The way I understand it, the code above allows arbitrary code (or program) execution — what makes this vulnerable, and how does one take advantage of this? Answer You can override the PATH variable to point to a directory with your custom version of echo and since echo is executed using env, it isn’t treated as a built-in. This constitues
Tag: c++
Undefined references in makefile
Ok, ive read about 10 tutorials, but i keep getting errors all the time, i have 5 files, main.cpp class.cpp, class.h and functions.cpp and functions.h. All of those use functions from different objects meaning that functions in functions.cpp uses objects from classes.cpp. My makefile looks as follows I keeps telling me that it has undefined references. What am i missing?
Adding a status bar to c++ console applications
I am making a linux application using C++ and it will print info out to the console. Parts of the program will take a while to compute and I would like to add a status bar in the console similar to the one used in wget (I put my own depiction below). What would be the best way to accomplish
A simple C++ shared memory program written on linux: segmentation fault
I got the code from a tutorial on shared memory. It worked until I defined struct LOCK and tried to write LOCKs instead of char* into the shared memory. Could someone please help me figure out the problem here that causes the segmentation fault? Answer You are placing vectors and strings into shared memory. Both those classes allocate memory of
Is malloc deterministic?
Is malloc deterministic? Say If I have a forked process, that is, a replica of another process, and at some point both of them call the malloc function. Would the address allocated be the same in both processes? Assuming that other parts of execution are also deterministic. Note: Here, I’m only talking about virtual memory, not physical one. Answer There
Why makecontext does not work with pthreads
From makecontext() manual… Due to limitations in the current pthread implementation, makecontext should not be used in programs which link against the pthread(3) library (whether threads are used or not). Now my question is, why it doesn’t work and what are the alternative methods. Actually I’m interested in switching stacks in a user-level thread at some points, but I’m seeing
Turn on core/crash dumps programmatically
I know I can run “ulimit -c unlimited” In the shell to turn on core dumps for the current user. What I am wondering is how can I do this programmatically from C? I see there is a ulimit call, but it’s been deprecated in favour of get/setrlimit. What I want to know is what is the equivalent call to
undefined reference to sync_fetch_and_add_4
Whenever I try to use __sync_fetch_and_add with -m32 on a 64 bit machine, I get the following error, while it compiles fine with normal 64 bit. I am using gcc compiler 4.1.2. What can be the problem here and what is the solution? Answer Using -march=i486 flag did the trick for me.
Linking C function lib to x86 assembly program in modern 64bit Linux
I’m going through a book focusing on x86 programming (Professional Assembly Language, WROX 2005). I had some problems last night and I was hoping to sort this out before returning home today so I can get a running-start and continue the text. My machine runs x64 Ubuntu (11.04 if I’m not mistaken) so the text focusing on 32bit x86 is
Implementing clipboard functionality on X (*nix) without access to event loop?
Is it possible to implement copy-paste of text if you have a window but no access to the event loop, and can only make function calls to X. I’ve implemented clipboard on Windows and OSX with nothing but API function calls. Is the same possible on *nix with X? I was told you absolutely need access to the X event