c - 自己的 shell -> 在子节点上使用 pipe 和 dup2 后挂断

Question

我正在做我自己的 tcsh 版本（用于家庭作业），当涉及到管道和重定向（现在是管道）时我遇到了问题。

正如我所说，我尝试将一个程序的输出重定向到另一个程序的输入。在遇到以下问题之前，我几乎做到了：执行的第二个程序挂起并等待不应该发生的用户输入。我的代码还有调试。有创建孩子的地方：

static int generate_child(shell_t *shell, parsing_t *cmd, char *path, char **env)
{
    pid_t child = 0;

    printf("Child fds will be: %i & %i\n", cmd->fds[STDIN_FILENO], cmd->fds[STDOUT_FILENO]);
    child = fork();
    if (child == -1)
        return (ERR_FORK);
    if (child != 0)
        wait_for_child(shell, cmd->args[0]);
    else {
        if (cmd->fds[STDIN_FILENO] > 0) {
            dup2(cmd->fds[STDIN_FILENO], STDIN_FILENO);
            printf("[#1] Closing fd: %i\n", cmd->fds[STDIN_FILENO]);
            close(cmd->fds[STDIN_FILENO]);
        }
        if (cmd->fds[STDOUT_FILENO] != -1 && cmd->fds[STDIN_FILENO] != 1) {
            dup2(cmd->fds[STDOUT_FILENO], STDOUT_FILENO);
            printf("[#2] Closing fd: %i\n", cmd->fds[STDOUT_FILENO]);
            close(cmd->fds[STDOUT_FILENO]);
        }
        execve(path, cmd->args, env);
        display_perror(shell, cmd->args[0]);
        _exit(ERR_CHILD);
    }
    return (ERR_NONE);
}

创建新的 fd 并将当前节点/cmd 与下一个链接。

int link_pipe(shell_t *shell, parsing_t *current)
{
    int new_pipe[2];

    if (pipe2(new_pipe, O_CLOEXEC))
        return (ERR_PIPE);
    current->piped[STDOUT_FILENO] = new_pipe[STDOUT_FILENO];
    current->piped[STDIN_FILENO] = new_pipe[STDIN_FILENO];
    printf("[Pipe] %s s' fds are: %i & %i\n", current->args[0], current->piped[STDIN_FILENO], current->piped[STDOUT_FILENO]);
    if (current->fds[STDOUT_FILENO] == -1)
        current->fds[STDOUT_FILENO] = current->piped[STDOUT_FILENO];
    if (current->next != NULL)
        current->next->fds[STDIN_FILENO] = current->piped[STDIN_FILENO];
    return (ERR_NONE);
}

Aaand，执行所有命令：

static int affect_all_cmds(shell_t *shell)
{
    parsing_t *current = shell->cmds;
    int returned_val = ERR_NONE;

    while (current != NULL) {
        execute_alias(shell, &current->args);
        returned_val = apply_linkers(shell, current); // link_pipe is used here
        if (returned_val != ERR_NONE)
            return (returned_val);
        returned_val = redirect_cmds(shell, current); // generate_child is used here
        if (returned_val != ERR_NONE)
            return (returned_val);
        current = current->next;
    }
    remove_all_queued_cmd(&shell->cmds); // Here are removed (from 'piped[...]') every fds open by 'pipe2'
    return (returned_val);
}

我可能确定我没有正确关闭某些东西，但我没有找到它。一周以来我尝试了很多东西，但没有任何效果。此外，对于我的测试，我会执行以下操作：ls | grep c我现在得到的结果是：

$ ls | grep c
ls -> 2 // Detecting a pipe 
[Pipe] ls s fds are: 3 & 5 // Generating fds
Child fds will be: 0 & 5 // Running 'ls' with edited fds
grep -> 0 // No pipe or redirections detected
Child fds will be: 3 & -1 // Running 'grep'
[#1] Closing fd: 3
cmake-build-debug
include
main.c
src

之后它会一直挂，直到我按 CTRL+C。

标签： cshell