text: /*
   * utils.c - various utility functions used in pppd.
   *
   * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
   *
   * Permission to use, copy, modify, and distribute this software and its
   * documentation is hereby granted, provided that the above copyright
   * notice appears in all copies.
   *
   * SUN MAKES NO REPRESENTATION OR WARRANTIES ABOUT THE SUITABILITY OF
   * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
   * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
   * PARTICULAR PURPOSE, OR NON-INFRINGEMENT.  SUN SHALL NOT BE LIABLE FOR
   * ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
   * DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES
   *
   * Copyright (c) 1999 The Australian National University.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms are permitted
   * provided that the above copyright notice and this paragraph are
   * duplicated in all such forms and that any documentation,
   * advertising materials, and other materials related to such
   * distribution and use acknowledge that the software was developed
   * by the Australian National University.  The name of the University
   * may not be used to endorse or promote products derived from this
   * software without specific prior written permission.
   * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
   * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
   */
  
  #ifdef __linux__
  #define	_GNU_SOURCE
  #endif
  #include <stdio.h>
  #include <ctype.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <signal.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <syslog.h>
  #include <netdb.h>
  #include <utmp.h>
  #include <pwd.h>
  #include <sys/param.h>
  #include <sys/types.h>
  #include <sys/wait.h>
  #include <sys/time.h>
  #include <sys/resource.h>
  #include <sys/stat.h>
  #include <sys/socket.h>
  #include <netinet/in.h>
  #ifdef SVR4
  #include <sys/mkdev.h>
  #endif
  
  #include "pppd.h"
  
  #if defined(SUNOS4)
  extern char *strerror();
  #endif
  
  /* Don't log to stdout until we're sure it's ok to do so. */
  bool early_log = 1;
  
  static void pr_log __P((void *, const char *, ...));
  static void logit __P((int, const char *, va_list));
  static void vslp_printer __P((void *, const char *, ...));
  static void format_packet __P((u_char *, int,
      void (*) (void *, const char *, ...), void *));
  
  struct buffer_info {
      char *ptr;
      int len;
  };
  
  /*
   * strllen - like strlen, but doesn't run past end of input.
   */
  size_t
  strllen(str, len)
      const char *str;
      size_t len;
  {
      size_t ret;
  
      for (ret = 0; ret < len; ret++)
  	if (*str++ == '\0')
  	    break;
      return (ret);
  }
  
  /*
   * slprintf - format a message into a buffer.  Like sprintf except we
   * also specify the length of the output buffer, and we handle %m
   * (error message), %v (visible string), %q (quoted string), %t
   * (current time), %I (IP address), %P (PPP packet), and %B (sequence
   * of bytes) formats.  Doesn't do floating-point formats.  Returns the
   * number of chars put into buf.
   */
  int
  slprintf __V((char *buf, int buflen, const char *fmt, ...))
  {
      va_list args;
      int n;
  
  #if defined(__STDC__)
      va_start(args, fmt);
  #else
      char *buf;
      int buflen;
      const char *fmt;
      va_start(args);
      buf = va_arg(args, char *);
      buflen = va_arg(args, int);
      fmt = va_arg(args, const char *);
  #endif
      n = vslprintf(buf, buflen, fmt, args);
      va_end(args);
      return (n);
  }
  
  /*
   * Print to file or, if argument is NULL, to syslog at debug level.
   */
  int
  flprintf __V((FILE *strptr, const char *fmt, ...))
  {
      va_list args;
      int n;
      char buf[1024], *bp, *nlp, *ebp;
  
  #if defined(__STDC__)
      va_start(args, fmt);
  #else
      FILE *strptr;
      const char *fmt;
      va_start(args);
      strptr = va_arg(args, FILE *);
      fmt = va_arg(args, const char *);
  #endif
      n = vslprintf(buf, sizeof (buf), fmt, args);
      va_end(args);
      if (strptr == NULL) {
  	bp = buf;
  	ebp = buf + n;
  	while (bp < ebp) {
  	    if ((nlp = strchr(bp, '\n')) == NULL)
  		nlp = ebp;
  	    if (nlp > bp) {
  		*nlp = '\0';
  		syslog(LOG_DEBUG, "%s", bp);
  	    }
  	    bp = nlp + 1;
  	}
      } else {
  	n = fwrite(buf, 1, n, strptr);
      }
      return (n);
  }
  
