fork时产生的错误

Question

我有以下代码，它分叉两个新进程来获取其中一个进程的标准输出内容并将其保存到文件中。它运行得很好并保存了文件，但是在返回调用函数中的以下行（无论它是什么）后，会抛出 EXC_BAD_ACCESS 错误。为什么？

void test(vector<string> inp,int i){
    int fds[2]; // file descriptors
    long count;  // used for reading from stdout
    int fd;     // single file descriptor
    char c;     // used for writing and reading a character at a time
    pid_t pid;  // will hold process ID; used with fork()

    pipe(fds);

    // child process #1.
    fd = open((inp[i+1]).c_str(), O_RDWR | O_CREAT, 0666);
    if (fork() == 0) {
        if (fd < 0) {
            return;
        }

        dup2(fds[0], 0);

        // Don't need stdout end of pipe.
        close(fds[1]);

        // Read from stdout...
        while ((count = read(0, &c, 1)) > 0)
            write(fd, &c, 1); // Write to file.

        exit(0);
        // child process #2
    } else if ((pid = fork()) == 0) {
        dup2(fds[1], 1);

        // Don't need stdin end of pipe.
        close(fds[0]);

        // Output contents of the given file to stdout.
        char **arguments = getArguments(inp[i]);
        execvp(arguments[0], arguments);
        perror("execvp failed");
        exit(0);
        // parent process
    } else {
        waitpid(pid, NULL, 0);
        close(fds[0]);
        close(fds[1]);
    }
}

Answer 1

这对我来说很有效：

#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <sys/wait.h>

void test(/*vector<string> inp,int i*/){
    int fds[2]; // file descriptors
    long count;  // used for reading from stdout
    int fd;     // single file descriptor
    char c;     // used for writing and reading a character at a time
    pid_t pid;  // will hold process ID; used with fork()

    pipe(fds);

    // child process #1.
    fd = open(/*(inp[i+1]).c_str()*/"/tmp/output", O_RDWR | O_CREAT, 0666);
    if (fork() == 0) {
        if (fd < 0) {
            return;
        }

        dup2(fds[0], 0);

        // Don't need stdout end of pipe.
        close(fds[1]);

        // Read from stdout...
        while ((count = read(0, &c, 1)) > 0)
            write(fd, &c, 1); // Write to file.

        _exit(0);
        // child process #2
    } else if ((pid = fork()) == 0) {
        dup2(fds[1], 1);

        // Don't need stdin end of pipe.
        close(fds[0]);

        // Output contents of the given file to stdout.
        char **arguments = new char*[2];/*getArguments(inp[i]);*/
        arguments[0]=(char*)"/bin/bash";
        arguments[1]=0;
        execvp(arguments[0], arguments);
        perror("execvp failed");
        _exit(0);
        // parent process
    } else {
        waitpid(pid, NULL, 0);
        close(fds[0]);
        close(fds[1]);
    }
}

int main(int argc, char* argv[]){
    test();
}

尝试告诉你的错误到底出现在哪里，或者显示你的程序的更多内容，这样我就可以尝试复制你的条件。