/* $Id$ Part of SWI-Prolog Author: Jan Wielemaker E-mail: jan@swi.psy.uva.nl WWW: http://www.swi-prolog.org Copyright (C): 1985-2004, University of Amsterdam This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA As a special exception, if you link this library with other files, compiled with a Free Software compiler, to produce an executable, this library does not by itself cause the resulting executable to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the executable file might be covered by the GNU General Public License. */ #include #include #include #ifdef __WINDOWS__ #include /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - This file provides a windows alternative to an anonymous pipe that can be waited for in the same pool as sockets using by tcp_select/3. It is a work-around that allows a socket-based server using tcp_select/3 for IO multiplexing to create an additional communication channal for controlling the server. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ #define PIPE_MAGIC 0x6b3a914cL #define ISPIPE(p) if ( p->magic != PIPE_MAGIC ) \ { errno = EINVAL; \ return -1; \ } typedef struct pipe { long magic; /* magic code */ int size; /* size of the pipe */ char *buf; /* Buffer */ int in; int out; int writers; /* write open count */ int readers; /* read open count */ int blocking; /* pipe is blocking */ CRITICAL_SECTION mutex; HANDLE event; /* signal if data is available */ } pipe; static pipe * create_pipe(int size, int blocking) { pipe *p = PL_malloc(sizeof(*p)); p->buf = PL_malloc(size); p->size = size; p->in = p->out = 0; p->readers = p->writers = 0; p->blocking = blocking; InitializeCriticalSection(&p->mutex); p->event = CreateEvent(NULL, FALSE, FALSE, NULL); p->magic = PIPE_MAGIC; return p; } static int destroy_pipe(pipe *p) { ISPIPE(p); EnterCriticalSection(&p->mutex); PL_free(p->buf); CloseHandle(p->event); LeaveCriticalSection(&p->mutex); DeleteCriticalSection(&p->mutex); p->magic = 0; PL_free(p); return 0; } static int write_pipe(pipe *pipe, char *buf, int size) { ISPIPE(pipe); EnterCriticalSection(&pipe->mutex); for(;;) { if ( pipe->in + size <= pipe->size ) { memcpy(pipe->buf+pipe->in, buf, size); pipe->in += size; SetEvent(pipe->event); LeaveCriticalSection(&pipe->mutex); return size; } if ( pipe->out > 0 ) { memmove(pipe->buf, pipe->buf+pipe->out, pipe->in - pipe->out); pipe->in -= pipe->out; pipe->out = 0; } if ( size > pipe->size ) size = pipe->size; } } /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Non-blocking read from our pipe. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ static int read_pipe(pipe *pipe, char *buf, int size) { int avail; ISPIPE(pipe); retry: EnterCriticalSection(&pipe->mutex); avail = pipe->in - pipe->out; if ( avail > 0 ) { if ( size < avail ) avail = size; memcpy(buf, pipe->buf+pipe->out, avail); pipe->out += avail; if ( pipe->in == pipe->out ) pipe->in = pipe->out = 0; LeaveCriticalSection(&pipe->mutex); return avail; } if ( pipe->writers == 0 ) { LeaveCriticalSection(&pipe->mutex); return 0; } if ( pipe->blocking ) { int rc; LeaveCriticalSection(&pipe->mutex); rc = MsgWaitForMultipleObjects(1, &pipe->event, FALSE, /* wait for either event */ INFINITE, QS_ALLINPUT); if ( rc == WAIT_OBJECT_0+1 ) /* message arrived */ { MSG msg; while( PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) ) { TranslateMessage(&msg); DispatchMessage(&msg); if ( PL_handle_signals() < 0 ) { errno = EINTR; /* exception */ return -1; } } } goto retry; } errno = EWOULDBLOCK; LeaveCriticalSection(&pipe->mutex); return -1; } static int reader_close_pipe(pipe *p) { ISPIPE(p); p->readers--; if ( p->readers <= 0 && p->writers <= 0 ) return destroy_pipe(p); return 0; } static int writer_close_pipe(pipe *p) { ISPIPE(p); p->writers--; if ( p->readers <= 0 && p->writers <= 0 ) return destroy_pipe(p); if ( p->writers <= 0 ) { SetEvent(p->event); /* Signal EOF */ } return 0; } static IOFUNCTIONS pipe_read_functions = { (Sread_function) read_pipe, (Swrite_function) write_pipe, (Sseek_function) 0, (Sclose_function) reader_close_pipe, (Scontrol_function) 0 }; static IOFUNCTIONS pipe_write_functions = { (Sread_function) read_pipe, (Swrite_function) write_pipe, (Sseek_function) 0, (Sclose_function) writer_close_pipe, (Scontrol_function) 0 }; static foreign_t tcp_pipe(term_t in, term_t out) { pipe *p = create_pipe(4096, TRUE); IOSTREAM *sin, *sout; sin = Snew(p, SIO_FBUF|SIO_INPUT|SIO_RECORDPOS, &pipe_read_functions); p->readers++; sout = Snew(p, SIO_FBUF|SIO_OUTPUT|SIO_RECORDPOS, &pipe_write_functions); p->writers++; if ( !PL_unify_stream(in, sin) || !PL_unify_stream(out, sout) ) { Sclose(sin); Sclose(sout); return FALSE; } return TRUE; } #else /*__WINDOWS__*/ static foreign_t tcp_pipe(term_t Read, term_t Write) { int fd[2]; IOSTREAM *in, *out; if ( pipe(fd) != 0 ) return pl_error("pipe", 2, NULL, ERR_ERRNO, errno, "create", "pipe", 0); in = Sfdopen(fd[0], "r"); out = Sfdopen(fd[1], "w"); if ( PL_unify_stream(Read, in) && PL_unify_stream(Write, out) ) return TRUE; Sclose(in); Sclose(out); return FALSE; } #endif /*__WINDOWS__*/ install_t install_winpipe() { PL_register_foreign("tcp_pipe", 2, tcp_pipe, 0); }