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drv_generic_serial.c

/* $Id: drv_generic_serial.c,v 1.17 2005/05/08 04:32:44 reinelt Exp $
 *
 * generic driver helper for serial and usbserial displays
 *
 * Copyright (C) 1999, 2000 Michael Reinelt <reinelt@eunet.at>
 * Copyright (C) 2004 The LCD4Linux Team <lcd4linux-devel@users.sourceforge.net>
 *
 * This file is part of LCD4Linux.
 *
 * LCD4Linux is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 *
 * LCD4Linux is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 * $Log: drv_generic_serial.c,v $
 * Revision 1.17  2005/05/08 04:32:44  reinelt
 * CodingStyle added and applied
 *
 * Revision 1.16  2005/01/18 06:30:23  reinelt
 * added (C) to all copyright statements
 *
 * Revision 1.15  2004/06/26 12:04:59  reinelt
 *
 * uh-oh... the last CVS log message messed up things a lot...
 *
 * Revision 1.14  2004/06/26 09:27:21  reinelt
 *
 * added '-W' to CFLAGS
 * changed all C++ comments to C ones
 * cleaned up a lot of signed/unsigned mistakes
 *
 * Revision 1.13  2004/06/26 06:12:15  reinelt
 *
 * support for Beckmann+Egle Compact Terminals
 * some mostly cosmetic changes in the MatrixOrbital and USBLCD driver
 * added debugging to the generic serial driver
 * fixed a bug in the generic text driver where icons could be drawn outside
 * the display bounds
 *
 * Revision 1.12  2004/06/20 10:09:55  reinelt
 *
 * 'const'ified the whole source
 *
 * Revision 1.11  2004/06/01 06:45:30  reinelt
 *
 * some Fixme's processed
 * documented some code
 *
 * Revision 1.10  2004/05/31 21:05:13  reinelt
 *
 * fixed lots of bugs in the Cwlinux driver
 * do not emit EAGAIN error on the first retry
 * made plugin_i2c_sensors a bit less 'chatty'
 * moved init and exit functions to the bottom of plugin_pop3
 *
 * Revision 1.9  2004/05/28 13:51:42  reinelt
 *
 * ported driver for Beckmann+Egle Mini-Terminals
 * added 'flags' parameter to serial_init()
 *
 * Revision 1.8  2004/03/03 04:44:16  reinelt
 * changes (cosmetics?) to the big patch from Martin
 * hash patch un-applied
 *
 * Revision 1.7  2004/03/03 03:47:04  reinelt
 * big patch from Martin Hejl:
 * - use qprintf() where appropriate
 * - save CPU cycles on gettimeofday()
 * - add quit() functions to free allocated memory
 * - fixed lots of memory leaks
 *
 * Revision 1.6  2004/02/14 11:56:17  reinelt
 * M50530 driver ported
 * changed lots of 'char' to 'unsigned char'
 *
 * Revision 1.5  2004/02/04 19:10:51  reinelt
 * Crystalfontz driver nearly finished
 *
 * Revision 1.4  2004/02/01 08:05:12  reinelt
 * Crystalfontz 633 extensions (CRC checking and stuff)
 * Models table for HD44780
 * Noritake VFD BVrightness patch from Bill Paxton
 *
 * Revision 1.3  2004/01/29 04:40:02  reinelt
 * every .c file includes "config.h" now
 *
 * Revision 1.2  2004/01/25 05:30:09  reinelt
 * plugin_netdev for parsing /proc/net/dev added
 *
 * Revision 1.1  2004/01/20 14:26:09  reinelt
 * moved drv_generic to drv_generic_serial
 *
 * Revision 1.2  2004/01/20 05:36:59  reinelt
 * moved text-display-specific stuff to drv_generic_text
 * moved all the bar stuff from drv_generic_bar to generic_text
 *
 * Revision 1.1  2004/01/20 04:51:39  reinelt
 * moved generic stuff from drv_MatrixOrbital to drv_generic
 * implemented new-stylish bars which are nearly finished
 *
 */