  /*
   * vslprintf - like slprintf, takes a va_list instead of a list of args.
   */
  #define OUTCHAR(c)	(buflen > 0? (--buflen, *buf++ = (c)): 0)
  
  int
  vslprintf(buf, buflen, fmt, args)
      char *buf;
      int buflen;
      const char *fmt;
      va_list args;
  {
      int c, n, longs;
      int width, prec, fillch;
      int base, len, neg, quoted;
  #ifdef SOL2
      uint64_t val;
      int64_t sval;
  #else
      unsigned long val;
      long sval;
  #endif
      char *buf0, *mstr;
      const char *f, *str;
      unsigned char *p;
      char num[32];	/* 2^64 is 20 chars decimal, 22 octal */
      time_t t;
      u_int32_t ip;
      static const char hexchars[] = "0123456789abcdef";
      struct buffer_info bufinfo;
  
      buf0 = buf;
      --buflen;
      while (buflen > 0) {
  	for (f = fmt; *f != '%' && *f != 0; ++f)
  	    ;
  	if (f > fmt) {
  	    len = f - fmt;
  	    if (len > buflen)
  		len = buflen;
  	    (void) memcpy(buf, fmt, len);
  	    buf += len;
  	    buflen -= len;
  	    fmt = f;
  	}
  	if (*fmt == 0)
  	    break;
  	c = *++fmt;
  	width = 0;
  	prec = -1;
  	fillch = ' ';
  	if (c == '0') {
  	    fillch = '0';
  	    c = *++fmt;
  	}
  	if (c == '*') {
  	    width = va_arg(args, int);
  	    c = *++fmt;
  	} else {
  	    while (isdigit(c)) {
  		width = width * 10 + c - '0';
  		c = *++fmt;
  	    }
  	}
  	if (c == '.') {
  	    c = *++fmt;
  	    if (c == '*') {
  		prec = va_arg(args, int);
  		c = *++fmt;
  	    } else {
  		prec = 0;
  		while (isdigit(c)) {
  		    prec = prec * 10 + c - '0';
  		    c = *++fmt;
  		}
  	    }
  	}
  	longs = 0;
  	if (c == 'l') {
  	    longs++;
  	    c = *++fmt;
  	    if (c == 'l') {
  		longs++;
  		c = *++fmt;
  	    }
  	}
  	str = 0;
  	base = 0;
  	neg = 0;
  	val = 0;
  	++fmt;
  	switch (c) {
  	case 'u':
  #ifdef SOL2
  	    if (longs >= 2)
  		val = va_arg(args, uint64_t);
  	    else
  #endif
  	    if (longs > 0)
  		val = va_arg(args, unsigned long);
  	    else
  		val = va_arg(args, unsigned int);
  	    base = 10;
  	    break;
  	case 'd':
  #ifdef SOL2
  	    if (longs >= 2)
  		sval = va_arg(args, int64_t);
  	    else
  #endif
  	    if (longs > 0)
  		sval = va_arg(args, long);
  	    else
  		sval = va_arg(args, int);
  	    if (sval < 0) {
  		neg = 1;
  		val = -sval;
  	    } else
  		val = sval;
  	    base = 10;
  	    break;
  	case 'o':
  #ifdef SOL2
  	    if (longs >= 2)
  		val = va_arg(args, uint64_t);
  	    else
  #endif
  	    if (longs > 0)
  		val = va_arg(args, unsigned long);
  	    else
  		val = va_arg(args, unsigned int);
  	    base = 8;
  	    break;
  	case 'x':
  	case 'X':
  #ifdef SOL2
  	    if (longs >= 2)
  		val = va_arg(args, uint64_t);
  	    else
  #endif
  	    if (longs > 0)
  		val = va_arg(args, unsigned long);
  	    else
  		val = va_arg(args, unsigned int);
  	    base = 16;
  	    break;
  	case 'p':
  	    val = (unsigned long) va_arg(args, void *);
  	    base = 16;
  	    neg = 2;
  	    break;
  	case 's':
  	    str = va_arg(args, const char *);
  	    break;
  	case 'c':
  	    num[0] = va_arg(args, int);
  	    num[1] = 0;
  	    str = num;
  	    break;
  	case 'm':
  	    str = strerror(errno);
  	    break;
  	case 'I':
  	    ip = va_arg(args, u_int32_t);
  	    ip = ntohl(ip);
  	    (void) slprintf(num, sizeof(num), "%d.%d.%d.%d", (ip >> 24) & 0xff,
