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  • Serialize a C# class to binary be used by C++. How to handle alignment?

    - by glenn.danthi
    I am currently serializing a C# class into a binary stream using BinaryWriter. I take each element of the class and write it out using BinaryWriter. This worked fine as the C++ application reading this binary file supported packed structs and hence the binary file could be loaded directly. Now I have got a request to handle alignment as a new application has popped up which cannot support packed structs. What's the best way to convert the C# class and exporting it out as a binary keeping both 2 byte as well as 4 byte alignment in mind? The user can choose the alignment.

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  • Detecting if a file is binary or plain text?

    - by dr. evil
    How can I detect if a file is binary or a plain text? Basically my .NET app is processing batch files and extracting data however I don't want to process binary files. As a solution I'm thinking about analysing first X bytes of the file and if there are more unprintable characters than printable characters it should be binary. Is this the right way to do it? Is there nay better implementation for this task?

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  • How could I represent 1.625 by 0 or a 1 (binary digit)?

    - by pepito
    This is an excerpt from wikipedia about 'full rate' speech coding standard. Full Rate or FR or GSM-FR or GSM 06.10 was the first digital speech coding standard used in the GSM digital mobile phone system. The bit rate of the codec is 13 kbit/s, or 1.625 bits/audio sample. And this one is an excerpt from wikipedia about bit. In computing parlance, bit is the abbreviation for a single binary digit, represented by a 0 or a 1. How could I represent 1.625 by 0 or a 1? Actually, that's my lecturer's question that I could not answer. Some links to papers are more than welcome. Thanks in advance.

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  • How to implement dynamic binary search for search and insert operations of n element (C or C++)

    - by iecut
    The idea is to use multiple arrays, each of length 2^k, to store n elements, according to binary representation of n.Each array is sorted and different arrays are not ordered in any way. In the above mentioned data structure, SEARCH is carried out by a sequence of binary search on each array. INSERT is carried out by a sequence of merge of arrays of the same length until an empty array is reached. More Detail: Lets suppose we have a vertical array of length 2^k and to each node of that array there attached horizontal array of length 2^k. That is, to the first node of vertical array, a horizontal array of length 2^0=1 is connected,to the second node of vertical array, a horizontal array of length 2^1= 2 is connected and so on. So the insert is first carried out in the first horizontal array, for the second insert the first array becomes empty and second horizontal array is full with 2 elements, for the third insert 1st and 2nd array horiz. array are filled and so on. I implemented the normal binary search for search and insert as follows: int main() { int a[20]= {0}; int n, i, j, temp; int *beg, *end, *mid, target; printf(" enter the total integers you want to enter (make it less then 20):\n"); scanf("%d", &n); if (n = 20) return 0; printf(" enter the integer array elements:\n" ); for(i = 0; i < n; i++) { scanf("%d", &a[i]); } // sort the loaded array, binary search! for(i = 0; i < n-1; i++) { for(j = 0; j < n-i-1; j++) { if (a[j+1] < a[j]) { temp = a[j]; a[j] = a[j+1]; a[j+1] = temp; } } } printf(" the sorted numbers are:"); for(i = 0; i < n; i++) { printf("%d ", a[i]); } // point to beginning and end of the array beg = &a[0]; end = &a[n]; // use n = one element past the loaded array! // mid should point somewhere in the middle of these addresses mid = beg += n/2; printf("\n enter the number to be searched:"); scanf("%d",&target); // binary search, there is an AND in the middle of while()!!! while((beg <= end) && (*mid != target)) { // is the target in lower or upper half? if (target < *mid) { end = mid - 1; // new end n = n/2; mid = beg += n/2; // new middle } else { beg = mid + 1; // new beginning n = n/2; mid = beg += n/2; // new middle } } // find the target? if (*mid == target) { printf("\n %d found!", target); } else { printf("\n %d not found!", target); } getchar(); // trap enter getchar(); // wait return 0; } Could anyone please suggest how to modify this program or a new program to implement dynamic binary search that works as explained above!!