/* 
 *
 * exported fuctions:
 *
 * int drv_generic_serial_open (char *section, char *driver, unsigned int flags)
 *   opens the serial port
 *
 * int drv_generic_serial_poll (char *string, int len)
 *   reads from the serial or USB port
 *   without retry
 *
 * int drv_generic_serial_read (char *string, int len);
 *   reads from the serial or USB port
 *   with retry
 *
 * void drv_generic_serial_write (char *string, int len);
 *   writes to the serial or USB port
 *
 * int drv_generic_serial_close (void);
 *   closes the serial port
 *
 */

#include "config.h"

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

#include "debug.h"
#include "qprintf.h"
#include "cfg.h"
#include "drv_generic_serial.h"


static char *Section;
static char *Driver;
static char *Port;
static speed_t Speed;
static int Device = -1;


#define LOCK "/var/lock/LCK..%s"


/****************************************/
/*** generic serial/USB communication ***/
/****************************************/

static pid_t drv_generic_serial_lock_port(const char *Port)
{
    char lockfile[256];
    char tempfile[256];
    char buffer[16];
    char *port, *p;
    int fd, len, pid;

    if (strncmp(Port, "/dev/", 5) == 0) {
      port = strdup(Port + 5);
    } else {
      port = strdup(Port);
    }

    while ((p = strchr(port, '/')) != NULL) {
      *p = '_';
    }

    qprintf(lockfile, sizeof(lockfile), LOCK, port);
    qprintf(tempfile, sizeof(tempfile), LOCK, "TMP.XXXXXX");

    free(port);

    if ((fd = mkstemp(tempfile)) == -1) {
      error("mkstemp(%s) failed: %s", tempfile, strerror(errno));
      return -1;
    }

    if (fchmod(fd, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) == -1) {
      error("fchmod(%s) failed: %s", tempfile, strerror(errno));
      close(fd);
      unlink(tempfile);
      return -1;
    }

    snprintf(buffer, sizeof(buffer), "%10d\n", (int) getpid());
    len = strlen(buffer);
    if (write(fd, buffer, len) != len) {
      error("write(%s) failed: %s", tempfile, strerror(errno));
      close(fd);
      unlink(tempfile);
      return -1;
    }
    close(fd);


    while (link(tempfile, lockfile) == -1) {

      if (errno != EEXIST) {
          error("link(%s, %s) failed: %s", tempfile, lockfile, strerror(errno));
          unlink(tempfile);
          return -1;
      }

      if ((fd = open(lockfile, O_RDONLY)) == -1) {
          if (errno == ENOENT)
            continue;   /* lockfile disappared */
          error("open(%s) failed: %s", lockfile, strerror(errno));
          unlink(tempfile);
          return -1;
      }

      len = read(fd, buffer, sizeof(buffer) - 1);
      if (len < 0) {
          error("read(%s) failed: %s", lockfile, strerror(errno));
          unlink(tempfile);
          return -1;
      }

      buffer[len] = '\0';
      if (sscanf(buffer, "%d", &pid) != 1 || pid == 0) {
          error("scan(%s) failed.", lockfile);
          unlink(tempfile);
          return -1;
      }

      if (pid == getpid()) {
          error("%s already locked by us. uh-oh...", lockfile);
          unlink(tempfile);
          return 0;
      }

      if ((kill(pid, 0) == -1) && errno == ESRCH) {
          error("removing stale lockfile %s", lockfile);
          if (unlink(lockfile) == -1 && errno != ENOENT) {
            error("unlink(%s) failed: %s", lockfile, strerror(errno));
            unlink(tempfile);
            return pid;
          }
          continue;
      }
      unlink(tempfile);
      return pid;
    }

    unlink(tempfile);
    return 0;
}


static pid_t drv_generic_serial_unlock_port(const char *Port)
{
    char lockfile[256];
    char *port, *p;

    if (strncmp(Port, "/dev/", 5) == 0) {
      port = strdup(Port + 5);
    } else {
      port = strdup(Port);
    }

    while ((p = strchr(port, '/')) != NULL) {
      *p = '_';
    }

    qprintf(lockfile, sizeof(lockfile), LOCK, port);
    unlink(lockfile);
    free(port);

    return 0;
}


int drv_generic_serial_open(const char *section, const char *driver, const unsigned int flags)
{
    int i, fd;
    pid_t pid;
    struct termios portset;

