summaryrefslogtreecommitdiff
path: root/hw/xquartz/mach-startup/bundle-main.c
blob: 6f7bbfdc2f5995e19c60cf6708654a3c7adf421a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
/* main.c -- X application launcher
 
 Copyright (c) 2007 Jeremy Huddleston
 Copyright (c) 2007 Apple Inc
 
 Permission is hereby granted, free of charge, to any person
 obtaining a copy of this software and associated documentation files
 (the "Software"), to deal in the Software without restriction,
 including without limitation the rights to use, copy, modify, merge,
 publish, distribute, sublicense, and/or sell copies of the Software,
 and to permit persons to whom the Software is furnished to do so,
 subject to the following conditions:
 
 The above copyright notice and this permission notice shall be
 included in all copies or substantial portions of the Software.
 
 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 NONINFRINGEMENT.  IN NO EVENT SHALL THE ABOVE LISTED COPYRIGHT
 HOLDER(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 DEALINGS IN THE SOFTWARE.
 
 Except as contained in this notice, the name(s) of the above
 copyright holders shall not be used in advertising or otherwise to
 promote the sale, use or other dealings in this Software without
 prior written authorization. */

#include <CoreFoundation/CoreFoundation.h>
#include <AvailabilityMacros.h>

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <X11/Xlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <stdbool.h>
#include <signal.h>

#include <sys/socket.h>
#include <sys/un.h>

#include <sys/time.h>
#include <fcntl.h>

#include <mach/mach.h>
#include <mach/mach_error.h>
#include <servers/bootstrap.h>
#include "mach_startup.h"
#include "mach_startupServer.h"

#include "launchd_fd.h"
/* From darwinEvents.c ... but don't want to pull in all the server cruft */
void DarwinListenOnOpenFD(int fd);

extern int noPanoramiXExtension;

#define DEFAULT_CLIENT X11BINDIR "/xterm"
#define DEFAULT_STARTX X11BINDIR "/startx"
#define DEFAULT_SHELL  "/bin/sh"

#ifndef BUILD_DATE
#define BUILD_DATE ""
#endif
#ifndef XSERVER_VERSION
#define XSERVER_VERSION "?"
#endif

static char __crashreporter_info_buff__[4096] = {0};
static const char *__crashreporter_info__ = &__crashreporter_info_buff__[0];
#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
// This is actually a toolchain requirement, but I'm not sure the correct check,
// but it should be fine to just only include it for Leopard and later.  This line
// just tells the linker to never strip this symbol (such as for space optimization)
asm (".desc ___crashreporter_info__, 0x10");
#endif

static const char *__crashreporter_info__base = "X.Org X Server " XSERVER_VERSION " Build Date: " BUILD_DATE;

static char *launchd_id_prefix = NULL;
static char *server_bootstrap_name = NULL;

#define DEBUG 1

/* This is in quartzStartup.c */
int server_main(int argc, char **argv, char **envp);

static int execute(const char *command);
static char *command_from_prefs(const char *key, const char *default_value);

/*** Pthread Magics ***/
static pthread_t create_thread(void *func, void *arg) {
    pthread_attr_t attr;
    pthread_t tid;
	
    pthread_attr_init (&attr);
    pthread_attr_setscope (&attr, PTHREAD_SCOPE_SYSTEM);
    pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
    pthread_create (&tid, &attr, func, arg);
    pthread_attr_destroy (&attr);
	
    return tid;
}

/*** Mach-O IPC Stuffs ***/

union MaxMsgSize {
	union __RequestUnion__mach_startup_subsystem req;
	union __ReplyUnion__mach_startup_subsystem rep; 
};

static mach_port_t checkin_or_register(char *bname) {
    kern_return_t kr;
    mach_port_t mp;

    /* If we're started by launchd or the old mach_init */
    kr = bootstrap_check_in(bootstrap_port, bname, &mp);
    if (kr == KERN_SUCCESS)
        return mp;

