aboutsummaryrefslogtreecommitdiff
path: root/qemu-file.c
blob: e5ec798e0b5f61fb12b2c32f5b90ba1c14e16fd1 (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
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
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
#include "qemu-common.h"
#include "qemu/iov.h"
#include "qemu/sockets.h"
#include "block/coroutine.h"
#include "migration/migration.h"
#include "migration/qemu-file.h"

#define IO_BUF_SIZE 32768
#define MAX_IOV_SIZE MIN(IOV_MAX, 64)

struct QEMUFile {
    const QEMUFileOps *ops;
    void *opaque;

    int64_t bytes_xfer;
    int64_t xfer_limit;

    int64_t pos; /* start of buffer when writing, end of buffer
                    when reading */
    int buf_index;
    int buf_size; /* 0 when writing */
    uint8_t buf[IO_BUF_SIZE];

    struct iovec iov[MAX_IOV_SIZE];
    unsigned int iovcnt;

    int last_error;
};

typedef struct QEMUFileStdio {
    FILE *stdio_file;
    QEMUFile *file;
} QEMUFileStdio;

typedef struct QEMUFileSocket {
    int fd;
    QEMUFile *file;
} QEMUFileSocket;

static ssize_t socket_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
                                    int64_t pos)
{
    QEMUFileSocket *s = opaque;
    ssize_t len;
    ssize_t size = iov_size(iov, iovcnt);

    len = iov_send(s->fd, iov, iovcnt, 0, size);
    if (len < size) {
        len = -socket_error();
    }
    return len;
}

static int socket_get_fd(void *opaque)
{
    QEMUFileSocket *s = opaque;

    return s->fd;
}

static int socket_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
    QEMUFileSocket *s = opaque;
    ssize_t len;

    for (;;) {
        len = qemu_recv(s->fd, buf, size, 0);
        if (len != -1) {
            break;
        }
        if (socket_error() == EAGAIN) {
            yield_until_fd_readable(s->fd);
        } else if (socket_error() != EINTR) {
            break;
        }
    }

    if (len == -1) {
        len = -socket_error();
    }
    return len;
}

static int socket_close(void *opaque)
{
    QEMUFileSocket *s = opaque;
    closesocket(s->fd);
    g_free(s);
    return 0;
}

static int stdio_get_fd(void *opaque)
{
    QEMUFileStdio *s = opaque;

    return fileno(s->stdio_file);
}

static int stdio_put_buffer(void *opaque, const uint8_t *buf, int64_t pos,
                            int size)
{
    QEMUFileStdio *s = opaque;
    int res;

    res = fwrite(buf, 1, size, s->stdio_file);

    if (res != size) {
        return -errno;
    }
    return res;
}

static int stdio_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
    QEMUFileStdio *s = opaque;
    FILE *fp = s->stdio_file;
    int bytes;

    for (;;) {
        clearerr(fp);
        bytes = fread(buf, 1, size, fp);
        if (bytes != 0 || !ferror(fp)) {
            break;
        }
        if (errno == EAGAIN) {
            yield_until_fd_readable(fileno(fp));
        } else if (errno != EINTR) {
            break;
        }
    }
    return bytes;
}

static int stdio_pclose(void *opaque)
{
    QEMUFileStdio *s = opaque;
    int ret;
    ret = pclose(s->stdio_file);
    if (ret == -1) {
        ret = -errno;
    } else if (!WIFEXITED(ret) || WEXITSTATUS(ret) != 0) {
        /* close succeeded, but non-zero exit code: */
        ret = -EIO; /* fake errno value */
    }
    g_free(s);
    return ret;
}

static int stdio_fclose(void *opaque)
{
    QEMUFileStdio *s = opaque;
    int ret = 0;

    if (s->file->ops->put_buffer || s->file->ops->writev_buffer) {
        int fd = fileno(s->stdio_file);
        struct stat st;

        ret = fstat(fd, &st);
        if (ret == 0 && S_ISREG(st.st_mode)) {
            /*
             * If the file handle is a regular file make sure the
             * data is flushed to disk before signaling success.
             */
            ret = fsync(fd);
            if (ret != 0) {
                ret = -errno;
                return ret;
            }
        }
    }
    if (fclose(s->stdio_file) == EOF) {
        ret = -errno;
    }
    g_free(s);
    return ret;
}

static const QEMUFileOps stdio_pipe_read_ops = {
    .get_fd =     stdio_get_fd,
    .get_buffer = stdio_get_buffer,
    .close =      stdio_pclose
};

static const QEMUFileOps stdio_pipe_write_ops = {
    .get_fd =     stdio_get_fd,
    .put_buffer = stdio_put_buffer,
    .close =      stdio_pclose
};

