year”. Almost no other country in the world uses this format. I’ve been fortunate in my life to have done some international travel, so I’ve been aware of this difference for many years, but never really thought much about it. Until recently, I had been developing software for exclusively US-based audiences and remained blissfully ignorant of the different date formats employed by other countries around the world. The web application I work on is being rolled out to users in different countries, so I was recently tasked with updating it to support different date formats. As it turns out, .NET has a great mechanism for dealing with different date formats right out of the box. Supporting date formats for different cultures is actually pretty easy once you understand this mechanism. Pulling the Curtain Back On the Parse Method Have you ever taken a look at the different flavors (read: overloads) that the DateTime.Parse method comes in? In it’s simplest form, it takes a single string parameter and returns the corresponding DateTime value (if it can divine what the date value should be). You can optionally provide two additional parameters to this method: an ‘System.IFormatProvider’ and a ‘System.Globalization.DateTimeStyles’. Both of these optional parameters have some bearing on the assumptions that get made while parsing a date, but for the purposes of this article I’m going to focus on the ‘System.IFormatProvider’ parameter. The IFormatProvider exposes a single method called ‘GetFormat’ that returns an object to be used for determining the proper format for displaying and parsing things like numbers and dates. This interface plays a big role in the globalization capabilities that are built into the .NET Framework. The cornerstone of these globalization capabilities can be found in the ‘System.Globalization.CultureInfo’ class. To put it simply, the CultureInfo class is used to encapsulate information related to things like language, writing system, and date formats for a certain culture. Support for many cultures are “baked in” to the .NET Framework and there is capacity for defining custom cultures if needed (thought I’ve never delved into that). While the details of the CultureInfo class are beyond the scope of this post, so for now let me just point out that the CultureInfo class implements the IFormatInfo interface. This means that a CultureInfo instance created for a given culture can be provided to the DateTime.Parse method in order to tell it what date formats it should expect. So what happens when you don’t provide this value? Let’s crack this method open in Reflector: When no IFormatInfo parameter is provided (i.e. we use the simple DateTime.Parse(string) overload), the ‘DateTimeFormatInfo.CurrentInfo’ is used instead. Drilling down a bit further we can see the implementation of the DateTimeFormatInfo.CurrentInfo property: From this property we can determine that, in the absence of an IFormatProvider being specified, the DateTime.Parse method will assume that the provided date should be treated as if it were in the format defined by the CultureInfo object that is attached to the current thread. The culture specified by the CultureInfo instance on the current thread can vary depending on several factors, but if you’re writing an application where a single instance might be used by people from different cultures (i.e. a web application with an international user base), it’s important to know what this value is. Having a solid strategy for setting the current thread’s culture for each incoming request in an internationally used ASP .NET application is obviously important, and might make a good topic for a future post. For now, let’s think about what the implications of not having the correct culture set on the current thread. Let’s say you’re running an ASP .NET application on a server in the United States. The server was setup by English speakers in the United States, so it’s configured for US English. It exposes a web page where users can enter order data, one piece of which is an anticipated order delivery date. Most users are in the US, and therefore enter dates in a ‘month/day/year’ format. The application is using the DateTime.Parse(string) method to turn the values provided by the user into actual DateTime instances that can be stored in the database. This all works fine, because your users and your server both think of dates in the same way. Now you need to support some users in South America, where a ‘day/month/year’ format is used. The best case scenario at this point is a user will enter March 13, 2011 as ‘25/03/2011’. This would cause the call to DateTime.Parse to blow up since that value doesn’t look like a valid date in the US English culture (Note: In all likelihood you might be using the DateTime.TryParse(string) method here instead, but that method behaves the same way with regard to date formats). “But wait a minute”, you might be saying to yourself, “I thought you said that this was the best case scenario?” This scenario would prevent users from entering orders in the system, which is bad, but it could be worse! What if the order needs to be delivered a day earlier than that, on March 12, 2011? Now the user enters ‘12/03/2011’. Now the call to DateTime.Parse sees what it thinks is a valid date, but there’s just one problem: it’s not the right date. Now this order won’t get delivered until December 3, 2011. In my opinion, that kind of data corruption is a much bigger problem than having the Parse call fail. What To Do? My order entry example is a bit contrived, but I think it serves to illustrate the potential issues with accepting date input from users. There are some approaches you can take to make this easier on you and your users: Eliminate ambiguity by using a graphical date input control. I’m personally a fan of a jQuery UI Datepicker widget. It’s pretty easy to setup, can be themed to match the look and feel of your site, and has support for multiple languages and cultures. Be sure you have a way to track the culture preference of each user in your system. For a web application this could be done using something like a cookie or session state variable. Ensure that the current user’s culture is being applied correctly to DateTime formatting and parsing code. This can be accomplished by ensuring that each request has the handling thread’s CultureInfo set properly, or by using the Format and Parse method overloads that accept an IFormatProvider instance where the provided value is a CultureInfo object constructed using the current user’s culture preference. When in doubt, favor formats that are internationally recognizable. Using the string ‘2010-03-05’ is likely to be recognized as March, 5 2011 by users from most (if not all) cultures. Favor standard date format strings over custom ones. So far we’ve only talked about turning a string into a DateTime, but most of the same “gotchas” apply when doing the opposite. Consider this code: someDateValue.ToString("MM/dd/yyyy"); This will output the same string regardless of what the current thread’s culture is set to (with the exception of some cultures that don’t use the Gregorian calendar system, but that’s another issue all together). For displaying dates to users, it would be better to do this: someDateValue.ToString("d"); This standard format string of “d” will use the “short date format” as defined by the culture attached to the current thread (or provided in the IFormatProvider instance in the proper method overload). This means that it will honor the proper month/day/year, year/month/day, or day/month/year format for the culture. Knowing Your Audience The examples and suggestions shown above can go a long way toward getting an application in shape for dealing with date inputs from users in multiple cultures. There are some instances, however, where taking approaches like these would not be appropriate. In some cases, the provider or consumer of date values that pass through your application are not people, but other applications (or other portions of your own application). For example, if your site has a page that accepts a date as a query string parameter, you’ll probably want to format that date using invariant date format. Otherwise, the same URL could end up evaluating to a different page depending on the user that is viewing it. In addition, if your application exports data for consumption by other systems, it’s best to have an agreed upon format that all systems can use and that will not vary depending upon whether or not the users of the systems on either side prefer a month/day/year or day/month/year format. I’ll look more at some approaches for dealing with these situations in a future post. If you take away one thing from this post, make it an understanding of the importance of knowing where the dates that pass through your system come from and are going to. You will likely want to vary your parsing and formatting approach depending on your audience.

