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  • Why use buffers to read/write Streams

    - by James Hay
    Following reading various questions on reading and writing Streams, all the various answers define something like this as the correct way to do it: private void CopyStream(Stream input, Stream output) { byte[] buffer = new byte[16 * 1024]; int read; while ((read = input.Read(buffer, 0, buffer.Length)) > 0) { output.Write(buffer, 0, read); } } Two questions: Why read and write in these smaller chunks? What is the significance of the buffer size used?

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  • How can I determine if a file is read-only for my process on *nix?

    - by user109078
    Using the stat function, I can get the read/write permissions for: owner user other ...but this isn't what I want. I want to know the read/write permissions of a file for my process (i.e. the application I'm writing). The owner/user/other is only helpful if I know if my process is running as the owner/user/other of the file...so maybe that's the solution but I'm not sure of the steps to get there.

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  • Versioning freindly, extendible binary file format

    - by Bas Bossink
    In the project I'm currently working on there is a need to save a sizeable data structure to disk. Being in optimist I thought their must be a standard solution for such a problem however upto now I haven't found a solution that satisfies the following requirements: .net 2.0 support, preferably with a foss implementation version friendly (this should be interpreted as reading an old version of the format should be relatively simple if the changes in the underlying data structure are simple, say adding/dropping fields) ability to do some form of random access where part of the data can be extended after initial creation (think of this as extending intermediate results) space and time efficient (xml has been excluded as option given this requierement) Options considered so far: Protocol Buffers : was turned down by verdict of the documentation about Large Data Sets since this comment suggest adding another layer on top, this would call for additional complexity which I wish to have handled by the file format itself. HDF5,EXI : do not seem to have .net implementations SQLite : the data structure at hand would result in a pretty complex table structure that seems to heavyweight for the intended use BSON : does not appear to support requirement 3. Fast Infoset : only seems to have buyware .net implementations Any recommendations or pointers are greatly appreciated. Furthermore if you believe any of the information above is not true please provide pointers/examples to proove me wrong.

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  • Flow control in a batch file

    - by dboarman-FissureStudios
    Reference Iterating arrays in a batch file I have the following: for /f "tokens=1" %%Q in ('query termserver') do ( if not ERRORLEVEL ( echo Checking %%Q for /f "tokens=1" %%U in ('query user %UserID% /server:%%Q') do (echo %%Q) ) ) When running query termserver from the command line, the first two lines are: Known ------------------------- ...followed by the list of terminal servers. However, I do not want to include these as part of the query user command. Also, there are about 4 servers I do not wish to include. When I supply UserID with this code, the program is promptly exiting. I know it has something to do with the if statement. Is this not possible to nest flow control inside the for-loop? I had tried setting a variable to exactly the names of the servers I wanted to check, but the iteration would end on the first server: set TermServers=Server1.Server2.Server3.Server7.Server8.Server10 for /f "tokens=2 delims=.=" %%Q in ('set TermServers') do ( echo Checking %%Q for /f "tokens=1" %%U in ('query user %UserID% /server:%%Q') do (echo %%Q) ) I would prefer this second example over the first if nothing else for cleanliness. Any help regarding either of these issues would be greatly appreciated.

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  • Versioning friendly, extendible binary file format

    - by Bas Bossink
    In the project I'm currently working on there is a need to save a sizable data structure to disk (edit: think dozens of MB's). Being an optimist, I thought that there must be a standard solution for such a problem; however, up to now I haven't found a solution that satisfies the following requirements: .NET 2.0 support, preferably with a FOSS implementation Version friendly (this should be interpreted as: reading an old version of the format should be relatively simple if the changes in the underlying data structure are simple, say adding/dropping fields) Ability to do some form of random access where part of the data can be extended after initial creation (think of this as extending intermediate results) Space and time efficient (XML has been excluded as option given this requirement) Options considered so far: Protocol Buffers: was turned down by verdict of the documentation about Large Data Sets - since this comment suggested adding another layer on top, this would call for additional complexity which I wish to have handled by the file format itself. HDF5,EXI: do not seem to have .net implementations SQLite/SQL Server Compact edition: the data structure at hand would result in a pretty complex table structure that seems too heavyweight for the intended use BSON: does not appear to support requirement 3. Fast Infoset: only seems to have paid .NET implementations. Any recommendations or pointers are greatly appreciated. Furthermore if you believe any of the information above is not true, please provide pointers/examples to prove me wrong.

