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• Need help in translating code from C to Java.

  - by Vuntic

  From this article. Here's the code: float InvSqrt(float x){ // line 0 float xhalf = 0.5f * x; int i = *(int*)&x; // store floating-point bits in integer i = 0x5f3759d5 - (i >> 1); // initial guess for Newton's method x = *(float*)&i; // convert new bits into float x = x*(1.5f - xhalf*x*x); // One round of Newton's method return x; } ...I can't even tell if that's C or C++. [okay apparently it's C, thanks] Could someone translate it to Java for me, please? It's (only, I hope) lines 2 and 4 that are confusing me.

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• What is the most efficient way to encode an arbitrary GUID into readable ASCII (33-127)?

  - by mark

  Dear ladies and sirs. The standard string representation of GUID takes about 36 characters. Which is very nice, but also really wasteful. I am wondering, how to encode it in the shortest possible way using all the ASCII characters in the range 33-127. The naive implementation produces 22 characters, simply because 128 bits / 6 bits yields 22. Huffman encoding is my second best, the only question is how to choose the codes.... Any more ideas? Thanks. P.S. The encoding must be lossless, of course.

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• Dynamic binary from file

  - by Aurel300

  This is a little bit of weird problem here. Say I have a C++ code, running on a specific platform. The only purpose of this code is to run files containing binary, NATIVE to that platform. Now - my question is - HOW would I get the data from these files (could even be by bits, like 1024 bits a cycle) to the memory of machine running my code so that this data would be in the execution part? In other words, can I get the data to somewhere where I can point the instruction pointer? If yes, how? I don't mind if I have to use assembler for this - just so it would work.

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• An MP3 parser to extract numbered frames?

  - by Xepoch

  I am writing a streaming application for MP3 (CBR). It is all passthru, meaning I don't have to decode/encode, I just need to pass on the data as I see it come through. I want to be able to count the MP3 frames as they passthru (and some other stuff like throughput calculations). According to the MP3 frame header spec, the sync word appears to be 11 bits of 1s, however I notice (naturally) that the frame payload which I should safely assume to be binary and thus it is not odd at all to see 11 1s in sequence. My questions: Is there a Unix/Linux MP3 parser utility (dd-style) that can pull numbered frames from an MP3 file/pipe? Any perl wisdom here? How does one delineate an MP3 header block from any other binary payload data? and lastly: Is a constant bitrate (CBR) MP3 defined by payload bytes or are the header bytes included in the aggregate # of bytes/bits per any given timeslice? Thanks,

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• Bit conversion operations in PHP

  - by Goro

  Hello, I find myself in need of performing bit-level conversion on variables in PHP. In more detail, I have a bit stream that is read as an integer by hardware, and I need to do some operations on the bits to make it into what its actually supposed to be (a float). I have to do this a few times for different formats, and the functionality I need is Being able to select and move individual bits in a variable Being able to cast statically one type of variable to the other (ie. int to float) I know php natively supports bitwise AND, OR, etc, and shift operations, but I was wondering if: there may already be a library in php that does this sort of thing I would be better off with delegating the calculations to some other language Thanks,

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• x86 and Memory Addressing

  - by IM

  I've been reading up on memory models in an assembly book I picked up and I have a question or two. Let's say that the address bus has 32 lines, the data bus has 32 lines and the CPU is 32-bit (for simplicity). Now if the CPU makes a read request and sends the 32bit address, but only needs 8 bits, all 32 bits come back anyway? Also, the addresses in memory are still addressed per byte correct? So fetching one byte would bring back 0000 0001 to address 0000 0004? Thanks in advance

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• C# Dataset usage necessary before passing to GridView datasource?

  - by Goober

  Scenario Lets say for example I have a series of events that fire continually every half second presenting me with an object containing some bits of information. There are always between 10 and 15 objects that are being updated constantly. Since these bits of information are changing continually I want to display them in a GridView. When I do so, I want the user to see the data displayed in the gridview and actually be updated as opposed to just a continually extending list being printed and incrementing (like writeline on the console). Question Is the best way to achieve this to map my objects to a dataset and have the dataset mapped to the gridview? Thoughts Will this allow the gridview to just be "UPDATED" as opposed to being added to? Any implementation suggestions would be greatly appreciated. EDIT: it MUST be windows forms (I use DevExpress too)

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• RequestFactoryEditorDriver getting edited data after flush

  - by Deanna

  Let me start with I have a solution, but I don't really think it is elegant. So, I am looking for a cleaner way to do this. I have an EntityProxy displayed in a view panel. The view panel is a RequestFactoryEditorDriver only using display mode. The user clicks on a data element and opens a popup editor to edit a data element of the EntityProxy with a few more bits of data than is displayed in the view panel. When the user saves the element I need the view panel to update the display. I ran into a problem because the RequestFactoryEditorDriver of the popup editor flow doesn't let you get to the edited data. The driver uses the passed in context and sends it to the server. The context returned out of flush only allows a Receiver even if you cast it to the type of context you stored in the editor driver in the edit() call. It doesn't appear to send and EntityProxyChanged event either, so I couldn't listen for that and update the display view. The solution I found was to change my domain object persist to return the newly saved entity. Then create the popup editor like this editor.getSaveButtonClickHandler().addClickHandler(createSaveHandler(driver, editor)); // initialize the Driver and edit the given text. driver.initialize(rf, editor); PlayerProfileCtx ctx = rf.playerProfile(); ctx.persist().using(playerProfile).with(driver.getPaths()) .to(new Receiver<PlayerProfileProxy>(){ @Override public void onSuccess(PlayerProfileProxy profile) { editor.hide(); playerProfile = profile; viewDriver.display(playerProfile); } }); driver.edit(playerProfile, ctx); editor.centerAndShow(); Then in the save handler I just fire the context I get from the flush. While this approach works, it doesn't seem right. It would seem I should subscribe to the entitychanged event in the display view and update the entity and the view from there. Also this approach saves the complete entity, not just the changed bits, which will increase bandwidth usage. What I would think should happen, is when you flush the entity it should 'optimistically' update the rf managed version of the entity and fire the entity proxy changed event. Only reverting the entity if something went wrong in the save. The actual save should only send the changed bits. In this way there isn't a need to refetch the whole entity and send that complete data over the wire twice. Is there a better solution?

