to_erl.c

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/* ``The contents of this file are subject to the Erlang Public License,
 * Version 1.1, (the "License"); you may not use this file except in
 * compliance with the License. You should have received a copy of the
 * Erlang Public License along with this software. If not, it can be
 * retrieved via the world wide web at http://www.erlang.org/.
 * 
 * Software distributed under the License is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
 * the License for the specific language governing rights and limitations
 * under the License.
 * 
 * The Initial Developer of the Original Code is Ericsson Utvecklings AB.
 * Portions created by Ericsson are Copyright 1999, Ericsson Utvecklings
 * AB. All Rights Reserved.''
 * 
 *     $Id$
 */
/* 
 * Module: to_erl.c
 * 
 * This module implements a process that opens two specified FIFOs, one
 * for reading and one for writing; reads from its stdin, and writes what
 * ithas read to the write FIF0; reads from the read FIFO, and writes to
 * its stdout.
 *
 */
#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

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

#if defined(O_NONBLOCK)
# define DONT_BLOCK_PLEASE O_NONBLOCK
#else
# define DONT_BLOCK_PLEASE O_NDELAY
# if !defined(EAGAIN)
#  define EAGAIN -3898734
# endif
#endif

#define noDEBUG

#define PIPE_DIR        "/tmp/"
#define PIPE_STUBNAME   "erlang.pipe"
#define PIPE_STUBLEN    strlen(PIPE_STUBNAME)

#ifdef DEBUG
#define STATUS(s)  { fprintf(stderr, (s)); fflush(stderr); }
#else
#define STATUS(s)
#endif

#ifndef FILENAME_MAX
#define FILENAME_MAX 250
#endif

static struct termios tty_smode, tty_rmode;
static int tty_eof = 0;
static int ctrlc = 0;

#ifdef DEBUG
static void show_terminal_settings(struct termios *);
#endif

static void handle_ctrlc(int sig) {
  /* Reinstall the handler, and signal break flag */
  signal(SIGINT,handle_ctrlc);
  ctrlc = 1;
}  

static void usage(char *pname)
{
  fprintf(stderr, "Usage: %s [pipe_name|pipe_dir/]\n", pname);
}

int main(int argc, char **argv)
{
    char  FIFO1[FILENAME_MAX], FIFO2[FILENAME_MAX];
    int i, len, wfd, rfd, result = 0;
    fd_set readfds;
    char buf[BUFSIZ];
    char pipename[FILENAME_MAX];
    
    if (argc < 1) {
	usage(argv[0]);
	exit(1);
    }
    
#ifdef DEBUG
    fprintf(stderr, "%s: pid is : %d\n", argv[0], (int)getpid());
#endif
    
    if(argv[1])
	strcpy(pipename,argv[1]);
    else
	strcpy(pipename,PIPE_DIR);
    
    if(*pipename && pipename[strlen(pipename)-1] == '/') {
	/* The user wishes us to find a unique pipe name in the specified */
	/* directory */
	int highest_pipe_num = 0;
	DIR *dirp;
	struct dirent *direntp;

	dirp = opendir(pipename);
	if(!dirp) {
	    fprintf(stderr, "Can't access pipe directory %s.\n", pipename);
	    exit(1);
	}

	/* Check the directory for existing pipes */
    
	while((direntp=readdir(dirp)) != NULL) {
	    if(strncmp(direntp->d_name,PIPE_STUBNAME,PIPE_STUBLEN)==0) {
		int num = atoi(direntp->d_name+PIPE_STUBLEN+1);
		if(num > highest_pipe_num)
		    highest_pipe_num = num;
	    }
	}	
	closedir(dirp);
	sprintf(pipename+strlen(pipename),
		(highest_pipe_num?"%s.%d":"%s"),PIPE_STUBNAME,highest_pipe_num);
    } /* if */
    
    /* read FIFO */
    strncpy(FIFO1, pipename, FILENAME_MAX);
    strncat(FIFO1, ".r", FILENAME_MAX - strlen(FIFO1));
    /* write FIFO */
    strncpy(FIFO2, pipename, FILENAME_MAX);
    strncat(FIFO2, ".w", FILENAME_MAX - strlen(FIFO2));
    
    if ((rfd = open (FIFO1, O_RDONLY|DONT_BLOCK_PLEASE, 0)) < 0) {
#ifdef DEBUG
	fprintf(stderr, "Could not open FIFO %s for reading.\n", FIFO1);
#endif
	fprintf(stderr, "No running Erlang on pipe %s.\n", pipename);
	exit(1);
    }
#ifdef DEBUG
    fprintf(stderr, "to_erl: %s opened for reading\n", FIFO1);
#endif
    
    if ((wfd = open (FIFO2, O_WRONLY|DONT_BLOCK_PLEASE, 0)) < 0) {
#ifdef DEBUG
	fprintf(stderr, "Could not open FIFO %s for writing.\n", FIFO2);
#endif
	fprintf(stderr, "No running Erlang on pipe %s.\n", pipename);
	close(rfd);
	exit(1);
    }
#ifdef DEBUG
    fprintf(stderr, "to_erl: %s opened for writing\n", FIFO2);
#endif
    
    fprintf(stderr, "Attaching to %s (^D to exit)\n\n", pipename);
    