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  • How to save a picture to a file?

    - by Peter vdL
    I'm trying to use a standard Intent that will take a picture, then allow approval or retake. Then I want to save the picture into a file. Here's the Intent I am using: Intent intent = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE ); startActivityForResult( intent, 22 ); The docs at http://developer.android.com/reference/android/provider/MediaStore.html#ACTION_IMAGE_CAPTURE say "The caller may pass an extra EXTRA_OUTPUT to control where this image will be written. If the EXTRA_OUTPUT is not present, then a small sized image is returned as a Bitmap object in the extra field. If the EXTRA_OUTPUT is present, then the full-sized image will be written to the Uri value of EXTRA_OUTPUT." I don't pass extra output, I hope to get a Bitmap object in the extra field of the Intent passed into onActivityResult() (for this request). So where/how do you extract it? Intent has a getExtras(), but that returns a Bundle, and Bundle wants a key string to give you something back. What do you invoke on the Intent to extract the bitmap?

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  • aio_read from file error on OS X

    - by Pyetras
    The following code: #include <fcntl.h> #include <unistd.h> #include <stdio.h> #include <aio.h> #include <errno.h> int main (int argc, char const *argv[]) { char name[] = "abc"; int fdes; if ((fdes = open(name, O_RDWR | O_CREAT, 0600 )) < 0) printf("%d, create file", errno); int buffer[] = {0, 1, 2, 3, 4, 5}; if (write(fdes, &buffer, sizeof(buffer)) == 0){ printf("writerr\n"); } struct aiocb aio; int n = 2; while (n--){ aio.aio_reqprio = 0; aio.aio_fildes = fdes; aio.aio_offset = sizeof(int); aio.aio_sigevent.sigev_notify = SIGEV_NONE; int buffer2; aio.aio_buf = &buffer2; aio.aio_nbytes = sizeof(buffer2); if (aio_read(&aio) != 0){ printf("%d, readerr\n", errno); }else{ const struct aiocb *aio_l[] = {&aio}; if (aio_suspend(aio_l, 1, 0) != 0){ printf("%d, suspenderr\n", errno); }else{ printf("%d\n", *(int *)aio.aio_buf); } } } return 0; } Works fine on Linux (Ubuntu 9.10, compiled with -lrt), printing 1 1 But fails on OS X (10.6.6 and 10.6.5, I've tested it on two machines): 1 35, readerr Is this possible that this is due to some library error on OS X, or am I doing something wrong?

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  • [UNIX] Sort lines of massive file by number of words on line (ideally in parallel)

    - by conradlee
    I am working on a community detection algorithm for analyzing social network data from Facebook. The first task, detecting all cliques in the graph, can be done efficiently in parallel, and leaves me with an output like this: 17118 17136 17392 17064 17093 17376 17118 17136 17356 17318 12345 17118 17136 17356 17283 17007 17059 17116 Each of these lines represents a unique clique (a collection of node ids), and I want to sort these lines in descending order by the number of ids per line. In the case of the example above, here's what the output should look like: 17118 17136 17356 17318 12345 17118 17136 17356 17283 17118 17136 17392 17064 17093 17376 17007 17059 17116 (Ties---i.e., lines with the same number of ids---can be sorted arbitrarily.) What is the most efficient way of sorting these lines. Keep the following points in mind: The file I want to sort could be larger than the physical memory of the machine Most of the machines that I'm running this on have several processors, so a parallel solution would be ideal An ideal solution would just be a shell script (probably using sort), but I'm open to simple solutions in python or perl (or any language, as long as it makes the task simple) This task is in some sense very easy---I'm not just looking for any old solution, but rather for a simple and above all efficient solution

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  • What arguments to use to explain why SQL Server is far better then a flat file

    - by jamone
    The higher ups in my company were told by good friends that flat files are the way to go, and we should switch from SQL Server to them for everything we do. We have over 300 servers and hundreds of different databases. From just the few I'm involved with we have 10 billion records in quite a few of them with upwards of 100k new records a day and who knows how many updates... Me and a couple others need to come up with a response saying why we shouldn't do this. Most of our stuff is ASP.NET with some legacy ASP. We thought that making a simple console app that tests/times the same interactions between a flat file (stored on the network) and SQL over the network doing large inserts, searches, updates etc along with things like network disconnects randomly. This would show them how bad flat files can be especially when you are dealing with millions of records. What things should I use in my response? What should I do with my demo code to illustrate this? My sort list so far: Security Concurrent access Performance with large amounts of data Amount of time to do such a massive rewrite/switch Lack of transactions PITA to map relational data to flat files NTFS doesn't support tons of files in a directory well I fear that this will be a great post on the Daily WTF someday if I can't stop it now.