QEMUFile *qemu_popen_cmd(const char *command, const char *mode)
{
    FILE *stdio_file;
    QEMUFileStdio *s;

    if (mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || mode[1] != 0) {
        fprintf(stderr, "qemu_popen: Argument validity check failed\n");
        return NULL;
    }

    stdio_file = popen(command, mode);
    if (stdio_file == NULL) {
        return NULL;
    }

    s = g_malloc0(sizeof(QEMUFileStdio));

    s->stdio_file = stdio_file;

    if (mode[0] == 'r') {
        s->file = qemu_fopen_ops(s, &stdio_pipe_read_ops);
    } else {
        s->file = qemu_fopen_ops(s, &stdio_pipe_write_ops);
    }
    return s->file;
}

static const QEMUFileOps stdio_file_read_ops = {
    .get_fd =     stdio_get_fd,
    .get_buffer = stdio_get_buffer,
    .close =      stdio_fclose
};

static const QEMUFileOps stdio_file_write_ops = {
    .get_fd =     stdio_get_fd,
    .put_buffer = stdio_put_buffer,
    .close =      stdio_fclose
};

static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt,
                                  int64_t pos)
{
    QEMUFileSocket *s = opaque;
    ssize_t len, offset;
    ssize_t size = iov_size(iov, iovcnt);
    ssize_t total = 0;

    assert(iovcnt > 0);
    offset = 0;
    while (size > 0) {
        /* Find the next start position; skip all full-sized vector elements  */
        while (offset >= iov[0].iov_len) {
            offset -= iov[0].iov_len;
            iov++, iovcnt--;
        }

        /* skip `offset' bytes from the (now) first element, undo it on exit */
        assert(iovcnt > 0);
        iov[0].iov_base += offset;
        iov[0].iov_len -= offset;

        do {
            len = writev(s->fd, iov, iovcnt);
        } while (len == -1 && errno == EINTR);
        if (len == -1) {
            return -errno;
        }

        /* Undo the changes above */
        iov[0].iov_base -= offset;
        iov[0].iov_len += offset;

        /* Prepare for the next iteration */
        offset += len;
        total += len;
        size -= len;
    }

    return total;
}

static int unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size)
{
    QEMUFileSocket *s = opaque;
    ssize_t len;

    for (;;) {
        len = read(s->fd, buf, size);
        if (len != -1) {
            break;
        }
        if (errno == EAGAIN) {
            yield_until_fd_readable(s->fd);
        } else if (errno != EINTR) {
            break;
        }
    }

    if (len == -1) {
        len = -errno;
    }
    return len;
}

static int unix_close(void *opaque)
{
    QEMUFileSocket *s = opaque;
    close(s->fd);
    g_free(s);
    return 0;
}

static const QEMUFileOps unix_read_ops = {
    .get_fd =     socket_get_fd,
    .get_buffer = unix_get_buffer,
    .close =      unix_close
};

static const QEMUFileOps unix_write_ops = {
    .get_fd =     socket_get_fd,
    .writev_buffer = unix_writev_buffer,
    .close =      unix_close
};