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• iPhone platform: endianness (detection & swapping)

  - by quixoto

  Hi all, I'm doing some endian-sensitive file manipulation on iPhone. Are there standard macros or #defines in that environment that indicate native endianness and offer swapping if necessary? I know I can check in advance and just do the right thing for this particular architecture, but wondering if there are cleaner ways of doing the right thing. (The file format is little endian; if it were big-endian, I'd probably just use the htons/htonl family.) Thanks.

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• Why is floating point byte swapping different from integer byte swapping?

  - by CJ

  I have a binary file of doubles that I need to load using C++. However, my problem is that it was written in big-endian format but the fstream operator will then read the number wrong because my machine is little-endian. It seems like a simple problem to resolve for integers, but for doubles and floats the solutions I have found won't work. How can I (or should I) fix this? I read this as a reference for integer byte swapping: http://stackoverflow.com/questions/105252/how-do-i-convert-between-big-endian-and-little-endian-values-in-c

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• New Source Database Added for EBS 12 + 11gR2 Transportable Tablespaces

  - by John Abraham

  The Transportable Tablespaces (TTS) process was originally certified for the migration of E-Business Suite R12 databases going from a source database of 11gR1 or 11gR2 to a target of 11gR2. This requirement has now been expanded to include a source database of 10gR2 (10.2.0.5) - this will potentially save time for existing 10gR2 customers as they can remove on a crucial upgrade step prior to performing the platform migration. The migration process requires an updated Controlled patch delivered by the Oracle E-Business Suite Platform Engineering team, i.e. it requires a password obtainable from Oracle Support. We released the patch in this manner to gauge uptake, and help identify and monitor any customer issues due to the nature of this technology. This patch has been updated to now include supporting 10gR2 as a source database. Does it meet your requirements?Note that for migration across platforms of the same "endian" format, users are advised to use the Transportable Database (TDB) migration process instead for large databases. The "endian-ness" target platforms can be verified by querying the view V$DB_TRANSPORTABLE_PLATFORM using SQL*Plus (connected as sysdba) on the source platform:SQL>select platform_name from v$db_transportable_platform;If the intended target platform does not appear in the output, it means that it is of a different endian format from the source. Consequently. database migration will need to be performed via Transportable Tablespaces (for large databases) or export/import.The use of Transportable Tablespaces can greatly speed up the migration of the data portion of the database. However, it does not affect metadata, which must still be migrated using export/import. We recommend that users initially perform a test migration on their database, using export/import with the 'metrics=y' parameter. This will help identify the relative amounts of data and metadata, and provide a basis for assessing likely gains in timing. In general, the larger the amount of data (compared to metadata), the greater the reduction in downtime that can be expected from using TTS as a migration process. For smaller databases or for those that have relatively small data compared to metadata, TTS will not be as beneficial for cross endian migration and the use of export/import (datapump) for the whole database is recommended. Where can I find more information? Using Transportable Tablespaces to Migrate Oracle E-Business Suite Release 12 Using Oracle Database 11g Release 2 Enterprise Edition (My Oracle Support Document 1311487.1) Oracle Database Administrator's Guide 11g Release 2 (11.2) Related Articles Database Migration using 11gR2 Transportable Tablespaces Now Certified for EBS 12 New Source Databases Added for Transportable Tablespaces + EBS 11i 10gR2 Transportable Tablespaces Certified for EBS 11i Migrating E-Business Suite Release 11i Databases Between Platforms Migrating E-Business Suite Release 12 Databases Between Platforms

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• Endianness and C API's: Specifically OpenSSL.

  - by Hassan Syed

  I have an algorithm that uses the following OpenSSL calls: HMAC_update() / HMAC_final() // ripe160 EVP_CipherUpdate() / EVP_CipherFinal() // cbc_blowfish These algorithm take a unsigned char * into the "plain text". My input data is comes from a C++ std::string::c_str() which originate from a protocol buffer object as a encoded UTF-8 string. UTF-8 strings are meant to be endian neutrial. However I'm a bit paranoid about how OpenSSL may perform operations on the data. My understanding is that encryption algorithms work on 8-bit blocks of data, and if a unsigned char * is used for pointer arithmetic when the operations are performed the algorithms should be endian neutral and I do not need to worry about anything. My uncertainty is compounded by the fact that I am working on a little-endian machine and have never done any real cross-architecture programming. My beliefs/reasoning are/is based on the following two properties std::string (not wstring) internally uses a 8-bit ptr and a the resulting c_str() ptr will itterate the same way regardless of the CPU architecture. Encryption algorithms are either by design, or by implementation, endian neutral. I know the best way to get a definitive answer is to use QEMU and do some cross-platform unit tests (which I plan to do). My question is a request for comments on my reasoning, and perhaps will assist other programmers when faced with similar problems.

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• What's up with OCFS2?

