Messages in this thread | | | Date | Wed, 12 Feb 2003 15:38:46 -0800 | From | Chris Wedgwood <> | Subject | Re: O_DIRECT foolish question |
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On Wed, Feb 12, 2003 at 06:33:23PM -0500, Bruno Diniz de Paula wrote:
> But your code doesn't use O_DIRECT:
Sorry, you need to edit it (see my previous email). A better version (appended) gives the following results.
cw:3@tapu(cw)$ cp od.c test cw:3@tapu(cw)$ gcc -Wall od.c cw:3@tapu(cw)$ ./a.out read 503 bytes read 0 bytes
> Let me know whether including O_DIRECT the test worked.
Seems to. I get 0 the 2nd time about, presumably this is EOF but arguably it should return something else.
--cw
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <stdlib.h> #include <stdio.h>
int main() { int h; int ps; char *buf; ssize_t n;
ps = getpagesize(); if (!(buf = valloc(ps))) return 1; if ((h = open("test", O_RDONLY|O_DIRECT)) < 0) return 1; do { n = read(h, buf, ps); if (n == -1) { perror("read"); break; } printf("read %d bytes\n", n); } while(n);
close(h);
return 0; }
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