  		(ip >> 16) & 0xff, (ip >> 8) & 0xff, ip & 0xff);
  	    str = num;
  	    break;
  	case 't':
  	    (void) time(&t);
  	    mstr = ctime(&t);
  	    mstr += 4;		/* chop off the day name */
  	    mstr[15] = 0;	/* chop off year and newline */
  	    str = (const char *)mstr;
  	    break;
  	case 'v':		/* "visible" string */
  	case 'q':		/* quoted string */
  	    quoted = c == 'q';
  	    p = va_arg(args, unsigned char *);
  	    if (fillch == '0' && prec >= 0) {
  		n = prec;
  	    } else {
  		n = strlen((char *)p);
  		if (prec >= 0 && n > prec)
  		    n = prec;
  	    }
  	    while (n > 0 && buflen > 0) {
  		c = *p++;
  		--n;
  		if (!quoted && c >= 0x80) {
  		    (void) OUTCHAR('M');
  		    (void) OUTCHAR('-');
  		    c -= 0x80;
  		}
  		if (quoted && (c == '"' || c == '\\'))
  		    (void) OUTCHAR('\\');
  		if (c < 0x20 || (0x7f <= c && c < 0xa0)) {
  		    if (quoted) {
  			(void) OUTCHAR('\\');
  			switch (c) {
  			case '\t':	(void) OUTCHAR('t');	break;
  			case '\n':	(void) OUTCHAR('n');	break;
  			case '\b':	(void) OUTCHAR('b');	break;
  			case '\f':	(void) OUTCHAR('f');	break;
  			default:
  			    (void) OUTCHAR('x');
  			    (void) OUTCHAR(hexchars[c >> 4]);
  			    (void) OUTCHAR(hexchars[c & 0xf]);
  			}
  		    } else {
  			if (c == '\t')
  			    (void) OUTCHAR(c);
  			else {
  			    (void) OUTCHAR('^');
  			    (void) OUTCHAR(c ^ 0x40);
  			}
  		    }
  		} else
  		    (void) OUTCHAR(c);
  	    }
  	    continue;
  	case 'P':		/* print PPP packet */
  	    bufinfo.ptr = buf;
  	    bufinfo.len = buflen + 1;
  	    p = va_arg(args, unsigned char *);
  	    n = va_arg(args, int);
  	    format_packet(p, n, vslp_printer, &bufinfo);
  	    buf = bufinfo.ptr;
  	    buflen = bufinfo.len - 1;
  	    continue;
  	case 'B':
  	    p = va_arg(args, unsigned char *);
  	    if ((n = prec) > width && width > 0)
  		n = width;
  	    /* For safety's sake */
  	    if (n > 2000)
  		    n = 2000;
  	    while (--n >= 0) {
  		c = *p++;
  		if (fillch == ' ')
  		    (void) OUTCHAR(' ');
  		(void) OUTCHAR(hexchars[(c >> 4) & 0xf]);
  		(void) OUTCHAR(hexchars[c & 0xf]);
  	    }
  	    if (prec > width && width > 0) {
  		(void) OUTCHAR('.');
  		(void) OUTCHAR('.');
  		(void) OUTCHAR('.');
  	    }
  	    continue;
  	default:
  	    *buf++ = '%';
  	    if (c != '%')
  		--fmt;		/* so %z outputs %z etc. */
  	    --buflen;
  	    continue;
  	}
  	if (base != 0) {
  	    mstr = num + sizeof(num);
  	    *--mstr = 0;
  	    while (mstr > num + neg) {
  		*--mstr = hexchars[val % base];
  		val = val / base;
  		if (--prec <= 0 && val == 0)
  		    break;
  	    }
  	    switch (neg) {
  	    case 1:
  		*--mstr = '-';
  		break;
  	    case 2:
  		*--mstr = 'x';
  		*--mstr = '0';
  		break;
  	    }
  	    len = num + sizeof(num) - 1 - mstr;
  	    str = (const char *)mstr;
  	} else {
  	    len = strlen(str);
  	    if (prec >= 0 && len > prec)
  		len = prec;
  	}
  	if (width > 0) {
  	    if (width > buflen)
  		width = buflen;
  	    if ((n = width - len) > 0) {
  		buflen -= n;
  		for (; n > 0; --n)
  		    *buf++ = fillch;
  	    }
  	}
  	if (len > buflen)
  	    len = buflen;
  	(void) memcpy(buf, str, len);
  	buf += len;
  	buflen -= len;
      }
      *buf = 0;
      return (buf - buf0);
  }
  