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  • Batch File to Delete Folders

    - by Homebrew
    I found some code to delete folders, in this case deleting all but 'n' # of folders. I created 10 test folders, plus 1 that was already there. I want to delete all but 4. The code works, it leaves 4 of my test folders, except that it also leaves the other folder. Is there some attribute of the other folder that's getting checked in the batch file that's stopping it from getting deleted ? It was created through a job a couple of weeks ago. Here's the code I stole (but don't really understand the details): rem DOS - Delete Folders if # folders > n @Echo Off :: User Variables :: Set this to the number of folders you want to keep Set _NumtoKeep=4 :: Set this to the folder that contains the folders to check and delete Set _Path=C:\MyFolder_Temp\FolderTest If Exist "%temp%\tf}1{" Del "%temp%\tf}1{" PushD %_Path% Set _s=%_NumtoKeep% If %_NumtoKeep%==1 set _s=single For /F "tokens=* skip=%_NumtoKeep%" %%I In ('dir "%_Path%" /AD /B /O-D /TW') Do ( If Exist "%temp%\tf}1{" ( Echo %%I:%%~fI >>"%temp%\tf}1{" ) Else ( Echo.>"%temp%\tf}1{" Echo Do you wish to delete the following folders?>>"%temp%\tf}1{" Echo Date Name>>"%temp%\tf}1{" Echo %%I:%%~fI >>"%temp%\tf}1{" )) PopD If Not Exist "%temp%\tf}1{" Echo No Folders Found to delete & Goto _Done Type "%temp%\tf}1{" | More Set _rdflag= /q Goto _Removeold Set _rdflag= :_Removeold For /F "tokens=1* skip=3 Delims=:" %%I In ('type "%temp%\tf}1{"') Do ( If "%_rdflag%"=="" Echo Deleting rd /s%_rdflag% "%%J") :_Done If Exist "%temp%\tf}1{" Del "%temp%\tf}1{"

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  • C++ File manipulation problem

    - by Carlucho
    I am trying to open a file which normally has content, for the purpose of testing i will like to initialize the program without the files being available/existing so then the program should create empty ones, but am having issues implementing it. This is my code originally void loadFiles() { fstream city; city.open("city.txt", ios::in); fstream latitude; latitude.open("lat.txt", ios::in); fstream longitude; longitude.open("lon.txt", ios::in); while(!city.eof()){ city >> cityName; latitude >> lat; longitude >> lon; t.add(cityName, lat, lon); } city.close(); latitude.close(); longitude.close(); } I have tried everything i can think of, ofstream, ifstream, adding ios::out all all its variations. Could anybody explain me what to do in order to fix the problem. Thanks!

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  • loading files through one file to hide locations

    - by Phil Jackson
    Hello all. Im currently doing a project in which my client does not want to location ( ie folder names and locations ) to be displayed. so I have done something like this: <link href="./?0000=css&0001=0001&0002=css" rel="stylesheet" type="text/css" /> <link href="./?0000=css&0001=0002&0002=css" rel="stylesheet" type="text/css" /> <script src="./?0000=js&0001=0000&0002=script" type="text/javascript"></script> </head> <body> <div id="wrapper"> <div id="header"> <div id="left_header"> <img src="./?0000=jpg&0001=0001&0002=pic" width="277" height="167" alt="" /> </div> <div id="right_header"> <div id="top-banner"></div> <ul id="navigation"> <li><a href="#" title="#" id="nav-home">Home</a></li> <li><a href="#" title="#">Signup</a></li> all works but my question being is or will this cause any complications i.e. speed of the site as all requests are being made to one single file and then loading in the appropriate data. Regards, Phil

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  • SQL query error while trying to put a file in the database

