Question

我正在使用 openpty，NSTask和NSTextView 撰写a simple terminal。如何实施 Ctrl C 和 Ctrl D ？

我开始这样的shell：

int amaster = 0, aslave = 0;
if (openpty(&amaster, &aslave, NULL, NULL, NULL) == -1) {
    NSLog(@"openpty failed");
    return;
}

masterHandle = [[NSFileHandle alloc] initWithFileDescriptor:amaster closeOnDealloc:YES];
NSFileHandle *slaveHandle = [[NSFileHandle alloc] initWithFileDescriptor:aslave closeOnDealloc:YES];

NSTask *task = [NSTask new];
task.launchPath = @"/bin/bash";
task.arguments = @[@"-i", @"-l"];
task.standardInput = slaveHandle;
task.standardOutput = slaveHandle;
task.standardError = errorOutputPipe = [NSPipe pipe];
[task launch];

然后我拦截 Ctrl C 并将-[interrupt]发送到NSTask，如下所示：

- (void)keyDown:(NSEvent *)theEvent
{
    NSUInteger flags = theEvent.modifierFlags;
    unsigned short keyCode = theEvent.keyCode;

    if ((flags & NSControlKeyMask) && keyCode == 8) { // ctrl-c
        [task interrupt]; // ???
    } else if ((flags & NSControlKeyMask) && keyCode == 2) { // ctrl-d
        // ???
    } else {
        [super keyDown:theEvent];
    }
}

然而，中断似乎并没有杀死shell正在执行的任何程序。如果shell没有子进程，则中断会取消当前输入行。

我不知道如何实施 Ctrl D 。

Answer 1

我在Linux上的gdb中逐步浏览了st（这个无用的终端，其代码实际上很小且很简单，可以理解），当你按Ctrl-C和Ctrl-D时，它分别将\003和\004写入流程。我在我的项目中在OS X上尝试了这个，它也很有用。

因此，在上面代码的上下文中，处理每个热键的解决方案是：

Ctrl-C：[masterHandle writeData:[NSData dataWithBytes:"\003" length:1]];
Ctrl-D：[masterHandle writeData:[NSData dataWithBytes:"\004" length:1]];

Answer 2

我也在俄罗斯Cocoa Developers Slack频道询问了这个问题，并收到Dmitry Rodionov的回答。他用俄语回答了这个要点：ctrlc-ptty-nstask.markdown并允许我在这里发布英文版本。

他的实现是基于Pokey McPokerson所建议的，但更直接：他使用Technical Q&A QA1123 Getting List of All Processes on Mac OS X中的GetBSDProcessList()来获取子进程列表并向每个进程发送SIGINT：

kinfo_proc *procs = NULL;
size_t count;
if (0 != GetBSDProcessList(&procs, &count)) {
    return;
}
BOOL hasChildren = NO;
for (size_t i = 0; i < count; i++) {
    // If the process if a child of our bash process we send SIGINT to it
    if (procs[i].kp_eproc.e_ppid == task.processIdentifier) {
        hasChildren = YES;

        kill(procs[i].kp_proc.p_pid, SIGINT);
    }
}
free(procs);

如果进程没有子进程，则直接将SIGINT发送到该进程：

if (hasChildren == NO) {
    kill(task.processIdentifier, SIGINT);
}

这种方法很有效，但有两个可能的问题（我个人并不关心我现在正在编写自己的玩具终端）：

每按一次Ctrl-C，枚举所有进程都是详尽无遗的。也许有更好的方法来寻找子流程。
我和Dmitriy我们都不确定是否杀死所有子进程是Ctrl-C在实际终端中的工作方式。

Dmitriy代码的完整版本如下：

- (void)keyDown:(NSEvent *)theEvent
{
    NSUInteger flags = theEvent.modifierFlags;
    unsigned short keyCode = theEvent.keyCode;

    if ((flags & NSControlKeyMask) && keyCode == 8) {

        [self sendCtrlC];

    } else if ((flags & NSControlKeyMask) && keyCode == 2) {
        [masterHandle writeData:[NSData dataWithBytes: "\004" length:1]];
    } else if ((flags & NSDeviceIndependentModifierFlagsMask) == 0 && keyCode == 126) {
        NSLog(@"up");
    } else if ((flags & NSDeviceIndependentModifierFlagsMask) == 0 && keyCode == 125) {
        NSLog(@"down");
    } else {
        [super keyDown:theEvent];
    }
}

// #include <sys/sysctl.h>
// typedef struct kinfo_proc kinfo_proc;