    /* We probably were not started by launchd or the old mach_init */
    kr = mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &mp);
    if (kr != KERN_SUCCESS) {
        fprintf(stderr, "mach_port_allocate(): %s\n", mach_error_string(kr));
        exit(EXIT_FAILURE);
    }

    kr = mach_port_insert_right(mach_task_self(), mp, mp, MACH_MSG_TYPE_MAKE_SEND);
    if (kr != KERN_SUCCESS) {
        fprintf(stderr, "mach_port_insert_right(): %s\n", mach_error_string(kr));
        exit(EXIT_FAILURE);
    }

    kr = bootstrap_register(bootstrap_port, bname, mp);
    if (kr != KERN_SUCCESS) {
        fprintf(stderr, "bootstrap_register(): %s\n", mach_error_string(kr));
        exit(EXIT_FAILURE);
    }

    return mp;
}

/*** $DISPLAY handoff ***/
static int accept_fd_handoff(int connected_fd) {
    int launchd_fd;
    
    char databuf[] = "display";
    struct iovec iov[1];
    
    union {
        struct cmsghdr hdr;
        char bytes[CMSG_SPACE(sizeof(int))];
    } buf;
    
    struct msghdr msg;
    struct cmsghdr *cmsg;

    iov[0].iov_base = databuf;
    iov[0].iov_len  = sizeof(databuf);
    
    msg.msg_iov = iov;
    msg.msg_iovlen = 1;
    msg.msg_control = buf.bytes;
    msg.msg_controllen = sizeof(buf);
    msg.msg_name = 0;
    msg.msg_namelen = 0;
    msg.msg_flags = 0;
    
    cmsg = CMSG_FIRSTHDR (&msg);
    cmsg->cmsg_level = SOL_SOCKET;
    cmsg->cmsg_type = SCM_RIGHTS;
    cmsg->cmsg_len = CMSG_LEN(sizeof(int));
    
    msg.msg_controllen = cmsg->cmsg_len;
    
    *((int*)CMSG_DATA(cmsg)) = -1;
    
    if(recvmsg(connected_fd, &msg, 0) < 0) {
        fprintf(stderr, "X11.app: Error receiving $DISPLAY file descriptor.  recvmsg() error: %s\n", strerror(errno));
        return -1;
    }
    
    launchd_fd = *((int*)CMSG_DATA(cmsg));
    
    return launchd_fd;
}

typedef struct {
    int fd;
    string_t filename;
} socket_handoff_t;

/* This thread accepts an incoming connection and hands off the file
 * descriptor for the new connection to accept_fd_handoff()
 */
static void socket_handoff_thread(void *arg) {
    socket_handoff_t *handoff_data = (socket_handoff_t *)arg;
    int launchd_fd = -1;
    int connected_fd;
    unsigned remain;

    /* Now actually get the passed file descriptor from this connection
     * If we encounter an error, keep listening.
     */
    while(launchd_fd == -1) {
        connected_fd = accept(handoff_data->fd, NULL, NULL);
        if(connected_fd == -1) {
            fprintf(stderr, "X11.app: Failed to accept incoming connection on socket (fd=%d): %s\n", handoff_data->fd, strerror(errno));
            sleep(2);
            continue;
        }

        launchd_fd = accept_fd_handoff(connected_fd);
        if(launchd_fd == -1)
            fprintf(stderr, "X11.app: Error receiving $DISPLAY file descriptor, no descriptor received?  Waiting for another connection.\n");

        close(connected_fd);
    }

    close(handoff_data->fd);
    unlink(handoff_data->filename);
    free(handoff_data);
    
    /* TODO: Clean up this race better... giving xinitrc time to run... need to wait for 1.5 branch:
     *
     * From ajax:
     * There's already an internal callback chain for setting selection [in 1.5]
     * ownership.  See the CallSelectionCallback at the bottom of
     * ProcSetSelectionOwner, and xfixes/select.c for an example of how to hook
     * into it.
     */
    
    remain = 3000000;
    fprintf(stderr, "X11.app: Received new $DISPLAY fd: %d ... sleeping to allow xinitrc to catchup.\n", launchd_fd);
    while((remain = usleep(remain)) > 0);
    
    fprintf(stderr, "X11.app Handing off fd to server thread via DarwinListenOnOpenFD(%d)\n", launchd_fd);
    DarwinListenOnOpenFD(launchd_fd);
}

static int create_socket(char *filename_out) {
    struct sockaddr_un servaddr_un;
    struct sockaddr *servaddr;
    socklen_t servaddr_len;
    int ret_fd;
    size_t try, try_max;
    
    for(try=0, try_max=5; try < try_max; try++) {
        tmpnam(filename_out);
        