  /*
   * vslp_printer - used in processing a %P format
   */
  static void
  vslp_printer __V((void *arg, const char *fmt, ...))
  {
      int n;
      va_list pvar;
      struct buffer_info *bi;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      void *arg;
      const char *fmt;
      va_start(pvar);
      arg = va_arg(pvar, void *);
      fmt = va_arg(pvar, const char *);
  #endif
  
      bi = (struct buffer_info *) arg;
      n = vslprintf(bi->ptr, bi->len, fmt, pvar);
      va_end(pvar);
  
      bi->ptr += n;
      bi->len -= n;
  }
  
  /*
   * log_packet - format a packet and log it.
   */
  
  static char line[256];		/* line to be logged accumulated here */
  static char *linep;
  
  void
  log_packet(p, len, prefix, level)
      u_char *p;
      int len;
      const char *prefix;
      int level;
  {
      (void) strlcpy(line, prefix, sizeof(line));
      linep = line + strlen(line);
      format_packet(p, len, pr_log, (void *)level);
      if (linep != line)
  	syslog(level, "%s", line);
  }
  
  /*
   * format_packet - make a readable representation of a packet,
   * calling `printer(arg, format, ...)' to output it.
   */
  static void
  format_packet(p, len, printer, arg)
      u_char *p;
      int len;
      void (*printer) __P((void *, const char *, ...));
      void *arg;
  {
      int i, n;
      u_short proto;
      struct protent *protp;
  
      if (len >= PPP_HDRLEN && p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
  	p += 2;
  	GETSHORT(proto, p);
  	len -= PPP_HDRLEN;
  	for (i = 0; (protp = protocols[i]) != NULL; ++i)
  	    if (proto == protp->protocol)
  		break;
  	if (protp != NULL) {
  	    printer(arg, "[%s", protp->name);
  	    n = (*protp->printpkt)(p, len, printer, arg);
  	    printer(arg, "]");
  	    p += n;
  	    len -= n;
  	} else {
  	    for (i = 0; (protp = protocols[i]) != NULL; ++i)
  		if (proto == (protp->protocol & ~0x8000))
  		    break;
  	    if (protp != NULL && protp->data_name != NULL) {
  		printer(arg, "[%s data] %8.*B", protp->data_name, len, p);
  		len = 0;
  	    } else
  		printer(arg, "[proto=0x%x]", proto);
  	}
      }
  
      printer(arg, "%32.*B", len, p);
  }
  
  static void
  pr_log __V((void *arg, const char *fmt, ...))
  {
      int n;
      va_list pvar;
      char buf[256];
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      void *arg;
      const char *fmt;
      va_start(pvar);
      arg = va_arg(pvar, void *);
      fmt = va_arg(pvar, const char *);
  #endif
  
      n = vslprintf(buf, sizeof(buf), fmt, pvar);
      va_end(pvar);
  
      if (linep + n + 1 > line + sizeof(line)) {
  	syslog((int)arg, "%s", line);
  	linep = line;
      }
      (void) strlcpy(linep, buf, line + sizeof(line) - linep);
      linep += n;
  }
  
  /*
   * print_string - print a readable representation of a string using
   * printer.
   */
  void
  print_string(p, len, printer, arg)
      char *p;
      int len;
      void (*printer) __P((void *, const char *, ...));
      void *arg;
  {
      int c;
  
      printer(arg, "\"");
      for (; len > 0; --len) {
  	c = *p++;
  	if (isprint(c)) {
  	    if (c == '\\' || c == '"')
  		printer(arg, "\\");
  	    printer(arg, "%c", c);
  	} else {
  	    switch (c) {
  	    case '\n':
  		printer(arg, "\\n");
  		break;
  	    case '\r':
  		printer(arg, "\\r");
  		break;
  	    case '\t':
  		printer(arg, "\\t");
  		break;
  	    default:
  		printer(arg, "\\%.3o", c);
  	    }
  	}
      }
      printer(arg, "\"");
  }
  
  /*
   * logit - does the hard work for fatal et al.
   */
  static void
  logit(level, fmt, args)
      int level;
      const char *fmt;
      va_list args;
  {
      int n;
      char buf[1024];
  
      n = vslprintf(buf, sizeof(buf), fmt, args);
      syslog(level, "%s", buf);
      if (log_to_fd >= 0 && (level != LOG_DEBUG || debug) &&
  	(!early_log || log_to_specific_fd)) {
  	if (buf[n-1] != '\n')
  	    buf[n++] = '\n';
  	if (write(log_to_fd, buf, n) != n)
  	    log_to_fd = -1;
      }
  }
  