  - by wcoekaer

  On Linux there are many filesystem choices and even from Oracle we provide a number of filesystems, all with their own advantages and use cases. Customers often confuse ACFS with OCFS or OCFS2 which then causes assumptions to be made such as one replacing the other etc... I thought it would be good to write up a summary of how OCFS2 got to where it is, what we're up to still, how it is different from other options and how this really is a cool native Linux cluster filesystem that we worked on for many years and is still widely used. Work on a cluster filesystem at Oracle started many years ago, in the early 2000's when the Oracle Database Cluster development team wrote a cluster filesystem for Windows that was primarily focused on providing an alternative to raw disk devices and help customers with the deployment of Oracle Real Application Cluster (RAC). Oracle RAC is a cluster technology that lets us make a cluster of Oracle Database servers look like one big database. The RDBMS runs on many nodes and they all work on the same data. It's a Shared Disk database design. There are many advantages doing this but I will not go into detail as that is not the purpose of my write up. Suffice it to say that Oracle RAC expects all the database data to be visible in a consistent, coherent way, across all the nodes in the cluster. To do that, there were/are a few options : 1) use raw disk devices that are shared, through SCSI, FC, or iSCSI 2) use a network filesystem (NFS) 3) use a cluster filesystem(CFS) which basically gives you a filesystem that's coherent across all nodes using shared disks. It is sort of (but not quite) combining option 1 and 2 except that you don't do network access to the files, the files are effectively locally visible as if it was a local filesystem. So OCFS (Oracle Cluster FileSystem) on Windows was born. Since Linux was becoming a very important and popular platform, we decided that we would also make this available on Linux and thus the porting of OCFS/Windows started. The first version of OCFS was really primarily focused on replacing the use of Raw devices with a simple filesystem that lets you create files and provide direct IO to these files to get basically native raw disk performance. The filesystem was not designed to be fully POSIX compliant and it did not have any where near good/decent performance for regular file create/delete/access operations. Cache coherency was easy since it was basically always direct IO down to the disk device and this ensured that any time one issues a write() command it would go directly down to the disk, and not return until the write() was completed. Same for read() any sort of read from a datafile would be a read() operation that went all the way to disk and return. We did not cache any data when it came down to Oracle data files. So while OCFS worked well for that, since it did not have much of a normal filesystem feel, it was not something that could be submitted to the kernel mail list for inclusion into Linux as another native linux filesystem (setting aside the Windows porting code ...) it did its job well, it was very easy to configure, node membership was simple, locking was disk based (so very slow but it existed), you could create regular files and do regular filesystem operations to a certain extend but anything that was not database data file related was just not very useful in general. Logfiles ok, standard filesystem use, not so much. Up to this point, all the work was done, at Oracle, by Oracle developers. Once OCFS (1) was out for a while and there was a lot of use in the database RAC world, many customers wanted to do more and were asking for features that you'd expect in a normal native filesystem, a real "general purposes cluster filesystem". So the team sat down and basically started from scratch to implement what's now known as OCFS2 (Oracle Cluster FileSystem release 2). Some basic criteria were : Design it with a real Distributed Lock Manager and use the network for lock negotiation instead of the disk Make it a Linux native filesystem instead of a native shim layer and a portable core Support standard Posix compliancy and be fully cache coherent with all operations Support all the filesystem features Linux offers (ACL, extended Attributes, quotas, sparse files,...) Be modern, support large files, 32/64bit, journaling, data ordered journaling, endian neutral, we can mount on both endian /cross architecture,.. Needless to say, this was a huge development effort that took many years to complete. A few big milestones happened along the way... OCFS2 was development in the open, we did not have a private