    /* Set break handler to our handler */
    signal(SIGINT,handle_ctrlc);
    
    /* 
     * Save the current state of the terminal, and set raw mode.
     */
    if (tcgetattr(0, &tty_rmode) , 0) {
	fprintf(stderr, "Cannot get terminals current mode\n");
	exit(-1);
    }
    tty_smode = tty_rmode;
    tty_eof = '\004'; /* Ctrl+D to exit */
#ifdef DEBUG
    show_terminal_settings(&tty_rmode);
#endif
    tty_smode.c_iflag =
	1*BRKINT |/*Signal interrupt on break.*/
	    1*IGNPAR |/*Ignore characters with parity errors.*/
		1*ISTRIP |/*Strip character.*/
		    0;
    
#if 0
0*IGNBRK |/*Ignore break condition.*/
0*PARMRK |/*Mark parity errors.*/
0*INPCK  |/*Enable input parity check.*/
0*INLCR  |/*Map NL to CR on input.*/
0*IGNCR  |/*Ignore CR.*/
0*ICRNL  |/*Map CR to NL on input.*/
0*IUCLC  |/*Map upper-case to lower-case on input.*/
0*IXON   |/*Enable start/stop output control.*/
0*IXANY  |/*Enable any character to restart output.*/
0*IXOFF  |/*Enable start/stop input control.*/
0*IMAXBEL|/*Echo BEL on input line too long.*/
#endif
						
    tty_smode.c_oflag =
	1*OPOST  |/*Post-process output.*/
	    1*ONLCR  |/*Map NL to CR-NL on output.*/
#ifdef XTABS
		1*XTABS  |/*Expand tabs to spaces. (Linux)*/
#endif
#ifdef OXTABS
		    1*OXTABS  |/*Expand tabs to spaces. (FreeBSD)*/
#endif
#ifdef NL0
			1*NL0    |/*Select newline delays*/
#endif
#ifdef CR0
			    1*CR0    |/*Select carriage-return delays*/
#endif
#ifdef TAB0
				1*TAB0   |/*Select horizontal tab delays*/
#endif
#ifdef BS0
				    1*BS0    |/*Select backspace delays*/
#endif
#ifdef VT0
					1*VT0    |/*Select vertical tab delays*/
#endif
#ifdef FF0
					    1*FF0    |/*Select form feed delays*/
#endif
											    0;
    
#if 0
0*OLCUC  |/*Map lower case to upper on output.*/
0*OCRNL  |/*Map CR to NL on output.*/
0*ONOCR  |/*No CR output at column 0.*/
0*ONLRET |/*NL performs CR function.*/
0*OFILL  |/*Use fill characters for delay.*/
0*OFDEL  |/*Fill is DEL, else NULL.*/
0*NL1    |
0*CR1    |
0*CR2    |
0*CR3    |
0*TAB1   |
0*TAB2   |
0*TAB3   |/*Expand tabs to spaces.*/
0*BS1    |
0*VT1    |
0*FF1    |
#endif
								    
    /* JALI: removed setting the tty_smode.c_cflag flags, since this is not */
    /* advisable if this is a *real* terminal, such as the console. In fact */
    /* this may hang the entire machine, deep, deep down (signalling break */
    /* or toggling the abort switch doesn't help) */
    
    tty_smode.c_lflag =
									0;
    
#if 0
0*ISIG   |/*Enable signals.*/
0*ICANON |/*Canonical input (erase and kill processing).*/
0*XCASE  |/*Canonical upper/lower presentation.*/
0*ECHO   |/*Enable echo.*/
0*ECHOE  |/*Echo erase character as BS-SP-BS.*/
0*ECHOK  |/*Echo NL after kill character.*/
0*ECHONL |/*Echo NL.*/
0*NOFLSH |/*Disable flush after interrupt or quit.*/
0*TOSTOP |/*Send SIGTTOU for background output.*/
0*ECHOCTL|/*Echo control characters as ^char, delete as ^?.*/
0*ECHOPRT|/*Echo erase character as character erased.*/
0*ECHOKE |/*BS-SP-BS erase entire line on line kill.*/
0*FLUSHO |/*Output is being flushed.*/
0*PENDIN |/*Retype pending input at next read or input character.*/
0*IEXTEN |/*Enable extended (implementation-defined) functions.*/
#endif
								
    tty_smode.c_cc[VMIN]      =0;/* Note that VMIN is the same as VEOF! */
    tty_smode.c_cc[VTIME]     =0;/* Note that VTIME is the same as VEOL! */
    tty_smode.c_cc[VINTR]     =3;
    
    tcsetattr(0, TCSANOW, &tty_smode);
    
