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Cygwin: AF_UNIX: grab_admin_pkg: refactor

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Extract from grab_admin_pkg two new methods, record_shut_info and
process_admin_pkg.  Also add a new 'peek' argument to grab_admin_pkg.
If this is true, peek to see if the next packet in the pipe is an
administrative packet.  Otherwise, assume we already know it is.
This commit is contained in:
Ken Brown 2020-10-19 09:52:51 -04:00
parent c60fcf1116
commit 99490d2825
2 changed files with 79 additions and 59 deletions
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4
winsup/cygwin/fhandler.h
View File

@ -1055,7 +1055,9 @@ class fhandler_socket_unix : public fhandler_socket
wchar_t get_type_char ();
void set_pipe_non_blocking (bool nonblocking);
int send_sock_info (bool from_bind);
int grab_admin_pkg ();
void record_shut_info (af_unix_pkt_hdr_t *packet);
void process_admin_pkt (af_unix_pkt_hdr_t *packet);
int grab_admin_pkt (bool peek = true);
int recv_peer_info ();
static NTSTATUS npfs_handle (HANDLE &nph);
HANDLE create_pipe (bool single_instance);

134
winsup/cygwin/fhandler_socket_unix.cc
View File

@ -76,10 +76,10 @@ GUID __cygwin_socket_guid = {
for the entire packet, as well as for all three data blocks. The
combined maximum size of a packet is 64K, including the header.
A connecting, bound STREAM socket sends it's local sun_path once after
A connecting, bound STREAM socket sends its local sun_path once after
a successful connect. An already connected socket also sends its local
sun_path after a successful bind (border case, but still...). These
packages don't contain any other data (cmsg_len == 0, data_len == 0).
packets don't contain any other data (cmsg_len == 0, data_len == 0).
A bound DGRAM socket sends its sun_path with each sendmsg/sendto.
*/
@ -90,7 +90,7 @@ class af_unix_pkt_hdr_t
{
public:
uint16_t pckt_len; /* size of packet including header */
bool admin_pkg : 1; /* admin packets are marked as such */
bool admin_pkt : 1; /* admin packets are marked as such */
shut_state shut_info : 2; /* _SHUT_RECV /_SHUT_SEND. */
uint8_t name_len; /* size of name, a sockaddr_un */
uint16_t cmsg_len; /* size of ancillary data block */
@ -100,7 +100,7 @@ class af_unix_pkt_hdr_t
{ init (a, s, n, c, d); }
void init (bool a, shut_state s, uint8_t n, uint16_t c, uint16_t d)
{
admin_pkg = a;
admin_pkt = a;
shut_info = s;
name_len = n;
cmsg_len = c;
@ -710,73 +710,91 @@ fhandler_socket_unix::send_sock_info (bool from_bind)
return 0;
}
/* Checks if the next packet in the pipe is an administrative packet.
If so, it reads it from the pipe, handles it. Returns an error code. */
void
fhandler_socket_unix::record_shut_info (af_unix_pkt_hdr_t *packet)
{
if (packet->shut_info)
{
state_lock ();
/* Peer's shutdown sends the SHUT flags as used by the peer.
They have to be reversed for our side. */
int shut_info = saw_shutdown ();
if (packet->shut_info & _SHUT_RECV)
shut_info |= _SHUT_SEND;
if (packet->shut_info & _SHUT_SEND)
shut_info |= _SHUT_RECV;
saw_shutdown (shut_info);
/* FIXME: anything else here? */
state_unlock ();
}
}
void
fhandler_socket_unix::process_admin_pkt (af_unix_pkt_hdr_t *packet)
{
record_shut_info (packet);
state_lock ();
if (packet->name_len > 0)
peer_sun_path (AF_UNIX_PKT_NAME (packet), packet->name_len);
if (packet->cmsg_len > 0)
{
struct cmsghdr *cmsg = (struct cmsghdr *)
alloca (packet->cmsg_len);
memcpy (cmsg, AF_UNIX_PKT_CMSG (packet), packet->cmsg_len);
if (cmsg->cmsg_level == SOL_SOCKET
&& cmsg->cmsg_type == SCM_CREDENTIALS)