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• VHDL Simulation Timing Behaviour

  - by chris

  I'm trying to write some VHDL code that simply feeds sequential bits from a std_logic_vector into a model of an FSM. However, the bits don't seem to be updating correctly. To try figure out the issue, I have the following code, where instead of getting a bit out of a vector, I'm just toggling the signal x (the same place I'd be getting a bit out). clk <= NOT clk after 10 ns; process(clk) begin if count = 8 then assert false report "Simulation ended" severity failure; elsif (clk = '1') then x <= test1(count); count <= count + 1; end if; end process; EDIT: It appears I was confused.I've put it back to trying to take bit by bit out of the vector. This is the output. I would have thought that on when count is 1, x would take on the value of test1(1) which is a 1.

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• Population count of rightmost n integers

  - by Jason Baker

  I'm implementing Bagwell's Ideal Hash Trie in Haskell. To find an element in a sub-trie, he says to do the following: Finding the arc for a symbol s, requires ?nding its corresponding bit in the bit map and then counting the one bits below it in the map to compute an index into the ordered sub-trie. What is the best way to do this? It sounds like the most straightforward way of doing this is to select the bits below that bit and do a population count on the resulting number. Is there a faster or better way to do this?

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• How to generate distinct random numbers per distinct threads in .NET?

  - by mark

  Dear ladies and sirs. I have to generate 19 bit random numbers. However, there is a constraint - two threads may not generate the same random number when running certain code. The simplest solution is lock the entire code. However, I would like to know if there is a non locking solution. I thought, I can incorporate ManagedThreadId within the produced random numbers, but the ManagedThreadId documentation on the Internet mentions that it may span the whole Int32 range. Unmanaged thread id seems to be limited to 11 bits, still this leaves me with just 8 truly random bits. Are there any other ways? Somehow to utilize the Thread Local Storage, may be? Thanks.

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• New replicaset resident memory is larger than the existing sets

  - by eded

  From the mongodb tutorial of how to resync a set, I wipe all the files in /data/db and restart the mongod process to resync the data. Everything looks ok, I get the same number of documents as the existing two sets(primary and one secondary). However, when I check the memory on MMS. it shows me my new resynced set/mongod process has a different memory status value than the other two. For existing twos using db.serverStatus.mem shows like the following: "mem" : { "bits" : 64, "resident" : 239, "virtual" : 66348, "supported" : true, "mapped" : 32865, "mappedWithJournal" : 65730 } however, the new resynced set shows like: "mem" : { "bits" : 64, "resident" : 1239, "virtual" : 52447, "supported" : true, "mapped" : 25700, "mappedWithJournal" : 51400 } the resynced resident memory is 6-10 times more than the existing ones. I wouder if it is normal because all data comes in suddenly during the resyncing?? and even virtual and mapped value are different too. Can anyone explain?? thanks

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• Are there any real life uses for the Java byte primitive type?

  - by Thorbjørn Ravn Andersen

  For some inexplicable reason the byte primitive type is signed in Java. This mean that valid values are -128..127 instead of the usual 0..255 range representing 8 significant bits in a byte (without a sign bit). This mean that all byte manipulation code usually does integer calculations and end up masking out the last 8 bits. I was wondering if there is any real life scenario where the Java byte primitive type fits perfectly or if it is simply a completely useless design decision? EDIT: The sole actual use case was a single-byte placeholder for native code. In other words, not to be manipulated as a byte inside Java code.

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• Need help in translating code from C or C++ to Java.

  - by Vuntic

  From this article. Here's the code: float InvSqrt(float x){ // line 0 float xhalf = 0.5f * x; int i = *(int*)&x; // store floating-point bits in integer i = 0x5f3759d5 - (i >> 1); // initial guess for Newton's method x = *(float*)&i; // convert new bits into float x = x*(1.5f - xhalf*x*x); // One round of Newton's method return x; } ...I can't even tell if that's C or C++. Could someone translate it to Java for me, please? It's (only, I hope) lines 2 and 4 that are confusing me. I'll edit out the confusion about C/C++ from the tags once somebody tells me which it is.

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• How to combine two 32-bit integers into one 64-bit integer?

  - by Bei337

  I have a count register, which is made up of two 32-bit unsigned integers, one for the higher 32 bits of the value (most significant word), and other for the lower 32 bits of the value (least significant word). What is the best way in C to combine these two 32-bit unsigned integers and then display as a large number? In specific: leastSignificantWord = 4294967295; //2^32-1 printf("Counter: %u%u", mostSignificantWord,leastSignificantWord); This would print fine. When the number is incremented to 4294967296, I have it so the leastSignificantWord wipes to 0, and mostSignificantWord (0 initially) is now 1. The whole counter should now read 4294967296, but right now it just reads 10, because I'm just concatenating 1 from mostSignificantWord and 0 from leastSignificantWord. How should I make it display 4294967296 instead of 10?

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• ssh authentication nfs

  - by user40135

  Hi all I would like to do ssh from machine "ub0" to another machine "ub1" without using passwords. I setup using nfs on "ub0" but still I am asked to insert a password. Here is my scenario: * machine ub0 and ub1 have the same user "mpiu", with same pwd, same userid, and same group id * the 2 servers are sharing a folder that is the HOME directory for "mpiu" * I did a chmod 700 on the .ssh * I created a key using ssh-keygene -t dsa * I did "cat id_dsa.pub authorized_keys". On this last file I tried also chmod 600 and chmod 640 * off course I can guarantee that on machine ub1 the user "shared_user" can see the same fodler that wes mounted with no problem. Below the content of my .ssh folder Code: authorized_keys id_dsa id_dsa.pub known_hosts After all of this calling wathever function "ssh ub1 hostname" I am requested my password. Do you know what I can try? I also UNcommented in the ssh_config file for both machines this line IdentityFile ~/.ssh/id_dsa I also tried ssh -i $HOME/.ssh/id_dsa mpiu@ub1 Below the ssh -vv Code: OpenSSH_5.1p1 Debian-3ubuntu1, OpenSSL 0.9.8g 19 Oct 2007 OpenSSH_5.1p1 Debian-3ubuntu1, OpenSSL 0.9.8g 19 Oct 2007 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to ub1 [192.168.2.9] port 22. debug1: Connection established. debug2: key_type_from_name: unknown key type '-----BEGIN' debug2: key_type_from_name: unknown key type '-----END' debug1: identity file /mirror/mpiu/.ssh/id_dsa type 2 debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024 debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024 debug1: Remote protocol version 2.0, remote software version lshd-2.0.4 lsh - a GNU ssh debug1: no match: lshd-2.0.4 lsh - a GNU ssh debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-3ubuntu1 debug2: fd 3 setting O_NONBLOCK debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour128,arcfour256,arcfour,aes192-cbc,aes256-cbc,[email protected],aes128-ctr,aes192-ctr,aes256-ctr debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,spki-sign-rsa debug2: kex_parse_kexinit: aes256-cbc,3des-cbc,blowfish-cbc,arcfour debug2: kex_parse_kexinit: aes256-cbc,3des-cbc,blowfish-cbc,arcfour debug2: kex_parse_kexinit: hmac-sha1,hmac-md5 debug2: kex_parse_kexinit: hmac-sha1,hmac-md5 debug2: kex_parse_kexinit: none,zlib debug2: kex_parse_kexinit: none,zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server-client 3des-cbc hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client-server 3des-cbc hmac-md5 none debug2: dh_gen_key: priv key bits set: 183/384 debug2: bits set: 1028/2048 debug1: sending SSH2_MSG_KEXDH_INIT debug1: expecting SSH2_MSG_KEXDH_REPLY debug1: Host 'ub1' is known and matches the RSA host key. debug1: Found key in /mirror/mpiu/.ssh/known_hosts:1 debug2: bits set: 1039/2048 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /mirror/mpiu/.ssh/id_dsa (0xb874b098) debug1: Authentications that can continue: password,publickey debug1: Next authentication method: publickey debug1: Offering public key: /mirror/mpiu/.ssh/id_dsa debug2: we sent a publickey packet, wait for reply debug1: Authentications that can continue: password,publickey debug2: we did not send a packet, disable method debug1: Next authentication method: password mpiu@ub1's password: I hangs here!