    - by DaGhostman Dimitrov
    Hey Guys I have a big problem that I have no Idea why.. I have few forms that upload files to the database, all of them work fine except one.. I use the same query in all(simple insert). I think that it has something to do with the files i am trying to upload but I am not sure. Here is the code: if ($_POST['action'] == 'hndlDocs') { $ref = $_POST['reference']; // Numeric value of $doc = file_get_contents($_FILES['doc']['tmp_name']); $link = mysqli_connect('localhost','XXXXX','XXXXX','documents'); mysqli_query($link,"SET autocommit = 0"); $query = "INSERT INTO documents ({$ref}, '{$doc}', '{$_FILES['doc']['type']}') ;"; mysqli_query($link,$query); if (mysqli_error($link)) { var_dump(mysqli_error($link)); mysqli_rollback($link); } else { print("<script> window.history.back(); </script>"); mysqli_commit($link); } } The database has only these fields: DATABASE documents ( reference INT(5) NOT NULL, //it is unsigned zerofill doc LONGBLOB NOT NULL, //this should contain the binary data mime_type TEXT NOT NULL // the mime type of the file php allows only application/pdf and image/jpeg ); And the error I get is : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '00001, '????' at line 1 I will appreciate every help. Cheers!

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  • reading the file name from user input in MIPS assembly

    - by Hassan Al-Jeshi
    I'm writing a MIPS assembly code that will ask the user for the file name and it will produce some statistics about the content of the file. However, when I hard code the file name into a variable from the beginning it works just fine, but when I ask the user to input the file name it does not work. after some debugging, I have discovered that the program adds 0x00 char and 0x0a char (check asciitable.com) at the end of user input in the memory and that's why it does not open the file based on the user input. anyone has any idea about how to get rid of those extra chars, or how to open the file after getting its name from the user?? here is my complete code (it is working fine except for the file name from user thing, and anybody is free to use it for any purpose he/she wants to): .data fin: .ascii "" # filename for input msg0: .asciiz "aaaa" msg1: .asciiz "Please enter the input file name:" msg2: .asciiz "Number of Uppercase Char: " msg3: .asciiz "Number of Lowercase Char: " msg4: .asciiz "Number of Decimal Char: " msg5: .asciiz "Number of Words: " nline: .asciiz "\n" buffer: .asciiz "" .text #----------------------- li $v0, 4 la $a0, msg1 syscall li $v0, 8 la $a0, fin li $a1, 21 syscall jal fileRead #read from file move $s1, $v0 #$t0 = total number of bytes li $t0, 0 # Loop counter li $t1, 0 # Uppercase counter li $t2, 0 # Lowercase counter li $t3, 0 # Decimal counter li $t4, 0 # Words counter loop: bge $t0, $s1, end #if end of file reached OR if there is an error in the file lb $t5, buffer($t0) #load next byte from file jal checkUpper #check for upper case jal checkLower #check for lower case jal checkDecimal #check for decimal jal checkWord #check for words addi $t0, $t0, 1 #increment loop counter j loop end: jal output jal fileClose li $v0, 10 syscall fileRead: # Open file for reading li $v0, 13 # system call for open file la $a0, fin # input file name li $a1, 0 # flag for reading li $a2, 0 # mode is ignored syscall # open a file move $s0, $v0 # save the file descriptor # reading from file just opened li $v0, 14 # system call for reading from file move $a0, $s0 # file descriptor la $a1, buffer # address of buffer from which to read li $a2, 100000 # hardcoded buffer length syscall # read from file jr $ra output: li $v0, 4 la $a0, msg2 syscall li $v0, 1 move $a0, $t1 syscall li $v0, 4 la $a0, nline syscall li $v0, 4 la $a0, msg3 syscall li $v0, 1 move $a0, $t2 syscall li $v0, 4 la $a0, nline syscall li $v0, 4 la $a0, msg4 syscall li $v0, 1 move $a0, $t3 syscall li $v0, 4 la $a0, nline syscall li $v0, 4 la $a0, msg5 syscall addi $t4, $t4, 1 li $v0, 1 move $a0, $t4 syscall jr $ra checkUpper: blt $t5, 0x41, L1 #branch if less than 'A' bgt $t5, 0x5a, L1 #branch if greater than 'Z' addi $t1, $t1, 1 #increment Uppercase counter L1: jr $ra checkLower: blt $t5, 0x61, L2 #branch if less than 'a' bgt $t5, 0x7a, L2 #branch if greater than 'z' addi $t2, $t2, 1 #increment Lowercase counter L2: jr $ra checkDecimal: blt $t5, 0x30, L3 #branch if less than '0' bgt $t5, 0x39, L3 #branch if greater than '9' addi $t3, $t3, 1 #increment Decimal counter L3: jr $ra checkWord: bne $t5, 0x20, L4 #branch if 'space' addi $t4, $t4, 1 #increment words counter L4: jr $ra fileClose: # Close the file li $v0, 16 # system call for close file move $a0, $s0 # file descriptor to close syscall # close file jr $ra Note: I'm using MARS Simulator, if that makes any different