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  • ubuntu 13.10 kvm binary is deprecated, please use qemu-system-x86_64

    - by ??1986
    I just upgrade from 13.04 to 13.10 and I have this issue when I run my KVM Unable to complete install: 'internal error: process exited while connecting to monitor: W: kvm binary is deprecated, please use qemu-system-x86_64 instead char device redirected to /dev/pts/10 (label charserial0) failed to initialize KVM: Device or resource busy Detail Error: Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/asyncjob.py", line 96, in cb_wrapper callback(asyncjob, *args, **kwargs) File "/usr/share/virt-manager/virtManager/create.py", line 1983, in do_install guest.start_install(False, meter=meter) File "/usr/lib/python2.7/dist-packages/virtinst/Guest.py", line 1246, in start_install noboot) File "/usr/lib/python2.7/dist-packages/virtinst/Guest.py", line 1314, in _create_guest dom = self.conn.createLinux(start_xml or final_xml, 0) File "/usr/lib/python2.7/dist-packages/libvirt.py", line 2892, in createLinux if ret is None:raise libvirtError('virDomainCreateLinux() failed', conn=self) libvirtError: internal error: process exited while connecting to monitor: W: kvm binary is deprecated, please use qemu-system-x86_64 instead char device redirected to /dev/pts/8 (label charserial0) failed to initialize KVM: Device or resource busy

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  • Is it safe to delete rotated MySQL binary logs?

    - by Milan Babuškov
    I have a MySQL server with binary logging active. Once a days logs file is "rotated", i.e. MySQL seems to stop writing to it and creates and new log file. For example, I currently have these files in /var/lib/mysql -rw-rw---- 1 mysql mysql 10485760 Jun 7 09:26 ibdata1 -rw-rw---- 1 mysql mysql 5242880 Jun 7 09:26 ib_logfile0 -rw-rw---- 1 mysql mysql 5242880 Jun 2 15:20 ib_logfile1 -rw-rw---- 1 mysql mysql 1916844 Jun 6 09:20 mybinlog.000004 -rw-rw---- 1 mysql mysql 61112500 Jun 7 09:26 mybinlog.000005 -rw-rw---- 1 mysql mysql 15609789 Jun 7 13:57 mybinlog.000006 -rw-rw---- 1 mysql mysql 54 Jun 7 09:26 mybinlog.index and mybinlog.000006 is growing. Can I simply take mybinlog.000004 and mybinlog.000005, zip them up and transfer to another server, or I need to do something else before? What info is stored in mybinlog.index? Only the info about the latest binary log? UPDATE: I understand I can delete the logs with PURGE BINARY LOGS which updates mybinlog.index file. However, I need to transfer logs to another computer before deleting them (I test if backup is valid on another machine). To reduce the transfer size, I wish to bzip2 the files. What will PURGE BINARY LOGS do if log files are not "there" anymore?

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  • How can I find the common ancestor of two nodes in a binary tree?

    - by Siddhant
    The Binary Tree here is not a Binary Search Tree. Its just a Binary Tree. The structure could be taken as - struct node { int data; struct node *left; struct node *right; }; The maximum solution I could work out with a friend was something of this sort - Consider this binary tree (from http://lcm.csa.iisc.ernet.in/dsa/node87.html) : The inorder traversal yields - 8, 4, 9, 2, 5, 1, 6, 3, 7 And the postorder traversal yields - 8, 9, 4, 5, 2, 6, 7, 3, 1 So for instance, if we want to find the common ancestor of nodes 8 and 5, then we make a list of all the nodes which are between 8 and 5 in the inorder tree traversal, which in this case happens to be [4, 9, 2]. Then we check which node in this list appears last in the postorder traversal, which is 2. Hence the common ancestor for 8 and 5 is 2. The complexity for this algorithm, I believe is O(n) (O(n) for inorder/postorder traversals, the rest of the steps again being O(n) since they are nothing more than simple iterations in arrays). But there is a strong chance that this is wrong. :-) But this is a very crude approach, and I'm not sure if it breaks down for some case. Is there any other (possibly more optimal) solution to this problem?

