©2004 by Marc J. Rochkind. All rights reserved. Portions marked "Open Source" may be copied under license.

 

                 

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c2/syncio.c

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/*
    Synchronized I/O test program
    AUP2, Sec. 2.16.2 (not in book)

    Copyright 2003 by Marc J. Rochkind. All rights reserved.
    May be copied only for purposes and under conditions described
    on the Web page www.basepath.com/aup/copyright.htm.

    The Example Files are provided "as is," without any warranty;
    without even the implied warranty of merchantability or fitness
    for a particular purpose. The author and his publisher are not
    responsible for any damages, direct or incidental, resulting
    from the use or non-use of these Example Files.

    The Example Files may contain defects, and some contain deliberate
    coding mistakes that were included for educational reasons.
    You are responsible for determining if and how the Example Files
    are to be used.

*/
#include "defs.h"

#define NUM_WRITES 250

int main(void)
{
    int try, fd, i;
    char buf[512], *caption;

#ifdef _POSIX_SYNCHRONIZED_IO
    printf("_POSIX_SYNCHRONIZED_IO is defined\n");
#else
    printf("_POSIX_SYNCHRONIZED_IO is undefined\n");
#endif

    memset(buf, 0, sizeof(buf));

    for (try = 0; try < 4; try++) {
        if ((fd = creat("a.tmp", PERM_FILE)) == -1)
            syserr("creat");
        timestart();
        for (i = 0; i < NUM_WRITES; i++) {
            if (write(fd, buf, sizeof(buf)) == -1)
                syserr("write");
            switch (try) {
            case 0:
                caption = "normal";
                break;
            case 1:
                sync();
                caption = "sync";
                break;
            case 2:
#if defined(_POSIX_SYNCHRONIZED_IO) || defined(FREEBSD)
                fsync(fd);
                caption = "fsync";
#else
                sync();
                caption = "fsync not defined; using sync";
#endif
                break;
            case 3:
#if defined(_POSIX_SYNCHRONIZED_IO)
                fdatasync(fd);
                caption = "fdatasync";
#else
                sync();
                caption = "fdatasync not defined; using sync";
#endif
            }
        }
        timestop(caption);
        if (close(fd) == -1)
            syserr("close");
    }

    exit(EXIT_SUCCESS);
}

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