tree that we worked on without external code review from the Linux Filesystem maintainers, great folks like Christopher Hellwig reviewed the code regularly to make sure we were not doing anything out of line, we submitted the code for review on lkml a number of times to see if we were getting close for it to be included into the mainline kernel. Using this development model is standard practice for anyone that wants to write code that goes into the kernel and having any chance of doing so without a complete rewrite or.. shall I say flamefest when submitted. It saved us a tremendous amount of time by not having to re-fit code for it to be in a Linus acceptable state. Some other filesystems that were trying to get into the kernel that didn't follow an open development model had a lot harder time and a lot harsher criticism. March 2006, when Linus released 2.6.16, OCFS2 officially became part of the mainline kernel, it was accepted a little earlier in the release candidates but in 2.6.16. OCFS2 became officially part of the mainline Linux kernel tree as one of the many filesystems. It was the first cluster filesystem to make it into the kernel tree. Our hope was that it would then end up getting picked up by the distribution vendors to make it easy for everyone to have access to a CFS. Today the source code for OCFS2 is approximately 85000 lines of code. We made OCFS2 production with full support for customers that ran Oracle database on Linux, no extra or separate support contract needed. OCFS2 1.0.0 started being built for RHEL4 for x86, x86-64, ppc, s390x and ia64. For RHEL5 starting with OCFS2 1.2. SuSE was very interested in high availability and clustering and decided to build and include OCFS2 with SLES9 for their customers and was, next to Oracle, the main contributor to the filesystem for both new features and bug fixes. Source code was always available even prior to inclusion into mainline and as of 2.6.16, source code was just part of a Linux kernel download from kernel.org, which it still is, today. So the latest OCFS2 code is always the upstream mainline Linux kernel. OCFS2 is the cluster filesystem used in Oracle VM 2 and Oracle VM 3 as the virtual disk repository filesystem. Since the filesystem is in the Linux kernel it's released under the GPL v2 The release model has always been that new feature development happened in the mainline kernel and we then built consistent, well tested, snapshots that had versions, 1.2, 1.4, 1.6, 1.8. But these releases were effectively just snapshots in time that were tested for stability and release quality. OCFS2 is very easy to use, there's a simple text file that contains the node information (hostname, node number, cluster name) and a file that contains the cluster heartbeat timeouts. It is very small, and very efficient. As Sunil Mushran wrote in the manual : OCFS2 is an efficient, easily configured, quickly installed, fully integrated and compatible, feature-rich, architecture and endian neutral, cache coherent, ordered data journaling, POSIX-compliant, shared disk cluster file system. Here is a list of some of the important features that are included : Variable Block and Cluster sizes Supports block sizes ranging from 512 bytes to 4 KB and cluster sizes ranging from 4 KB to 1 MB (increments in power of 2). Extent-based Allocations Tracks the allocated space in ranges of clusters making it especially efficient for storing very large files. Optimized Allocations Supports sparse files, inline-data, unwritten extents, hole punching and allocation reservation for higher performance and efficient storage. File Cloning/snapshots REFLINK is a feature which introduces copy-on-write clones of files in a cluster coherent way. Indexed Directories Allows efficient access to millions of objects in a directory. Metadata Checksums Detects silent corruption in inodes and directories. Extended Attributes Supports attaching an unlimited number of name:value pairs to the file system objects like regular files, directories, symbolic links, etc. Advanced Security Supports POSIX ACLs and SELinux in addition to the traditional file access permission model. Quotas Supports user and group quotas. Journaling Supports both ordered and writeback data journaling modes to provide file system consistency in the event of power failure or system crash. Endian and Architecture neutral Supports a cluster of nodes with mixed architectures. Allows concurrent mounts on nodes running 32-bit and 64-bit, little-endian (x86, x86_64, ia64) and big-endian (ppc64) architectures. In-built Cluster-stack with DLM Includes an easy to configure, in-kernel cluster-stack with a distributed lock