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git://sourceware.org/git/newlib-cygwin.git
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Cygwin: AF_UNIX: prepare for use of message queues
We will switch to using POSIX message queues instead of Windows pipes for data transport. In preparation for that, update the commentary in fhandler_socket_unix.cc. Also move the definition of class af_unix_pkt_hdr_t to fhandler.h and make a few minor changes.
This commit is contained in:
Ken Brown
parent
19a7e4723c
commit
90f4337ea1
@ -909,6 +909,8 @@ public:
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}
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};
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#ifdef __WITH_AF_UNIX
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/* Internal representation of shutdown states */
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enum shut_state {
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_SHUT_NONE = 0,
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@ -1007,7 +1009,31 @@ class af_unix_shmem_t
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struct ucred *peer_cred () { return &_peer_cred; }
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};
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#ifdef __WITH_AF_UNIX
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/* See the commentary in fhandler_socket_unix.cc. */
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class af_unix_pkt_hdr_t
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{
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public:
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uint16_t pckt_len; /* size of packet including header */
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bool admin_pkt : 1; /* admin packets are marked as such */
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shut_state shut_info : 2; /* _SHUT_RECV /_SHUT_SEND. */
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uint8_t name_len; /* size of name, a sockaddr_un */
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uint16_t cmsg_len; /* size of ancillary data block */
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uint16_t data_len; /* size of user data */
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af_unix_pkt_hdr_t (bool a, shut_state s, uint8_t n, uint16_t c, uint16_t d)
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{ init (a, s, n, c, d); }
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void init (bool a, shut_state s, uint8_t n, uint16_t c, uint16_t d)
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{
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admin_pkt = a;
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shut_info = s;
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name_len = n;
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cmsg_len = c;
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data_len = d;
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pckt_len = sizeof (*this) + name_len + cmsg_len + data_len;
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}
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};
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#define MAX_AF_UN_PKT_LEN UINT16_MAX
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class fhandler_socket_unix : public fhandler_socket
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{
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@ -1064,7 +1090,7 @@ class fhandler_socket_unix : public fhandler_socket
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wchar_t get_type_char ();
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void set_pipe_non_blocking (bool nonblocking);
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int send_sock_info (bool from_bind);
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int grab_admin_pkg ();
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int grab_admin_pkt ();
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int recv_peer_info ();
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static NTSTATUS npfs_handle (HANDLE &nph);
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HANDLE create_pipe (bool single_instance);
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@ -27,6 +27,7 @@ GUID __cygwin_socket_guid = {
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#include <sys/param.h>
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#include <sys/statvfs.h>
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#include <cygwin/acl.h>
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#include <mqueue.h>
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#include "cygerrno.h"
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#include "path.h"
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#include "fhandler.h"
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@ -38,6 +39,14 @@ GUID __cygwin_socket_guid = {
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#include "tls_pbuf.h"
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/*
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Message queue:
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A socket that wants to read creates a POSIX message queue. The
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name of the mqueue is "/af-unix-[sd]-<uniq_id>".
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- [sd] is s for SOCK_STREAM, d for SOCK_DGRAM
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- <uniq_id> is an 8 byte hex unique number
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Abstract socket:
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An abstract socket is represented by a symlink in the native
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@ -50,24 +59,16 @@ GUID __cygwin_socket_guid = {
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<sun_path> is the transposed sun_path string, including the leading
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NUL. The transposition is simplified in that it uses every byte
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in the valid sun_path name as is, no extra multibyte conversion.
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The content of the symlink is the basename of the underlying pipe.
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The content of the symlink is the name of the underlying mqueue.
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Named socket:
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A named socket is represented by a reparse point with a Cygwin-specific
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tag and GUID. The GenericReparseBuffer content is the basename of the
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underlying pipe.