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  • SQL SERVER – Windows File/Folder and Share Permissions – Notes from the Field #029

    - by Pinal Dave
    [Note from Pinal]: This is a 29th episode of Notes from the Field series. Security is the task which we should give it to the experts. If there is a small overlook or misstep, there are good chances that security of the organization is compromised. This is very true, but there are always devils’s advocates who believe everyone should know the security. As a DBA and Administrator, I often see people not taking interest in the Windows Security hiding behind the reason of not expert of Windows Server. We all often miss the important mission statement for the success of any organization – Teamwork. In this blog post Brian tells the story in very interesting lucid language. Read On! In this episode of the Notes from the Field series database expert Brian Kelley explains a very crucial issue DBAs and Developer faces on their production server. Linchpin People are database coaches and wellness experts for a data driven world. Read the experience of Brian in his own words. When I talk security among database professionals, I find that most have at least a working knowledge of how to apply security within a database. When I talk with DBAs in particular, I find that most have at least a working knowledge of security at the server level if we’re speaking of SQL Server. One area I see continually that is weak is in the area of Windows file/folder (NTFS) and share permissions. The typical response is, “I’m a database developer and the Windows system administrator is responsible for that.” That may very well be true – the system administrator may have the primary responsibility and accountability for file/folder and share security for the server. However, if you’re involved in the typical activities surrounding databases and moving data around, you should know these permissions, too. Otherwise, you could be setting yourself up where someone is able to get to data he or she shouldn’t, or you could be opening the door where human error puts bad data in your production system. File/Folder Permission Basics: I wrote about file/folder permissions a few years ago to give the basic permissions that are most often seen. Here’s what you must know as a minimum at the file/folder level: Read - Allows you to read the contents of the file or folder. Having read permissions allows you to copy the file or folder. Write  – Again, as the name implies, it allows you to write to the file or folder. This doesn’t include the ability to delete, however, nothing stops a person with this access from writing an empty file. Delete - Allows the file/folder to be deleted. If you overwrite files, you may need this permission. Modify - Allows read, write, and delete. Full Control - Same as modify + the ability to assign permissions. File/Folder permissions aggregate, unless there is a DENY (where it trumps, just like within SQL Server), meaning if a person is in one group that gives Read and antoher group that gives Write, that person has both Read and Write permissions. As you might expect me to say, always apply the Principle of Least Privilege. This likely means that any additional permission you might add does not need Full Control. Share Permission Basics: At the share level, here are the permissions. Read - Allows you to read the contents on the share. Change - Allows you to read, write, and delete contents on the share. Full control - Change + the ability to modify permissions. Like with file/folder permissions, these permissions aggregate, and DENY trumps. So What Access Does a Person / Process Have? Figuring out what someone or some process has depends on how the location is being accessed: Access comes through the share (\\ServerName\Share) – a combination of permissions is considered. Access is through a drive letter (C:\, E:\, S:\, etc.) – only the file/folder permissions are considered. The only complicated one here is access through the share. Here’s what Windows does: Figures out what the aggregated permissions are at the file/folder level. Figures out what the aggregated permissions are at the share level. Takes the most restrictive of the two sets of permissions. You can test this by granting Full Control over a folder (this is likely already in place for the Users local group) and then setting up a share. Give only Read access through the share, and that includes to Administrators (if you’re creating a share, likely you have membership in the Administrators group). Try to read a file through the share. Now try to modify it. The most restrictive permission is the Share level permissions. It’s set to only allow Read. Therefore, if you come through the share, it’s the most restrictive. Does This Knowledge Really Help Me? In my experience, it does. I’ve seen cases where sensitive files were accessible by every authenticated user through a share. Auditors, as you might expect, have a real problem with that. I’ve also seen cases where files to be imported as part of the nightly processing were overwritten by files intended from development. And I’ve seen cases where a process can’t get to the files it needs for a process because someone changed the permissions. If you know file/folder and share permissions, you can spot and correct these types of security flaws. Given that there are a lot of database professionals that don’t understand these permissions, if you know it, you set yourself apart. And if you’re able to help on critical processes, you begin to set yourself up as a linchpin (link to .pdf) for your organization. If you want to get started with performance tuning and database security with the help of experts, read more over at Fix Your SQL Server. Reference: Pinal Dave (http://blog.sqlauthority.com)Filed under: Notes from the Field, PostADay, SQL, SQL Authority, SQL Query, SQL Security, SQL Server, SQL Tips and Tricks, T SQL

