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[Bug libc/19557] recvmsg fails retrieving SCM_CREDENTIALS with error EOPNOTSUPP
- From: "alan.griffiths at canonical dot com" <sourceware-bugzilla at sourceware dot org>
- To: glibc-bugs at sourceware dot org
- Date: Wed, 03 Feb 2016 10:08:17 +0000
- Subject: [Bug libc/19557] recvmsg fails retrieving SCM_CREDENTIALS with error EOPNOTSUPP
- Auto-submitted: auto-generated
- References: <bug-19557-131 at http dot sourceware dot org/bugzilla/>
https://sourceware.org/bugzilla/show_bug.cgi?id=19557
--- Comment #2 from Alan Griffiths <alan.griffiths at canonical dot com> ---
Additional information: this happens with the latest Xenial 4.4.0-2-generic
kernel, but not with the previous 4.3.0-7-generic kernel.
Revised test case:
#include <stdlib.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
int main()
{
enum { server, client, size };
int socket_fd[size];
int const opt = 1;
assert(socketpair(AF_LOCAL, SOCK_STREAM, 0, socket_fd) == 0);
char const msg[] = "A random message";
send(socket_fd[client], msg, sizeof msg, MSG_DONTWAIT | MSG_NOSIGNAL);
assert(setsockopt(socket_fd[server], SOL_SOCKET, SO_PASSCRED, &opt,
sizeof(opt)) != -1);
union {
struct cmsghdr cmh;
char control[CMSG_SPACE(sizeof(ucred))];
} control_un;
control_un.cmh.cmsg_len = CMSG_LEN(sizeof(ucred));
control_un.cmh.cmsg_level = SOL_SOCKET;
control_un.cmh.cmsg_type = SCM_CREDENTIALS;
msghdr msgh;
msgh.msg_name = NULL;
msgh.msg_namelen = 0;
msgh.msg_iov = NULL;
msgh.msg_iovlen = 0;
msgh.msg_control = control_un.control;
msgh.msg_controllen = sizeof(control_un.control);
errno = 0;
if (recvmsg(socket_fd[server], &msgh, MSG_PEEK) == -1)
{
printf("Error: %s\n", strerror(errno));
exit(EXIT_FAILURE);
}
else
{
printf("Success!\n");
exit(EXIT_FAILURE);
}
}
Expected:
$ g++ test.c -o test && ./test
Success!
Actual:
$ g++ test.c -o test && ./test
Error: Operation not supported
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