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• What are the advantages of Ceylon over Java?

  - by Anuj Balan

  Looking for the recent and powerful upcoming programming languages over net, I came across Ceylon. I dropped in at ceylon-lang.org and it says: Ceylon is deeply influenced by Java. You see, we're fans of Java, but we know its limitations inside out. Ceylon keeps the best bits of Java but improves things that in our experience are annoying, tedious, frustrating, difficult to understand, or bugprone. What are the advantages of Ceylon over Java?

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• Displaying an image on a LED matrix with a Netduino

  - by Bertrand Le Roy

  In the previous post, we’ve been flipping bits manually on three ports of the Netduino to simulate the data, clock and latch pins that a shift register expected. We did all that in order to control one line of a LED matrix and create a simple Knight Rider effect. It was rightly pointed out in the comments that the Netduino has built-in knowledge of the sort of serial protocol that this shift register understands through a feature called SPI. That will of course make our code a whole lot simpler, but it will also make it a whole lot faster: writing to the Netduino ports is actually not that fast, whereas SPI is very, very fast. Unfortunately, the Netduino documentation for SPI is severely lacking. Instead, we’ve been reliably using the documentation for the Fez, another .NET microcontroller. To send data through SPI, we’ll just need  to move a few wires around and update the code. SPI uses pin D11 for writing, pin D12 for reading (which we won’t do) and pin D13 for the clock. The latch pin is a parameter that can be set by the user. This is very close to the wiring we had before (data on D11, clock on D12 and latch on D13). We just have to move the latch from D13 to D10, and the clock from D12 to D13. The code that controls the shift register has slimmed down considerably with that change. Here is the new version, which I invite you to compare with what we had before: public class ShiftRegister74HC595 { protected SPI Spi; public ShiftRegister74HC595(Cpu.Pin latchPin) : this(latchPin, SPI.SPI_module.SPI1) { } public ShiftRegister74HC595(Cpu.Pin latchPin, SPI.SPI_module spiModule) { var spiConfig = new SPI.Configuration( SPI_mod: spiModule, ChipSelect_Port: latchPin, ChipSelect_ActiveState: false, ChipSelect_SetupTime: 0, ChipSelect_HoldTime: 0, Clock_IdleState: false, Clock_Edge: true, Clock_RateKHz: 1000 ); Spi = new SPI(spiConfig); } public void Write(byte buffer) { Spi.Write(new[] {buffer}); } } All we have to do here is configure SPI. The write method couldn’t be any simpler. Everything is now handled in hardware by the Netduino. We set the frequency to 1MHz, which is largely sufficient for what we’ll be doing, but it could potentially go much higher. The shift register addresses the columns of the matrix. The rows are directly wired to ports D0 to D7 of the Netduino. The code writes to only one of those eight lines at a time, which will make it fast enough. The way an image is displayed is that we light the lines one after the other so fast that persistence of vision will give the illusion of a stable image: foreach (var bitmap in matrix.MatrixBitmap) { matrix.OnRow(row, bitmap, true); matrix.OnRow(row, bitmap, false); row++; } Now there is a twist here: we need to run this code as fast as possible in order to display the image with as little flicker as possible, but we’ll eventually have other things to do. In other words, we need the code driving the display to run in the background, except when we want to change what’s being displayed. Fortunately, the .NET Micro Framework supports multithreading. In our implementation, we’ve added an Initialize method that spins a new thread that is tied to the specific instance of the matrix it’s being called on. public LedMatrix Initialize() { DisplayThread = new Thread(() => DoDisplay(this)); DisplayThread.Start(); return this; } I quite like this way to spin a thread. As you may know, there is another, built-in way to contextualize a thread by passing an object into the Start method. For the method to work, the thread must have been constructed with a ParameterizedThreadStart delegate, which takes one parameter of type object. I like to use object as little as possible, so instead I’m constructing a closure with a Lambda, currying it with the current instance. This way, everything remains strongly-typed and there’s no casting to do. Note that this method would extend perfectly to several parameters. Of note as well is the return value of Initialize, a common technique to add some fluency to the API and enabling the matrix to be instantiated and initialized in a single line: using (var matrix = new LedMS88SR74HC595().Initialize()) The “using” in the previous line is because we have implemented IDisposable so that the matrix kills the thread and clears the display when the user code is done with it: public void Dispose() { Clear(); DisplayThread.Abort(); } Thanks to the multi-threaded version of the matrix driver class, we can treat the display as a simple bitmap with a very synchronous programming model: matrix.Set(someimage); while (button.Read()) { Thread.Sleep(10); } Here, the call into Set returns immediately and from the moment the bitmap is set, the background display thread will constantly continue refreshing no matter what happens in the main thread. That enables us to wait or read a button’s port on the main thread knowing that the current image will continue displaying unperturbed and without requiring manual refreshing. We’ve effectively hidden the implementation of the display behind a convenient, synchronous-looking API. Pretty neat, eh? Before I wrap up this post, I want to talk about one small caveat of using SPI rather than driving the shift register directly: when we got to the point where we could actually display images, we noticed that they were a mirror image of what we were sending in. Oh noes! Well, the reason for it is that SPI is sending the bits in a big-endian fashion, in other words backwards. Now sure you could fix that in software by writing some bit-level code to reverse the bits we’re sending in, but there is a far more efficient solution than that. We are doing hardware here, so we can simply reverse the order in which the outputs of the shift register are connected to the columns of the matrix. That’s switching 8 wires around once, as compared to doing bit operations every time we send a line to display. All right, so bringing it all together, here is the code we need to write to display two images in succession, separated by a press on the board’s button: var button = new InputPort(Pins.ONBOARD_SW1, false, Port.ResistorMode.Disabled); using (var matrix = new LedMS88SR74HC595().Initialize()) { // Oh, prototype is so sad! var sad = new byte[] { 0x66, 0x24, 0x00, 0x18, 0x00, 0x3C, 0x42, 0x81 }; DisplayAndWait(sad, matrix, button); // Let's make it smile! var smile = new byte[] { 0x42, 0x18, 0x18, 0x81, 0x7E, 0x3C, 0x18, 0x00 }; DisplayAndWait(smile, matrix, button); } And here is a video of the prototype running: The prototype in action I’ve added an artificial delay between the display of each row of the matrix to clearly show what’s otherwise happening very fast. This way, you can clearly see each of the two images being displayed line by line. Next time, we’ll do no hardware changes, focusing instead on building a nice programming model for the matrix, with sprites, text and hardware scrolling. Fun stuff. By the way, can any of my reader guess where we’re going with all that? The code for this prototype can be downloaded here: http://weblogs.asp.net/blogs/bleroy/Samples/NetduinoLedMatrixDriver.zip