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  • Java: confirm method Binary division and find remainder is correct?

    - by cadwag
    I am parsing binary files and have to implement a CRC algorithm to ensure the file is not corrupted. Problem is that I can't seem to get the binary math working when using larger numbers. The example I'm trying to get working: BigInteger G = new BigInteger("11001", 2); BigInteger M = new BigInteger("1110010000", 2); BigInteger R = M.remainder(G); I am expecting: R = "0101" But I am getting: R = "1100" I am assuming the remainder of 0101 is correct since it is given to me in this book I am using as a reference for the CRC algorithm (it's not based in Java), but I can't seem to get it working. I can get small binary calculations to work that I have solved by hand, but not the larger ones. I'll admit that I haven't worked the larger ones by hand yet, that is my next step, but I wanted to see if someone could point out a glaring flaw I have in my code. Can anyone confirm or deny that my methodology is correct? Thanks

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  • what is the format of a binary image & how is it different from jpg, png images?

    - by Rahulsingh190
    I searched the internet for the basic formats of image files (e.g. .jpg, .png, .gif) as there is a specific format for .doc, .pdf etc. But didn't got anything relevant. And today I also came with an .bin image format. BIN signifies that the image is in the Binary format. So, what is the Internal format of .jpg image file. And How is it different from .bin (Binary) format. Because everything is Basically saved in Binary Form. And How is BITMAP Image different from .jpg format.

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  • C++ how to store integer into a binary file??

    - by blaxc
    i gt a struct with 2 integer, i want to store them in a binary file and read it again... here is my code... struct pw { int a; int b; }; void main(){ pw* p = new pw(); pw* q = new pw(); std::ofstream fout(ADMIN_FILE, ios_base::out | ios_base::binary | ios_base::trunc); std::ifstream fin(ADMIN_FILE, ios_base::in | ios_base::binary); p->a=123; p->b=321; fout.write((const char*)p, sizeof(pw)); fin.write((char*)q, sizeof(pw)); fin.close(); cout<< q->a << endl;} my output is 0. anyone can tell me what is the problem?

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  • How to generate and encode (for use in GA), random, strict, binary rooted trees with N leaves?

    - by Peter Simon
    First, I am an engineer, not a computer scientist, so I apologize in advance for any misuse of nomenclature and general ignorance of CS background. Here is the motivational background for my question: I am contemplating writing a genetic algorithm optimizer to aid in designing a power divider network (also called a beam forming network, or BFN for short). The BFN is intended to distribute power to each of N radiating elements in an array of antennas. The fraction of the total input power to be delivered to each radiating element has been specified. Topologically speaking, a BFN is a strictly binary, rooted tree. Each of the (N-1) interior nodes of the tree represents the input port of an unequal, binary power splitter. The N leaves of the tree are the power divider outputs. Given a particular power divider topology, one is still free to map the power divider outputs to the array inputs in an arbitrary order. There are N! such permutations of the outputs. There are several considerations in choosing the desired ordering: 1) The power ratio for each binary coupler should be within a specified range of values. 2) The ordering should be chosen to simplify the mechanical routing of the transmission lines connecting the power divider. The number of ouputs N of the BFN may range from, say, 6 to 22. I have already written a genetic algorithm optimizer that, given a particular BFN topology and desired array input power distribution, will search through the N! permutations of the BFN outputs to generate a design with compliant power ratios and good mechanical routing. I would now like to generalize my program to automatically generate and search through the space of possible BFN topologies. As I understand it, for N outputs (leaves of the binary tree), there are $C_{N-1}$ different topologies that can be constructed, where $C_N$ is the Catalan number. I would like to know how to encode an arbitrary tree having N leaves in a way that is consistent with a chromosomal description for use in a genetic algorithm. Also associated with this is the need to generate random instances for filling the initial population, and to implement crossover and mutations operators for this type of chromosome. Any suggestions will be welcome. Please minimize the amount of CS lingo in your reply, since I am not likely to be acquainted with it. Thanks in advance, Peter

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  • How to create a complete binary tree of height 'h' using Python?

