kc3-lang/libbsd/src/flopen.c

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• Hash : 98a2479f
  Author :
  Date : 2010-01-09T23:49:32
  

  Add flopen function
  
  Taken from FreeBSD.
  

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• src/flopen.c

• /*-
   * Copyright (c) 2007 Dag-Erling Coïdan Smørgrav
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer
   *    in this position and unchanged.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  #include <sys/file.h>
  #include <sys/stat.h>
  
  #include <errno.h>
  #include <stdarg.h>
  #include <unistd.h>
  
  #include <libutil.h>
  
  int
  flopen(const char *path, int flags, ...)
  {
  	int fd, operation, serrno, trunc;
  	struct stat sb, fsb;
  	mode_t mode;
  
  #ifdef O_EXLOCK
  	flags &= ~O_EXLOCK;
  #endif
  
  	mode = 0;
  	if (flags & O_CREAT) {
  		va_list ap;
  
  		va_start(ap, flags);
  		mode = (mode_t)va_arg(ap, int); /* mode_t promoted to int */
  		va_end(ap);
  	}
  
          operation = LOCK_EX;
          if (flags & O_NONBLOCK)
                  operation |= LOCK_NB;
  
  	trunc = (flags & O_TRUNC);
  	flags &= ~O_TRUNC;
  
  	for (;;) {
  		if ((fd = open(path, flags, mode)) == -1)
  			/* non-existent or no access */
  			return (-1);
  		if (flock(fd, operation) == -1) {
  			/* unsupported or interrupted */
  			serrno = errno;
  			(void)close(fd);
  			errno = serrno;
  			return (-1);
  		}
  		if (stat(path, &sb) == -1) {
  			/* disappeared from under our feet */
  			(void)close(fd);
  			continue;
  		}
  		if (fstat(fd, &fsb) == -1) {
  			/* can't happen [tm] */
  			serrno = errno;
  			(void)close(fd);
  			errno = serrno;
  			return (-1);
  		}
  		if (sb.st_dev != fsb.st_dev ||
  		    sb.st_ino != fsb.st_ino) {
  			/* changed under our feet */
  			(void)close(fd);
  			continue;
  		}
  		if (trunc && ftruncate(fd, 0) != 0) {
  			/* can't happen [tm] */
  			serrno = errno;
  			(void)close(fd);
  			errno = serrno;
  			return (-1);
  		}
  		return (fd);
  	}
  }
  

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