manager. Buffered, Direct, Asynchronous, Splice and Memory Mapped I/Os Supports all modes of I/Os for maximum flexibility and performance. Comprehensive Tools Support Provides a familiar EXT3-style tool-set that uses similar parameters for ease-of-use. The filesystem was distributed for Linux distributions in separate RPM form and this had to be built for every single kernel errata release or every updated kernel provided by the vendor. We provided builds from Oracle for Oracle Linux and all kernels released by Oracle and for Red Hat Enterprise Linux. SuSE provided the modules directly for every kernel they shipped. With the introduction of the Unbreakable Enterprise Kernel for Oracle Linux and our interest in reducing the overhead of building filesystem modules for every minor release, we decide to make OCFS2 available as part of UEK. There was no more need for separate kernel modules, everything was built-in and a kernel upgrade automatically updated the filesystem, as it should. UEK allowed us to not having to backport new upstream filesystem code into an older kernel version, backporting features into older versions introduces risk and requires extra testing because the code is basically partially rewritten. The UEK model works really well for continuing to provide OCFS2 without that extra overhead. Because the RHEL kernel did not contain OCFS2 as a kernel module (it is in the source tree but it is not built by the vendor in kernel module form) we stopped adding the extra packages to Oracle Linux and its RHEL compatible kernel and for RHEL. Oracle Linux customers/users obviously get OCFS2 included as part of the Unbreakable Enterprise Kernel, SuSE customers get it by SuSE distributed with SLES and Red Hat can decide to distribute OCFS2 to their customers if they chose to as it's just a matter of compiling the module and making it available. OCFS2 today, in the mainline kernel is pretty much feature complete in terms of integration with every filesystem feature Linux offers and it is still actively maintained with Joel Becker being the primary maintainer. Since we use OCFS2 as part of Oracle VM, we continue to look at interesting new functionality to add, REFLINK was a good example, and as such we continue to enhance the filesystem where it makes sense. Bugfixes and any sort of code that goes into the mainline Linux kernel that affects filesystems, automatically also modifies OCFS2 so it's in kernel, actively maintained but not a lot of new development happening at this time. We continue to fully support OCFS2 as part of Oracle Linux and the Unbreakable Enterprise Kernel and other vendors make their own decisions on support as it's really a Linux cluster filesystem now more than something that we provide to customers. It really just is part of Linux like EXT3 or BTRFS etc, the OS distribution vendors decide. Do not confuse OCFS2 with ACFS (ASM cluster Filesystem) also known as Oracle Cloud Filesystem. ACFS is a filesystem that's provided by Oracle on various OS platforms and really integrates into Oracle ASM (Automatic Storage Management). It's a very powerful Cluster Filesystem but it's not distributed as part of the Operating System, it's distributed with the Oracle Database product and installs with and lives inside Oracle ASM. ACFS obviously is fully supported on Linux (Oracle Linux, Red Hat Enterprise Linux) but OCFS2 independently as a native Linux filesystem is also, and continues to also be supported. ACFS is very much tied into the Oracle RDBMS, OCFS2 is just a standard native Linux filesystem with no ties into Oracle products. Customers running the Oracle database and ASM really should consider using ACFS as it also provides storage/clustered volume management. Customers wanting to use a simple, easy to use generic Linux cluster filesystem should consider using OCFS2. To learn more about OCFS2 in detail, you can find good documentation on http://oss.oracle.com/projects/ocfs2 in the Documentation area, or get the latest mainline kernel from http://kernel.org and read the source. One final, unrelated note - since I am not always able to publicly answer or respond to comments, I do not want to selectively publish comments from readers. Sometimes I forget to publish comments, sometime I publish them and sometimes I would publish them but if for some reason I cannot publicly comment on them, it becomes a very one-sided stream. So for now I am going to not publish comments from anyone, to be fair to all sides. You are always welcome to email me and I will do my best to respond to technical questions, questions about strategy or direction are sometimes not possible to answer for obvious reasons.