peer_cred ((struct ucred *) CMSG_DATA(cmsg));
}
state_unlock ();
}
/* Reads an administrative packet from the pipe and handles it. If
PEEK is true, checks first to see if the next packet in the pipe is
an administrative packet; otherwise the caller must check this.
Returns an error code.
FIXME: Currently we always return 0, and no callers check for error. */
int
fhandler_socket_unix::grab_admin_pkg ()
fhandler_socket_unix::grab_admin_pkt (bool peek)
{
HANDLE evt;
NTSTATUS status;
IO_STATUS_BLOCK io;
/* MAX_PATH is more than sufficient for admin packets. */
PFILE_PIPE_PEEK_BUFFER pbuf = (PFILE_PIPE_PEEK_BUFFER) alloca (MAX_PATH);
void *buffer = alloca (MAX_PATH);
af_unix_pkt_hdr_t *packet;
if (!(evt = create_event ()))
return 0;
io_lock ();
ULONG ret_len;
status = peek_pipe (pbuf, MAX_PATH, evt, ret_len);
/* FIXME: Check status and handle error. */
if (pbuf->NumberOfMessages == 0 || ret_len < sizeof (af_unix_pkt_hdr_t))
if (peek)
{
PFILE_PIPE_PEEK_BUFFER pbuf = (PFILE_PIPE_PEEK_BUFFER) buffer;
io_lock ();
ULONG ret_len;
status = peek_pipe (pbuf, MAX_PATH, evt, ret_len);
/* FIXME: Check status and handle error? */
io_unlock ();
NtClose (evt);
return 0;
packet = (af_unix_pkt_hdr_t *) pbuf->Data;
if (pbuf->NumberOfMessages == 0 || ret_len < sizeof (af_unix_pkt_hdr_t)
|| !packet->admin_pkt)
goto out;
}
af_unix_pkt_hdr_t *packet = (af_unix_pkt_hdr_t *) pbuf->Data;
if (!packet->admin_pkg)
io_unlock ();
else
packet = (af_unix_pkt_hdr_t *) buffer;
io_lock ();
status = NtReadFile (get_handle (), evt, NULL, NULL, &io, packet,
MAX_PATH, NULL, NULL);
if (status == STATUS_PENDING)
{
packet = (af_unix_pkt_hdr_t *) pbuf;
status = NtReadFile (get_handle (), evt, NULL, NULL, &io, packet,
MAX_PATH, NULL, NULL);
if (status == STATUS_PENDING)
{
/* Very short-lived */
status = NtWaitForSingleObject (evt, FALSE, NULL);
if (NT_SUCCESS (status))
status = io.Status;
}
io_unlock ();
/* Very short-lived */
status = NtWaitForSingleObject (evt, FALSE, NULL);
if (NT_SUCCESS (status))
{
state_lock ();
if (packet->shut_info)
{
/* Peer's shutdown sends the SHUT flags as used by the peer.
They have to be reversed for our side. */
int shut_info = saw_shutdown ();
if (packet->shut_info & _SHUT_RECV)
shut_info |= _SHUT_SEND;
if (packet->shut_info & _SHUT_SEND)
shut_info |= _SHUT_RECV;
saw_shutdown (shut_info);
/* FIXME: anything else here? */
}
if (packet->name_len > 0)
peer_sun_path (AF_UNIX_PKT_NAME (packet), packet->name_len);
if (packet->cmsg_len > 0)
{
struct cmsghdr *cmsg = (struct cmsghdr *)
alloca (packet->cmsg_len);
memcpy (cmsg, AF_UNIX_PKT_CMSG (packet), packet->cmsg_len);
if (cmsg->cmsg_level == SOL_SOCKET
&& cmsg->cmsg_type == SCM_CREDENTIALS)
peer_cred ((struct ucred *) CMSG_DATA(cmsg));
}
state_unlock ();
}
status = io.Status;
}
io_unlock ();
if (NT_SUCCESS (status))
process_admin_pkt (packet);
out:
NtClose (evt);
return 0;
}
@ -1848,7 +1866,7 @@ fhandler_socket_unix::shutdown (int how)
{
/* Send shutdown info to peer. Note that it's not necessarily fatal
if the info isn't sent here. The info will be reproduced by any
followup package sent to the peer. */
followup packet sent to the peer. */
af_unix_pkt_hdr_t packet (true, (shut_state) new_shutdown_mask, 0, 0, 0);
io_lock ();
set_pipe_non_blocking (true);
@ -1936,7 +1954,7 @@ fhandler_socket_unix::evaluate_cmsg_data (af_unix_pkt_hdr_t *packet,
return true;
}
/* FIXME: Should recvmsg call grab_admin_pkg at appropriate places to
/* FIXME: Should recvmsg call grab_admin_pkt at appropriate places to
check whether peer has called shutdown? */
ssize_t
fhandler_socket_unix::recvmsg (struct msghdr *msg, int flags)