        /* Setup servaddr_un */
        memset (&servaddr_un, 0, sizeof (struct sockaddr_un));
        servaddr_un.sun_family = AF_UNIX;
        strlcpy(servaddr_un.sun_path, filename_out, sizeof(servaddr_un.sun_path));
        
        servaddr = (struct sockaddr *) &servaddr_un;
        servaddr_len = sizeof(struct sockaddr_un) - sizeof(servaddr_un.sun_path) + strlen(filename_out);
        
        ret_fd = socket(PF_UNIX, SOCK_STREAM, 0);
        if(ret_fd == -1) {
            fprintf(stderr, "X11.app: Failed to create socket (try %d / %d): %s - %s\n", (int)try+1, (int)try_max, filename_out, strerror(errno));
            continue;
        }
        
        if(bind(ret_fd, servaddr, servaddr_len) != 0) {
            fprintf(stderr, "X11.app: Failed to bind socket: %d - %s\n", errno, strerror(errno));
            close(ret_fd);
            return 0;
        }
        
        if(listen(ret_fd, 10) != 0) {
            fprintf(stderr, "X11.app: Failed to listen to socket: %s - %d - %s\n", filename_out, errno, strerror(errno));
            close(ret_fd);
            return 0;
        }
        
#ifdef DEBUG
        fprintf(stderr, "X11.app: Listening on socket for fd handoff:  (%d) %s\n", ret_fd, filename_out);
#endif
        
        return ret_fd;
    }
    
    return 0;
}

static int launchd_socket_handed_off = 0;

kern_return_t do_request_fd_handoff_socket(mach_port_t port, string_t filename) {
    socket_handoff_t *handoff_data;
    
    launchd_socket_handed_off = 1;

    handoff_data = (socket_handoff_t *)calloc(1,sizeof(socket_handoff_t));
    if(!handoff_data) {
        fprintf(stderr, "X11.app: Error allocating memory for handoff_data\n");
        return KERN_FAILURE;
    }

    handoff_data->fd = create_socket(handoff_data->filename);
    if(!handoff_data->fd) {
        free(handoff_data);
        return KERN_FAILURE;
    }

    strlcpy(filename, handoff_data->filename, STRING_T_SIZE);
    
    create_thread(socket_handoff_thread, handoff_data);
    
#ifdef DEBUG
    fprintf(stderr, "X11.app: Thread created for handoff.  Returning success to tell caller to connect and push the fd.\n");
#endif

    return KERN_SUCCESS;
}

kern_return_t do_request_pid(mach_port_t port, int *my_pid) {
    *my_pid = getpid();
    return KERN_SUCCESS;
}

/*** Server Startup ***/
kern_return_t do_start_x11_server(mach_port_t port, string_array_t argv,
                                  mach_msg_type_number_t argvCnt,
                                  string_array_t envp,
                                  mach_msg_type_number_t envpCnt) {
    /* And now back to char ** */
    char **_argv = alloca((argvCnt + 1) * sizeof(char *));
    char **_envp = alloca((envpCnt + 1) * sizeof(char *));
    size_t i;
    