    - by Jack
    Here is the node structure class Node: def __init__(self, data): # initializes the data members self.left = None self.right = None self.parent = None self.data = data complete binary tree Definition: A binary tree in which every level, except possibly the deepest, is completely filled. At depth n, the height of the tree, all nodes must be as far left as possible. -- http://www.itl.nist.gov/div897/sqg/dads/HTML/completeBinaryTree.html I am looking for an efficient algorithm.

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  • Can I use a binary literal in C or C++?

    - by hamza
    I need to work with a binary number. I tried writing: const x = 00010000 ; But it didn't work. I know that I can use an hexadecimal number that has the same value as 00010000 but I want to know if there is a type in C++ for binary numbers & if there isn't, is there another solution for my problem?

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  • Deserialization error using Runtime Serialization with the Binary Formatter

    - by Lily
    When I am deserializing a hierarchy I get the following error The input stream is not a valid binary format. The starting contents (in bytes) are The input stream is not a valid binary format. The starting contents (in bytes) are: 20-01-20-20-20-FF-FF-FF-FF-01-20-20-20-20-20-20-20 ..." Any help please? Extra info: public void Serialize(ISyntacticNode person) { Stream stream = File.Open(fileName, FileMode.OpenOrCreate); try { BinaryFormatter binary = new BinaryFormatter(); pList.Add(person); binary.Serialize(stream, pList); stream.Close(); } catch { stream.Close(); } } public List<ISyntacticNode> Deserialize() { Stream stream = File.Open(fileName, FileMode.OpenOrCreate); BinaryFormatter binary = new BinaryFormatter(); try { pList = (List<ISyntacticNode>)binary.Deserialize(stream); binary.Serialize(stream, pList); stream.Close(); } catch { pList = new List<ISyntacticNode>(); binary.Serialize(stream, pList); stream.Close(); } return pList; } I am Serializing a hierarchy which is of type Proxem.Antelope.Parsing.ISyntacticNode Now I have gotten this error System.Runtime.Serialization.SerializationException: Binary stream '116' does not contain a valid BinaryHeader. Possible causes are invalid stream or object version change between serialization and deserialization. i'm using a different instance. How may I avoid this error please

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  • 'Binary XML' for game data?

    - by bluescrn
    I'm working on a level editing tool that saves its data as XML. This is ideal during development, as it's painless to make small changes to the data format, and it works nicely with tree-like data. The downside, though, is that the XML files are rather bloated, mostly due to duplication of tag and attribute names. Also due to numeric data taking significantly more space than using native datatypes. A small level could easily end up as 1Mb+. I want to get these sizes down significantly, especially if the system is to be used for a game on the iPhone or other devices with relatively limited memory. The optimal solution, for memory and performance, would be to convert the XML to a binary level format. But I don't want to do this. I want to keep the format fairly flexible. XML makes it very easy to add new attributes to objects, and give them a default value if an old version of the data is loaded. So I want to keep with the hierarchy of nodes, with attributes as name-value pairs. But I need to store this in a more compact format - to remove the massive duplication of tag/attribute names. Maybe also to give attributes native types, so, for example floating-point data is stored as 4 bytes per float, not as a text string. Google/Wikipedia reveal that 'binary XML' is hardly a new problem - it's been solved a number of times already. Has anyone here got experience with any of the existing systems/standards? - are any ideal for games use - with a free, lightweight and cross-platform parser/loader library (C/C++) available? Or should I reinvent this wheel myself? Or am I better off forgetting the ideal, and just compressing my raw .xml data (it should pack well with zip-like compression), and just taking the memory/performance hit on-load?

