xcb_conn.c revision 1016ad83 
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#if HAVE_SENDMSG
218    if (c->out.out_fd.nfd) {
219        union {
220            struct cmsghdr cmsghdr;
221            char buf[CMSG_SPACE(XCB_MAX_PASS_FD * sizeof(int))];
222        } cmsgbuf;
223        struct msghdr msg = {
224            .msg_name = NULL,
225            .msg_namelen = 0,
226            .msg_iov = *vector,
227            .msg_iovlen = n,
228            .msg_control = cmsgbuf.buf,
229            .msg_controllen = CMSG_LEN(c->out.out_fd.nfd * sizeof (int)),
230        };
231        int i;
232        struct cmsghdr *hdr = CMSG_FIRSTHDR(&msg);
233
234        hdr->cmsg_len = msg.msg_controllen;
235        hdr->cmsg_level = SOL_SOCKET;
236        hdr->cmsg_type = SCM_RIGHTS;
237        memcpy(CMSG_DATA(hdr), c->out.out_fd.fd, c->out.out_fd.nfd * sizeof (int));
238
239        n = sendmsg(c->fd, &msg, 0);
240        if(n < 0 && errno == EAGAIN)
241            return 1;
242        for (i = 0; i < c->out.out_fd.nfd; i++)
243            close(c->out.out_fd.fd[i]);
244        c->out.out_fd.nfd = 0;
245    } else
246#endif
247    {
248        n = writev(c->fd, *vector, n);
249        if(n < 0 && errno == EAGAIN)
250            return 1;
251    }
252
253#endif /* _WIN32 */
254
255    if(n <= 0)
256    {
257        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
258        return 0;
259    }
260
261    for(; *count; --*count, ++*vector)
262    {
263        int cur = (*vector)->iov_len;
264        if(cur > n)
265            cur = n;
266        (*vector)->iov_len -= cur;
267        (*vector)->iov_base = (char *) (*vector)->iov_base + cur;
268        n -= cur;
269        if((*vector)->iov_len)
270            break;
271    }
272    if(!*count)
273        *vector = 0;
274    assert(n == 0);
275    return 1;
276}
277
278/* Public interface */
279
280const xcb_setup_t *xcb_get_setup(xcb_connection_t *c)
281{
282    if(c->has_error)
283        return 0;
284    /* doesn't need locking because it's never written to. */
285    return c->setup;
286}
287
288int xcb_get_file_descriptor(xcb_connection_t *c)
289{
290    if(c->has_error)
291        return -1;
292    /* doesn't need locking because it's never written to. */
293    return c->fd;
294}
295
296int xcb_connection_has_error(xcb_connection_t *c)
297{
298    /* doesn't need locking because it's read and written atomically. */
299    return c->has_error;
300}
301
302xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info)
303{
304    xcb_connection_t* c;
305
306#ifndef _WIN32
307#ifndef USE_POLL
308    if(fd >= FD_SETSIZE) /* would overflow in FD_SET */
309    {
310        close(fd);
311        return _xcb_conn_ret_error(XCB_CONN_ERROR);
312    }
313#endif
314#endif /* !_WIN32*/
315
316    c = calloc(1, sizeof(xcb_connection_t));
317    if(!c) {
318        close(fd);
319        return _xcb_conn_ret_error(XCB_CONN_CLOSED_MEM_INSUFFICIENT) ;
320    }
321
322    c->fd = fd;
323
324    if(!(
325        set_fd_flags(fd) &&
326        pthread_mutex_init(&c->iolock, 0) == 0 &&
327        _xcb_in_init(&c->in) &&
328        _xcb_out_init(&c->out) &&
329        write_setup(c, auth_info) &&
330        read_setup(c) &&
331        _xcb_ext_init(c) &&
332        _xcb_xid_init(c)
333        ))
334    {
335        xcb_disconnect(c);
336        return _xcb_conn_ret_error(XCB_CONN_ERROR);
337    }
338
339    return c;
340}
341
342void xcb_disconnect(xcb_connection_t *c)
343{
344    if(c->has_error)
345        return;
346
347    free(c->setup);
348
349    /* disallow further sends and receives */
350    shutdown(c->fd, SHUT_RDWR);
351    close(c->fd);
352
353    pthread_mutex_destroy(&c->iolock);
354    _xcb_in_destroy(&c->in);
355    _xcb_out_destroy(&c->out);
356
357    _xcb_ext_destroy(c);
358    _xcb_xid_destroy(c);
359
360    free(c);
361
362#ifdef _WIN32
363    WSACleanup();
364#endif
365}
366
367/* Private interface */
368
369void _xcb_conn_shutdown(xcb_connection_t *c, int err)
370{
371    c->has_error = err;
372}
373
374/* Return connection error state.