QEMUFile *qemu_fdopen(int fd, const char *mode)
{
    QEMUFileSocket *s;

    if (mode == NULL ||
        (mode[0] != 'r' && mode[0] != 'w') ||
        mode[1] != 'b' || mode[2] != 0) {
        fprintf(stderr, "qemu_fdopen: Argument validity check failed\n");
        return NULL;
    }

    s = g_malloc0(sizeof(QEMUFileSocket));
    s->fd = fd;

    if (mode[0] == 'r') {
        s->file = qemu_fopen_ops(s, &unix_read_ops);
    } else {
        s->file = qemu_fopen_ops(s, &unix_write_ops);
    }
    return s->file;
}

static const QEMUFileOps socket_read_ops = {
    .get_fd =     socket_get_fd,
    .get_buffer = socket_get_buffer,
    .close =      socket_close
};

static const QEMUFileOps socket_write_ops = {
    .get_fd =     socket_get_fd,
    .writev_buffer = socket_writev_buffer,
    .close =      socket_close
};

bool qemu_file_mode_is_not_valid(const char *mode)
{
    if (mode == NULL ||
        (mode[0] != 'r' && mode[0] != 'w') ||
        mode[1] != 'b' || mode[2] != 0) {
        fprintf(stderr, "qemu_fopen: Argument validity check failed\n");
        return true;
    }

    return false;
}

QEMUFile *qemu_fopen_socket(int fd, const char *mode)
{
    QEMUFileSocket *s;

    if (qemu_file_mode_is_not_valid(mode)) {
        return NULL;
    }

    s = g_malloc0(sizeof(QEMUFileSocket));
    s->fd = fd;
    if (mode[0] == 'w') {
        qemu_set_block(s->fd);
        s->file = qemu_fopen_ops(s, &socket_write_ops);
    } else {
        s->file = qemu_fopen_ops(s, &socket_read_ops);
    }
    return s->file;
}

QEMUFile *qemu_fopen(const char *filename, const char *mode)
{
    QEMUFileStdio *s;

    if (qemu_file_mode_is_not_valid(mode)) {
        return NULL;
    }

    s = g_malloc0(sizeof(QEMUFileStdio));

    s->stdio_file = fopen(filename, mode);
    if (!s->stdio_file) {
        goto fail;
    }

    if (mode[0] == 'w') {
        s->file = qemu_fopen_ops(s, &stdio_file_write_ops);
    } else {
        s->file = qemu_fopen_ops(s, &stdio_file_read_ops);
    }
    return s->file;
fail:
    g_free(s);
    return NULL;
}

QEMUFile *qemu_fopen_ops(void *opaque, const QEMUFileOps *ops)
{
    QEMUFile *f;

    f = g_malloc0(sizeof(QEMUFile));

    f->opaque = opaque;
    f->ops = ops;
    return f;
}

/*
 * Get last error for stream f
 *
 * Return negative error value if there has been an error on previous
 * operations, return 0 if no error happened.
 *
 */
int qemu_file_get_error(QEMUFile *f)
{
    return f->last_error;
}

void qemu_file_set_error(QEMUFile *f, int ret)
{
    if (f->last_error == 0) {
        f->last_error = ret;
    }
}

static inline bool qemu_file_is_writable(QEMUFile *f)
{
    return f->ops->writev_buffer || f->ops->put_buffer;
}

/**
 * Flushes QEMUFile buffer
 *
 * If there is writev_buffer QEMUFileOps it uses it otherwise uses
 * put_buffer ops.
 */
void qemu_fflush(QEMUFile *f)
{
    ssize_t ret = 0;

    if (!qemu_file_is_writable(f)) {
        return;
    }

    if (f->ops->writev_buffer) {
        if (f->iovcnt > 0) {
            ret = f->ops->writev_buffer(f->opaque, f->iov, f->iovcnt, f->pos);
        }
    } else {
        if (f->buf_index > 0) {
            ret = f->ops->put_buffer(f->opaque, f->buf, f->pos, f->buf_index);
        }
    }
    if (ret >= 0) {
        f->pos += ret;
    }
    f->buf_index = 0;
    f->iovcnt = 0;
    if (ret < 0) {
        qemu_file_set_error(f, ret);
    }
}

void ram_control_before_iterate(QEMUFile *f, uint64_t flags)
{
    int ret = 0;

    if (f->ops->before_ram_iterate) {
        ret = f->ops->before_ram_iterate(f, f->opaque, flags);
        if (ret < 0) {
            qemu_file_set_error(f, ret);
        }
    }
}

void ram_control_after_iterate(QEMUFile *f, uint64_t flags)
{
    int ret = 0;

    if (f->ops->after_ram_iterate) {
        ret = f->ops->after_ram_iterate(f, f->opaque, flags);
        if (ret < 0) {
            qemu_file_set_error(f, ret);
        }
    }
}

