epicsTempFile.c

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/*************************************************************************\
* Copyright (c) 2002 The University of Chicago, as Operator of Argonne
*     National Laboratory.
* Copyright (c) 2002 The Regents of the University of California, as
*     Operator of Los Alamos National Laboratory.
* EPICS BASE is distributed subject to a Software License Agreement found
* in file LICENSE that is included with this distribution.
\*************************************************************************/

/*
 *  Author: Jeff Hill
 */

#include <stdlib.h>
#include <string.h>
#include <io.h>
#include <fcntl.h>
#include <sys/stat.h>

#include "epicsTempFile.h"

/*
 * epicsTmpFile
 *
 * allow the teporary file directory to be set with the
 * TMP environment varianble
 */
LIBCOM_API FILE * epicsStdCall epicsTempFile ()
{
    char * pName = _tempnam("c:\\tmp", "epics");
    if (pName) {
        /* We use open followed by fdopen so that the _O_EXCL
         * flag can be used. This causes detection of a race
         * condition where two programs end up receiving the
         * same temporary file name.
         *
         * _O_CREAT create if non-existant
         * _O_EXCL file must not exist
         * _O_RDWR read and write the file
         * _O_TEMPORARY delete file on close
         * _O_BINARY no translation
         * _O_SHORT_LIVED avoid flush to disk
         */
        int openFlag = _O_CREAT | _O_EXCL | _O_RDWR |
            _O_SHORT_LIVED | _O_BINARY | _O_TEMPORARY;
        int fd = open(pName, openFlag, _S_IWRITE);
        FILE * pNewFile = 0;
        if (fd >=0) {
            pNewFile = _fdopen(fd, "w+b");
        }
        else {
            printf("Temporary file \"%s\" open failed because "
                "\"%s\"\n", pName, strerror(errno));
        }
        free(pName);
        return pNewFile;
    }
    return 0;
}