fopen_uniq.c

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/*                    F O P E N _ U N I Q . C
 * BRL-CAD
 *
 * Copyright (c) 2001-2006 United States Government as represented by
 * the U.S. Army Research Laboratory.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * as published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this file; see the file named COPYING for more
 * information.
 */

/** \addtogroup bu_log */
/*@{*/
/** @file fopen_uniq.c
 *
 * @brief Routine to open a unique filename.
 *
 *  @author Lee A. Butler
 *
 *  @par Source
 *      SECAD/VLD Computing Consortium, Bldg 394        @n
 *      The U. S. Army Ballistic Research Laboratory    @n
 *      Aberdeen Proving Ground, Maryland  21005
 *
 */

#include "common.h"

#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>     /* for strerror() */
#ifdef HAVE_SYS_PARAM_H
#  include <sys/param.h>
#endif
#include <ctype.h>
#include <math.h>
#ifdef HAVE_STRING_H
#  include <string.h>
#else
#  include <strings.h>
#endif

#include "machine.h"
#include "bu.h"

/**
 *  B U _ F O P E N _ U N I Q
 *@brief
 *  Open a file for output.  Assures that the file did not previously exist.
 *
 *  Typical Usages:
@code
 *      static int n = 0;
 *      FILE *fp;
 *
 *      fp = bu_fopen_uniq("writing to %s for results", "output%d.pl", n++);
 *      ...
 *      fclose(fp);
 *
 *
 *      fp = bu_fopen_uniq((char *)NULL, "output%d.pl", n++);
 *      ...
 *      fclose(fp);
@endcode
 */
FILE *
bu_fopen_uniq(const char *outfmt, const char *namefmt, int n)
{
    char filename[MAXPATHLEN];
    int fd;
    FILE *fp;

    if ( ! namefmt || ! *namefmt)
        bu_bomb("bu_uniq_file called with null string\n");

    bu_semaphore_acquire( BU_SEM_SYSCALL);
    sprintf(filename, namefmt, n);
    if ((fd = open(filename, O_RDWR|O_CREAT|O_EXCL, 0600)) < 0) {
        fprintf(stderr, "Cannot open %s, %s\n", filename, strerror(errno));
        exit(-1);
    }
    if ( (fp=fdopen(fd, "w")) == (FILE *)NULL) {
        fprintf(stderr, strerror(errno));
        exit(-1);
    }

    if (outfmt)
        fprintf(stderr, outfmt, filename);

    bu_semaphore_release( BU_SEM_SYSCALL);

    return fp;
}
/*@}*/

/*
 * Local Variables:
 * mode: C
 * tab-width: 8
 * c-basic-offset: 4
 * indent-tabs-mode: t
 * End:
 * ex: shiftwidth=4 tabstop=8
 */

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