xcb_conn.c revision 21298544 
1/* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a
4 * copy of this software and associated documentation files (the "Software"),
5 * to deal in the Software without restriction, including without limitation
6 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
7 * and/or sell copies of the Software, and to permit persons to whom the
8 * Software is furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
17 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
18 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
19 *
20 * Except as contained in this notice, the names of the authors or their
21 * institutions shall not be used in advertising or otherwise to promote the
22 * sale, use or other dealings in this Software without prior written
23 * authorization from the authors.
24 */
25
26/* Connection management: the core of XCB. */
27
28#ifdef HAVE_CONFIG_H
29#include "config.h"
30#endif
31
32#include <assert.h>
33#include <string.h>
34#include <stdio.h>
35#include <unistd.h>
36#include <stdlib.h>
37#include <fcntl.h>
38#include <errno.h>
39#include <limits.h>
40
41#include "xcb.h"
42#include "xcbint.h"
43#if USE_POLL
44#include <poll.h>
45#elif !defined _WIN32
46#include <sys/select.h>
47#endif
48
49#ifdef _WIN32
50#include "xcb_windefs.h"
51#else
52#include <sys/socket.h>
53#include <netinet/in.h>
54#endif /* _WIN32 */
55
56/* SHUT_RDWR is fairly recent and is not available on all platforms */
57#if !defined(SHUT_RDWR)
58#define SHUT_RDWR 2
59#endif
60
61typedef struct {
62    uint8_t  status;
63    uint8_t  pad0[5];
64    uint16_t length;
65} xcb_setup_generic_t;
66
67static const int xcb_con_error = XCB_CONN_ERROR;
68static const int xcb_con_closed_mem_er = XCB_CONN_CLOSED_MEM_INSUFFICIENT;
69static const int xcb_con_closed_parse_er = XCB_CONN_CLOSED_PARSE_ERR;
70static const int xcb_con_closed_screen_er = XCB_CONN_CLOSED_INVALID_SCREEN;
71
72static int set_fd_flags(const int fd)
73{
74/* Win32 doesn't have file descriptors and the fcntl function. This block sets the socket in non-blocking mode */
75
76#ifdef _WIN32
77   u_long iMode = 1; /* non-zero puts it in non-blocking mode, 0 in blocking mode */
78   int ret = 0;
79
80   ret = ioctlsocket(fd, FIONBIO, &iMode);
81   if(ret != 0)
82       return 0;
83   return 1;
84#else
85    int flags = fcntl(fd, F_GETFL, 0);
86    if(flags == -1)
87        return 0;
88    flags |= O_NONBLOCK;
89    if(fcntl(fd, F_SETFL, flags) == -1)
90        return 0;
91    if(fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
92        return 0;
93    return 1;
94#endif /* _WIN32 */
95}
96
97static int write_setup(xcb_connection_t *c, xcb_auth_info_t *auth_info)
98{
99    static const char pad[3];
100    xcb_setup_request_t out;
101    struct iovec parts[6];
102    int count = 0;
103    static const uint32_t endian = 0x01020304;
104    int ret;
105
106    memset(&out, 0, sizeof(out));
107
108    /* B = 0x42 = MSB first, l = 0x6c = LSB first */
109    if(htonl(endian) == endian)
110        out.byte_order = 0x42;
111    else
112        out.byte_order = 0x6c;
113    out.protocol_major_version = X_PROTOCOL;
114    out.protocol_minor_version = X_PROTOCOL_REVISION;
115    out.authorization_protocol_name_len = 0;
116    out.authorization_protocol_data_len = 0;
117    parts[count].iov_len = sizeof(xcb_setup_request_t);
118    parts[count++].iov_base = &out;
119    parts[count].iov_len = XCB_PAD(sizeof(xcb_setup_request_t));
120    parts[count++].iov_base = (char *) pad;
121
122    if(auth_info)
123    {
124        parts[count].iov_len = out.authorization_protocol_name_len = auth_info->namelen;
125        parts[count++].iov_base = auth_info->name;
126        parts[count].iov_len = XCB_PAD(out.authorization_protocol_name_len);
127        parts[count++].iov_base = (char *) pad;
128        parts[count].iov_len = out.authorization_protocol_data_len = auth_info->datalen;
129        parts[count++].iov_base = auth_info->data;
130        parts[count].iov_len = XCB_PAD(out.authorization_protocol_data_len);
131        parts[count++].iov_base = (char *) pad;
132    }
133    assert(count <= (int) (sizeof(parts) / sizeof(*parts)));
134
135    pthread_mutex_lock(&c->iolock);
136    ret = _xcb_out_send(c, parts, count);
137    pthread_mutex_unlock(&c->iolock);
138    return ret;
139}
140
141static int read_setup(xcb_connection_t *c)
142{
143    /* Read the server response */
144    c->setup = malloc(sizeof(xcb_setup_generic_t));
145    if(!c->setup)
146        return 0;
147
148    if(_xcb_in_read_block(c, c->setup, sizeof(xcb_setup_generic_t)) != sizeof(xcb_setup_generic_t))
149        return 0;
150
151    {
152        void *tmp = realloc(c->setup, c->setup->length * 4 + sizeof(xcb_setup_generic_t));
153        if(!tmp)
