Training courses

Kernel and Embedded Linux

Bootlin training courses

Embedded Linux, kernel,
Yocto Project, Buildroot, real-time,
graphics, boot time, debugging...

Bootlin logo

Elixir Cross Referencer

  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
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "apr.h"
#include "apr_lib.h"
#include "apr_strings.h"
#include "apr_pools.h"
#include "apr_tables.h"
#include "apr_buckets.h"
#include "apr_errno.h"
#define APR_WANT_MEMFUNC
#define APR_WANT_STRFUNC
#include "apr_want.h"

#if APR_HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif

static apr_status_t brigade_cleanup(void *data) 
{
    return apr_brigade_cleanup(data);
}

APU_DECLARE(apr_status_t) apr_brigade_cleanup(void *data)
{
    apr_bucket_brigade *b = data;
    apr_bucket *e;

    while (!APR_BRIGADE_EMPTY(b)) {
        e = APR_BRIGADE_FIRST(b);
        apr_bucket_delete(e);
    }
    /* We don't need to free(bb) because it's allocated from a pool. */
    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_destroy(apr_bucket_brigade *b)
{
    apr_pool_cleanup_kill(b->p, b, brigade_cleanup);
    return apr_brigade_cleanup(b);
}

APU_DECLARE(apr_bucket_brigade *) apr_brigade_create(apr_pool_t *p,
                                                     apr_bucket_alloc_t *list)
{
    apr_bucket_brigade *b;

    b = apr_palloc(p, sizeof(*b));
    b->p = p;
    b->bucket_alloc = list;

    APR_RING_INIT(&b->list, apr_bucket, link);

    apr_pool_cleanup_register(b->p, b, brigade_cleanup, apr_pool_cleanup_null);
    return b;
}

APU_DECLARE(apr_bucket_brigade *) apr_brigade_split_ex(apr_bucket_brigade *b,
                                                       apr_bucket *e,
                                                       apr_bucket_brigade *a)
{
    apr_bucket *f;

    if (!a) {
        a = apr_brigade_create(b->p, b->bucket_alloc);
    }
    else if (!APR_BRIGADE_EMPTY(a)) {
        apr_brigade_cleanup(a);
    }
    /* Return an empty brigade if there is nothing left in 
     * the first brigade to split off 
     */
    if (e != APR_BRIGADE_SENTINEL(b)) {
        f = APR_RING_LAST(&b->list);
        APR_RING_UNSPLICE(e, f, link);
        APR_RING_SPLICE_HEAD(&a->list, e, f, apr_bucket, link);
    }

    APR_BRIGADE_CHECK_CONSISTENCY(a);
    APR_BRIGADE_CHECK_CONSISTENCY(b);

    return a;
}

APU_DECLARE(apr_bucket_brigade *) apr_brigade_split(apr_bucket_brigade *b,
                                                    apr_bucket *e)
{
    return apr_brigade_split_ex(b, e, NULL);
}

APU_DECLARE(apr_status_t) apr_brigade_partition(apr_bucket_brigade *b,
                                                apr_off_t point,
                                                apr_bucket **after_point)
{
    apr_bucket *e;
    const char *s;
    apr_size_t len;
    apr_uint64_t point64;
    apr_status_t rv;

    if (point < 0) {
        /* this could cause weird (not necessarily SEGV) things to happen */
        return APR_EINVAL;
    }
    if (point == 0) {
        *after_point = APR_BRIGADE_FIRST(b);
        return APR_SUCCESS;
    }

    /*
     * Try to reduce the following casting mess: We know that point will be
     * larger equal 0 now and forever and thus that point (apr_off_t) and
     * apr_size_t will fit into apr_uint64_t in any case.
     */
    point64 = (apr_uint64_t)point;