    Section = (char *) section;
    Driver = (char *) driver;

    Port = cfg_get(section, "Port", NULL);
    if (Port == NULL || *Port == '\0') {
      error("%s: no '%s.Port' entry from %s", Driver, section, cfg_source());
      return -1;
    }

    if (cfg_number(section, "Speed", 19200, 1200, 115200, &i) < 0)
      return -1;
    switch (i) {
    case 1200:
      Speed = B1200;
      break;
    case 2400:
      Speed = B2400;
      break;
    case 4800:
      Speed = B4800;
      break;
    case 9600:
      Speed = B9600;
      break;
    case 19200:
      Speed = B19200;
      break;
    case 38400:
      Speed = B38400;
      break;
    case 57600:
      Speed = B57600;
      break;
    case 115200:
      Speed = B115200;
      break;
    default:
      error("%s: unsupported speed '%d' from %s", Driver, i, cfg_source());
      return -1;
    }

    info("%s: using port '%s' at %d baud", Driver, Port, i);

    if ((pid = drv_generic_serial_lock_port(Port)) != 0) {
      if (pid == -1)
          error("%s: port %s could not be locked", Driver, Port);
      else
          error("%s: port %s is locked by process %d", Driver, Port, pid);
      return -1;
    }

    fd = open(Port, O_RDWR | O_NOCTTY | O_NDELAY);
    if (fd == -1) {
      error("%s: open(%s) failed: %s", Driver, Port, strerror(errno));
      drv_generic_serial_unlock_port(Port);
      return -1;
    }

    if (tcgetattr(fd, &portset) == -1) {
      error("%s: tcgetattr(%s) failed: %s", Driver, Port, strerror(errno));
      drv_generic_serial_unlock_port(Port);
      return -1;
    }

    cfmakeraw(&portset);
    portset.c_cflag |= flags;
    cfsetispeed(&portset, Speed);
    cfsetospeed(&portset, Speed);
    if (tcsetattr(fd, TCSANOW, &portset) == -1) {
      error("%s: tcsetattr(%s) failed: %s", Driver, Port, strerror(errno));
      drv_generic_serial_unlock_port(Port);
      return -1;
    }

    Device = fd;
    return Device;
}


int drv_generic_serial_poll(char *string, const int len)
{
    int ret;
    if (Device == -1)
      return -1;
    ret = read(Device, string, len);
    if (ret < 0 && errno != EAGAIN) {
      error("%s: read(%s) failed: %s", Driver, Port, strerror(errno));
    }
    return ret;
}


int drv_generic_serial_read(char *string, const int len)
{
    int count, run, ret;

    count = len < 0 ? -len : len;

    for (run = 0; run < 10; run++) {
      ret = drv_generic_serial_poll(string, count);
      if (ret >= 0 || errno != EAGAIN)
          break;
      info("%s: read(%s): EAGAIN", Driver, Port);
      usleep(1000);
    }

    if (ret > 0 && ret != count && len > 0) {
      error("%s: partial read(%s): len=%d ret=%d", Driver, Port, len, ret);
    }

    return ret;
}


void drv_generic_serial_write(const char *string, const int len)
{
    int run, ret;

#if 0
    int i;
    for (i = 0; i < len; i++) {
      int c = string[i];
      debug("serial_write: %03d %03o 0x%02x %c", c, c, c, iscntrl(c) ? '*' : c);
    }
#endif

    if (Device == -1)
      return;
    for (run = 0; run < 10; run++) {
      ret = write(Device, string, len);
      if (ret >= 0 || errno != EAGAIN)
          break;
      if (run > 0)
          info("%s: write(%s): EAGAIN #%d", Driver, Port, run);
      usleep(1000);
    }

    if (ret < 0) {
      error("%s: write(%s) failed: %s", Driver, Port, strerror(errno));
    } else if (ret != len) {
      error("%s: partial write(%s): len=%d ret=%d", Driver, Port, len, ret);
    }

    return;
}


int drv_generic_serial_close(void)
{
    info("%s: closing port %s", Driver, Port);
    close(Device);
    drv_generic_serial_unlock_port(Port);
    free(Port);
    return 0;
}

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