154            return 0;
155        c->setup = tmp;
156    }
157
158    if(_xcb_in_read_block(c, (char *) c->setup + sizeof(xcb_setup_generic_t), c->setup->length * 4) <= 0)
159        return 0;
160
161    /* 0 = failed, 2 = authenticate, 1 = success */
162    switch(c->setup->status)
163    {
164    case 0: /* failed */
165        {
166            xcb_setup_failed_t *setup = (xcb_setup_failed_t *) c->setup;
167            write(STDERR_FILENO, xcb_setup_failed_reason(setup), xcb_setup_failed_reason_length(setup));
168            return 0;
169        }
170
171    case 2: /* authenticate */
172        {
173            xcb_setup_authenticate_t *setup = (xcb_setup_authenticate_t *) c->setup;
174            write(STDERR_FILENO, xcb_setup_authenticate_reason(setup), xcb_setup_authenticate_reason_length(setup));
175            return 0;
176        }
177    }
178
179    return 1;
180}
181
182/* precondition: there must be something for us to write. */
183static int write_vec(xcb_connection_t *c, struct iovec **vector, int *count)
184{
185    int n;
186    assert(!c->out.queue_len);
187
188#ifdef _WIN32
189    int i = 0;
190    int ret = 0,err = 0;
191    struct iovec *vec;
192    n = 0;
193
194    /* Could use the WSASend win32 function for scatter/gather i/o but setting up the WSABUF struct from
195       an iovec would require more work and I'm not sure of the benefit....works for now */
196    vec = *vector;
197    while(i < *count)
198    {
199         ret = send(c->fd,vec->iov_base,vec->iov_len,0);
200         if(ret == SOCKET_ERROR)
201         {
202             err  = WSAGetLastError();
203             if(err == WSAEWOULDBLOCK)
204             {
205                 return 1;
206             }
207         }
208         n += ret;
209         *vec++;
210         i++;
211    }
212#else
213    n = *count;
214    if (n > IOV_MAX)
215	n = IOV_MAX;
216
217    n = writev(c->fd, *vector, n);
218    if(n < 0 && errno == EAGAIN)
219        return 1;
220#endif /* _WIN32 */
221
222    if(n <= 0)
223    {
224        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
225        return 0;
226    }
227
228    for(; *count; --*count, ++*vector)
229    {
230        int cur = (*vector)->iov_len;
231        if(cur > n)
232            cur = n;
233        (*vector)->iov_len -= cur;
234        (*vector)->iov_base = (char *) (*vector)->iov_base + cur;
235        n -= cur;
236        if((*vector)->iov_len)
237            break;
238    }
239    if(!*count)
240        *vector = 0;
241    assert(n == 0);
242    return 1;
243}
244
245/* Public interface */
246
247const xcb_setup_t *xcb_get_setup(xcb_connection_t *c)
248{
249    if(c->has_error)
250        return 0;
251    /* doesn't need locking because it's never written to. */
252    return c->setup;
253}
254
255int xcb_get_file_descriptor(xcb_connection_t *c)
256{
257    if(c->has_error)
258        return -1;
259    /* doesn't need locking because it's never written to. */
260    return c->fd;
261}
262
263int xcb_connection_has_error(xcb_connection_t *c)
264{
265    /* doesn't need locking because it's read and written atomically. */
266    return c->has_error;
267}
268
269xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
270{
271    xcb_connection_t* c;
272
273#ifndef _WIN32
274#ifndef USE_POLL
275    if(fd >= FD_SETSIZE) /* would overflow in FD_SET */
276    {
277        close(fd);
278        return _xcb_conn_ret_error(XCB_CONN_ERROR);
279    }
280#endif
281#endif /* !_WIN32*/
282
283    c = calloc(1, sizeof(xcb_connection_t));
284    if(!c) {
285        close(fd);
286        return _xcb_conn_ret_error(XCB_CONN_CLOSED_MEM_INSUFFICIENT) ;
287    }
288
289    c->fd = fd;
290
291    if(!(
292        set_fd_flags(fd) &&
293        pthread_mutex_init(&c->iolock, 0) == 0 &&
294        _xcb_in_init(&c->in) &&
295        _xcb_out_init(&c->out) &&
296        write_setup(c, auth_info) &&
297        read_setup(c) &&
298        _xcb_ext_init(c) &&
299        _xcb_xid_init(c)
300        ))
301    {
302        xcb_disconnect(c);
303        return _xcb_conn_ret_error(XCB_CONN_ERROR);
304    }
305
306    return c;
307}
308
309void xcb_disconnect(xcb_connection_t *c)
310{
311    if(c->has_error)
312        return;
313
314    free(c->setup);
315
316    /* disallow further sends and receives */
317    shutdown(c->fd, SHUT_RDWR);
318    close(c->fd);
319
320    pthread_mutex_destroy(&c->iolock);
321    _xcb_in_destroy(&c->in);
322    _xcb_out_destroy(&c->out);
323
324    _xcb_ext_destroy(c);
325    _xcb_xid_destroy(c);
326
327    free(c);
328
329#ifdef _WIN32
330    WSACleanup();
331#endif
332}
333
334/* Private interface */
335
336void _xcb_conn_shutdown(xcb_connection_t *c, int err)
337{
338    c->has_error = err;
339}
340
341/* Return connection error state.
