sendfile() fails with regular files on RHEL5.10
 

Hello All,

I am executing following program on RHEL5.10, sendfile() is failing with errno:22

uname -rvio
2.6.18-366.el5 #1 SMP Fri Jul 19 13:36:15 EDT 2013 ppc64 GNU/Linux

#include <sys/sendfile.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

int main( int argc, char *argv[] )
{
int in_file, out_file;

if ( argc != 3 )
{
fprintf( stderr, "usage: %s <in-file> <out-file>\n", argv[0] );
exit( 1 );
}

if (( in_file = open( argv[1], O_RDONLY )) == -1 ) err( 1, "open" );
if (( out_file = open( argv[2], O_WRONLY | O_CREAT | O_TRUNC, 0644 )) == -1 )
err( 1, "open(2)" );

if ( sendfile( out_file, in_file, NULL, 4 ) == -1 ) err( 1, "sendfile" );

exit( 0 );
}


Here sendfile fails with : EINVAL

> part of strace output:
----------------------------------------------------------------------
open("input_file", O_RDONLY) = 3
open("output_file", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 4
sendfile(4, 3, NULL, 4) = -1 EINVAL (Invalid argument)
-----------------------------------------------------------------------

Please, let me know if sendfile() supports regular files on "2.6.18-366.el5"

Thanks in advance :)

Do you have permissions to the files that you are giving as arguments?

For what it's worth, I copied your code and compiled it, and it worked for me. I created in.txt, and out.txt, and ran the program with those 2 files as arguments, and here is the last portion of strace:

...
open("in.txt", O_RDONLY) = 3
open("out.txt", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 4
sendfile(4, 3, NULL, 4) = 4
exit_group(0) = ?

However, I am running kernel 2.6.38-8-generic #42-Ubuntu SMP x86_64

The man page for sendfile says about the error code EINVAL: Descriptor is not valid or locked, or an mmap(2)-like operation is not available for in_fd.

You can find other info about it in the man page that may be useful for your particular files.

Hi,

Thanks for quick reply ...

The input and output files have read/write permissions.

I tested code on "3.0.80-0.7-ppc64 #1 SMP Tue Jun 25 18:32:49 UTC 2013 (25740f8) ppc64 GNU/Linux" and test passes.

I am seeing the issue only : "Linux 2.6.18-366.el5 #1 SMP Fri Jul 19 13:36:15 EDT 2013 ppc64 ppc64 ppc64 GNU/Linux"

Regarding man page: There is a reference to kernel release -
---------------------
Presently (Linux 2.6.9): in_fd, must correspond to a file which supports mmap(2)-like operations (i.e., it cannot be a socket); and out_fd must refer to a socket.
---------------------

Following link also mentions "sendfile()" supports regular file only after "since Linux 2.6.33".
Link: http://marc.info/?l=linux-man&m=129767829918385

So want to know if sendfile() supports regular file for "fd_out".