1 /* 2 * Copyright (C) 2000 - 2003 Jeff Dike (jdike@addtoit.com) 3 * Licensed under the GPL 4 */ 5 6 #include <unistd.h> 7 #include <stdlib.h> 8 #include <errno.h> 9 #include <termios.h> 10 #include <string.h> 11 #include <signal.h> 12 #include <sched.h> 13 #include <sys/stat.h> 14 #include <sys/ioctl.h> 15 #include <sys/socket.h> 16 #include "kern_util.h" 17 #include "chan_user.h" 18 #include "user.h" 19 #include "os.h" 20 #include "choose-mode.h" 21 #include "mode.h" 22 23 int generic_console_write(int fd, const char *buf, int n) 24 { 25 struct termios save, new; 26 int err; 27 28 if(isatty(fd)){ 29 CATCH_EINTR(err = tcgetattr(fd, &save)); 30 if (err) 31 goto error; 32 new = save; 33 /* The terminal becomes a bit less raw, to handle \n also as 34 * "Carriage Return", not only as "New Line". Otherwise, the new 35 * line won't start at the first column.*/ 36 new.c_oflag |= OPOST; 37 CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new)); 38 if (err) 39 goto error; 40 } 41 err = generic_write(fd, buf, n, NULL); 42 /* Restore raw mode, in any case; we *must* ignore any error apart 43 * EINTR, except for debug.*/ 44 if(isatty(fd)) 45 CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); 46 return(err); 47 error: 48 return(-errno); 49 } 50 51 /* 52 * UML SIGWINCH handling 53 * 54 * The point of this is to handle SIGWINCH on consoles which have host ttys and 55 * relay them inside UML to whatever might be running on the console and cares 56 * about the window size (since SIGWINCH notifies about terminal size changes). 57 * 58 * So, we have a separate thread for each host tty attached to a UML device 59 * (side-issue - I'm annoyed that one thread can't have multiple controlling 60 * ttys for purposed of handling SIGWINCH, but I imagine there are other reasons 61 * that doesn't make any sense). 62 * 63 * SIGWINCH can't be received synchronously, so you have to set up to receive it 64 * as a signal. That being the case, if you are going to wait for it, it is 65 * convenient to sit in sigsuspend() and wait for the signal to bounce you out of 66 * it (see below for how we make sure to exit only on SIGWINCH). 67 */ 68 69 static void winch_handler(int sig) 70 { 71 } 72 73 struct winch_data { 74 int pty_fd; 75 int pipe_fd; 76 }; 77 78 static int winch_thread(void *arg) 79 { 80 struct winch_data *data = arg; 81 sigset_t sigs; 82 int pty_fd, pipe_fd; 83 int count, err; 84 char c = 1; 85 86 pty_fd = data->pty_fd; 87 pipe_fd = data->pipe_fd; 88 count = os_write_file(pipe_fd, &c, sizeof(c)); 89 if(count != sizeof(c)) 90 printk("winch_thread : failed to write synchronization " 91 "byte, err = %d\n", -count); 92 93 /* We are not using SIG_IGN on purpose, so don't fix it as I thought to 94 * do! If using SIG_IGN, the sigsuspend() call below would not stop on 95 * SIGWINCH. */ 96 97 signal(SIGWINCH, winch_handler); 98 sigfillset(&sigs); 99 /* Block all signals possible. */ 100 if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){ 101 printk("winch_thread : sigprocmask failed, errno = %d\n", 102 errno); 103 exit(1); 104 } 105 /* In sigsuspend(), block anything else than SIGWINCH. */ 106 sigdelset(&sigs, SIGWINCH); 107 108 if(setsid() < 0){ 109 printk("winch_thread : setsid failed, errno = %d\n", errno); 110 exit(1); 111 } 112 113 err = os_new_tty_pgrp(pty_fd, os_getpid()); 114 if(err < 0){ 115 printk("winch_thread : new_tty_pgrp failed, err = %d\n", -err); 116 exit(1); 117 } 118 119 /* These are synchronization calls between various UML threads on the 120 * host - since they are not different kernel threads, we cannot use 121 * kernel semaphores. We don't use SysV semaphores because they are 122 * persistent. */ 123 count = os_read_file(pipe_fd, &c, sizeof(c)); 124 if(count != sizeof(c)) 125 printk("winch_thread : failed to read synchronization byte, " 126 "err = %d\n", -count); 127 128 while(1){ 129 /* This will be interrupted by SIGWINCH only, since other signals 130 * are blocked.*/ 131 sigsuspend(&sigs); 132 133 count = os_write_file(pipe_fd, &c, sizeof(c)); 134 if(count != sizeof(c)) 135 printk("winch_thread : write failed, err = %d\n", 136 -count); 137 } 138 } 139 140 static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) 141 { 142 struct winch_data data; 143 unsigned long stack; 144 int fds[2], n, err; 145 char c; 146 147 err = os_pipe(fds, 1, 1); 148 if(err < 0){ 149 printk("winch_tramp : os_pipe failed, err = %d\n", -err); 150 goto out; 151 } 152 153 data = ((struct winch_data) { .pty_fd = fd, 154 .pipe_fd = fds[1] } ); 155 /* CLONE_FILES so this thread doesn't hold open files which are open 156 * now, but later closed. This is a problem with /dev/net/tun. 157 */ 158 err = run_helper_thread(winch_thread, &data, CLONE_FILES, &stack, 0); 159 if(err < 0){ 160 printk("fork of winch_thread failed - errno = %d\n", -err); 161 goto out_close; 162 } 163 164 *fd_out = fds[0]; 165 n = os_read_file(fds[0], &c, sizeof(c)); 166 if(n != sizeof(c)){ 167 printk("winch_tramp : failed to read synchronization byte\n"); 168 printk("read failed, err = %d\n", -n); 169 printk("fd %d will not support SIGWINCH\n", fd); 170 err = -EINVAL; 171 goto out_close; 172 } 173 return err ; 174 175 out_close: 176 os_close_file(fds[1]); 177 os_close_file(fds[0]); 178 out: 179 return err; 180 } 181 182 void register_winch(int fd, struct tty_struct *tty) 183 { 184 int pid, thread, thread_fd = -1; 185 int count; 186 char c = 1; 187 188 if(!isatty(fd)) 189 return; 190 191 pid = tcgetpgrp(fd); 192 if(!CHOOSE_MODE_PROC(is_tracer_winch, is_skas_winch, pid, fd, 193 tty) && (pid == -1)){ 194 thread = winch_tramp(fd, tty, &thread_fd); 195 if(thread > 0){ 196 register_winch_irq(thread_fd, fd, thread, tty); 197 198 count = os_write_file(thread_fd, &c, sizeof(c)); 199 if(count != sizeof(c)) 200 printk("register_winch : failed to write " 201 "synchronization byte, err = %d\n", 202 -count); 203 } 204 } 205 } 206