调用exec返回带有绝对路径的errno 14（错误地址） [英] Calling exec returns errno 14 (bad address) with absolute path

问题描述

为课程制作一个简单的cgi服务器。为此，我必须制作一个fork / exec来启动cgi处理程序，问题是exec不断返回errno14。我已经尝试了以下代码的独立版本，无论是否使用绝对值，都可以使用路径。

in making a simple cgi server for a course. To do that in some point I have to make a fork/exec to launch the cgi handler, the problem is that the exec keep returning errno 14. I've tried the following code in a standalone version an it works with and without the absolute path.

这是代码：

static void _process_cgi(int fd, http_context_t* ctx)
{
    pid_t childProcess;
    int ret;
    char returnValue[1024];
    log(LOG, "calling cgi", &ctx->uri[1], 0);

    if((childProcess = fork()) != 0)
    {
        ///
        /// Set the CGI standard output to the socket.
        ///
        dup2(fd, STANDARD_OUTPUT);
            //ctx->uri = "/simple.cgi"

        execl("/home/dvd/nwebdir/simple.cgi",&ctx->uri[1]);
        sprintf(returnValue,"%d",errno);

        log(LOG, "exec returned ", returnValue, 0);
        return -1;
    }

    ret = waitpid(childProcess,NULL,0);
    sprintf(returnValue,"%d",ret);
    log(LOG, "cgi returned", returnValue, 0);
}

这是服务器在到达我的代码之前通过的sys调用列表（按顺序）：
-chdir
-叉
-setpqrp
-叉
我不知道这是否有意义，但是在我的测试程序中没有chdir或setpqrp。

Here is the list of sys calls that the server passes before reaching my code (in order): - chdir - fork - setpqrp - fork I don't know if this is relevant or not, but in my test program I don't have chdir nor setpqrp.

测试代码如下：

pid_t pid;

    if ((pid = fork()) != 0)
    {
        execl("simple.cgi","simple");
        //execl("/home/dvd/nwebdir/simple.cgi","simple");
        return 0;
    }
    printf("waiting\n");
    waitpid(pid, NULL, 0);
    printf("Parent exiting\n");

注意我已经在服务器代码中同时尝试了execl和execlp。

Note I've tried both execl and execlp in the server code.

您可以在这里找到基本的服务器实现（没有CGI），我所做的唯一更改是在Web函数中：
http://www.ibm.com/developerworks/systems/library/es-nweb/index.html

You can find the basic server implementation (without CGI) in here, the only changes I made was in the web funcion: http://www.ibm.com/developerworks/systems/library/es-nweb/index.html

致谢

推荐答案

execl("simple.cgi","simple", NULL);

因为execl（）是一个varargs函数，所以需要null。

The null is needed because execl() is a varargs - function.

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