285 lines
8.0 KiB
C
285 lines
8.0 KiB
C
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/*
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* Copyright (C) 2011 by Nelson Elhage
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <sys/select.h>
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#include <sys/ioctl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <string.h>
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#include <stdarg.h>
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#include <termios.h>
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#include <signal.h>
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//#include "reptyr.h"
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#ifndef __linux__
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#error reptyr is currently Linux-only.
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#endif
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static int verbose = 0;
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void _debug(const char *pfx, const char *msg, va_list ap) {
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if (pfx)
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fprintf(stderr, "%s", pfx);
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vfprintf(stderr, msg, ap);
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fprintf(stderr, "\n");
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}
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void die(const char *msg, ...) {
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va_list ap;
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va_start(ap, msg);
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_debug("[!] ", msg, ap);
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va_end(ap);
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exit(1);
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}
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void debug(const char *msg, ...) {
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va_list ap;
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if (!verbose)
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return;
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va_start(ap, msg);
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_debug("[+] ", msg, ap);
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va_end(ap);
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}
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void error(const char *msg, ...) {
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va_list ap;
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va_start(ap, msg);
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_debug("[-] ", msg, ap);
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va_end(ap);
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}
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void setup_raw(struct termios *save) {
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struct termios set;
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if (tcgetattr(0, save) < 0)
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die("Unable to read terminal attributes: %m");
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set = *save;
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cfmakeraw(&set);
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if (tcsetattr(0, TCSANOW, &set) < 0)
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die("Unable to set terminal attributes: %m");
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}
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void resize_pty(int pty) {
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struct winsize sz;
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if (ioctl(0, TIOCGWINSZ, &sz) < 0)
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return;
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ioctl(pty, TIOCSWINSZ, &sz);
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}
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int writeall(int fd, const void *buf, ssize_t count) {
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ssize_t rv;
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while (count > 0) {
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rv = write(fd, buf, count);
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if (rv < 0) {
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if (errno == EINTR)
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continue;
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return rv;
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}
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count -= rv;
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buf += rv;
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}
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return 0;
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}
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volatile sig_atomic_t winch_happened = 0;
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void do_winch(int signal) {
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winch_happened = 1;
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}
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void do_proxy(int pty) {
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char buf[4096];
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ssize_t count;
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fd_set set;
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while (1) {
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if (winch_happened) {
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winch_happened = 0;
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/*
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* FIXME: If a signal comes in after this point but before
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* select(), the resize will be delayed until we get more
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* input. signalfd() is probably the cleanest solution.
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*/
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resize_pty(pty);
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}
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FD_ZERO(&set);
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FD_SET(0, &set);
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FD_SET(pty, &set);
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if (select(pty+1, &set, NULL, NULL, NULL) < 0) {
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if (errno == EINTR)
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continue;
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fprintf(stderr, "select: %m");
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return;
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}
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if (FD_ISSET(0, &set)) {
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count = read(0, buf, sizeof buf);
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if (count < 0)
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return;
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writeall(pty, buf, count);
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}
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if (FD_ISSET(pty, &set)) {
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count = read(pty, buf, sizeof buf);
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if (count < 0)
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return;
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writeall(1, buf, count);
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}
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}
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}
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void usage(char *me) {
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fprintf(stderr, "Usage: %s [-s] PID\n", me);
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fprintf(stderr, " %s -l|-L [COMMAND [ARGS]]\n", me);
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fprintf(stderr, " -l Create a new pty pair and print the name of the slave.\n");
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fprintf(stderr, " if there are command-line arguments after -l\n");
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fprintf(stderr, " they are executed with REPTYR_PTY set to path of pty.\n");
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fprintf(stderr, " -L Like '-l', but also redirect the child's stdio to the slave.\n");
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fprintf(stderr, " -s Attach fds 0-2 on the target, even if it is not attached to a tty.\n");
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fprintf(stderr, " -h Print this help message and exit.\n");
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fprintf(stderr, " -v Print the version number and exit.\n");
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fprintf(stderr, " -V Print verbose debug output.\n");
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}
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void check_yama_ptrace_scope(void) {
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int fd = open("/proc/sys/kernel/yama/ptrace_scope", O_RDONLY);
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if (fd >= 0) {
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char buf[256];
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int n;
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n = read(fd, buf, sizeof buf);
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close(fd);
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if (n > 0) {
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if (!atoi(buf)) {
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return;
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}
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}
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} else if (errno == ENOENT)
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return;
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fprintf(stderr, "The kernel denied permission while attaching. If your uid matches\n");
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fprintf(stderr, "the target's, check the value of /proc/sys/kernel/yama/ptrace_scope.\n");
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fprintf(stderr, "For more information, see /etc/sysctl.d/10-ptrace.conf\n");
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}
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int main(int argc, char **argv) {
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struct termios saved_termios;
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struct sigaction act;
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int pty;
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int arg = 1;
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int do_attach = 1;
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int force_stdio = 0;
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int unattached_script_redirection = 0;
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if (argc < 2) {
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usage(argv[0]);
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return 2;
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}
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if (argv[arg][0] == '-') {
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switch(argv[arg][1]) {
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case 'h':
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usage(argv[0]);
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return 0;
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case 'l':
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do_attach = 0;
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break;
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case 'L':
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do_attach = 0;
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unattached_script_redirection = 1;
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break;
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case 's':
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arg++;
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force_stdio = 1;
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break;
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case 'v':
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printf("This is reptyr version %s.\n", REPTYR_VERSION);
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printf(" by Nelson Elhage <nelhage@nelhage.com>\n");
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printf("http://github.com/nelhage/reptyr/\n");
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return 0;
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case 'V':
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arg++;
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verbose = 1;
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break;
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default:
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usage(argv[0]);
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return 1;
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}
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}
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if (do_attach && arg >= argc) {
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fprintf(stderr, "%s: No pid specified to attach\n", argv[0]);
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usage(argv[0]);
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return 1;
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}
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if ((pty = open("/dev/ptmx", O_RDWR|O_NOCTTY)) < 0)
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die("Unable to open /dev/ptmx: %m");
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if (unlockpt(pty) < 0)
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die("Unable to unlockpt: %m");
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if (grantpt(pty) < 0)
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die("Unable to grantpt: %m");
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if (do_attach) {
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pid_t child = atoi(argv[arg]);
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int err;
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if ((err = attach_child(child, ptsname(pty), force_stdio))) {
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fprintf(stderr, "Unable to attach to pid %d: %s\n", child, strerror(err));
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if (err == EPERM) {
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check_yama_ptrace_scope();
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}
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return 1;
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}
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} else {
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printf("Opened a new pty: %s\n", ptsname(pty));
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fflush(stdout);
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if (argc > 2) {
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if(!fork()) {
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setenv("REPTYR_PTY", ptsname(pty), 1);
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if (unattached_script_redirection) {
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int f;
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setpgid(0, getppid());
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setsid();
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f = open(ptsname(pty), O_RDONLY, 0); dup2(f, 0); close(f);
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f = open(ptsname(pty), O_WRONLY, 0); dup2(f, 1); dup2(f,2); close(f);
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}
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close(pty);
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execvp(argv[2], argv+2);
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exit(1);
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}
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}
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}
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setup_raw(&saved_termios);
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memset(&act, 0, sizeof act);
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act.sa_handler = do_winch;
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act.sa_flags = 0;
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sigaction(SIGWINCH, &act, NULL);
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resize_pty(pty);
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do_proxy(pty);
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tcsetattr(0, TCSANOW, &saved_termios);
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return 0;
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}
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