用execvp在构建串问题 [英] Problems with using execvp on a constructed string

问题描述

我试图写一个shell，它的建设的一部分，是由用户输入的字符串（缓冲区）执行code。然而，当我试图用execvp附加输入字符串（AE，回声），它总是螺丝狗并返回-1。我不知所措，为什么。下面是相关的部分：

 的char *缓冲区=释放calloc（100的sizeof（字符））;
...
与fgets（缓冲，100，标准输入）;
缓冲液[strlen的（缓冲器） -  1] = 0;因为与fgets插入新行的//必要
...
CMD = strsep（安培;缓冲器，）;
字符*海峡=的malloc（50 * sizeof的（炭））;
strcat的（STR，./）;
strcat的（STR，CMD）;
strcat的（STR.OUT）;
...
I = execvp（STR（字符*。*）缓冲区）;
 

解决方案

参数缓存是错误的。 execvp 的第二个参数是一个指针数组。与此转换，你是hidding编译器警告，但它不工作

I'm trying to write a shell, and part of its construction is executing code from a user-inputted string (buffer). However, when I attempt to execvp the string with additional inputs (ae. echo a), it always screws the pooch and returns -1. I'm at a loss as to why. Here's the relevant pieces:

char * buffer = calloc(100, sizeof(char));
...
fgets(buffer, 100, stdin);
buffer[strlen(buffer) - 1] = 0; // necessary because of a newline inserted by fgets
...
cmd = strsep(&buffer, " ");
char * str = malloc(50 * sizeof(char));
strcat(str, "./");
strcat(str, cmd);
strcat(str, ".out");
...
i = execvp(str, (char * *) buffer);

解决方案

The argument buffer is wrong. The second argument of execvp is an array of pointers. With this cast, you are hidding a compiler warning, but it does not work.

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