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• Grand Theft Mario [Video]

  - by Asian Angel

  What do you get when you mix Mario and Grand Theft Auto? The “real” answer to where Mario got his racing kart! Here is the original GTA V official trailer that Grand Theft Mario is based on. Grand Theft Mario [via Dorkly Bits] HTG Explains: How Hackers Take Over Web Sites with SQL Injection / DDoS Use Your Android Phone to Comparison Shop: 4 Scanner Apps Reviewed How to Run Android Apps on Your Desktop the Easy Way

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• Silverlight Cream for March 22, 2010 -- #817

  - by Dave Campbell

  In this Issue: Bart Czernicki, Tim Greenfield, Andrea Boschin(-2-), AfricanGeek, Fredrik Normén, Ian Griffiths, Christian Schormann, Pete Brown, Jeff Handley, Brad Abrams, and Tim Heuer. Shoutout: At the beginning of MIX10, Brad Abrams reported Silverlight 4 and RIA Services Release Candidate Available NOW From SilverlightCream.com: Using the Bing Maps Silverlight control on the Windows Phone 7 Bart Czernicki has a very cool BingMaps and WP7 tutorial up... you're going to want to bookmark this one for sure! Code included and external links... thanks Bart! Silverlight Rx DataClient within MVVM Tim Greenfield has a great post up about Rx and MVVM with Silverlight 3. Lots of good insight into Rx and interesting code bits. SilverVNC - a VNC Viewer with Silverlight 4.0 RC Andrea Boschin digs into Silverlight 4 RC and it's full-trust on sockets and builds an implementation of RFB protocol... give it a try and give Andrea some feedback. Chromeless Window for OOB applications in Silverlight 4.0 RC Andrea Boschin also has a post up on investigating the OOB no-chrome features in SL4RC. Windows Phone 7 and WCF AfricanGeek has his latest video tutorial up and it's on WCF and WP7... I've got a feeling we're all going to have to get our arms around this. Some steps for moving WCF RIA Services Preveiw to the RC version Fredrik Normén details his steps in transitioning to the RC version of RIA Services. Silverlight Business Apps: Module 8.5 - The Value of MEF with Silverlight Ian Griffiths has a video tutorial up at Channel 9 on MEF and Silverlight, posted by John Papa Introducing Blend 4 – For Silverlight, WPF and Windows Phone Christian Schormann has an early MIX10 post up about te new features in Expression Blend with regard to Silverlight, WPF, and WP7. Building your first Silverlight for Windows Phone Application Pete Brown has his first post up on building a WP7 app with the MIX10 bits. Lookups in DataGrid and DataForm with RIA Services Jeff Handley elaborates on a post by someone else about using lookup data in the DataGrid and DataForm with RIA Services Silverlight 4 + RIA Services - Ready for Business: Starting a New Project with the Business Application Template Brad Abrams is starting a series highlighting the key features of Silverlight 4 and RIA with the new releases. He has a post up Silverlight 4 + RIA Services - Ready for Business: Index, including links and source. Then in this first post of the series, he introduces the Business Application Template. Custom Window Chrome and Events Watch a tutorial video by Tim Heuer on creating custom chrome for OOB apps. Stay in the 'Light! Twitter SilverlightNews | Twitter WynApse | WynApse.com | Tagged Posts | SilverlightCream Join me @ SilverlightCream | Phoenix Silverlight User Group Technorati Tags: Silverlight    Silverlight 3    Silverlight 4    Windows Phone MIX10

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• The Sim City Monster Hates how Your City was Made [Video]

  - by Asian Angel

  The Giant Doom Orb arrives in Sim City to rain destruction and terror down on the helpless citizens, but changes his mind at the last minute. What happened to cause his change of heart? Watch to find out! Sim City Monster Hates Your City [Dorkly Bits] What is a Histogram, and How Can I Use it to Improve My Photos?How To Easily Access Your Home Network From Anywhere With DDNSHow To Recover After Your Email Password Is Compromised

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• SSH new connection begins to hang (not reject or terminate) after a day or so on Ubuntu 13.04 server