    APR_BRIGADE_CHECK_CONSISTENCY(b);

    for (e = APR_BRIGADE_FIRST(b);
         e != APR_BRIGADE_SENTINEL(b);
         e = APR_BUCKET_NEXT(e))
    {
        /* For an unknown length bucket, while 'point64' is beyond the possible
         * size contained in apr_size_t, read and continue...
         */
        if ((e->length == (apr_size_t)(-1))
            && (point64 > (apr_uint64_t)APR_SIZE_MAX)) {
            /* point64 is too far out to simply split this bucket,
             * we must fix this bucket's size and keep going... */
            rv = apr_bucket_read(e, &s, &len, APR_BLOCK_READ);
            if (rv != APR_SUCCESS) {
                *after_point = e;
                return rv;
            }
        }
        else if ((point64 < (apr_uint64_t)e->length)
                 || (e->length == (apr_size_t)(-1))) {
            /* We already consumed buckets where point64 is beyond
             * our interest ( point64 > APR_SIZE_MAX ), above.
             * Here point falls between 0 and APR_SIZE_MAX
             * and is within this bucket, or this bucket's len
             * is undefined, so now we are ready to split it.
             * First try to split the bucket natively... */
            if ((rv = apr_bucket_split(e, (apr_size_t)point64)) 
                    != APR_ENOTIMPL) {
                *after_point = APR_BUCKET_NEXT(e);
                return rv;
            }

            /* if the bucket cannot be split, we must read from it,
             * changing its type to one that can be split */
            rv = apr_bucket_read(e, &s, &len, APR_BLOCK_READ);
            if (rv != APR_SUCCESS) {
                *after_point = e;
                return rv;
            }

            /* this assumes that len == e->length, which is okay because e
             * might have been morphed by the apr_bucket_read() above, but
             * if it was, the length would have been adjusted appropriately */
            if (point64 < (apr_uint64_t)e->length) {
                rv = apr_bucket_split(e, (apr_size_t)point64);
                *after_point = APR_BUCKET_NEXT(e);
                return rv;
            }
        }
        if (point64 == (apr_uint64_t)e->length) {
            *after_point = APR_BUCKET_NEXT(e);
            return APR_SUCCESS;
        }
        point64 -= (apr_uint64_t)e->length;
    }
    *after_point = APR_BRIGADE_SENTINEL(b); 
    return APR_INCOMPLETE;
}

APU_DECLARE(apr_status_t) apr_brigade_length(apr_bucket_brigade *bb,
                                             int read_all, apr_off_t *length)
{
    apr_off_t total = 0;
    apr_bucket *bkt;
    apr_status_t status = APR_SUCCESS;

    for (bkt = APR_BRIGADE_FIRST(bb);
         bkt != APR_BRIGADE_SENTINEL(bb);
         bkt = APR_BUCKET_NEXT(bkt))
    {
        if (bkt->length == (apr_size_t)(-1)) {
            const char *ignore;
            apr_size_t len;

            if (!read_all) {
                total = -1;
                break;
            }

            if ((status = apr_bucket_read(bkt, &ignore, &len,
                                          APR_BLOCK_READ)) != APR_SUCCESS) {
                break;
            }
        }

        total += bkt->length;
    }

    *length = total;
    return status;
}

APU_DECLARE(apr_status_t) apr_brigade_flatten(apr_bucket_brigade *bb,
                                              char *c, apr_size_t *len)
{
    apr_size_t actual = 0;
    apr_bucket *b;
 
    for (b = APR_BRIGADE_FIRST(bb);
         b != APR_BRIGADE_SENTINEL(bb);
         b = APR_BUCKET_NEXT(b))
    {
        const char *str;
        apr_size_t str_len;
        apr_status_t status;

        status = apr_bucket_read(b, &str, &str_len, APR_BLOCK_READ);
        if (status != APR_SUCCESS) {
            return status;
        }

        /* If we would overflow. */
        if (str_len + actual > *len) {
            str_len = *len - actual;
        }

        /* XXX: It appears that overflow of the final bucket
         * is DISCARDED without any warning to the caller.
         *
         * No, we only copy the data up to their requested size.  -- jre
         */
        memcpy(c, str, str_len);

        c += str_len;
        actual += str_len;

        /* This could probably be actual == *len, but be safe from stray
         * photons. */
        if (actual >= *len) {
            break;
        }
    }

    *len = actual;
    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_pflatten(apr_bucket_brigade *bb,
                                               char **c,
                                               apr_size_t *len,
                                               apr_pool_t *pool)
{
    apr_off_t actual;
    apr_size_t total;
    apr_status_t rv;

    apr_brigade_length(bb, 1, &actual);
    
    /* XXX: This is dangerous beyond belief.  At least in the
     * apr_brigade_flatten case, the user explicitly stated their
     * buffer length - so we don't up and palloc 4GB for a single
     * file bucket.  This API must grow a useful max boundry,
     * either compiled-in or preset via the *len value.
     *
     * Shouldn't both fn's grow an additional return value for 
     * the case that the brigade couldn't be flattened into the
     * provided or allocated buffer (such as APR_EMOREDATA?)
     * Not a failure, simply an advisory result.
     */
    total = (apr_size_t)actual;

    *c = apr_palloc(pool, total);
    
    rv = apr_brigade_flatten(bb, *c, &total);

    if (rv != APR_SUCCESS) {
        return rv;
    }

    *len = total;
    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_split_line(apr_bucket_brigade *bbOut,
                                                 apr_bucket_brigade *bbIn,
                                                 apr_read_type_e block,
                                                 apr_off_t maxbytes)
{
    apr_off_t readbytes = 0;

    while (!APR_BRIGADE_EMPTY(bbIn)) {
        const char *pos;
        const char *str;
        apr_size_t len;
        apr_status_t rv;
        apr_bucket *e;

        e = APR_BRIGADE_FIRST(bbIn);
        rv = apr_bucket_read(e, &str, &len, block);

        if (rv != APR_SUCCESS) {
            return rv;
        }

        pos = memchr(str, APR_ASCII_LF, len);
        /* We found a match. */
        if (pos != NULL) {
            apr_bucket_split(e, pos - str + 1);
            APR_BUCKET_REMOVE(e);
            APR_BRIGADE_INSERT_TAIL(bbOut, e);
            return APR_SUCCESS;
        }
        APR_BUCKET_REMOVE(e);
        if (APR_BUCKET_IS_METADATA(e) || len > APR_BUCKET_BUFF_SIZE/4) {
            APR_BRIGADE_INSERT_TAIL(bbOut, e);
        }
        else {
            if (len > 0) {
                rv = apr_brigade_write(bbOut, NULL, NULL, str, len);
                if (rv != APR_SUCCESS) {
                    return rv;
                }
            }
            apr_bucket_destroy(e);
        }
        readbytes += len;
        /* We didn't find an APR_ASCII_LF within the maximum line length. */
        if (readbytes >= maxbytes) {
            break;
        }
    }

    return APR_SUCCESS;
}


APU_DECLARE(apr_status_t) apr_brigade_to_iovec(apr_bucket_brigade *b, 
                                               struct iovec *vec, int *nvec)
{
    int left = *nvec;
    apr_bucket *e;
    struct iovec *orig;
    apr_size_t iov_len;
    const char *iov_base;
    apr_status_t rv;

    orig = vec;

    for (e = APR_BRIGADE_FIRST(b);
         e != APR_BRIGADE_SENTINEL(b);
         e = APR_BUCKET_NEXT(e))
    {
        if (left-- == 0)
            break;

        rv = apr_bucket_read(e, &iov_base, &iov_len, APR_NONBLOCK_READ);
        if (rv != APR_SUCCESS)
            return rv;
        /* Set indirectly since types differ: */
        vec->iov_len = iov_len;
        vec->iov_base = (void *)iov_base;
        ++vec;
    }

    *nvec = (int)(vec - orig);
    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_vputstrs(apr_bucket_brigade *b, 
                                               apr_brigade_flush flush,
                                               void *ctx,
                                               va_list va)
{
#define MAX_VECS    8
    struct iovec vec[MAX_VECS];
    apr_size_t i = 0;

    for (;;) {
        char *str = va_arg(va, char *);
        apr_status_t rv;

        if (str == NULL)
            break;

        vec[i].iov_base = str;
        vec[i].iov_len = strlen(str);
        i++;

        if (i == MAX_VECS) {
            rv = apr_brigade_writev(b, flush, ctx, vec, i);
            if (rv != APR_SUCCESS)
                return rv;
            i = 0;
        }
    }
    if (i != 0)
       return apr_brigade_writev(b, flush, ctx, vec, i);

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_putc(apr_bucket_brigade *b,
                                           apr_brigade_flush flush, void *ctx,
                                           const char c)
{
    return apr_brigade_write(b, flush, ctx, &c, 1);
}

APU_DECLARE(apr_status_t) apr_brigade_write(apr_bucket_brigade *b,
                                            apr_brigade_flush flush,
                                            void *ctx, 
                                            const char *str, apr_size_t nbyte)
{
    apr_bucket *e = APR_BRIGADE_LAST(b);
    apr_size_t remaining = APR_BUCKET_BUFF_SIZE;
    char *buf = NULL;

    /*
     * If the last bucket is a heap bucket and its buffer is not shared with
     * another bucket, we may write into that bucket.
     */
    if (!APR_BRIGADE_EMPTY(b) && APR_BUCKET_IS_HEAP(e)
        && ((apr_bucket_heap *)(e->data))->refcount.refcount == 1) {
        apr_bucket_heap *h = e->data;

        /* HEAP bucket start offsets are always in-memory, safe to cast */
        remaining = h->alloc_len - (e->length + (apr_size_t)e->start);
        buf = h->base + e->start + e->length;
    }

    if (nbyte > remaining) {
        /* either a buffer bucket exists but is full, 
         * or no buffer bucket exists and the data is too big
         * to buffer.  In either case, we should flush.  */
        if (flush) {
            e = apr_bucket_transient_create(str, nbyte, b->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            return flush(b, ctx);
        }
        else {
            e = apr_bucket_heap_create(str, nbyte, NULL, b->bucket_alloc);
            APR_BRIGADE_INSERT_TAIL(b, e);
            return APR_SUCCESS;
        }
    }
    else if (!buf) {
        /* we don't have a buffer, but the data is small enough
         * that we don't mind making a new buffer */
        buf = apr_bucket_alloc(APR_BUCKET_BUFF_SIZE, b->bucket_alloc);
        e = apr_bucket_heap_create(buf, APR_BUCKET_BUFF_SIZE,
                                   apr_bucket_free, b->bucket_alloc);
        APR_BRIGADE_INSERT_TAIL(b, e);
        e->length = 0;   /* We are writing into the brigade, and
                          * allocating more memory than we need.  This
                          * ensures that the bucket thinks it is empty just
                          * after we create it.  We'll fix the length
                          * once we put data in it below.
                          */
    }

    /* there is a sufficiently big buffer bucket available now */
    memcpy(buf, str, nbyte);
    e->length += nbyte;

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_writev(apr_bucket_brigade *b,
                                             apr_brigade_flush flush,
                                             void *ctx,
                                             const struct iovec *vec,
                                             apr_size_t nvec)
{
    apr_bucket *e;
    apr_size_t total_len;
    apr_size_t i;
    char *buf;

    /* Compute the total length of the data to be written.
     */
    total_len = 0;
    for (i = 0; i < nvec; i++) {
       total_len += vec[i].iov_len;
    }

    /* If the data to be written is very large, try to convert
     * the iovec to transient buckets rather than copying.
     */
    if (total_len > APR_BUCKET_BUFF_SIZE) {
        if (flush) {
            for (i = 0; i < nvec; i++) {
                e = apr_bucket_transient_create(vec[i].iov_base,
                                                vec[i].iov_len,
                                                b->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(b, e);
            }
            return flush(b, ctx);
        }
        else {
            for (i = 0; i < nvec; i++) {
                e = apr_bucket_heap_create((const char *) vec[i].iov_base,
                                           vec[i].iov_len, NULL,
                                           b->bucket_alloc);
                APR_BRIGADE_INSERT_TAIL(b, e);
            }
            return APR_SUCCESS;
        }
    }

    i = 0;

    /* If there is a heap bucket at the end of the brigade
     * already, and its refcount is 1, copy into the existing bucket.
     */
    e = APR_BRIGADE_LAST(b);
    if (!APR_BRIGADE_EMPTY(b) && APR_BUCKET_IS_HEAP(e)
        && ((apr_bucket_heap *)(e->data))->refcount.refcount == 1) {
        apr_bucket_heap *h = e->data;
        apr_size_t remaining = h->alloc_len -
            (e->length + (apr_size_t)e->start);
        buf = h->base + e->start + e->length;

        if (remaining >= total_len) {
            /* Simple case: all the data will fit in the
             * existing heap bucket
             */
            for (; i < nvec; i++) {
                apr_size_t len = vec[i].iov_len;
                memcpy(buf, (const void *) vec[i].iov_base, len);
                buf += len;
            }
            e->length += total_len;
            return APR_SUCCESS;
        }
        else {
            /* More complicated case: not all of the data
             * will fit in the existing heap bucket.  The
             * total data size is <= APR_BUCKET_BUFF_SIZE,
             * so we'll need only one additional bucket.
             */
            const char *start_buf = buf;
            for (; i < nvec; i++) {
                apr_size_t len = vec[i].iov_len;
                if (len > remaining) {
                    break;
                }
                memcpy(buf, (const void *) vec[i].iov_base, len);
                buf += len;
                remaining -= len;
            }
            e->length += (buf - start_buf);
            total_len -= (buf - start_buf);

            if (flush) {
                apr_status_t rv = flush(b, ctx);
                if (rv != APR_SUCCESS) {
                    return rv;
                }
            }

            /* Now fall through into the case below to
             * allocate another heap bucket and copy the
             * rest of the array.  (Note that i is not
             * reset to zero here; it holds the index
             * of the first vector element to be
             * written to the new bucket.)
             */
        }
    }

    /* Allocate a new heap bucket, and copy the data into it.
     * The checks above ensure that the amount of data to be
     * written here is no larger than APR_BUCKET_BUFF_SIZE.
     */
    buf = apr_bucket_alloc(APR_BUCKET_BUFF_SIZE, b->bucket_alloc);
    e = apr_bucket_heap_create(buf, APR_BUCKET_BUFF_SIZE,
                               apr_bucket_free, b->bucket_alloc);
    for (; i < nvec; i++) {
        apr_size_t len = vec[i].iov_len;
        memcpy(buf, (const void *) vec[i].iov_base, len);
        buf += len;
    }
    e->length = total_len;
    APR_BRIGADE_INSERT_TAIL(b, e);

    return APR_SUCCESS;
}

APU_DECLARE(apr_status_t) apr_brigade_puts(apr_bucket_brigade *bb,
                                           apr_brigade_flush flush, void *ctx,
                                           const char *str)
{
    return apr_brigade_write(bb, flush, ctx, str, strlen(str));
}

APU_DECLARE_NONSTD(apr_status_t) apr_brigade_putstrs(apr_bucket_brigade *b, 
                                                     apr_brigade_flush flush,
                                                     void *ctx, ...)
{
    va_list va;
    apr_status_t rv;

    va_start(va, ctx);
    rv = apr_brigade_vputstrs(b, flush, ctx, va);
    va_end(va);
    return rv;
}

APU_DECLARE_NONSTD(apr_status_t) apr_brigade_printf(apr_bucket_brigade *b, 
                                                    apr_brigade_flush flush,
                                                    void *ctx, 
                                                    const char *fmt, ...)
{
    va_list ap;
    apr_status_t rv;

    va_start(ap, fmt);
    rv = apr_brigade_vprintf(b, flush, ctx, fmt, ap);
    va_end(ap);
    return rv;
}

struct brigade_vprintf_data_t {
    apr_vformatter_buff_t vbuff;

    apr_bucket_brigade *b;  /* associated brigade */
    apr_brigade_flush *flusher; /* flushing function */
    void *ctx;

    char *cbuff; /* buffer to flush from */
};

static apr_status_t brigade_flush(apr_vformatter_buff_t *buff)
{
    /* callback function passed to ap_vformatter to be
     * called when vformatter needs to buff and
     * buff.curpos > buff.endpos
     */

    /* "downcast," have really passed a brigade_vprintf_data_t* */
    struct brigade_vprintf_data_t *vd = (struct brigade_vprintf_data_t*)buff;
    apr_status_t res = APR_SUCCESS;

    res = apr_brigade_write(vd->b, *vd->flusher, vd->ctx, vd->cbuff,
                          APR_BUCKET_BUFF_SIZE);

    if(res != APR_SUCCESS) {
      return -1;
    }

    vd->vbuff.curpos = vd->cbuff;
    vd->vbuff.endpos = vd->cbuff + APR_BUCKET_BUFF_SIZE;

    return res;
}

APU_DECLARE(apr_status_t) apr_brigade_vprintf(apr_bucket_brigade *b,
                                              apr_brigade_flush flush,
                                              void *ctx,
                                              const char *fmt, va_list va)
{
    /* the cast, in order of appearance */
    struct brigade_vprintf_data_t vd;
    char buf[APR_BUCKET_BUFF_SIZE];
    int written;

    vd.vbuff.curpos = buf;
    vd.vbuff.endpos = buf + APR_BUCKET_BUFF_SIZE;
    vd.b = b;
    vd.flusher = &flush;
    vd.ctx = ctx;
    vd.cbuff = buf;

    written = apr_vformatter(brigade_flush, &vd.vbuff, fmt, va);

    if (written == -1) {
      return -1;
    }

    /* write out what remains in the buffer */
    return apr_brigade_write(b, flush, ctx, buf, vd.vbuff.curpos - buf);
}

/* A "safe" maximum bucket size, 1Gb */
#define MAX_BUCKET_SIZE (0x40000000)

APU_DECLARE(apr_bucket *) apr_brigade_insert_file(apr_bucket_brigade *bb,
                                                  apr_file_t *f,
                                                  apr_off_t start,
                                                  apr_off_t length,
                                                  apr_pool_t *p)
{
    apr_bucket *e;

    if (sizeof(apr_off_t) == sizeof(apr_size_t) || length < MAX_BUCKET_SIZE) {
        e = apr_bucket_file_create(f, start, (apr_size_t)length, p, 
                                   bb->bucket_alloc);
    }
    else {
        /* Several buckets are needed. */        
        e = apr_bucket_file_create(f, start, MAX_BUCKET_SIZE, p, 
                                   bb->bucket_alloc);

        while (length > MAX_BUCKET_SIZE) {
            apr_bucket *ce;
            apr_bucket_copy(e, &ce);
            APR_BRIGADE_INSERT_TAIL(bb, ce);
            e->start += MAX_BUCKET_SIZE;
            length -= MAX_BUCKET_SIZE;
        }
        e->length = (apr_size_t)length; /* Resize just the last bucket */
    }
    
    APR_BRIGADE_INSERT_TAIL(bb, e);
    return e;
}