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Pipe:
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The pipe is named \\.\pipe\cygwin-<installation_key>-unix-[sd]-<uniq_id>
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- <installation_key> is the 8 byte hex Cygwin installation key
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- [sd] is s for SOCK_STREAM, d for SOCK_DGRAM
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- <uniq_id> is an 8 byte hex unique number
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tag and GUID. The GenericReparseBuffer content is the name of the
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underlying mqueue.
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Note: We use MAX_PATH below for convenience where sufficient. It's
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big enough to hold sun_paths as well as pipe names as well as packet
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big enough to hold sun_paths as well as mqueue names as well as packet
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headers etc., so we don't have to use tmp_pathbuf as often.
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Every packet sent to a peer is a combination of the socket name of the
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@ -76,37 +77,13 @@ GUID __cygwin_socket_guid = {
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for the entire packet, as well as for all three data blocks. The
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combined maximum size of a packet is 64K, including the header.
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A connecting, bound STREAM socket sends it's local sun_path once after
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A connecting, bound STREAM socket sends its local sun_path once after
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a successful connect. An already connected socket also sends its local
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sun_path after a successful bind (border case, but still...). These
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packages don't contain any other data (cmsg_len == 0, data_len == 0).
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packets don't contain any other data (cmsg_len == 0, data_len == 0).
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A bound DGRAM socket sends its sun_path with each sendmsg/sendto.
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*/
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class af_unix_pkt_hdr_t
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{
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public:
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uint16_t pckt_len; /* size of packet including header */
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bool admin_pkg : 1; /* admin packets are marked as such */
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shut_state shut_info : 2; /* _SHUT_RECV /_SHUT_SEND. */
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uint8_t name_len; /* size of name, a sockaddr_un */
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uint16_t cmsg_len; /* size of ancillary data block */
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uint16_t data_len; /* size of user data */
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af_unix_pkt_hdr_t (bool a, shut_state s, uint8_t n, uint16_t c, uint16_t d)
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{ init (a, s, n, c, d); }
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void init (bool a, shut_state s, uint8_t n, uint16_t c, uint16_t d)
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{
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admin_pkg = a;
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shut_info = s;
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name_len = n;
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cmsg_len = c;
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data_len = d;
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pckt_len = sizeof (*this) + name_len + cmsg_len + data_len;
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}
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};
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#define MAX_AF_UN_PKT_LEN UINT16_MAX
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static inline ptrdiff_t
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AF_UNIX_PKT_OFFSETOF_NAME (af_unix_pkt_hdr_t *phdr)
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@ -276,7 +253,13 @@ fhandler_socket_unix::reopen_shmem ()
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#define CYGWIN_PIPE_SOCKET_NAME_LEN 47
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/* Character position encoding the socket type in a pipe name. */
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#define CYGWIN_PIPE_SOCKET_TYPE_POS 29
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#define CYGWIN_PIPE_SOCKET_TYPE_POS 29
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/* Character length of mqueue name, excluding trailing NUL. */
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#define CYGWIN_MQUEUE_SOCKET_NAME_LEN 27
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/* Character position encoding the socket type in an mqueue name. */
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#define CYGWIN_MQUEUE_SOCKET_TYPE_POS 9
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void
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fhandler_socket_unix::gen_pipe_name ()
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@ -709,7 +692,7 @@ fhandler_socket_unix::send_sock_info (bool from_bind)
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/* Checks if the next packet in the pipe is an administrative packet.
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If so, it reads it from the pipe, handles it. Returns an error code. */
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int
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fhandler_socket_unix::grab_admin_pkg ()
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fhandler_socket_unix::grab_admin_pkt ()
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{
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HANDLE evt;
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NTSTATUS status;
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@ -727,7 +710,7 @@ fhandler_socket_unix::grab_admin_pkg ()
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return 0;
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}
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af_unix_pkt_hdr_t *packet = (af_unix_pkt_hdr_t *) pbuf->Data;
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if (!packet->admin_pkg)
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if (!packet->admin_pkt)
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io_unlock ();
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else
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{
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