  - by kross

  Recently we upgraded the server from 12.04 LTS server to 13.04. All was well, including after a reboot. With all packages updated we began to see a strange issue, ssh works for a day or so (unclear on timing) then a later request for SSH hangs (cannot ctrl+c, nothing). It is up and serving webserver traffic etc. Port 22 is open (ips etc altered slightly for posting): nmap -T4 -A x.acme.com Starting Nmap 6.40 ( http://nmap.org ) at 2013-09-12 16:01 CDT Nmap scan report for x.acme.com (69.137.56.18) Host is up (0.026s latency). rDNS record for 69.137.56.18: c-69-137-56-18.hsd1.tn.provider.net Not shown: 998 filtered ports PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 6.1p1 Debian 4 (protocol 2.0) | ssh-hostkey: 1024 54:d3:e3:38:44:f4:20:a4:e7:42:49:d0:a7:f1:3e:21 (DSA) | 2048 dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 (RSA) |_256 45:69:10:79:5a:9f:0b:f0:66:15:39:87:b9:a1:37:f7 (ECDSA) 80/tcp open http Jetty 7.6.2.v20120308 | http-title: Log in as a Bamboo user - Atlassian Bamboo |_Requested resource was http://x.acme.com/userlogin!default.action;jsessionid=19v135zn8cl1tgso28fse4d50?os_destination=%2Fstart.action Service Info: OS: Linux; CPE: cpe:/o:linux:linux_kernel Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 12.89 seconds Here is the ssh -vvv: ssh -vvv x.acme.com OpenSSH_5.9p1, OpenSSL 0.9.8x 10 May 2012 debug1: Reading configuration data /Users/tfergeson/.ssh/config debug1: Reading configuration data /etc/ssh_config debug1: /etc/ssh_config line 20: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to x.acme.com [69.137.56.18] port 22. debug1: Connection established. debug3: Incorrect RSA1 identifier debug3: Could not load "/Users/tfergeson/.ssh/id_rsa" as a RSA1 public key debug1: identity file /Users/tfergeson/.ssh/id_rsa type 1 debug1: identity file /Users/tfergeson/.ssh/id_rsa-cert type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa type -1 debug1: identity file /Users/tfergeson/.ssh/id_dsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.1p1 Debian-4 debug1: match: OpenSSH_6.1p1 Debian-4 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.9 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: [email protected],[email protected],ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: [email protected],[email protected],ssh-rsa,[email protected],[email protected],ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-256-96,hmac-sha2-512,hmac-sha2-512-96,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: none,[email protected],zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256 debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,[email protected] debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,[email protected],hmac-sha2-256,hmac-sha2-512,hmac-ripemd160,[email protected],hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: none,[email protected] debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 130/256 debug2: bits set: 503/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA dc:21:77:3b:f4:4e:74:d0:87:33:14:40:04:68:33:a6 debug3: load_hostkeys: loading entries for host "x.acme.com" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:10 debug3: load_hostkeys: loaded 1 keys debug3: load_hostkeys: loading entries for host "69.137.56.18" from file "/Users/tfergeson/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /Users/tfergeson/.ssh/known_hosts:6 debug3: load_hostkeys: loaded 1 keys debug1: Host 'x.acme.com' is known and matches the RSA host key. debug1: Found key in /Users/tfergeson/.ssh/known_hosts:10 debug2: bits set: 493/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /Users/tfergeson/.ssh/id_rsa (0x7ff189c1d7d0) debug2: key: /Users/tfergeson/.ssh/id_dsa (0x0) debug1: Authentications that can continue: publickey debug3: start over, passed a different list publickey debug3: preferred publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Offering RSA public key: /Users/tfergeson/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug1: Server accepts key: pkalg ssh-rsa blen 277 debug2: input_userauth_pk_ok: fp 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug3: sign_and_send_pubkey: RSA 3c:e5:29:6c:9d:27:d1:7d:e8:09:a2:e8:8e:6e:af:6f debug1: read PEM private key done: type RSA debug1: Authentication succeeded (publickey). Authenticated to x.acme.com ([69.137.56.18]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting [email protected] debug1: Entering interactive session. debug2: callback start debug2: client_session2_setup: id 0 debug2: fd 3 setting TCP_NODELAY debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env ATLAS_OPTS debug3: Ignored env rvm_bin_path debug3: Ignored env TERM_PROGRAM debug3: Ignored env GEM_HOME debug3: Ignored env SHELL debug3: Ignored env TERM debug3: Ignored env CLICOLOR debug3: Ignored env IRBRC debug3: Ignored env TMPDIR debug3: Ignored env Apple_PubSub_Socket_Render debug3: Ignored env TERM_PROGRAM_VERSION debug3: Ignored env MY_RUBY_HOME debug3: Ignored env TERM_SESSION_ID debug3: Ignored env USER debug3: Ignored env COMMAND_MODE debug3: Ignored env rvm_path debug3: Ignored env COM_GOOGLE_CHROME_FRAMEWORK_SERVICE_PROCESS/USERS/tfergeson/LIBRARY/APPLICATION_SUPPORT/GOOGLE/CHROME_SOCKET debug3: Ignored env JPDA_ADDRESS debug3: Ignored env APDK_HOME debug3: Ignored env SSH_AUTH_SOCK debug3: Ignored env Apple_Ubiquity_Message debug3: Ignored env __CF_USER_TEXT_ENCODING debug3: Ignored env rvm_sticky_flag debug3: Ignored env MAVEN_OPTS debug3: Ignored env LSCOLORS debug3: Ignored env rvm_prefix debug3: Ignored env PATH debug3: Ignored env PWD debug3: Ignored env JAVA_HOME debug1: Sending env LANG = en_US.UTF-8 debug2: channel 0: request env confirm 0 debug3: Ignored env JPDA_TRANSPORT debug3: Ignored env rvm_version debug3: Ignored env M2_HOME debug3: Ignored env HOME debug3: Ignored env SHLVL debug3: Ignored env rvm_ruby_string debug3: Ignored env LOGNAME debug3: Ignored env M2_REPO debug3: Ignored env GEM_PATH debug3: Ignored env AWS_RDS_HOME debug3: Ignored env rvm_delete_flag debug3: Ignored env EC2_PRIVATE_KEY debug3: Ignored env RUBY_VERSION debug3: Ignored env SECURITYSESSIONID debug3: Ignored env EC2_CERT debug3: Ignored env _ debug2: channel 0: request shell confirm 1 debug2: callback done debug2: channel 0: open confirm rwindow 0 rmax 32768 I can hard reboot (only mac monitors at that location) and it will again be accessible. This now happens every single time. It is imperative that I get it sorted. The strange thing is that it behaves initially then starts to hang after several hours. I perused logs previously and nothing stood out. From the auth.log, I can see that it has allowed me in, but still I get nothing back on the client side: Sep 20 12:47:50 cbear sshd[25376]: Accepted publickey for tfergeson from 10.1.10.14 port 54631 ssh2 Sep 20 12:47:50 cbear sshd[25376]: pam_unix(sshd:session): session opened for user tfergeson by (uid=0) UPDATES: Still occurring even after setting UseDNS no and commenting out #session optional pam_mail.so standard noenv This does not appear to be a network/dns related issue, as all services running on the machine are as responsive and accessible as ever, with the exception of sshd. Any thoughts on where to start?

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• ASP.NET and Visual Studio 2010 – Service Pack 1

  - by Ken Cox [MVP]

  Want to have a say in what goes into the ASP.NET bits of service pack 1 for VS 2010? Well, spend a few minutes filling out the online survey posted by the ASP.NET team: http://www.surveymonkey.com/s/MLCDPN7 If your most urgent fix doesn’t make it into service pack 1, it might be because you didn’t speak up and provide details at the right time – like now!   Ken...(read more)

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• Ancillary Objects: Separate Debug ELF Files For Solaris

  - by Ali Bahrami

  We introduced a new object ELF object type in Solaris 11 Update 1 called the Ancillary Object. This posting describes them, using material originally written during their development, the PSARC arc case, and the Solaris Linker and Libraries Manual. ELF objects contain allocable sections, which are mapped into memory at runtime, and non-allocable sections, which are present in the file for use by debuggers and observability tools, but which are not mapped or used at runtime. Typically, all of these sections exist within a single object file. Ancillary objects allow them to instead go into a separate file. There are different reasons given for wanting such a feature. One can debate whether the added complexity is worth the benefit, and in most cases it is not. However, one important case stands out — customers with very large 32-bit objects who are not ready or able to make the transition to 64-bits. We have customers who build extremely large 32-bit objects. Historically, the debug sections in these objects have used the stabs format, which is limited, but relatively compact. In recent years, the industry has transitioned to the powerful but verbose DWARF standard. In some cases, the size of these debug sections is large enough to push the total object file size past the fundamental 4GB limit for 32-bit ELF object files. The best, and ultimately only, solution to overly large objects is to transition to 64-bits. However, consider environments where: Hundreds of users may be executing the code on large shared systems. (32-bits use less memory and bus bandwidth, and on sparc runs just as fast as 64-bit code otherwise). Complex finely tuned code, where the original authors may no longer be available. Critical production code, that was expensive to qualify and bring online, and which is otherwise serving its intended purpose without issue. Users in these risk adverse and/or high scale categories have good reasons to push 32-bits objects to the limit before moving on. Ancillary objects offer these users a longer runway. Design The design of ancillary objects is intended to be simple, both to help human understanding when examining elfdump output, and to lower the bar for debuggers such as dbx to support them. The primary and ancillary objects have the same set of section headers, with the same names, in the same order (i.e. each section has the same index in both files). A single added section of type SHT_SUNW_ANCILLARY is added to both objects, containing information that allows a debugger to identify and validate both files relative to each other. Given one of these files, the ancillary section allows you to identify the other. Allocable sections go in the primary object, and non-allocable ones go into the ancillary object. A small set of non-allocable objects, notably the symbol table, are copied into both objects. As noted above, most sections are only written to one of the two objects, but both objects have the same section header array. The section header in the file that does not contain the section data is tagged with the SHF_SUNW_ABSENT section header flag to indicate its placeholder status. Compiler writers and others who produce objects can set the SUNW_SHF_PRIMARY section header flag to mark non-allocable sections that should go to the primary object rather than the ancillary. If you don't request an ancillary object, the Solaris ELF format is unchanged. Users who don't use ancillary objects do not pay for the feature. This is important, because they exist to serve a small subset of our users, and must not complicate the common case. If you do request an ancillary object, the runtime behavior of the primary object will be the same as that of a normal object. There is no added runtime cost. The primary and ancillary object together represent a logical single object. This is facilitated by the use of a single set of section headers. One can easily imagine a tool that can merge a primary and ancillary object into a single file, or the reverse. (Note that although this is an interesting intellectual exercise, we don't actually supply such a tool because there's little practical benefit above and beyond using ld to create the files). Among the benefits of this approach are: There is no need for per-file symbol tables to reflect the contents of each file. The same symbol table that would be produced for a standard object can be used. The section contents are identical in either case — there is no need to alter data to accommodate multiple files. It is very easy for a debugger to adapt to these new files, and the processing involved can be encapsulated in input/output routines. Most of the existing debugger implementation applies without modification. The limit of a 4GB 32-bit output object is now raised to 4GB of code, and 4GB of debug data. There is also the future possibility (not currently supported) to support multiple ancillary objects, each of which could contain up to 4GB of additional debug data. It must be noted however that the 32-bit DWARF debug format is itself inherently 32-bit limited, as it uses 32-bit offsets between debug sections, so the ability to employ multiple ancillary object files may not turn out to be useful. Using Ancillary Objects (From the Solaris Linker and Libraries Guide) By default, objects contain both allocable and non-allocable sections. Allocable sections are the sections that contain executable code and the data needed by that code at runtime. Non-allocable sections contain supplemental information that is not required to execute an object at runtime. These sections support the operation of debuggers and other observability tools. The non-allocable sections in an object are not loaded into memory at runtime by the operating system, and so, they have no impact on memory use or other aspects of runtime performance no matter their size. For convenience, both allocable and non-allocable sections are normally maintained in the same file. However, there are situations in which it can be useful to separate these sections. To reduce the size of objects in order to improve the speed at which they can be copied across wide area networks. To support fine grained debugging of highly optimized code requires considerable debug data. In modern systems, the debugging data can easily be larger than the code it describes. The size of a 32-bit object is limited to 4 Gbytes. In very large 32-bit objects, the debug data can cause this limit to be exceeded and prevent the creation of the object. To limit the exposure of internal implementation details. Traditionally, objects have been stripped of non-allocable sections in order to address these issues. Stripping is effective, but destroys data that might be needed later. The Solaris link-editor can instead write non-allocable sections to an ancillary object. This feature is enabled with the -z ancillary command line option. $ ld ... -z ancillary[=outfile] ...By default, the ancillary file is given the same name as the primary output object, with a .anc file extension. However, a different name can be provided by providing an outfile value to the -z ancillary option. When -z ancillary is specified, the link-editor performs the following actions. All allocable sections are written to the primary object. In addition, all non-allocable sections containing one or more input sections that have the SHF_SUNW_PRIMARY section header flag set are written to the primary object. All remaining non-allocable sections are written to the ancillary object. The following non-allocable sections are written to both the primary object and ancillary object. .shstrtab The section name string table. .symtab The full non-dynamic symbol table. .symtab_shndx The symbol table extended index section associated with .symtab. .strtab The non-dynamic string table associated with .symtab. .SUNW_ancillary Contains the information required to identify the primary and ancillary objects, and to identify the object being examined. The primary object and all ancillary objects contain the same array of sections headers. Each section has the same section index in every file. Although the primary and ancillary objects all define the same section headers, the data for most sections will be written to a single file as described above. If the data for a section is not present in a given file, the SHF_SUNW_ABSENT section header flag is set, and the sh_size field is 0. This organization makes it possible to acquire a full list of section headers, a complete symbol table, and a complete list of the primary and ancillary objects from either of the primary or ancillary objects. The following example illustrates the underlying implementation of ancillary objects. An ancillary object is created by adding the -z ancillary command line option to an otherwise normal compilation. The file utility shows that the result is an executable named a.out, and an associated ancillary object named a.out.anc. $ cat hello.c #include <stdio.h> int main(int argc, char **argv) { (void) printf("hello, world\n"); return (0); } $ cc -g -zancillary hello.c $ file a.out a.out.anc a.out: ELF 32-bit LSB executable 80386 Version 1 [FPU], dynamically linked, not stripped, ancillary object a.out.anc a.out.anc: ELF 32-bit LSB ancillary 80386 Version 1, primary object a.out $ ./a.out hello worldThe resulting primary object is an ordinary executable that can be executed in the usual manner. It is no different at runtime than an executable built without the use of ancillary objects, and then stripped of non-allocable content using the strip or mcs commands. As previously described, the primary object and ancillary objects contain the same section headers. To see how this works, it is helpful to use the elfdump utility to display these section headers and compare them. The following table shows the section header information for a selection of headers from the previous link-edit example. Index Section Name Type Primary Flags Ancillary Flags Primary Size Ancillary Size 13 .text PROGBITS ALLOC EXECINSTR ALLOC EXECINSTR SUNW_ABSENT 0x131 0 20 .data PROGBITS WRITE ALLOC WRITE ALLOC SUNW_ABSENT 0x4c 0 21 .symtab SYMTAB 0 0 0x450 0x450 22 .strtab STRTAB STRINGS STRINGS 0x1ad 0x1ad 24 .debug_info PROGBITS SUNW_ABSENT 0 0 0x1a7 28 .shstrtab STRTAB STRINGS STRINGS 0x118 0x118 29 .SUNW_ancillary SUNW_ancillary 0 0 0x30 0x30 The data for most sections is only present in one of the two files, and absent from the other file. The SHF_SUNW_ABSENT section header flag is set when the data is absent. The data for allocable sections needed at runtime are found in the primary object. The data for non-allocable sections used for debugging but not needed at runtime are placed in the ancillary file. A small set of non-allocable sections are fully present in both files. These are the .SUNW_ancillary section used to relate the primary and ancillary objects together, the section name string table .shstrtab, as well as the symbol table.symtab, and its associated string table .strtab. It is possible to strip the symbol table from the primary object. A debugger that encounters an object without a symbol table can use the .SUNW_ancillary section to locate the ancillary object, and access the symbol contained within. The primary object, and all associated ancillary objects, contain a .SUNW_ancillary section that allows all the objects to be identified and related together. $ elfdump -T SUNW_ancillary a.out a.out.anc a.out: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0x8724 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 a.out.anc: Ancillary Section: .SUNW_ancillary index tag value [0] ANC_SUNW_CHECKSUM 0xfbe2 [1] ANC_SUNW_MEMBER 0x1 a.out [2] ANC_SUNW_CHECKSUM 0x8724 [3] ANC_SUNW_MEMBER 0x1a3 a.out.anc [4] ANC_SUNW_CHECKSUM 0xfbe2 [5] ANC_SUNW_NULL 0 The ancillary sections for both objects contain the same number of elements, and are identical except for the first element. Each object, starting with the primary object, is introduced with a MEMBER element that gives the file name, followed by a CHECKSUM that identifies the object. In this example, the primary object is a.out, and has a checksum of 0x8724. The ancillary object is a.out.anc, and has a checksum of 0xfbe2. The first element in a .SUNW_ancillary section, preceding the MEMBER element for the primary object, is always a CHECKSUM element, containing the checksum for the file being examined. The presence of a .SUNW_ancillary section in an object indicates that the object has associated ancillary objects. The names of the primary and all associated ancillary objects can be obtained from the ancillary section from any one of the files. It is possible to determine which file is being examined from the larger set of files by comparing the first checksum value to the checksum of each member that follows. Debugger Access and Use of Ancillary Objects Debuggers and other observability tools must merge the information found in the primary and ancillary object files in order to build a complete view of the object. This is equivalent to processing the information from a single file. This merging is simplified by the primary object and ancillary objects containing the same section headers, and a single symbol table. The following steps can be used by a debugger to assemble the information contained in these files. Starting with the primary object, or any of the ancillary objects, locate the .SUNW_ancillary section. The presence of this section identifies the object as part of an ancillary group, contains information that can be used to obtain a complete list of the files and determine which of those files is the one currently being examined. Create a section header array in memory, using the section header array from the object being examined as an initial template. Open and read each file identified by the .SUNW_ancillary section in turn. For each file, fill in the in-memory section header array with the information for each section that does not have the SHF_SUNW_ABSENT flag set. The result will be a complete in-memory copy of the section headers with pointers to the data for all sections. Once this information has been acquired, the debugger can proceed as it would in the single file case, to access and control the running program. Note - The ELF definition of ancillary objects provides for a single primary object, and an arbitrary number of ancillary objects. At this time, the Oracle Solaris link-editor only produces a single ancillary object containing all non-allocable sections. This may change in the future. Debuggers and other observability tools should be written to handle the general case of multiple ancillary objects. ELF Implementation Details (From the Solaris Linker and Libraries Guide) To implement ancillary objects, it was necessary to extend the ELF format to add a new object type (ET_SUNW_ANCILLARY), a new section type (SHT_SUNW_ANCILLARY), and 2 new section header flags (SHF_SUNW_ABSENT, SHF_SUNW_PRIMARY). In this section, I will detail these changes, in the form of diffs to the Solaris Linker and Libraries manual. Part IV ELF Application Binary Interface Chapter 13: Object File Format Object File Format Edit Note: This existing section at the beginning of the chapter describes the ELF header. There's a table of object file types, which now includes the new ET_SUNW_ANCILLARY type. e_type Identifies the object file type, as listed in the following table. NameValueMeaning ET_NONE0No file type ET_REL1Relocatable file ET_EXEC2Executable file