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 <sys/stat.h> 13 #include <sys/ioctl.h> 14 #include <sys/socket.h> 15 #include "kern_util.h" 16 #include "user_util.h" 17 #include "chan_user.h" 18 #include "user.h" 19 #include "helper.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, void *unused) 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 int close_me; 78 }; 79 80 static int winch_thread(void *arg) 81 { 82 struct winch_data *data = arg; 83 sigset_t sigs; 84 int pty_fd, pipe_fd; 85 int count, err; 86 char c = 1; 87 88 os_close_file(data->close_me); 89 pty_fd = data->pty_fd; 90 pipe_fd = data->pipe_fd; 91 count = os_write_file(pipe_fd, &c, sizeof(c)); 92 if(count != sizeof(c)) 93 printk("winch_thread : failed to write synchronization " 94 "byte, err = %d\n", -count); 95 96 /* We are not using SIG_IGN on purpose, so don't fix it as I thought to 97 * do! If using SIG_IGN, the sigsuspend() call below would not stop on 98 * SIGWINCH. */ 99 100 signal(SIGWINCH, winch_handler); 101 sigfillset(&sigs); 102 /* Block all signals possible. */ 103 if(sigprocmask(SIG_SETMASK, &sigs, NULL) < 0){ 104 printk("winch_thread : sigprocmask failed, errno = %d\n", 105 errno); 106 exit(1); 107 } 108 /* In sigsuspend(), block anything else than SIGWINCH. */ 109 sigdelset(&sigs, SIGWINCH); 110 111 if(setsid() < 0){ 112 printk("winch_thread : setsid failed, errno = %d\n", errno); 113 exit(1); 114 } 115 116 err = os_new_tty_pgrp(pty_fd, os_getpid()); 117 if(err < 0){ 118 printk("winch_thread : new_tty_pgrp failed, err = %d\n", -err); 119 exit(1); 120 } 121 122 /* These are synchronization calls between various UML threads on the 123 * host - since they are not different kernel threads, we cannot use 124 * kernel semaphores. We don't use SysV semaphores because they are 125 * persistant. */ 126 count = os_read_file(pipe_fd, &c, sizeof(c)); 127 if(count != sizeof(c)) 128 printk("winch_thread : failed to read synchronization byte, " 129 "err = %d\n", -count); 130 131 while(1){ 132 /* This will be interrupted by SIGWINCH only, since other signals 133 * are blocked.*/ 134 sigsuspend(&sigs); 135 136 count = os_write_file(pipe_fd, &c, sizeof(c)); 137 if(count != sizeof(c)) 138 printk("winch_thread : write failed, err = %d\n", 139 -count); 140 } 141 } 142 143 static int winch_tramp(int fd, struct tty_struct *tty, int *fd_out) 144 { 145 struct winch_data data; 146 unsigned long stack; 147 int fds[2], n, err; 148 char c; 149 150 err = os_pipe(fds, 1, 1); 151 if(err < 0){ 152 printk("winch_tramp : os_pipe failed, err = %d\n", -err); 153 goto out; 154 } 155 156 data = ((struct winch_data) { .pty_fd = fd, 157 .pipe_fd = fds[1], 158 .close_me = fds[0] } ); 159 err = run_helper_thread(winch_thread, &data, 0, &stack, 0); 160 if(err < 0){ 161 printk("fork of winch_thread failed - errno = %d\n", errno); 162 goto out_close; 163 } 164 165 os_close_file(fds[1]); 166 *fd_out = fds[0]; 167 n = os_read_file(fds[0], &c, sizeof(c)); 168 if(n != sizeof(c)){ 169 printk("winch_tramp : failed to read synchronization byte\n"); 170 printk("read failed, err = %d\n", -n); 171 printk("fd %d will not support SIGWINCH\n", fd); 172 err = -EINVAL; 173 goto out_close1; 174 } 175 return err ; 176 177 out_close: 178 os_close_file(fds[1]); 179 out_close1: 180 os_close_file(fds[0]); 181 out: 182 return err; 183 } 184 185 void register_winch(int fd, struct tty_struct *tty) 186 { 187 int pid, thread, thread_fd = -1; 188 int count; 189 char c = 1; 190 191 if(!isatty(fd)) 192 return; 193 194 pid = tcgetpgrp(fd); 195 if(!CHOOSE_MODE_PROC(is_tracer_winch, is_skas_winch, pid, fd, 196 tty) && (pid == -1)){ 197 thread = winch_tramp(fd, tty, &thread_fd); 198 if(thread > 0){ 199 register_winch_irq(thread_fd, fd, thread, tty); 200 201 count = os_write_file(thread_fd, &c, sizeof(c)); 202 if(count != sizeof(c)) 203 printk("register_winch : failed to write " 204 "synchronization byte, err = %d\n", 205 -count); 206 } 207 } 208 } 209 210 /* 211 * Overrides for Emacs so that we follow Linus's tabbing style. 212 * Emacs will notice this stuff at the end of the file and automatically 213 * adjust the settings for this buffer only. This must remain at the end 214 * of the file. 215 * --------------------------------------------------------------------------- 216 * Local variables: 217 * c-file-style: "linux" 218 * End: 219 */ 220