  /*
   * fatal - log an error message and die horribly.
   */
  void
  fatal __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_ERR, fmt, pvar);
      va_end(pvar);
  
      die(1);			/* as promised */
  }
  
  /*
   * error - log an error message.
   */
  void
  error __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_ERR, fmt, pvar);
      va_end(pvar);
  }
  
  /*
   * warn - log a warning message.
   */
  void
  warn __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_WARNING, fmt, pvar);
      va_end(pvar);
  }
  
  /*
   * notice - log a notice-level message.
   */
  void
  notice __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_NOTICE, fmt, pvar);
      va_end(pvar);
  }
  
  /*
   * info - log an informational message.
   */
  void
  info __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_INFO, fmt, pvar);
      va_end(pvar);
  }
  
  /*
   * dbglog - log a debug message.
   */
  void
  dbglog __V((const char *fmt, ...))
  {
      va_list pvar;
  
  #if defined(__STDC__)
      va_start(pvar, fmt);
  #else
      const char *fmt;
      va_start(pvar);
      fmt = va_arg(pvar, const char *);
  #endif
  
      logit(LOG_DEBUG, fmt, pvar);
      va_end(pvar);
  }
  
  /*
   * Code names for regular PPP messages.  Used by LCP and most NCPs,
   * not used by authentication protocols.
   */
  const char *
  code_name(int code, int shortflag)
  {
      static const char *codelist[] = {
  	"Vendor-Extension", "Configure-Request", "Configure-Ack",
  	"Configure-Nak", "Configure-Reject", "Terminate-Request",
  	"Terminate-Ack", "Code-Reject", "Protocol-Reject",
  	"Echo-Request", "Echo-Reply", "Discard-Request",
  	"Identification", "Time-Remaining",
  	"Reset-Request", "Reset-Ack"
      };
      static const char *shortcode[] = {
  	"VendExt", "ConfReq", "ConfAck",
  	"ConfNak", "ConfRej", "TermReq",
  	"TermAck", "CodeRej", "ProtRej",
  	"EchoReq", "EchoRep", "DiscReq",
  	"Ident", "TimeRem",
  	"ResetReq", "ResetAck"
      };
      static char msgbuf[64];
  
      if (code < 0 || code >= sizeof (codelist) / sizeof (*codelist)) {
  	if (shortflag)
  	    (void) slprintf(msgbuf, sizeof (msgbuf), "Code#%d", code);
  	else
  	    (void) slprintf(msgbuf, sizeof (msgbuf), "unknown code %d", code);
  	return ((const char *)msgbuf);
      }
      return (shortflag ? shortcode[code] : codelist[code]);
  }
  
  /* Procedures for locking the serial device using a lock file. */
  #ifndef LOCK_DIR
  #ifdef _linux_
  #define LOCK_DIR	"/var/lock"
  #else
  #ifdef SVR4
  #define LOCK_DIR	"/var/spool/locks"
  #else
  #define LOCK_DIR	"/var/spool/lock"
  #endif
  #endif
  #endif /* LOCK_DIR */
  
  static char lock_file[MAXPATHLEN];
  
  /*
   * lock - create a lock file for the named device
   */
  int
  lock(dev)
      char *dev;
  {
  #ifdef LOCKLIB
      int result;
  
      result = mklock (dev, (void *) 0);
      if (result == 0) {
  	(void) strlcpy(lock_file, sizeof(lock_file), dev);
  	return (0);
      }
  
      if (result > 0)
          notice("Device %s is locked by pid %d", dev, result);
      else
  	error("Can't create lock file %s", lock_file);
      return (-1);
  
  #else /* LOCKLIB */
  
      char lock_buffer[12];
      int fd, pid, n;
  
  #ifdef SVR4
      struct stat sbuf;
  
      if (stat(dev, &sbuf) < 0) {
  	error("Can't get device number for %s: %m", dev);
  	return (-1);
      }
      if ((sbuf.st_mode & S_IFMT) != S_IFCHR) {
  	error("Can't lock %s: not a character device", dev);
  	return (-1);
      }
      (void) slprintf(lock_file, sizeof(lock_file), "%s/LK.%03d.%03d.%03d",
  	     LOCK_DIR, major(sbuf.st_dev),
  	     major(sbuf.st_rdev), minor(sbuf.st_rdev));
  #else
      char *p;
  
      if ((p = strrchr(dev, '/')) != NULL)
  	dev = p + 1;
      (void) slprintf(lock_file, sizeof(lock_file), "%s/LCK..%s", LOCK_DIR, dev);
  #endif
  
      while ((fd = open(lock_file, O_EXCL | O_CREAT | O_RDWR, 0644)) < 0) {
  	if (errno != EEXIST) {
  	    error("Can't create lock file %s: %m", lock_file);
  	    break;
  	}
  