#ifdef DEBUG
    show_terminal_settings(&tty_smode);
#endif
    /*
     * Write a ^R to the FIFO which causes the other end to redisplay
     * the input line.
     */
    write(wfd, "\022", 1);
    /*
     * read and write
     */
    while (1) {
	FD_ZERO(&readfds);
	FD_SET(0, &readfds);
	FD_SET(rfd, &readfds);
	if (select(rfd + 1, &readfds, NULL, NULL, NULL) < 0) {
	    if(ctrlc) {
		FD_ZERO(&readfds);
	    } else {
		fprintf(stderr, "Error in select.\n");
		result = -1;
		break;
	    }
	}
	/*
	 * Read from terminal, write to FIFO
	 */
	if (ctrlc || FD_ISSET(0, &readfds)) {
	    STATUS("Terminal read; ");
	    if(ctrlc) {
		ctrlc = 0;
		fprintf(stderr, "[Break]\n\r");
		buf[0] = '\003';
		len = 1;
	    } else if ((len = read(0, buf, BUFSIZ)) <= 0) {
		close(rfd);
		close(wfd);
		if (len < 0) {
		    fprintf(stderr, "Error in reading from stdin.\n");
		    result = -1;
		} else {
		    fprintf(stderr, "[EOF]\n\r");
		}
		break;
	    }
	    /* check if there is an eof character in input */
	    for (i = 0; i < len && buf[i] != tty_eof; i++);
	    if (buf[i] == tty_eof) {
		fprintf(stderr, "[Quit]\n\r");
		break;
	    }
	    STATUS("FIFO write; \"");

#ifdef DEBUG
	    write(1, buf, len);
#endif
	    if (write(wfd, buf, len) != len) {
		fprintf(stderr, "Error in writing to FIFO.\n");
		close(rfd);
		close(wfd);
		result = -1;
		break;
	    }
	    STATUS("\" OK\r\n");
	}

	/*
	 * Read from FIFO, write to terminal.
	 */
	if (FD_ISSET(rfd, &readfds)) {
	    STATUS("FIFO read: ");
	    len = read(rfd, buf, BUFSIZ);
	    if (len < 0 && errno == EAGAIN) {
		/*
		 * No data this time, but the writing end of the FIFO is still open.
		 * Do nothing.
		 */
		;
	    } else if (len <= 0) {
		/*
		 * Either an error or end of file. In either case, break out
		 * of the loop.
		 */
		close(rfd);
		close(wfd);
		if (len < 0) {
		    fprintf(stderr, "Error in reading from FIFO.\n");
		    result = -1;
		} else
		    fprintf(stderr, "[End]\n\r");
		break;
	    } else {
		/*
		 * We successfully read at least one character. Write what we got.
		 */
		STATUS("Terminal write: \"");
		if (write(1, buf, len) != len) {
		    fprintf(stderr, "Error in writing to terminal.\n");
		    close(rfd);
		    close(wfd);
		    result = -1;
		    break;
		}
		STATUS("\" OK\r\n");
	    }
	}
    }

    /* 
     * Reset terminal characterstics 
     * XXX
     */
    tcsetattr(0, TCSANOW, &tty_rmode);
    return 0;
}

#ifdef DEBUG
#define S(x)  ((x) > 0 ? 1 : 0)

static void show_terminal_settings(struct termios *t)
{
  fprintf(stderr,"c_iflag:\n");
  fprintf(stderr,"Signal interrupt on break:   BRKINT  %d\n", S(t->c_iflag & BRKINT));
  fprintf(stderr,"Map CR to NL on input:       ICRNL   %d\n", S(t->c_iflag & ICRNL));
  fprintf(stderr,"Ignore break condition:      IGNBRK  %d\n", S(t->c_iflag & IGNBRK));
  fprintf(stderr,"Ignore CR:                   IGNCR   %d\n", S(t->c_iflag & IGNCR));
  fprintf(stderr,"Ignore char with par. err's: IGNPAR  %d\n", S(t->c_iflag & IGNPAR));
  fprintf(stderr,"Map NL to CR on input:       INLCR   %d\n", S(t->c_iflag & INLCR));
  fprintf(stderr,"Enable input parity check:   INPCK   %d\n", S(t->c_iflag & INPCK));
  fprintf(stderr,"Strip character              ISTRIP  %d\n", S(t->c_iflag & ISTRIP));
  fprintf(stderr,"Enable start/stop input ctrl IXOFF   %d\n", S(t->c_iflag & IXOFF));
  fprintf(stderr,"ditto output ctrl            IXON    %d\n", S(t->c_iflag & IXON));
  fprintf(stderr,"Mark parity errors           PARMRK  %d\n", S(t->c_iflag & PARMRK));
  fprintf(stderr,"\n");
  fprintf(stderr,"c_oflag:\n");
  fprintf(stderr,"Perform output processing    OPOST   %d\n", S(t->c_oflag & OPOST));
  fprintf(stderr,"\n");
  fprintf(stderr,"c_cflag:\n");
  fprintf(stderr,"Ignore modem status lines    CLOCAL  %d\n", S(t->c_cflag & CLOCAL));
  fprintf(stderr,"\n");
  fprintf(stderr,"c_local:\n");
  fprintf(stderr,"Enable echo                  ECHO    %d\n", S(t->c_lflag & ECHO));
  fprintf(stderr,"\n");
  fprintf(stderr,"c_cc:\n");
  fprintf(stderr,"c_cc[VEOF]                           %d\n", t->c_cc[VEOF]);
}
#endif