375 * To make thread-safe, I need a seperate static
376 * variable for every possible error.
377 */
378xcb_connection_t *_xcb_conn_ret_error(int err)
379{
380
381    switch(err)
382    {
383        case XCB_CONN_CLOSED_MEM_INSUFFICIENT:
384        {
385            return (xcb_connection_t *) &xcb_con_closed_mem_er;
386        }
387        case XCB_CONN_CLOSED_PARSE_ERR:
388        {
389            return (xcb_connection_t *) &xcb_con_closed_parse_er;
390        }
391        case XCB_CONN_CLOSED_INVALID_SCREEN:
392        {
393            return (xcb_connection_t *) &xcb_con_closed_screen_er;
394        }
395        case XCB_CONN_ERROR:
396        default:
397        {
398            return (xcb_connection_t *) &xcb_con_error;
399        }
400    }
401}
402
403int _xcb_conn_wait(xcb_connection_t *c, pthread_cond_t *cond, struct iovec **vector, int *count)
404{
405    int ret;
406#if USE_POLL
407    struct pollfd fd;
408#else
409    fd_set rfds, wfds;
410#endif
411
412    /* If the thing I should be doing is already being done, wait for it. */
413    if(count ? c->out.writing : c->in.reading)
414    {
415        pthread_cond_wait(cond, &c->iolock);
416        return 1;
417    }
418
419#if USE_POLL
420    memset(&fd, 0, sizeof(fd));
421    fd.fd = c->fd;
422    fd.events = POLLIN;
423#else
424    FD_ZERO(&rfds);
425    FD_SET(c->fd, &rfds);
426#endif
427    ++c->in.reading;
428
429#if USE_POLL
430    if(count)
431    {
432        fd.events |= POLLOUT;
433        ++c->out.writing;
434    }
435#else
436    FD_ZERO(&wfds);
437    if(count)
438    {
439        FD_SET(c->fd, &wfds);
440        ++c->out.writing;
441    }
442#endif
443
444    pthread_mutex_unlock(&c->iolock);
445    do {
446#if USE_POLL
447        ret = poll(&fd, 1, -1);
448        /* If poll() returns an event we didn't expect, such as POLLNVAL, treat
449         * it as if it failed. */
450        if(ret >= 0 && (fd.revents & ~fd.events))
451        {
452            ret = -1;
453            break;
454        }
455#else
456        ret = select(c->fd + 1, &rfds, &wfds, 0, 0);
457#endif
458    } while (ret == -1 && errno == EINTR);
459    if(ret < 0)
460    {
461        _xcb_conn_shutdown(c, XCB_CONN_ERROR);
462        ret = 0;
463    }
464    pthread_mutex_lock(&c->iolock);
465
466    if(ret)
467    {
468        /* The code allows two threads to call select()/poll() at the same time.
469         * First thread just wants to read, a second thread wants to write, too.
470         * We have to make sure that we don't steal the reading thread's reply
471         * and let it get stuck in select()/poll().
472         * So a thread may read if either:
473         * - There is no other thread that wants to read (the above situation
474         *   did not occur).
475         * - It is the reading thread (above situation occurred).
476         */
477        int may_read = c->in.reading == 1 || !count;
478#if USE_POLL
479        if(may_read && (fd.revents & POLLIN) != 0)
480#else
481        if(may_read && FD_ISSET(c->fd, &rfds))
482#endif
483            ret = ret && _xcb_in_read(c);
484
485#if USE_POLL
486        if((fd.revents & POLLOUT) != 0)
487#else
488        if(FD_ISSET(c->fd, &wfds))
489#endif
490            ret = ret && write_vec(c, vector, count);
491    }
492
493    if(count)
494        --c->out.writing;
495    --c->in.reading;
496
497    return ret;
498}
499