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 "user_util.h" 18 #include "chan_user.h" 19 #include "user.h" 20 #include "os.h" 21 #include "choose-mode.h" 22 #include "mode.h" 23 24 int generic_console_write(int fd, const char *buf, int n) 25 { 26 struct termios save, new; 27 int err; 28 29 if(isatty(fd)){ 30 CATCH_EINTR(err = tcgetattr(fd, &save)); 31 if (err) 32 goto error; 33 new = save; 34 /* The terminal becomes a bit less raw, to handle \n also as 35 * "Carriage Return", not only as "New Line". Otherwise, the new 36 * line won't start at the first column.*/ 37 new.c_oflag |= OPOST; 38 CATCH_EINTR(err = tcsetattr(fd, TCSAFLUSH, &new)); 39 if (err) 40 goto error; 41 } 42 err = generic_write(fd, buf, n, NULL); 43 /* Restore raw mode, in any case; we *must* ignore any error apart 44 * EINTR, except for debug.*/ 45 if(isatty(fd)) 46 CATCH_EINTR(tcsetattr(fd, TCSAFLUSH, &save)); 47 return(err); 48 error: 49 return(-errno); 50 } 51 52 /* 53 * UML SIGWINCH handling 54 * 55 * The point of this is to handle SIGWINCH on consoles which have host ttys and 56 * relay them inside UML to whatever might be running on the console and cares 57 * about the window size (since SIGWINCH notifies about terminal size changes). 58 * 59 * So, we have a separate thread for each host tty attached to a UML device 60 * (side-issue - I'm annoyed that one thread can't have multiple controlling 61 * ttys for purposed of handling SIGWINCH, but I imagine there are other reasons 62 * that doesn't make any sense). 63 * 64 * SIGWINCH can't be received synchronously, so you have to set up to receive it 65 * as a signal. That being the case, if you are going to wait for it, it is 66 * convenient to sit in sigsuspend() and wait for the signal to bounce you out of 67 * it (see below for how we make sure to exit only on SIGWINCH). 68 */ 69 70 static void winch_handler(int sig) 71 { 72 } 73 74 struct winch_data { 75 int pty_fd; 76 int pipe_fd; 77 }; 78 79 static int winch_thread(void *arg) 80 { 81 struct winch_data *data = arg; 82 sigset_t sigs; 83 int pty_fd, pipe_fd; 84 int count, err; 85 char c = 1; 86 87 pty_fd = data->pty_fd; 88 pipe_fd = data->pipe_fd; 89 count = os_write_file(pipe_fd, &c, sizeof(c)); 90 if(count != sizeof(c)) 91 printk("winch_thread : failed to write synchronization " 92 "byte, err = %d\n", -count); 93 94 /* We are not using SIG_IGN on purpose, so don't fix it as I thought to 95 * do! If using SIG_IGN, the sigsuspend() call below would not stop on 96 * SIGWINCH. */ 97 98 signal(SIGWINCH, winch_handler); 99 sigfillset(&sigs); 100 /* Block all signals possible. */ 101 if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){ 102 printk("winch_thread : sigprocmask failed, errno = %d\n", 103 errno); 104 exit(1); 105 } 106 /* In sigsuspend(), block anything else than SIGWINCH. */ 107 sigdelset(&sigs, SIGWINCH); 108 109 if(setsid() < 0){ 110 printk("winch_thread : setsid failed, errno = %d\n", errno); 111 exit(1); 112 } 113 114 err = os_new_tty_pgrp(pty_fd, os_getpid()); 115 if(err < 0){ 116 printk("winch_thread : new_tty_pgrp failed, err = %d\n", -err); 117 exit(1); 118 } 119 120 /* These are synchronization calls between various UML threads on the 121 * host - since they are not different kernel threads, we cannot use 122 * kernel semaphores. We don't use SysV semaphores because they are 123 * persistant. */ 124 count = os_read_file(pipe_fd, &c, sizeof(c)); 125 if(count != sizeof(c)) 126 printk("winch_thread : failed to read synchronization byte, " 127 "err = %d\n", -count); 128 129 while(1){ 130 /* This will be interrupted by SIGWINCH only, since other signals 131 * are blocked.*/ 132 sigsuspend(&sigs); 133 134 count = os_write_file(pipe_fd, &c, sizeof(c)); 135 if(count != sizeof(c)) 136 printk("winch_thread : write failed, err = %d\n", 137 -count); 138 } 139 } 140 141 static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) 142 { 143 struct winch_data data; 144 unsigned long stack; 145 int fds[2], n, err; 146 char c; 147 148 err = os_pipe(fds, 1, 1); 149 if(err < 0){ 150 printk("winch_tramp : os_pipe failed, err = %d\n", -err); 151 goto out; 152 } 153 154 data = ((struct winch_data) { .pty_fd = fd, 155 .pipe_fd = fds[1] } ); 156 /* CLONE_FILES so this thread doesn't hold open files which are open 157 * now, but later closed. This is a problem with /dev/net/tun. 158 */ 159 err = run_helper_thread(winch_thread, &data, CLONE_FILES, &stack, 0); 160 if(err < 0){ 161 printk("fork of winch_thread failed - errno = %d\n", errno); 162 goto out_close; 163 } 164 165 *fd_out = fds[0]; 166 n = os_read_file(fds[0], &c, sizeof(c)); 167 if(n != sizeof(c)){ 168 printk("winch_tramp : failed to read synchronization byte\n"); 169 printk("read failed, err = %d\n", -n); 170 printk("fd %d will not support SIGWINCH\n", fd); 171 err = -EINVAL; 172 goto out_close; 173 } 174 return err ; 175 176 out_close: 177 os_close_file(fds[1]); 178 os_close_file(fds[0]); 179 out: 180 return err; 181 } 182 183 void register_winch(int fd, struct tty_struct *tty) 184 { 185 int pid, thread, thread_fd = -1; 186 int count; 187 char c = 1; 188 189 if(!isatty(fd)) 190 return; 191 192 pid = tcgetpgrp(fd); 193 if(!CHOOSE_MODE_PROC(is_tracer_winch, is_skas_winch, pid, fd, 194 tty) && (pid == -1)){ 195 thread = winch_tramp(fd, tty, &thread_fd); 196 if(thread > 0){ 197 register_winch_irq(thread_fd, fd, thread, tty); 198 199 count = os_write_file(thread_fd, &c, sizeof(c)); 200 if(count != sizeof(c)) 201 printk("register_winch : failed to write " 202 "synchronization byte, err = %d\n", 203 -count); 204 } 205 } 206 } 207 208 /* 209 * Overrides for Emacs so that we follow Linus's tabbing style. 210 * Emacs will notice this stuff at the end of the file and automatically 211 * adjust the settings for this buffer only. This must remain at the end 212 * of the file. 213 * --------------------------------------------------------------------------- 214 * Local variables: 215 * c-file-style: "linux" 216 * End: 217 */ 218