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  • Shell not finding binary when attempting to execute it (it's _definitely_ there)

    - by eegg
    I have a specific set of binaries installed at: ~/.GutenMark/binary/<binaries...> These were previously working correctly, but for seemingly no reason when I attempt to execute them the shell claims not to find them: james@anubis:~/.GutenMark/binary$ ls -al ... -rwxr-xr-x 1 james james 2979036 2009-05-10 13:34 GUItenMark ... -rwxrwxrwx 1 james james 76952 2009-05-10 13:34 GutenMark ... -rwxr-xr-x 1 james james 10156 2009-05-10 13:34 GutenSplit ... james@anubis:~/.GutenMark/binary$ ./GutenMark bash: ./GutenMark: No such file or directory james@anubis:~/.GutenMark/binary$ I've tried to isolate the cause of this, with no success. The same happens with zsh, bash, and sh (all giving their appropriate "file not found" error -- this is definitely not a strange output from the binary itself). The same happens either as user james or as root. Nor is it directory specific; if I move the whole directory installation, or just a single binary, to anywhere else, the same happens when attempting to execute it. The same even happens when I put the directory in $PATH and just execute "GutenMark". It also happens when I execute it from a script (I've tried Python's commands module -- though this appears to just call sh). The problem appears to be specific to the binaries themselves, yet they appear to never actually get executed. Any ideas?

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  • How to efficiently convert String, integer, double, datetime to binary and vica versa?

    - by Ben
    Hi, I'm quite new to C# (I'm using .NET 4.0) so please bear with me. I need to save some object properties (their properties are int, double, String, boolean, datetime) to a file. But I want to encrypt the files using my own encryption, so I can't use FileStream to convert to binary. Also I don't want to use object serialization, because of performance issues. The idea is simple, first I need to somehow convert objects (their properties) to binary (array), then encrypt (some sort of xor) the array and append it to the end of the file. When reading first decrypt the array and then somehow convert the binary array back to object properties (from which I'll generate objects). I know (roughly =) ) how to convert these things by hand and I could code it, but it would be useless (too slow). I think the best way would be just to get properties' representation in memory and save that. But I don't know how to do it using C# (maybe using pointers?). Also I though about using MemoryStream but again I think it would be inefficient. I am thinking about class Converter, but it does not support toByte(datetime) (documentation says it always throws exception). For converting back I think the only options is class Converter. Note: I know the structure of objects and they will not change, also the maximum String length is also known. Thank you for all your ideas and time. EDIT: I will be storing only parts of objects, in some cases also parts of different objects (a couple of properties from one object type and a couple from another), thus I think that serialization is not an option for me.

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  • sudo apt-get update problem