    /* If we didn't get handed a launchd DISPLAY socket, we should
     * unset DISPLAY or we can run into problems with pbproxy
     */
    if(!launchd_socket_handed_off) {
        fprintf(stderr, "X11.app: No launchd socket handed off, unsetting DISPLAY\n");
        unsetenv("DISPLAY");
    }
    
    if(!_argv || !_envp) {
        return KERN_FAILURE;
    }

    fprintf(stderr, "X11.app: do_start_x11_server(): argc=%d\n", argvCnt);
    for(i=0; i < argvCnt; i++) {
        _argv[i] = argv[i];
        fprintf(stderr, "\targv[%u] = %s\n", (unsigned)i, argv[i]);
    }
    _argv[argvCnt] = NULL;
    
    for(i=0; i < envpCnt; i++) {
        _envp[i] = envp[i];
    }
    _envp[envpCnt] = NULL;
    
    if(server_main(argvCnt, _argv, _envp) == 0)
        return KERN_SUCCESS;
    else
        return KERN_FAILURE;
}

static int startup_trigger(int argc, char **argv, char **envp) {
    Display *display;
    const char *s;
    
    /* Take care of the case where we're called like a normal DDX */
    if(argc > 1 && argv[1][0] == ':') {
        size_t i;
        kern_return_t kr;
        mach_port_t mp;
        string_array_t newenvp;
        string_array_t newargv;

        /* We need to count envp */
        int envpc;
        for(envpc=0; envp[envpc]; envpc++);

        /* We have fixed-size string lengths due to limitations in IPC,
         * so we need to copy our argv and envp.
         */
        newargv = (string_array_t)alloca(argc * sizeof(string_t));
        newenvp = (string_array_t)alloca(envpc * sizeof(string_t));
        
        if(!newargv || !newenvp) {
            fprintf(stderr, "Memory allocation failure\n");
            exit(EXIT_FAILURE);
        }
        
        for(i=0; i < argc; i++) {
            strlcpy(newargv[i], argv[i], STRING_T_SIZE);
        }
        for(i=0; i < envpc; i++) {
            strlcpy(newenvp[i], envp[i], STRING_T_SIZE);
        }

        kr = bootstrap_look_up(bootstrap_port, server_bootstrap_name, &mp);
        if (kr != KERN_SUCCESS) {
#if MAC_OS_X_VERSION_MIN_REQUIRED >= 1050
            fprintf(stderr, "bootstrap_look_up(%s): %s\n", server_bootstrap_name, bootstrap_strerror(kr));
#else
            fprintf(stderr, "bootstrap_look_up(%s): %ul\n", server_bootstrap_name, (unsigned long)kr);
#endif
            exit(EXIT_FAILURE);
        }

        kr = start_x11_server(mp, newargv, argc, newenvp, envpc);
        if (kr != KERN_SUCCESS) {
            fprintf(stderr, "start_x11_server: %s\n", mach_error_string(kr));
            exit(EXIT_FAILURE);
        }
        exit(EXIT_SUCCESS);
    }

    /* If we have a process serial number and it's our only arg, act as if
     * the user double clicked the app bundle: launch app_to_run if possible
     */
    if(argc == 1 || (argc == 2 && !strncmp(argv[1], "-psn_", 5))) {
        /* Now, try to open a display, if so, run the launcher */
        display = XOpenDisplay(NULL);
        if(display) {
            /* Could open the display, start the launcher */
            XCloseDisplay(display);

            return execute(command_from_prefs("app_to_run", DEFAULT_CLIENT));
        }
    }

    /* Start the server */
    if((s = getenv("DISPLAY"))) {
        fprintf(stderr, "X11.app: Could not connect to server (DISPLAY=\"%s\", unsetting).  Starting X server.\n", s);
        unsetenv("DISPLAY");
    } else {
        fprintf(stderr, "X11.app: Could not connect to server (DISPLAY is not set).  Starting X server.\n");
    }
    return execute(command_from_prefs("startx_script", DEFAULT_STARTX));
}

/** Setup the environment we want our child processes to inherit */
static void ensure_path(const char *dir) {
    char buf[1024], *temp;
    
    /* Make sure /usr/X11/bin is in the $PATH */
    temp = getenv("PATH");
    if(temp == NULL || temp[0] == 0) {
        snprintf(buf, sizeof(buf), "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:%s", dir);
        setenv("PATH", buf, TRUE);
    } else if(strnstr(temp, X11BINDIR, sizeof(temp)) == NULL) {
        snprintf(buf, sizeof(buf), "%s:%s", temp, dir);
        setenv("PATH", buf, TRUE);
    }
}

static void setup_env(void) {
    char *temp;
    const char *pds = NULL;
    const char *disp = getenv("DISPLAY");
    size_t len;

