的valgrind的strstr错误 [英] strstr valgrind error

问题描述

我需要一些帮助与的char * 初始化和的strstr 在C.这是普遍的问题：

I need some help with char* initialization and strstr in C. This is the general issue:

我有一个函数 FUNC1

func1的（）FUNC2（）;

func1() func2();

问题是，Valgrind的给出了一个错误基本上说，可能的strstr使用未初始化值。为了改善这种情况，我不得不做一些像的char *海峡=Hello World的; ，但我不能的realloc ，这是一个问题。

The issue is that valgrind gives an error basically saying that strstr might be using an uninitialized value. To rectify this, I'd have to do something like char* str = "hello world";, but then I can't realloc, which is an issue.

我已经测试我的程序随机字符串和问题是Valgrind是治疗的事实 STR 为未初始化的，但我只是不知道如何在不进行初始化摆脱以realloc的能力。有什么建议么？

I have tested my program with random strings and the issue is the fact that valgrind is treating str as uninitialized, but I just don't know how to initialize it without getting rid of the ability to realloc. Any suggestions?

该错误是：

==14356== Conditional jump or move depends on uninitialised value(s)
==14356==    at 0x4C29313: strstr (in path)
==14356==    by 0x401983: func2 (in path)
==14356==    by 0x401B06: func1 (in path)
==14356==    by 0x4013D7: main (in path)
==14356== 
==14358== Syscall param execve(argv[i]) points to uninitialised byte(s)
 at 0x4ECFCB7: execve (in path)
==14308==    by 0x4E6A76C: do_system (in path)
==14308==    by 0x4013ED: main 

编辑：增加了在实际的功能，改变了名字和这样的。

Edited: Added in the actual functions, changed names and such.

推荐答案

我相信这是你的问题：

在FUNC2：

    str = realloc(str, (stringLen + pathLen+1)*sizeof(char));

    memmove(&str[rplcIndx + pathLen], &str[rplcIndx+2], stringLen-rplcIndx-2);
    memcpy(&str[rplcIndx], path, pathLen);

的 memmove与不会复制空终止符（这是在位置 stringLen ，但复制的最后一个字节将 rpcIndx + 2 + stringLen-rpcIndx-2-1 = stringLen-1 （记得 SRC [LEN] 是第一个字节不被复制）。这意味着

The memmove doesn't copy the null terminator (it is at position stringLen, but the last byte copied would be rpcIndx+2+stringLen-rpcIndx-2-1 = stringLen-1 (remember src[len] is the first byte NOT copied). This means

• 空终止的位置没有初始化


• 的字符串可能非正常终止

顺便说一句，如果可以的话，使用 asprintf 是安全，方便和防呆做许多字符串处理任务的方式，虽然它可能会有点不太有效。

BTW, if you can, using asprintf is safe, easy and fool-proof way of doing many string-manipulation tasks, although it may be a little less effective.

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