void ram_control_load_hook(QEMUFile *f, uint64_t flags)
{
    int ret = -EINVAL;

    if (f->ops->hook_ram_load) {
        ret = f->ops->hook_ram_load(f, f->opaque, flags);
        if (ret < 0) {
            qemu_file_set_error(f, ret);
        }
    } else {
        qemu_file_set_error(f, ret);
    }
}

size_t ram_control_save_page(QEMUFile *f, ram_addr_t block_offset,
                         ram_addr_t offset, size_t size, int *bytes_sent)
{
    if (f->ops->save_page) {
        int ret = f->ops->save_page(f, f->opaque, block_offset,
                                    offset, size, bytes_sent);

        if (ret != RAM_SAVE_CONTROL_DELAYED) {
            if (bytes_sent && *bytes_sent > 0) {
                qemu_update_position(f, *bytes_sent);
            } else if (ret < 0) {
                qemu_file_set_error(f, ret);
            }
        }

        return ret;
    }

    return RAM_SAVE_CONTROL_NOT_SUPP;
}

static void qemu_fill_buffer(QEMUFile *f)
{
    int len;
    int pending;

    assert(!qemu_file_is_writable(f));

    pending = f->buf_size - f->buf_index;
    if (pending > 0) {
        memmove(f->buf, f->buf + f->buf_index, pending);
    }
    f->buf_index = 0;
    f->buf_size = pending;

    len = f->ops->get_buffer(f->opaque, f->buf + pending, f->pos,
                        IO_BUF_SIZE - pending);
    if (len > 0) {
        f->buf_size += len;
        f->pos += len;
    } else if (len == 0) {
        qemu_file_set_error(f, -EIO);
    } else if (len != -EAGAIN) {
        qemu_file_set_error(f, len);
    }
}

int qemu_get_fd(QEMUFile *f)
{
    if (f->ops->get_fd) {
        return f->ops->get_fd(f->opaque);
    }
    return -1;
}

void qemu_update_position(QEMUFile *f, size_t size)
{
    f->pos += size;
}

/** Closes the file
 *
 * Returns negative error value if any error happened on previous operations or
 * while closing the file. Returns 0 or positive number on success.
 *
 * The meaning of return value on success depends on the specific backend
 * being used.
 */
int qemu_fclose(QEMUFile *f)
{
    int ret;
    qemu_fflush(f);
    ret = qemu_file_get_error(f);

    if (f->ops->close) {
        int ret2 = f->ops->close(f->opaque);
        if (ret >= 0) {
            ret = ret2;
        }
    }
    /* If any error was spotted before closing, we should report it
     * instead of the close() return value.
     */
    if (f->last_error) {
        ret = f->last_error;
    }
    g_free(f);
    return ret;
}

static void add_to_iovec(QEMUFile *f, const uint8_t *buf, int size)
{
    /* check for adjacent buffer and coalesce them */
    if (f->iovcnt > 0 && buf == f->iov[f->iovcnt - 1].iov_base +
        f->iov[f->iovcnt - 1].iov_len) {
        f->iov[f->iovcnt - 1].iov_len += size;
    } else {
        f->iov[f->iovcnt].iov_base = (uint8_t *)buf;
        f->iov[f->iovcnt++].iov_len = size;
    }

    if (f->iovcnt >= MAX_IOV_SIZE) {
        qemu_fflush(f);
    }
}

void qemu_put_buffer_async(QEMUFile *f, const uint8_t *buf, int size)
{
    if (!f->ops->writev_buffer) {
        qemu_put_buffer(f, buf, size);
        return;
    }

    if (f->last_error) {
        return;
    }

    f->bytes_xfer += size;
    add_to_iovec(f, buf, size);
}

void qemu_put_buffer(QEMUFile *f, const uint8_t *buf, int size)
{
    int l;

    if (f->last_error) {
        return;
    }

    while (size > 0) {
        l = IO_BUF_SIZE - f->buf_index;
        if (l > size) {
            l = size;
        }
        memcpy(f->buf + f->buf_index, buf, l);
        f->bytes_xfer += l;
        if (f->ops->writev_buffer) {
            add_to_iovec(f, f->buf + f->buf_index, l);
        }
        f->buf_index += l;
        if (f->buf_index == IO_BUF_SIZE) {
            qemu_fflush(f);
        }
        if (qemu_file_get_error(f)) {
            break;
        }
        buf += l;
        size -= l;
    }
}