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• Copy Office files from a Mac to a PC

  - by Martin

  A friend of me recently dumped his Mac fpr a PC. He used Microsoft Office for Mac and has several hundred Files (Word, Excel) which were copied over to the new PC using a USB disk. Microsoft Office is now unable to read any of there files. I suspect this is because of little endian vs. big endian. Is there any tool which can converted all theses files automatically, doing this by hand would take ages.

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• Copy Office files from a Mac to a PC

  - by Martin

  A friend of me recently dumped his Mac fpr a PC. He used Microsoft Office for Mac and has several hundred Files (Word, Excel) which were copied over to the new PC using a USB disk. Microsoft Office is now unable to read any of there files. I suspect this is because of little endian vs. big endian. Is there any tool which can converted all theses files automatically, doing this by hand would take ages.

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• Suggestions for Windows 8 migration [closed]

  - by Big Endian

  I'm thinking of migrating to Windows 8. At first I hated it, but I'm pretty sure the Windows 8 model is the future, and I don't particularly want to end up hating the future like my parents, frustrated and bewildered by anything past Windows XP. I'm currently running Windows 7 and my system has been accumulating some problems. It's probably an accumulation of issues from installing too much software, changing firewall settings, installing Ubuntu alongside Windows, and... well I'm not sure, but my computer has been buggy in unexpected ways lately (freezing and unfreezing, display driver crashing and recovering, and what I call "deep freeze/thaw cycle" where the mouse won't even move for a while). I'm good at solving computer problems, but I can't seem to get to the root of these and my best idea for fixing them is making sure I've backed up every file then re-installing the entire OS. Luckily for me, a new OS is just around the corner so this would be a good time to get two things out of the way at once. The problem I see is that the upgrade options I see are all "seamless". I don't want a seamless upgrade. I want to wipe the slate clean and start all over. Does this mean I will have to buy a full, new copy of Windows 8 rather than one of the cheaper upgrading options? Or does it not make since for me to go to Windows 8 given that I have a laptop, not a tablet? Maybe I should just re-install Windows 7, or even call good enough good enough, try to eliminate the bugs, and start with a fresh slate in 2-3 years after this computer eventually dies entirely from (inevitable) hardware failure. What would be the advantages or disadvantages and costs of each option, how would I go about upgrading to Windows 8 if that's the option I choose, and what is your personal opinion about my situation?

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• Can I read a smartcard in a virtual machine?

  - by endian

  My employer requires a smartcard to login to their web-based remote working platform. I want to access this platform by using a Remote Desktop Connection on to my Windows 7 Virtual Machine, with the smartcard plugged into my home PC. However, whilst I can see the smartcard on my home PC, it doesn't appear in the virtual machine, despite me having "Smart Cards" enabled in the Local Resources page of Remote Desktop Connection. Is it possible to get this working?

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• Windows user moving to Ubuntu 12.04. Where are the system tools, or equivalents?

  - by Big Endian

  I am a Windows user who has begun experimenting with Ubuntu. Ubuntu seems great, but for all the things it seems like I CAN'T do. How do I get to advanced administration stuff, like the list of drivers, all of the installed software, and something equivalent to Windows' Device Manager. I always heard that Linux was supposed to be very raw, and you had to have lots of computer experience to make it work. This seems just the opposite. Ubuntu seems very modern and user friendly, better in some regards than any operating system I have seen. Unfortunately, I can't find any of the guts of this system beneath all of the user friendly frosting... gunk... crap... stuff. I'm reminded more and more of an Apple computer (except Linux is more affordable :). So how do I peel back this layer and start using the computer? A solution other than installing Gnome 3 would be appreciated.

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• Endianness manipulation - is there a C library for this?

  - by Malvineous

  Hi all, With the sort of programs I write (working with raw file data) I often need functions to convert between big and little endian. Usually I write these myself (which is covered by many other posts here) but I'm not that keen on doing this for a number of reasons - the main one being lack of testing. I don't really want to spend ages testing my code in a big endian emulator, and often just omit the code for big endian machines altogether. I also would rather make use of faster functions provided by various compilers, while still keeping my programs cross-platform. The only things I can find are socket calls like htons() but they require different #include files on each platform, and some GPL code like this, however that particular file, while comprehensive, seems to miss out on some of the high performance functions provided by some compilers. So, does anyone know of a library (ideally just a .h file) that is well tested and provides a standard set of functions for dealing with endianness across many compilers and platforms?