- (void)sendCtrlC
{
    [masterHandle writeData:[NSData dataWithBytes: "\003" length:1]];

    kinfo_proc *procs = NULL;
    size_t count;
    if (0 != GetBSDProcessList(&procs, &count)) {
        return;
    }
    BOOL hasChildren = NO;
    for (size_t i = 0; i < count; i++) {
        if (procs[i].kp_eproc.e_ppid == task.processIdentifier) {
            hasChildren = YES;
            kill(procs[i].kp_proc.p_pid, SIGINT);
        }
    }
    free(procs);

    if (hasChildren == NO) {
        kill(task.processIdentifier, SIGINT);
    }
}

static int GetBSDProcessList(kinfo_proc **procList, size_t *procCount)
// Returns a list of all BSD processes on the system.  This routine
// allocates the list and puts it in *procList and a count of the
// number of entries in *procCount.  You are responsible for freeing
// this list (use "free" from System framework).
// On success, the function returns 0.
// On error, the function returns a BSD errno value.
{
    int                 err;
    kinfo_proc *        result;
    bool                done;
    static const int    name[] = { CTL_KERN, KERN_PROC, KERN_PROC_ALL, 0 };
    // Declaring name as const requires us to cast it when passing it to
    // sysctl because the prototype doesn't include the const modifier.
    size_t              length;

    assert( procList != NULL);
    assert(*procList == NULL);
    assert(procCount != NULL);

    *procCount = 0;

    // We start by calling sysctl with result == NULL and length == 0.
    // That will succeed, and set length to the appropriate length.
    // We then allocate a buffer of that size and call sysctl again
    // with that buffer.  If that succeeds, we're done.  If that fails
    // with ENOMEM, we have to throw away our buffer and loop.  Note
    // that the loop causes use to call sysctl with NULL again; this
    // is necessary because the ENOMEM failure case sets length to
    // the amount of data returned, not the amount of data that
    // could have been returned.

    result = NULL;
    done = false;
    do {
        assert(result == NULL);

        // Call sysctl with a NULL buffer.

        length = 0;
        err = sysctl( (int *) name, (sizeof(name) / sizeof(*name)) - 1,
                     NULL, &length,
                     NULL, 0);
        if (err == -1) {
            err = errno;
        }

        // Allocate an appropriately sized buffer based on the results
        // from the previous call.

        if (err == 0) {
            result = malloc(length);
            if (result == NULL) {
                err = ENOMEM;
            }
        }

        // Call sysctl again with the new buffer.  If we get an ENOMEM
        // error, toss away our buffer and start again.

        if (err == 0) {
            err = sysctl( (int *) name, (sizeof(name) / sizeof(*name)) - 1,
                         result, &length,
                         NULL, 0);
            if (err == -1) {
                err = errno;
            }
            if (err == 0) {
                done = true;
            } else if (err == ENOMEM) {
                assert(result != NULL);
                free(result);
                result = NULL;
                err = 0;
            }
        }
    } while (err == 0 && ! done);

    // Clean up and establish post conditions.

    if (err != 0 && result != NULL) {
        free(result);
        result = NULL;
    }
    *procList = result;
    if (err == 0) {
        *procCount = length / sizeof(kinfo_proc);
    }
    assert( (err == 0) == (*procList != NULL) );
    return err;
}

Answer 3

NSTask是指实际的bash，而不是它运行的命令。因此，当您在其上调用terminate时，它会将该信号发送到bash进程。您可以通过打印[task processIdentifier]来检查这一点，并查看活动管理器中的PID。除非你找到一种方法来跟踪任何新创建的进程的PID，否则你将很难杀死它们。

有关跟踪PID的可能方法，请参阅this或this答案。我查看了您的项目，您可以通过更改didChangeText方法来实现类似的功能。例如：

// [self writeCommand:input]; Take this out
[self writeCommand:[NSString stringWithFormat:@"%@ & echo $! > /tmp/childpid\n", [input substringToIndex:[input length] - 2]]];

然后在你想要杀死孩子时从childpid文件中读取。额外的东西会出现在终端，但这并不好。

更好的选择可能是为每个进入的命令创建新的NSTasks（即不要将用户输入直接传递给bash），并将它们的输出发送到同一个处理程序。然后，您可以直接在其上致电terminate。

当你进行ctrl-c工作时，你可以像这样实现ctrl-d：

kill([task processIdentifier], SIGQUIT);

Source

如何用openpty实现Ctrl-C和Ctrl-D？

3 个答案: