valgrind

Microsoft's Visual C++ fills memory with 'magic numbers' if it hasn't been initialized by the programmer itself. This helps with debugging of uninitialized memory. ( In Visual Studio C++, what are the memory allocation representations? , 0xDEADBEEF vs. NULL ) Is there a similar function when using linux GNU tools (g++/gdb)? Thanks! John Zwinck You can override the C++ operator new to set allocations to your preferred byte pattern: void* operator new(size_t size) { void* mem = malloc(size); if (!mem) { throw std::bad_alloc(); } memset(mem, 0xEE, size); return mem; } You can see the full GCC

I have started using valgrind just one day ago as suggested by someone on SO itself .Its an amazing tool but today i got an issue with it.It gives the following error : definitely lost bytes but unable to tell the location of error. Here is the output of valgrind : udit@udit-Dabba ~ $ valgrind --leak-check=full sendip -v -p ipv6 -f file.txt -6s ::1 -p ah -as 0x20 -aq 0x40 -ak "yugal" -am xorauth.so -p udp -us 21 - ud 21 ::2 ==12885== Memcheck, a memory error detector ==12885== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==12885== Using Valgrind-3.6.1 and LibVEX; rerun with

This is my code: #include<stdio.h> #include<stdlib.h> #include<string.h> void main(int arge, char *argv[]) { FILE *f1; char ch,*fn="~/lyrics/"; strcat(fn,argv[1]); strcat(fn,".txt"); if( (f1 = fopen(fn,"r"))==NULL ) { printf("\nWrong filename\n%s not found",argv[1]); return; } while((ch=getw(f1))!=EOF) { printf("%c",ch); } } I compiled it using gcc -g -o file file.c and the compiler gave no error messages. But when I run it I get the error message: Segmentation fault (core dumped) Bad permissions for mapped region at address 0x8048659 at 0x402C36B: strcat (in /usr/lib/valgrind/vgpreload

Valgrind 概述 体系结构 Valgrind是一套Linux下，开放源代码（GPL V2）的仿真调试工具的集合。Valgrind由内核（core）以及基于内核的其他调试工具组成。内核类似于一个框架（framework），它模拟了一个CPU环境，并提供服务给其他工具；而其他工具则类似于插件 (plug-in)，利用内核提供的服务完成各种特定的内存调试任务。Valgrind的体系结构如下图所示： 图 1 Valgrind 体系结构 Valgrind包括如下一些工具： Memcheck。 这是valgrind应用最广泛的工具，一个重量级的内存检查器，能够发现开发中绝大多数内存错误使用情况，比如：使用未初始化的内存，使用已经释放了的内存，内存访问越界等。这也是本文将重点介绍的部分。 Callgrind 。它主要用来检查程序中函数调用过程中出现的问题。 Cachegrind 。它主要用来检查程序中缓存使用出现的问题。 Helgrind 。它主要用来检查多线程程序中出现的竞争问题。 Massif 。它主要用来检查程序中堆栈使用中出现的问题。 Extension。 可以利用core提供的功能，自己编写特定的内存调试工具。 Linux 程序内存空间布局 要发现Linux下的内存问题，首先一定要知道在Linux下，内存是如何被分配的？下图展示了一个典型的Linux C程序内存空间布局： 图 2

第一步： 获取Valgrind 包 可以先使用浏览器访问http://valgrind.org/downloads/查看当前版本 wget http://valgrind.org/downloads/valgrind-3.10.1.tar.bz2 第二步： 将下载的文件解压 tar -jxvf valgrind-3.10.1.tar.bz2 第三步： 安装和配置 ./autogen.sh ./configure make; make install Linux下利用Valgrind工具进行内存泄露检测和性能分析 Valgrind通常用来成分析程序性能及程序中的内存泄露错误 一 Valgrind工具集简绍 Valgrind包含下列工具： 1、memcheck：检查程序中的内存问题，如泄漏、越界、非法指针等。 2、callgrind：检测程序代码的运行时间和调用过程，以及分析程序性能。 3、cachegrind：分析CPU的cache命中率、丢失率，用于进行代码优化。 4、helgrind：用于检查多线程程序的竞态条件。 5、massif：堆栈分析器，指示程序中使用了多少堆内存等信息。 6、lackey： 7、nulgrind： 这几个工具的使用是通过命令：valgrand --tool=name 程序名来分别调用的，当不指定tool参数时默认是 --tool=memcheck 二

I really like the idea of the Flame Graph for profiling since it will help in eliminating unneeded function calls. There is a catch however in that it requires the profiler to do a complete stack dump each time it collects a sample. This can be accomplished with DTrace or SystemTap quite easily, but I need to be able to do this on an ARM device running ubuntu (which eliminates DTrace). I would also like to do this without recompiling the kernel (which eliminates SystemTap). Is it possible to get Valgrind/Callgrind or OProfile (or some other profiling tool that can run on an ARM device in

Context is developing an android app that uses several static executable binaries through sh syscall. One of the binaries eventually segfaults when using a samsung galaxy s4 cellphone (but not when using emulator or a Sony Xperia tipo cellphone), so following http://embetek.blogspot.com.es/2011/10/valgrind-for-arm.html with several custom modifications (CFLAGS='-static -march=armv7-a') end up getting a $ ldd valgrind not a dynamic executable $ file valgrind valgrind: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, for GNU/Linux 3.2.0, not stripped. Loaded on the target

I have the following code which execute a non valid command within a fork. The following code return a memory leak in valgrind. #include <stdio.h> #include <string.h> #include <stdlib.h> #include <stdarg.h> #include <errno.h> #include <unistd.h> int external_cmd(char **argv) { int pid; if ((pid = fork()) == -1) return -1; if (pid == 0) { /* child */ execvp(argv[0], argv); exit(0); } else if (pid < 0) return -1; int status; while (wait(&status) != pid); return 0; } int main () { char *argv[8] = {0}; argv[0] = "tawtaw"; //<--------- invalid command argv[1] = "-a"; char *mem = strdup("anychar");