    - by Jeon
    I have a problem with sudo apt-get update that I can't seem to fix and It's causing problems with alot of installations I want to do. I run Ubuntu 12.04. Ign http://ftp.availo.se precise InRelease Ign http://ftp.availo.se precise-updates InRelease Ign http://ftp.availo.se precise-backports InRelease Ign http://ftp.availo.se precise-security InRelease Get:1 http://repository.spotify.com stable InRelease [2,979 B] Ign http://ppa.launchpad.net precise InRelease Ign http://extras.ubuntu.com precise InRelease Ign http://archive.canonical.com precise InRelease Ign http://ppa.launchpad.net precise InRelease Ign http://ppa.launchpad.net precise InRelease Ign http://repository.spotify.com stable InRelease Ign http://ftp.availo.se precise Release.gpg Ign http://ftp.availo.se precise-updates Release.gpg Ign http://ftp.availo.se precise-backports Release.gpg Ign http://repository.spotify.com stable/non-free amd64 Packages/DiffIndex Hit http://ppa.launchpad.net precise Release.gpg Hit http://ppa.launchpad.net precise Release.gpg Hit http://archive.canonical.com precise Release.gpg Hit http://extras.ubuntu.com precise Release.gpg Ign http://ftp.availo.se precise-security Release.gpg Ign http://repository.spotify.com stable/non-free i386 Packages/DiffIndex Ign http://repository.spotify.com stable/non-free TranslationIndex Hit http://ppa.launchpad.net precise Release.gpg Hit http://archive.canonical.com precise Release Hit http://extras.ubuntu.com precise Release Ign http://ftp.availo.se precise Release Ign http://ftp.availo.se precise-updates Release Hit http://ppa.launchpad.net precise Release Hit http://archive.canonical.com precise/partner amd64 Packages Hit http://extras.ubuntu.com precise/main Sources Ign http://ftp.availo.se precise-backports Release Ign http://ftp.availo.se precise-security Release Hit http://ppa.launchpad.net precise Release Hit http://archive.canonical.com precise/partner i386 Packages Ign http://archive.canonical.com precise/partner TranslationIndex Hit http://ppa.launchpad.net precise Release Hit http://extras.ubuntu.com precise/main amd64 Packages Hit http://extras.ubuntu.com 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precise-backports/multiverse amd64 Packages 404 Not Found Err http://ftp.availo.se precise-backports/main i386 Packages 404 Not Found Err http://ftp.availo.se precise-backports/restricted i386 Packages 404 Not Found Err http://ftp.availo.se precise-backports/universe i386 Packages 404 Not Found Err http://ftp.availo.se precise-backports/multiverse i386 Packages 404 Not Found Err http://ftp.availo.se precise-security/main Sources 404 Not Found Err http://ftp.availo.se precise-security/restricted Sources 404 Not Found Err http://ftp.availo.se precise-security/universe Sources 404 Not Found Err http://ftp.availo.se precise-security/multiverse Sources 404 Not Found Err http://ftp.availo.se precise-security/main amd64 Packages 404 Not Found Err http://ftp.availo.se precise-security/restricted amd64 Packages 404 Not Found Err http://ftp.availo.se precise-security/universe amd64 Packages 404 Not Found Err http://ftp.availo.se precise-security/multiverse amd64 Packages 404 Not Found Err http://ftp.availo.se precise-security/main i386 Packages 404 Not Found Err http://ftp.availo.se precise-security/restricted i386 Packages 404 Not Found Err http://ftp.availo.se precise-security/universe i386 Packages 404 Not Found Err http://ftp.availo.se precise-security/multiverse i386 Packages 404 Not Found Ign http://ftp.availo.se precise/main Translation-en_US Ign http://ftp.availo.se precise/main Translation-en Ign http://ftp.availo.se precise/multiverse Translation-en_US Ign http://ftp.availo.se precise/multiverse Translation-en Ign http://ftp.availo.se precise/restricted Translation-en_US Ign http://ftp.availo.se precise/restricted Translation-en Ign http://ftp.availo.se precise/universe Translation-en_US Ign http://ftp.availo.se precise/universe Translation-en Ign http://ftp.availo.se precise-updates/main Translation-en_US Ign http://ftp.availo.se precise-updates/main Translation-en Ign http://ftp.availo.se precise-updates/multiverse Translation-en_US Ign http://ftp.availo.se precise-updates/multiverse Translation-en Ign http://ftp.availo.se precise-updates/restricted Translation-en_US Ign http://ftp.availo.se precise-updates/restricted Translation-en Ign http://ftp.availo.se precise-updates/universe Translation-en_US Ign http://ftp.availo.se precise-updates/universe Translation-en Ign http://ftp.availo.se precise-backports/main Translation-en_US Ign http://ftp.availo.se precise-backports/main Translation-en Ign http://ftp.availo.se precise-backports/multiverse Translation-en_US Ign http://ftp.availo.se precise-backports/multiverse Translation-en Ign http://ftp.availo.se precise-backports/restricted Translation-en_US Ign http://ftp.availo.se precise-backports/restricted Translation-en Ign http://ftp.availo.se precise-backports/universe Translation-en_US Ign http://ftp.availo.se precise-backports/universe Translation-en Ign http://ftp.availo.se precise-security/main Translation-en_US Ign http://ftp.availo.se precise-security/main Translation-en Ign http://ftp.availo.se precise-security/multiverse Translation-en_US Ign http://ftp.availo.se precise-security/multiverse Translation-en Ign http://ftp.availo.se precise-security/restricted Translation-en_US Ign http://ftp.availo.se precise-security/restricted Translation-en Ign http://ftp.availo.se precise-security/universe Translation-en_US Ign http://ftp.availo.se precise-security/universe Translation-en Fetched 2,979 B in 9s (328 B/s) W: GPG error: http://repository.spotify.com stable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 082CCEDF94558F59 W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/main/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/restricted/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/universe/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/multiverse/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/main/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/restricted/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/universe/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/multiverse/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/main/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/restricted/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/universe/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise/multiverse/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/main/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/restricted/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/universe/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/multiverse/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/main/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/restricted/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/universe/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/multiverse/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/main/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/restricted/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/universe/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-updates/multiverse/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/main/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/restricted/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/universe/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/multiverse/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/main/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/restricted/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/universe/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/multiverse/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/main/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/restricted/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/universe/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-backports/multiverse/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/main/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/restricted/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/universe/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/multiverse/source/Sources 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/main/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/restricted/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/universe/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/multiverse/binary-amd64/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/main/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/restricted/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/universe/binary-i386/Packages 404 Not Found W: Failed to fetch http://ftp.availo.se/ubuntu/dists/precise-security/multiverse/binary-i386/Packages 404 Not Found E: Some index files failed to download. They have been ignored, or old ones used instead. I would appreciate a fix to this. Thank you for the help.

