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Subject[PATCH] posix_fadvise bug (unexpected success on FIFO/pipe)
Hello, all.
I have the following problem with posix_fadvise :
the system call succeeds on a pipe or FIFO, although it has to fail with
ESPIPE (EINVAL on linux) return value.
Looks like a kernel bug.
I've attached a small test for posix_fadvise and a patch for linux
kernel 2.6.14 that fixes the problem.
The patch makes posix_fadvise return ESPIPE on FIFO/pipe in order to be
fully POSIX-compliant.
Please, take a look at these.
Thanks.
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>

int main()
{
int retval, fd;

if (mkfifo("fifo", 0666) < 0) {
printf("create fifo error\n");
return 1;
}

fd = open("fifo", O_RDWR);
if (fd < 0) {
printf("open fifo error\n");
remove("fifo");
return 1;
}

retval = posix_fadvise(fd, 0, 0, POSIX_FADV_NORMAL);
if (retval) {
printf("Expected fail - The fd argument is associated with a pipe or FIFO.\n");
if (retval != ESPIPE)
printf("Unexpected ERRNO %d (Expected %d)\n", retval, ESPIPE);
} else
printf("Unexpected success - The fd argument is associated with a pipe or FIFO.\n");

close(fd);
remove("fifo");

if (retval)
return 0;
return 1;
}
--- a/mm/fadvise.c 2005-10-10 22:54:29.000000000 +0400
+++ b/mm/fadvise.c 2005-12-06 23:04:19.980711464 +0300
@@ -37,6 +37,11 @@
if (!file)
return -EBADF;

+ if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) {
+ ret = -ESPIPE;
+ goto out;
+ }
+
mapping = file->f_mapping;
if (!mapping || len < 0) {
ret = -EINVAL;
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