source: neercs/trunk/src/grab.c @ 2516 Tweet

/*
 *  neercs        console-based window manager
 *  Copyright (c) 2008 Pascal Terjan
 *                All Rights Reserved
 *
 *  $Id$
 *
 *  This program is free software. It comes without any warranty, to
 *  the extent permitted by applicable law. You can redistribute it
 *  and/or modify it under the terms of the Do What The Fuck You Want
 *  To Public License, Version 2, as published by Sam Hocevar. See
 *  http://sam.zoy.org/wtfpl/COPYING for more details.
 */

#include "config.h"

#define _XOPEN_SOURCE 500 /* getsid() */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>

#if defined HAVE_LINUX_KDEV_T_H
#   include <linux/kdev_t.h>
#   include <linux/major.h>
#endif

#include "neercs.h"
#include "mytrace.h"

int grab_process(long pid, char *ptyname, int ptyfd)
{
#if defined HAVE_LINUX_KDEV_T_H
    char fdstr[1024];
    struct mytrace *parent, *child;
    int i, fd = 0, mode, ret;
    char to_open[3];
    struct stat stat_buf;

    debug("pty is %s", ptyname);

    parent = mytrace_attach(pid);
    if(!parent)
    {
        fprintf(stderr, "Cannot access process %ld\n", pid);
        return -1;
    }

    child = mytrace_fork(parent);
    pid = mytrace_getpid(child);

    /* Look for file descriptors that are PTYs */
    for(i = 0; i <= 2; i++)
    {
        snprintf(fdstr, sizeof(fdstr), "/proc/%ld/fd/%d", pid, i);
        to_open[i] = 0;
        lstat(fdstr, &stat_buf);
        if((stat_buf.st_mode & S_IRUSR) && (stat_buf.st_mode & S_IWUSR))
            mode = O_RDWR;
        else if(stat_buf.st_mode & S_IWUSR)
            mode = O_WRONLY;
        else
            mode = O_RDONLY;

        if(stat(fdstr, &stat_buf) < 0)
            continue;

        if(!S_ISCHR(stat_buf.st_mode)
            || MAJOR(stat_buf.st_rdev) != UNIX98_PTY_SLAVE_MAJOR)
            continue;

        debug("found pty %d", i);

        if(i == 2)
        {
            mytrace_write(parent, i, "\x1b]0;\x07", 5);
            mytrace_write(parent, i, "\x1b[1000l", 7);
            mytrace_write(parent, i, "\x1b[?12l\x1b[?25h", 12);
            mytrace_write(parent, i, "\n[Process stolen by neercs]\n", 28);
        }

        ret = mytrace_close(child, i);
        if(ret < 0)
        {
            perror("mytrace_close");
        }
        to_open[i] = 1;
    }

    /* Set the process's session ID */
    debug("Running setsid on process %ld (sid=%d)", pid, getsid(pid));

    ret = mytrace_setpgid(child, 0, getsid(pid));
    if(ret < 0)
    {
        fprintf(stderr, "syscall setpgid failed\n");
        mytrace_detach(child);
        return -1;
    }

    if(ret != 0)
    {
        fprintf(stderr, "setpgid returned %d\n", ret);
        mytrace_detach(child);
        return -1;
    }

    ret = mytrace_setsid(child);
    if(ret < 0)
    {
        fprintf(stderr, "syscall setsid failed\n");
        mytrace_detach(child);
        return -1;
    }

    debug("pid %ld has now sid %d", pid, getsid(pid));

    mytrace_exit(parent, 0);
    mytrace_detach(parent);

    /* Reopen PTY file descriptors */
    for(i = 0; i <= 2; i++)
    {
        if(!to_open[i])
            continue;
        fd = mytrace_open(child, ptyname, mode);
        if(fd < 0)
        {
            perror("mytrace_open");
        }
        ret = mytrace_dup2(child, fd, i);
        if(ret < 0)
        {
            perror("mytrace_dup2");
        }
    }

    kill(pid, SIGWINCH);
    mytrace_detach(child);

    return 0;
#else
    errno = ENOSYS;
    return -1;
#endif
}