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  • From Binary to Data Structures

    - by Cédric Menzi
    Table of Contents Introduction PE file format and COFF header COFF file header BaseCoffReader Byte4ByteCoffReader UnsafeCoffReader ManagedCoffReader Conclusion History This article is also available on CodeProject Introduction Sometimes, you want to parse well-formed binary data and bring it into your objects to do some dirty stuff with it. In the Windows world most data structures are stored in special binary format. Either we call a WinApi function or we want to read from special files like images, spool files, executables or may be the previously announced Outlook Personal Folders File. Most specifications for these files can be found on the MSDN Libarary: Open Specification In my example, we are going to get the COFF (Common Object File Format) file header from a PE (Portable Executable). The exact specification can be found here: PECOFF PE file format and COFF header Before we start we need to know how this file is formatted. The following figure shows an overview of the Microsoft PE executable format. Source: Microsoft Our goal is to get the PE header. As we can see, the image starts with a MS-DOS 2.0 header with is not important for us. From the documentation we can read "...After the MS DOS stub, at the file offset specified at offset 0x3c, is a 4-byte...". With this information we know our reader has to jump to location 0x3c and read the offset to the signature. The signature is always 4 bytes that ensures that the image is a PE file. The signature is: PE\0\0. To prove this we first seek to the offset 0x3c, read if the file consist the signature. So we need to declare some constants, because we do not want magic numbers.   private const int PeSignatureOffsetLocation = 0x3c; private const int PeSignatureSize = 4; private const string PeSignatureContent = "PE";   Then a method for moving the reader to the correct location to read the offset of signature. With this method we always move the underlining Stream of the BinaryReader to the start location of the PE signature.   private void SeekToPeSignature(BinaryReader br) { // seek to the offset for the PE signagure br.BaseStream.Seek(PeSignatureOffsetLocation, SeekOrigin.Begin); // read the offset int offsetToPeSig = br.ReadInt32(); // seek to the start of the PE signature br.BaseStream.Seek(offsetToPeSig, SeekOrigin.Begin); }   Now, we can check if it is a valid PE image by reading of the next 4 byte contains the content PE.   private bool IsValidPeSignature(BinaryReader br) { // read 4 bytes to get the PE signature byte[] peSigBytes = br.ReadBytes(PeSignatureSize); // convert it to a string and trim \0 at the end of the content string peContent = Encoding.Default.GetString(peSigBytes).TrimEnd('\0'); // check if PE is in the content return peContent.Equals(PeSignatureContent); }   With this basic functionality we have a good base reader class to try the different methods of parsing the COFF file header. COFF file header The COFF header has the following structure: Offset Size Field 0 2 Machine 2 2 NumberOfSections 4 4 TimeDateStamp 8 4 PointerToSymbolTable 12 4 NumberOfSymbols 16 2 SizeOfOptionalHeader 18 2 Characteristics If we translate this table to code, we get something like this:   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public MachineType Machine; public ushort NumberOfSections; public uint TimeDateStamp; public uint PointerToSymbolTable; public uint NumberOfSymbols; public ushort SizeOfOptionalHeader; public Characteristic Characteristics; } BaseCoffReader All readers do the same thing, so we go to the patterns library in our head and see that Strategy pattern or Template method pattern is sticked out in the bookshelf. I have decided to take the template method pattern in this case, because the Parse() should handle the IO for all implementations and the concrete parsing should done in its derived classes.   