sendfile(2) behaviour has changed ?

[Zilvinas Valinskas <zilvinas@gemtek.lt>]

[-- Attachment #1: Type: text/plain, Size: 470 bytes --]

This sample code copies a file using sendfile(2) call works just fine on 
2.2.x and 2.4.x kernels. On 2.5.x kernels (not sure starting which
version) it stopped working. Program terminates with EINVAL error. 

$ ./sendfile
sendfile: Invalid argument

Is this expected behaviour ? that sendfile(2) on 2.5.4x linux kernel requires
socket as an output fd paramter ? 

Was it ever legal to copy file(s) on filesystem using sendfile(2) ?
(which was kindda nice feature ... )

[-- Attachment #2: sendfile.c --]
[-- Type: text/x-csrc, Size: 642 bytes --]

#include <sys/sendfile.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

int main() 
{
	int fd_in  = 0;
	int fd_out = 0;
	struct stat stat_buf;
	off_t  offset = 0;
	ssize_t count = 0;

	if ((fd_in=open("sendfile.c",O_RDONLY))<0)
	{
		perror("open");
		exit(1);
	}
	if ((fd_out=open("sendfile.out",O_CREAT|O_TRUNC|O_WRONLY,S_IRWXU))<0)
	{
		perror("open");
		exit(1);
	}

	if (fstat(fd_in,&stat_buf)) {
		perror("fstat");
	}


	count = sendfile(fd_out,fd_in,&offset,stat_buf.st_size);

	if (count < 0)
		perror("sendfile");
	
	if (close(fd_in) < 0)
		perror("close");
	if (close(fd_out) < 0)
		perror("close");
	return 0;
}