  	/* Read the lock file to find out who has the device locked. */
  	fd = open(lock_file, O_RDONLY, 0);
  	if (fd < 0) {
  	    if (errno == ENOENT) /* This is just a timing problem. */
  		continue;
  	    error("Can't open existing lock file %s: %m", lock_file);
  	    break;
  	}
  #ifndef LOCK_BINARY
  	n = read(fd, lock_buffer, 11);
  #else
  	n = read(fd, &pid, sizeof(pid));
  #endif /* LOCK_BINARY */
  	(void) close(fd);
  	fd = -1;
  	if (n <= 0) {
  	    error("Can't read pid from lock file %s", lock_file);
  	    break;
  	}
  
  	/* See if the process still exists. */
  #ifndef LOCK_BINARY
  	lock_buffer[n] = 0;
  	pid = atoi(lock_buffer);
  #endif /* LOCK_BINARY */
  	if (pid == getpid())
  	    return (1);		/* somebody else locked it for us */
  	if (pid == 0
  	    || (kill(pid, 0) == -1 && errno == ESRCH)) {
  	    if (unlink (lock_file) == 0) {
  		notice("Removed stale lock on %s (pid %d)", dev, pid);
  		continue;
  	    }
  	    warn("Couldn't remove stale lock on %s", dev);
  	} else
  	    notice("Device %s is locked by pid %d", dev, pid);
  	break;
      }
  
      if (fd < 0) {
  	lock_file[0] = 0;
  	return (-1);
      }
  
      pid = getpid();
  #ifndef LOCK_BINARY
      (void) slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
      (void) write (fd, lock_buffer, 11);
  #else
      (void) write(fd, &pid, sizeof (pid));
  #endif
      (void) close(fd);
      return (0);
  
  #endif
  }
  
  /*
   * relock - called to update our lockfile when we are about to detach,
   * thus changing our pid (we fork, the child carries on, and the parent dies).
   * Note that this is called by the parent, with pid equal to the pid
   * of the child.  This avoids a potential race which would exist if
   * we had the child rewrite the lockfile (the parent might die first,
   * and another process could think the lock was stale if it checked
   * between when the parent died and the child rewrote the lockfile).
   */
  int
  relock(pid)
      int pid;
  {
  #ifdef LOCKLIB
      /* XXX is there a way to do this? */
      return (-1);
  #else /* LOCKLIB */
  
      int fd;
      char lock_buffer[12];
  
      if (lock_file[0] == 0)
  	return (-1);
      fd = open(lock_file, O_WRONLY, 0);
      if (fd < 0) {
  	error("Couldn't reopen lock file %s: %m", lock_file);
  	lock_file[0] = 0;
  	return (-1);
      }
  
  #ifndef LOCK_BINARY
      (void) slprintf(lock_buffer, sizeof(lock_buffer), "%10d\n", pid);
      (void) write (fd, lock_buffer, 11);
  #else
      (void) write(fd, &pid, sizeof(pid));
  #endif /* LOCK_BINARY */
      (void) close(fd);
      return (0);
  
  #endif /* LOCKLIB */
  }
  
  /*
   * unlock - remove our lockfile
   */
  void
  unlock()
  {
      if (lock_file[0]) {
  #ifdef LOCKLIB
  	(void) rmlock(lock_file, (void *) 0);
  #else
  	(void) unlink(lock_file);
  #endif
  	lock_file[0] = 0;
      }
  }
  
  const char *
  signal_name(int signum)
  {
  #if defined(SOL2) || defined(__linux__) || defined(_linux_)
      const char *cp;
  
      if ((cp = strsignal(signum)) != NULL)
  	return (cp);
  #else
      extern char *sys_siglist[];
      extern int sys_nsig;
  
      if (signum >= 0 && signum < sys_nsig && sys_siglist[signum] != NULL)
  	return (sys_siglist[signum]);
  #endif
      return ("??");
  }
  