public CoffHeader Parse() { using (var br = new BinaryReader(File.Open(_fileName, FileMode.Open, FileAccess.Read, FileShare.Read))) { SeekToPeSignature(br); if (!IsValidPeSignature(br)) { throw new BadImageFormatException(); } return ParseInternal(br); } } protected abstract CoffHeader ParseInternal(BinaryReader br);   First we open the BinaryReader, seek to the PE signature then we check if it contains a valid PE signature and rest is done by the derived implementations. Byte4ByteCoffReader The first solution is using the BinaryReader. It is the general way to get the data. We only need to know which order, which data-type and its size. If we read byte for byte we could comment out the first line in the CoffHeader structure, because we have control about the order of the member assignment.   protected override CoffHeader ParseInternal(BinaryReader br) { CoffHeader coff = new CoffHeader(); coff.Machine = (MachineType)br.ReadInt16(); coff.NumberOfSections = (ushort)br.ReadInt16(); coff.TimeDateStamp = br.ReadUInt32(); coff.PointerToSymbolTable = br.ReadUInt32(); coff.NumberOfSymbols = br.ReadUInt32(); coff.SizeOfOptionalHeader = (ushort)br.ReadInt16(); coff.Characteristics = (Characteristic)br.ReadInt16(); return coff; }   If the structure is as short as the COFF header here and the specification will never changed, there is probably no reason to change the strategy. But if a data-type will be changed, a new member will be added or ordering of member will be changed the maintenance costs of this method are very high. UnsafeCoffReader Another way to bring the data into this structure is using a "magically" unsafe trick. As above, we know the layout and order of the data structure. Now, we need the StructLayout attribute, because we have to ensure that the .NET Runtime allocates the structure in the same order as it is specified in the source code. We also need to enable "Allow unsafe code (/unsafe)" in the project's build properties. Then we need to add the following constructor to the CoffHeader structure.   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public CoffHeader(byte[] data) { unsafe { fixed (byte* packet = &data[0]) { this = *(CoffHeader*)packet; } } } }   The "magic" trick is in the statement: this = *(CoffHeader*)packet;. What happens here? We have a fixed size of data somewhere in the memory and because a struct in C# is a value-type, the assignment operator = copies the whole data of the structure and not only the reference. To fill the structure with data, we need to pass the data as bytes into the CoffHeader structure. This can be achieved by reading the exact size of the structure from the PE file.   protected override CoffHeader ParseInternal(BinaryReader br) { return new CoffHeader(br.ReadBytes(Marshal.SizeOf(typeof(CoffHeader)))); }   This solution is the fastest way to parse the data and bring it into the structure, but it is unsafe and it could introduce some security and stability risks. ManagedCoffReader In this solution we are using the same approach of the structure assignment as above. But we need to replace the unsafe part in the constructor with the following managed part:   [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)] public struct CoffHeader { public CoffHeader(byte[] data) { IntPtr coffPtr = IntPtr.Zero; try { int size = Marshal.SizeOf(typeof(CoffHeader)); coffPtr = Marshal.AllocHGlobal(size); Marshal.Copy(data, 0, coffPtr, size); this = (CoffHeader)Marshal.PtrToStructure(coffPtr, typeof(CoffHeader)); } finally { Marshal.FreeHGlobal(coffPtr); } } }     Conclusion We saw that we can parse well-formed binary data to our data structures using different approaches. The first is probably the clearest way, because we know each member and its size and ordering and we have control about the reading the data for each member. But if add member or the structure is going change by some reason, we need to change the reader. The two other solutions use the approach of the structure assignment. In the unsafe implementation we need to compile the project with the /unsafe option. We increase the performance, but we get some security risks.

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