    /* Pass on our prefs domain to startx and its inheritors (mainly for
     * quartz-wm and the Xquartz stub's MachIPC)
     */
    CFBundleRef bundle = CFBundleGetMainBundle();
    if(bundle) {
        CFStringRef pd = CFBundleGetIdentifier(bundle);
        if(pd) {
            pds = CFStringGetCStringPtr(pd, 0);
        }
    }

    /* fallback to hardcoded value if we can't discover it */
    if(!pds) {
        pds = LAUNCHD_ID_PREFIX".X11";
    }

    server_bootstrap_name = malloc(sizeof(char) * (strlen(pds) + 1));
    if(!server_bootstrap_name) {
        fprintf(stderr, "X11.app: Memory allocation error.\n");
        exit(1);
    }
    strcpy(server_bootstrap_name, pds);
    setenv("X11_PREFS_DOMAIN", server_bootstrap_name, 1);
    
    len = strlen(server_bootstrap_name);
    launchd_id_prefix = malloc(sizeof(char) * (len - 3));
    if(!launchd_id_prefix) {
        fprintf(stderr, "X11.app: Memory allocation error.\n");
        exit(1);
    }
    strlcpy(launchd_id_prefix, server_bootstrap_name, len - 3);
    
    /* We need to unset DISPLAY if it is not our socket */
    if(disp) {
        /* s = basename(disp) */
        const char *d, *s;
	    for(s = NULL, d = disp; *d; d++) {
            if(*d == '/')
                s = d + 1;
        }

        if(s && *s) {
            if(strcmp(launchd_id_prefix, "org.x") == 0 && strcmp(s, ":0") == 0) {
                fprintf(stderr, "X11.app: Detected old style launchd DISPLAY, please update xinit.\n");
            } else {
                temp = (char *)malloc(sizeof(char) * len);
                if(!temp) {
                    fprintf(stderr, "X11.app: Memory allocation error creating space for socket name test.\n");
                    exit(1);
                }
                strlcpy(temp, launchd_id_prefix, len);
                strlcat(temp, ":0", len);
            
                if(strcmp(temp, s) != 0) {
                    /* If we don't have a match, unset it. */
                    fprintf(stderr, "X11.app: DISPLAY (\"%s\") does not match our id (\"%s\"), unsetting.\n", disp, launchd_id_prefix);
                    unsetenv("DISPLAY");
                }
                free(temp);
            }
        } else {
            /* The DISPLAY environment variable is not formatted like a launchd socket, so reset. */
            fprintf(stderr, "X11.app: DISPLAY does not look like a launchd set variable, unsetting.\n");
            unsetenv("DISPLAY");
        }
    }

    /* Make sure PATH is right */
    ensure_path(X11BINDIR);
    
    /* cd $HOME */
    temp = getenv("HOME");
    if(temp != NULL && temp[0] != '\0')
        chdir(temp);
}

/*** Main ***/
int main(int argc, char **argv, char **envp) {
    Bool listenOnly = FALSE;
    int i;
    mach_msg_size_t mxmsgsz = sizeof(union MaxMsgSize) + MAX_TRAILER_SIZE;
    mach_port_t mp;
    kern_return_t kr;

    /* Setup our environment for our children */
    setup_env();
    
    /* The server must not run the PanoramiX operations. */
    noPanoramiXExtension = TRUE;

    /* Setup the initial crasherporter info */
    strlcpy(__crashreporter_info_buff__, __crashreporter_info__base, sizeof(__crashreporter_info_buff__));
    
    fprintf(stderr, "X11.app: main(): argc=%d\n", argc);
    for(i=0; i < argc; i++) {
        fprintf(stderr, "\targv[%u] = %s\n", (unsigned)i, argv[i]);
        if(!strcmp(argv[i], "--listenonly")) {
            listenOnly = TRUE;
        }
    }

    mp = checkin_or_register(server_bootstrap_name);
    if(mp == MACH_PORT_NULL) {
        fprintf(stderr, "NULL mach service: %s", server_bootstrap_name);
        return EXIT_FAILURE;
    }
    
