Hi,
I run:
Linux nice 2.4.18-pre7 #1 SMP Mon Jan 28 23:12:48 MET 2002 i686 unknown
I noticed that whenever I do:
setsockopt(fd, SOL_SOCKET, SO_SNDBUF....)
followed by
getsockopt(fd, SOL_SOCKET, SO_SNDBUF....)
to verify what the kernel has set, I read TWICE as much the amount used
for the set. That is, if I set 8192, I read 16384. Therefore, to set
the correct size, I need to half the parameter first.
Is this a known bug? Is it setsockopt or getsockopt which returns the
wrong size?
Here's sample code demonstrating the problem:
--------------------------
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
static void set_send_buf(int fd, int size)
{
int new_len;
int arglen = sizeof(new_len);
if (-1 == setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &size, sizeof(size)))
perror("setsockopt");
if (-1 == getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &new_len, &arglen))
perror("getsockopt");
printf("size was %d, but set %d\n", size, new_len);
}
main()
{
int fd = socket(AF_INET, SOCK_STREAM, 0);
set_send_buf(fd, 8192);
set_send_buf(fd, 16384);
}
--------------------------
When run, it displays:
size was 8192, but set 16384
size was 16384, but set 32768
Raphael
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This archive was generated by hypermail 2b29 : Thu Feb 28 2002 - 21:00:18 EST