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  • Add entries to Nautilus' right-click menu (copy, move to arbitrary directories)

    - by qbi
    Assume I want to copy a file from /home/foo/bar/baz to /opt/quuz/dir1/option3. When I try it with Nautilus, first I have to open the correct directory, copy the file, go to the other directory and paste it there. I was thinking of a better way and old KDE3 versions of Konqueror came to mind. It was possible to right-click on a file. The context menu had an option for copying, moving the file to some default directories. Furthermore you could select any directory under /. So for the above action one would right click on a file, select /opt first, a list of subdirectories will open, select /opt/quuz and so on. Using GNOME there are only two possible values (home and desktop). Is there any way to insert more directories to this context menu in GNOME? Can I copy somehow the behaviour of Konqueror?

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  • Is it possible to preview arbitrary formats in Nautilus?

    - by alfC
    I recently found out that Nautilus (Ubuntu 12.04 at least) can show thumbnails of files of non-image formats, for example (data grapher) grace files (.agr) shows a small version of the graph contained in its data. Obviously, there some library or script that is processing the file, making the image, and allowing nautilus to show a small version of it. This made me think that in principle any file that potentially can be processed into an image can serve as a Nautilus thumbnail. For example, a .tex file (which can be converted to .pdf) or a gnuplot script can be displayed as a thumbnail when possible. In the case of .tex file, the correspoding .pdf can be created by the command pdflatex file.tex. The question is, how can I tell Nautilus to create a thumbnail for an arbitrary format and how do I specify the commands to do so within Nautilus?

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  • Java: file write on finalize method

    - by sowrov
    In my understanding a singleton object will destroy only when the application is about to terminate. So in C++ I write a Singleton class to log my application and in that Singleton logger's destructor I log the time when my application was terminated. Things worked perfectly in C++. Now I want to have that same logger in Java, as in java there is no destructor so I implemented the finalize method for that singleton logger. But it seem that finalize method actually never get called. So, I add that System.runFinalizersOnExit(true); line, somewhere in my code (though I know it is deprecated) and that finalize method get called every time before termination of the app. But still there is a problem! If I try to write anything on file in that finalize method, It does not work, though System.out work without any problem! :( Can you guys help me on this problem? Here is a sample code of what I am try to do: Singleton Logger Class: public class MyLogger { FileWriter writer; private MyLogger() { try { this.writer = new FileWriter("log.txt"); } catch (IOException ex) { } } public static MyLogger getInstance() { return MyLoggerHolder.INSTANCE; } private static class MyLoggerHolder { private static final MyLogger INSTANCE = new MyLogger(); } @Override protected void finalize () { try { super.finalize(); System.out.println("Here"); //worked correctly. this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write("End"); this.writer.flush(); //does not work! this.writer.close(); } catch (Throwable ex) { } } public synchronized void log(String str) { try { this.writer.write(new Date().toString()+System.getProperty("line.separator")); this.writer.write(str+"\n"); this.writer.flush(); } catch (IOException ex) { } } } Main: public class Main { public static void main(String[] args) { System.runFinalizersOnExit(true); MyLogger logger = MyLogger.getInstance(); logger.log("test"); } }

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  • Do any database "styles" use discrete files for their tables?

    - by Brad
    I've been talking to some people at work who believe some versions of a database store their data in discrete tables. That is to say you might open up a folder and see one file for each table in the database then several other supporting files. They do not have a lot of experience with databases but I have only been working with them for a little over a half year so I am not a canonical source of info either. I've been touting the benefits of SQL Server over Access (and before this, Access over Excel. Great strides have been made :) ). But, other people were of the impression that the/one of the the benefit(s) of using SQL Server over Access was that all the data was not consolidated down into one file. Yet, SQL Server packs everything into a single .mdf file (plus the log file). My question is, is there an RDBMS which holds it's data in multiple discrete files instead of one master file? And if the answer is yes, why do it one way over the other?