342 * To make thread-safe, I need a seperate static
343 * variable for every possible error.
344 */
345xcb_connection_t *_xcb_conn_ret_error(int err)
346{
347
348    switch(err)
349    {
350        case XCB_CONN_CLOSED_MEM_INSUFFICIENT:
351        {
352            return (xcb_connection_t *) &xcb_con_closed_mem_er;
353        }
354        case XCB_CONN_CLOSED_PARSE_ERR:
355        {
356            return (xcb_connection_t *) &xcb_con_closed_parse_er;
357        }
358        case XCB_CONN_CLOSED_INVALID_SCREEN:
359        {
360            return (xcb_connection_t *) &xcb_con_closed_screen_er;
361        }
362        case XCB_CONN_ERROR:
363        default:
364        {
365            return (xcb_connection_t *) &xcb_con_error;
366        }
367    }
368}
369
370int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count)
371{
372    int ret;
373#if USE_POLL
374    struct pollfd fd;
375#else
376    fd_set rfds, wfds;
377#endif
378
379    /* If the thing I should be doing is already being done, wait for it. */
380    if(count ? c->out.writing : c->in.reading)
381    {
382        pthread_cond_wait(cond, &c->iolock);
383        return 1;
384    }
385
386#if USE_POLL
387    memset(&fd, 0, sizeof(fd));
388    fd.fd = c->fd;
389    fd.events = POLLIN;
390#else
391    FD_ZERO(&rfds);
392    FD_SET(c->fd, &rfds);
393#endif
394    ++c->in.reading;
395
396#if USE_POLL
397    if(count)
398    {
399        fd.events |= POLLOUT;
400        ++c->out.writing;
401    }
402#else
403    FD_ZERO(&wfds);
404    if(count)
405    {
406        FD_SET(c->fd, &wfds);
407        ++c->out.writing;
408    }
409#endif
410
411    pthread_mutex_unlock(&c->iolock);
412    do {
413#if USE_POLL
414        ret = poll(&fd, 1, -1);
415        /* If poll() returns an event we didn't expect, such as POLLNVAL, treat
416         * it as if it failed. */
417        if(ret >= 0 && (fd.revents & ~fd.events))
418        {
419            ret = -1;
420            break;
421        }
422#else
423        ret = select(c->fd + 1, &rfds, &wfds, 0, 0);
424#endif
425    } while (ret == -1 && errno == EINTR);
426    if(ret < 0)
427    {
428        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
429        ret = 0;
430    }
431    pthread_mutex_lock(&c->iolock);
432
433    if(ret)
434    {
435        /* The code allows two threads to call select()/poll() at the same time.
436         * First thread just wants to read, a second thread wants to write, too.
437         * We have to make sure that we don't steal the reading thread's reply
438         * and let it get stuck in select()/poll().
439         * So a thread may read if either:
440         * - There is no other thread that wants to read (the above situation
441         *   did not occur).
442         * - It is the reading thread (above situation occurred).
443         */
444        int may_read = c->in.reading == 1 || !count;
445#if USE_POLL
446        if(may_read && (fd.revents & POLLIN) == POLLIN)
447#else
448        if(may_read && FD_ISSET(c->fd, &rfds))
449#endif
450            ret = ret && _xcb_in_read(c);
451
452#if USE_POLL
453        if((fd.revents & POLLOUT) == POLLOUT)
454#else
455        if(FD_ISSET(c->fd, &wfds))
456#endif
457            ret = ret && write_vec(c, vector, count);
458    }
459
460    if(count)
461        --c->out.writing;
462    --c->in.reading;
463
464    return ret;
465}
466