    /* Check if we need to do something other than listen, and make another
     * thread handle it.
     */
    if(!listenOnly) {
        pid_t child1, child2;
        int status;

        /* Do the fork-twice trick to avoid having to reap zombies */
        child1 = fork();
        switch (child1) {
            case -1:                                /* error */
                break;

            case 0:                                 /* child1 */
                child2 = fork();

                switch (child2) {
                    int max_files, i;

                    case -1:                            /* error */
                        break;

                    case 0:                             /* child2 */
                        /* close all open files except for standard streams */
                        max_files = sysconf(_SC_OPEN_MAX);
                        for(i = 3; i < max_files; i++)
                            close(i);

                        /* ensure stdin is on /dev/null */
                        close(0);
                        open("/dev/null", O_RDONLY);

                        return startup_trigger(argc, argv, envp);

                    default:                            /* parent (child1) */
                        _exit(0);
                }
                break;

            default:                                /* parent */
              waitpid(child1, &status, 0);
        }
    }
    
    /* Main event loop */
    fprintf(stderr, "Waiting for startup parameters via Mach IPC.\n");
    kr = mach_msg_server(mach_startup_server, mxmsgsz, mp, 0);
    if (kr != KERN_SUCCESS) {
        fprintf(stderr, "%s.X11(mp): %s\n", LAUNCHD_ID_PREFIX, mach_error_string(kr));
        return EXIT_FAILURE;
    }
    
    return EXIT_SUCCESS;
}

static int execute(const char *command) {
    const char *newargv[4];
    const char **p;
    
    newargv[0] = command_from_prefs("login_shell", DEFAULT_SHELL);
    newargv[1] = "-c";
    newargv[2] = command;
    newargv[3] = NULL;
    
    fprintf(stderr, "X11.app: Launching %s:\n", command);
    for(p=newargv; *p; p++) {
        fprintf(stderr, "\targv[%ld] = %s\n", (long int)(p - newargv), *p);
    }

    execvp (newargv[0], (char * const *) newargv);
    perror ("X11.app: Couldn't exec.");
    return 1;
}

static char *command_from_prefs(const char *key, const char *default_value) {
    char *command = NULL;
    
    CFStringRef cfKey;
    CFPropertyListRef PlistRef;

    if(!key)
        return NULL;

    cfKey = CFStringCreateWithCString(NULL, key, kCFStringEncodingASCII);

    if(!cfKey)
        return NULL;

    PlistRef = CFPreferencesCopyAppValue(cfKey, kCFPreferencesCurrentApplication);
    
    if ((PlistRef == NULL) || (CFGetTypeID(PlistRef) != CFStringGetTypeID())) {
        CFStringRef cfDefaultValue = CFStringCreateWithCString(NULL, default_value, kCFStringEncodingASCII);
        int len = strlen(default_value) + 1;

        if(!cfDefaultValue)
            goto command_from_prefs_out;

        CFPreferencesSetAppValue(cfKey, cfDefaultValue, kCFPreferencesCurrentApplication);
        CFPreferencesAppSynchronize(kCFPreferencesCurrentApplication);
        CFRelease(cfDefaultValue);
        
        command = (char *)malloc(len * sizeof(char));
        if(!command)
            goto command_from_prefs_out;
        strcpy(command, default_value);
    } else {
        int len = CFStringGetLength((CFStringRef)PlistRef) + 1;
        command = (char *)malloc(len * sizeof(char));
        if(!command)
            goto command_from_prefs_out;
        CFStringGetCString((CFStringRef)PlistRef, command, len,  kCFStringEncodingASCII);
    }

command_from_prefs_out:
    if (PlistRef)
        CFRelease(PlistRef);
    if(cfKey)
        CFRelease(cfKey);
    return command;
}