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  • Webclient using download file to grab file from server - handling exceptions

    - by baron
    Hello everyone, I have a web service in which I am manipulating POST and GET methods to facilitate upload / download functionality for some files in a client/server style architecture. Basically the user is able to click a button to download a specific file, make some changes in the app, then click upload button to send it back. Problem I am having is with the download. Say the user expects 3 files 1.txt, 2.txt and 3.txt. Except 2.txt does not exist on the server. So I have code like (on server side): public class HttpHandler : IHttpHandler { public void ProcessRequest { if (context.Request.HttpMethod == "GET") { GoGetIt(context) } } private static void GoGetIt(HttpContext context) { var fileInfoOfWhereTheFileShouldBe = new FileInfo(......); if (!fileInfoOfWhereTheFileShouldBe.RefreshExists()) { throw new Exception("Oh dear the file doesn't exist"); } ... So the problem I have is that when I run the application, and I use a WebClient on client side to use DownloadFile method which then uses the code I have above, I get: WebException was unhandled: The remote server returned an error: (500) Internal Server Error. (While debugging) If I attach to the browser and use http://localhost:xxx/1.txt I can step through server side code and throw the exception as intended. So I guess I'm wondering how I can handle the internal server error on the client side properly so I can return something meaningful like "File doesn't exist". One thought was to use a try catch around the WebClient.DownloadFile(address, filename) method but i'm not sure thats the only error that will occur i.e. the file doesn't exist.

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  • input type file alternative and file upload best practice

    - by Ioxp
    Background: I am working on a file upload page that will extend an existing web portal. This page will allow for an end user to upload files from there local computer to our network (the files will not be stored on the web server, rather a remote workstation). The end user will have the ability to view the data that they have submitted by hyper-linking the files that have been uploaded on this page. Question 1: Is there an ASP.net alternative to the <input type="file" runat="server" /> HTML tag? The reason for asking is i would rather use an image button and display the file as an asp label on the portal to keep with a consistent style. Question 2: So i understand that giving the end user the ability to upload files to the server and then turn around to show them the data that they posted poses a security threat. So far i am using the id.PostedFile.ContentType and the file extension to reject the data if its not an accepted format (i.e. "text/plain", "application/pdf", "application/vnd.ms-excel", or "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"). Also the location where the files are uploaded to has a sufficient amount of virus and malware protection and this is not a concern. What, from the C# point of view, additional steps should i take to ensure that the end user cant take advantage and compromise the system in regards to allowing them to upload files?

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  • What file format can represent an uncompressed raster image at 48 or 64 bits per pixel?

    - by finnw
    I am creating screenshots under Windows and using the LockBits function from GDI+ to extract the pixel data, which will then be written to a file. To maximise performance I am also: Using the same PixelFormat as the source bitmap, to avoid format conversion Using the ImageLockModeUserInputBuf flag to extract the pixel data into a pre-allocated buffer This pre-allocated buffer (pointed to by BitmapData::Scan0) is part of a memory-mapped file (to avoid copying the pixel data again.) I will also be writing the code that reads the file, so I can use (or invent) any format I wish. However I would prefer to use a well-known format that existing programs (ideally web browsers) are able to read, because that means I can visually confirm that the images are correct before writing the code for the other program (that reads the image.) I have implemented this successfully for the PixelFormat32bppRGB format, which matches the format of a 32bpp BMP file, so if I extract the pixel data directly into the memory-mapped BMP file and prefix it with a BMP header I get a valid BMP image file that can be opened in Paint and most browsers. Unfortunately one of the machines I am testing on returns pixels in PixelFormat64bppPARGB format (presumably this is influenced by the video adapter driver) and there is no corresponding BMP pixel format for this. Converting to a 16, 24 or 32bpp BMP format slows the program down considerably (as well as being lossy) so I am looking for a file format that can use this pixel format without conversion, so I can extract directly into the memory-mapped file as I have done with the 32bpp format. What raster image file formats support 48bpp and/or 64bpp?

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