ET_DYN3Shared object file ET_CORE4Core file ET_LOSUNW0xfefeStart operating system specific range ET_SUNW_ANCILLARY0xfefeAncillary object file ET_HISUNW0xfefdEnd operating system specific range ET_LOPROC0xff00Start processor-specific range ET_HIPROC0xffffEnd processor-specific range Sections Edit Note: This overview section defines the section header structure, and provides a high level description of known sections. It was updated to define the new SHF_SUNW_ABSENT and SHF_SUNW_PRIMARY flags and the new SHT_SUNW_ANCILLARY section. ... sh_type Categorizes the section's contents and semantics. Section types and their descriptions are listed in Table 13-5. sh_flags Sections support 1-bit flags that describe miscellaneous attributes. Flag definitions are listed in Table 13-8. ... Table 13-5 ELF Section Types, sh_type NameValue . . . SHT_LOSUNW0x6fffffee SHT_SUNW_ancillary0x6fffffee . . . ... SHT_LOSUNW - SHT_HISUNW Values in this inclusive range are reserved for Oracle Solaris OS semantics. SHT_SUNW_ANCILLARY Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section. ... Table 13-8 ELF Section Attribute Flags NameValue . . . SHF_MASKOS0x0ff00000 SHF_SUNW_NODISCARD0x00100000 SHF_SUNW_ABSENT0x00200000 SHF_SUNW_PRIMARY0x00400000 SHF_MASKPROC0xf0000000 . . . ... SHF_SUNW_ABSENT Indicates that the data for this section is not present in this file. When ancillary objects are created, the primary object and any ancillary objects, will all have the same section header array, to facilitate merging them to form a complete view of the object, and to allow them to use the same symbol tables. Each file contains a subset of the section data. The data for allocable sections is written to the primary object while the data for non-allocable sections is written to an ancillary file. The SHF_SUNW_ABSENT flag is used to indicate that the data for the section is not present in the object being examined. When the SHF_SUNW_ABSENT flag is set, the sh_size field of the section header must be 0. An application encountering an SHF_SUNW_ABSENT section can choose to ignore the section, or to search for the section data within one of the related ancillary files. SHF_SUNW_PRIMARY The default behavior when ancillary objects are created is to write all allocable sections to the primary object and all non-allocable sections to the ancillary objects. The SHF_SUNW_PRIMARY flag overrides this behavior. Any output section containing one more input section with the SHF_SUNW_PRIMARY flag set is written to the primary object without regard for its allocable status. ... Two members in the section header, sh_link, and sh_info, hold special information, depending on section type. Table 13-9 ELF sh_link and sh_info Interpretation sh_typesh_linksh_info . . . SHT_SUNW_ANCILLARY The section header index of the associated string table. 0 . . . Special Sections Edit Note: This section describes the sections used in Solaris ELF objects, using the types defined in the previous description of section types. It was updated to define the new .SUNW_ancillary (SHT_SUNW_ANCILLARY) section. Various sections hold program and control information. Sections in the following table are used by the system and have the indicated types and attributes. Table 13-10 ELF Special Sections NameTypeAttribute . . . .SUNW_ancillarySHT_SUNW_ancillaryNone . . . ... .SUNW_ancillary Present when a given object is part of a group of ancillary objects. Contains information required to identify all the files that make up the group. See Ancillary Section for details. ... Ancillary Section Edit Note: This new section provides the format reference describing the layout of a .SUNW_ancillary section and the meaning of the various tags. Note that these sections use the same tag/value concept used for dynamic and capabilities sections, and will be familiar to anyone used to working with ELF. In addition to the primary output object, the Solaris link-editor can produce one or more ancillary objects. Ancillary objects contain non-allocable sections that would normally be written to the primary object. When ancillary objects are produced, the primary object and all of the associated ancillary objects contain a SHT_SUNW_ancillary section, containing information that identifies these related objects. Given any one object from such a group, the ancillary section provides the information needed to identify and interpret the others. This section contains an array of the following structures. See sys/elf.h. typedef struct { Elf32_Word a_tag; union { Elf32_Word a_val; Elf32_Addr a_ptr; } a_un; } Elf32_Ancillary; typedef struct { Elf64_Xword a_tag; union { Elf64_Xword a_val; Elf64_Addr a_ptr; } a_un; } Elf64_Ancillary; For each object with this type, a_tag controls the interpretation of a_un. a_val These objects represent integer values with various interpretations. a_ptr These objects represent file offsets or addresses. The following ancillary tags exist. Table 13-NEW1 ELF Ancillary Array Tags NameValuea_un ANC_SUNW_NULL0Ignored ANC_SUNW_CHECKSUM1a_val ANC_SUNW_MEMBER2a_ptr ANC_SUNW_NULL Marks the end of the ancillary section. ANC_SUNW_CHECKSUM Provides the checksum for a file in the c_val element. When ANC_SUNW_CHECKSUM precedes the first instance of ANC_SUNW_MEMBER, it provides the checksum for the object from which the ancillary section is being read. When it follows an ANC_SUNW_MEMBER tag, it provides the checksum for that member. ANC_SUNW_MEMBER Specifies an object name. The a_ptr element contains the string table offset of a null-terminated string, that provides the file name. An ancillary section must always contain an ANC_SUNW_CHECKSUM before the first instance of ANC_SUNW_MEMBER, identifying the current object. Following that, there should be an ANC_SUNW_MEMBER for each object that makes up the complete set of objects. Each ANC_SUNW_MEMBER should be followed by an ANC_SUNW_CHECKSUM for that object. A typical ancillary section will therefore be structured as: TagMeaning ANC_SUNW_CHECKSUMChecksum of this object ANC_SUNW_MEMBERName of object #1 ANC_SUNW_CHECKSUMChecksum for object #1 . . . ANC_SUNW_MEMBERName of object N ANC_SUNW_CHECKSUMChecksum for object N ANC_SUNW_NULL An object can therefore identify itself by comparing the initial ANC_SUNW_CHECKSUM to each of the ones that follow, until it finds a match. Related Other Work The GNU developers have also encountered the need/desire to support separate debug information files, and use the solution detailed at http://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html. At the current time, the separate debug file is constructed by building the standard object first, and then copying the debug data out of it in a separate post processing step, Hence, it is limited to a total of 4GB of code and debug data, just as a single object file would be. They are aware of this, and I have seen online comments indicating that they may add direct support for generating these separate files to their link-editor. It is worth noting that the GNU objcopy utility is available on Solaris, and that the Studio dbx debugger is able to use these GNU style separate debug files even on Solaris. Although this is interesting in terms giving Linux users a familiar environment on Solaris, the 4GB limit means it is not an answer to the problem of very large 32-bit objects. We have also encountered issues with objcopy not understanding Solaris-specific ELF sections, when using this approach. The GNU community also has a current effort to adapt their DWARF debug sections in order to move them to separate files before passing the relocatable objects to the linker. The details of Project Fission can be found at http://gcc.gnu.org/wiki/DebugFission. The goal of this project appears to be to reduce the amount of data seen by the link-editor. The primary effort revolves around moving DWARF data to separate .dwo files so that the link-editor never encounters them. The details of modifying the DWARF data to be usable in this form are involved — please see the above URL for details.

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