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• Migrating RISC to x86 - endianess 'issue'

  - by llaszews

  Endianess always comes up when migrating applications and databases from RISC to x86. The issue is often time overblown as if you are running on a relational database the database vendor will provide tools or automated methods to convert the data properly. Oracle RMAN is often the first choice. Oracle imp/exp, data pump, and GoldenGate can also be used. Migrating to Linux on Dell A bigger issue would be applications that access OS files. These OS files will need to be converted from big endian (RISC) to little endian (CISC) and then the application may be impacted because of the endianess differences.

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• getAudioInputStream can not convert [stereo, 4 bytes/frame] stream to [mono, 2 bytes/frame]

  - by brian_d

  Hello. I am using javasound and have an AudioInputStream of format PCM_SIGNED 8000.0 Hz, 16 bit, stereo, 4 bytes/frame, little-endian Using AudioSystem.getAudioInputStream(target_format, original_stream) produces an 'IllegalArgumentException: Unsupported Conversion' when the target_format is PCM_SIGNED 8000.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian Is it possible to convert this stream manually after every read() call? And if yes, how? In general, how can you compare two formats and tell if a conversion is possible?

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• Marshal.PtrToStructure (and back again) and generic solution for endianness swapping

  - by cgyDeveloper

  I have a system where a remote agent sends serialized structures (from and embedded C system) for me to read and store via IP/UDP. In some cases I need to send back the same structure types. I thought I had a nice setup using Marshal.PtrToStructure (receive) and Marshal.StructureToPtr (send). However, a small gotcha is that the network big endian integers need to be converted to my x86 little endian format to be used locally. When I'm sending them off again, big endian is the way to go. Here are the functions in question: private static T BytesToStruct<T>(ref byte[] rawData) where T: struct { T result = default(T); GCHandle handle = GCHandle.Alloc(rawData, GCHandleType.Pinned); try { IntPtr rawDataPtr = handle.AddrOfPinnedObject(); result = (T)Marshal.PtrToStructure(rawDataPtr, typeof(T)); } finally { handle.Free(); } return result; } private static byte[] StructToBytes<T>(T data) where T: struct { byte[] rawData = new byte[Marshal.SizeOf(data)]; GCHandle handle = GCHandle.Alloc(rawData, GCHandleType.Pinned); try { IntPtr rawDataPtr = handle.AddrOfPinnedObject(); Marshal.StructureToPtr(data, rawDataPtr, false); } finally { handle.Free(); } return rawData; } And a quick example structure that might be used like this: byte[] data = this.sock.Receive(ref this.ipep); Request request = BytesToStruct<Request>(ref data); Where the structure in question looks like: [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi, Pack = 1)] private struct Request { public byte type; public short sequence; [MarshalAs(UnmanagedType.ByValArray, SizeConst = 5)] public byte[] address; } What (generic) way can I swap the endianness when marshalling the structures? My need is such that the locally stored 'public short sequence' in this example will be little-endian for displaying to the user. I don't want to have to swap the endianness on a structure-specific way. My first thought was to use Reflection, but I'm not very familiar with that feature. Also, I hoped that there would be a better solution out there that somebody could point me towards. Thanks in advance :)

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• Can you change VS Win Forms designer code generation?

  - by Big Endian

  We implemented new standards, which call for our private members to have a leading underscore. Like so: private System.Windows.Forms.Label _label; Unfortunately VS will put out the default below when you drag a new label onto your form: private System.Windows.Forms.Label label1; Is there a way to change that to: private System.Windows.Forms.Label _label1; Cheers, Plamen

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