void qemu_put_byte(QEMUFile *f, int v)
{
    if (f->last_error) {
        return;
    }

    f->buf[f->buf_index] = v;
    f->bytes_xfer++;
    if (f->ops->writev_buffer) {
        add_to_iovec(f, f->buf + f->buf_index, 1);
    }
    f->buf_index++;
    if (f->buf_index == IO_BUF_SIZE) {
        qemu_fflush(f);
    }
}

void qemu_file_skip(QEMUFile *f, int size)
{
    if (f->buf_index + size <= f->buf_size) {
        f->buf_index += size;
    }
}

int qemu_peek_buffer(QEMUFile *f, uint8_t *buf, int size, size_t offset)
{
    int pending;
    int index;

    assert(!qemu_file_is_writable(f));

    index = f->buf_index + offset;
    pending = f->buf_size - index;
    if (pending < size) {
        qemu_fill_buffer(f);
        index = f->buf_index + offset;
        pending = f->buf_size - index;
    }

    if (pending <= 0) {
        return 0;
    }
    if (size > pending) {
        size = pending;
    }

    memcpy(buf, f->buf + index, size);
    return size;
}

int qemu_get_buffer(QEMUFile *f, uint8_t *buf, int size)
{
    int pending = size;
    int done = 0;

    while (pending > 0) {
        int res;

        res = qemu_peek_buffer(f, buf, pending, 0);
        if (res == 0) {
            return done;
        }
        qemu_file_skip(f, res);
        buf += res;
        pending -= res;
        done += res;
    }
    return done;
}

int qemu_peek_byte(QEMUFile *f, int offset)
{
    int index = f->buf_index + offset;

    assert(!qemu_file_is_writable(f));

    if (index >= f->buf_size) {
        qemu_fill_buffer(f);
        index = f->buf_index + offset;
        if (index >= f->buf_size) {
            return 0;
        }
    }
    return f->buf[index];
}

int qemu_get_byte(QEMUFile *f)
{
    int result;

    result = qemu_peek_byte(f, 0);
    qemu_file_skip(f, 1);
    return result;
}

int64_t qemu_ftell(QEMUFile *f)
{
    qemu_fflush(f);
    return f->pos;
}

int qemu_file_rate_limit(QEMUFile *f)
{
    if (qemu_file_get_error(f)) {
        return 1;
    }
    if (f->xfer_limit > 0 && f->bytes_xfer > f->xfer_limit) {
        return 1;
    }
    return 0;
}

int64_t qemu_file_get_rate_limit(QEMUFile *f)
{
    return f->xfer_limit;
}

void qemu_file_set_rate_limit(QEMUFile *f, int64_t limit)
{
    f->xfer_limit = limit;
}

void qemu_file_reset_rate_limit(QEMUFile *f)
{
    f->bytes_xfer = 0;
}

void qemu_put_be16(QEMUFile *f, unsigned int v)
{
    qemu_put_byte(f, v >> 8);
    qemu_put_byte(f, v);
}

void qemu_put_be32(QEMUFile *f, unsigned int v)
{
    qemu_put_byte(f, v >> 24);
    qemu_put_byte(f, v >> 16);
    qemu_put_byte(f, v >> 8);
    qemu_put_byte(f, v);
}

void qemu_put_be64(QEMUFile *f, uint64_t v)
{
    qemu_put_be32(f, v >> 32);
    qemu_put_be32(f, v);
}

unsigned int qemu_get_be16(QEMUFile *f)
{
    unsigned int v;
    v = qemu_get_byte(f) << 8;
    v |= qemu_get_byte(f);
    return v;
}

unsigned int qemu_get_be32(QEMUFile *f)
{
    unsigned int v;
    v = qemu_get_byte(f) << 24;
    v |= qemu_get_byte(f) << 16;
    v |= qemu_get_byte(f) << 8;
    v |= qemu_get_byte(f);
    return v;
}

uint64_t qemu_get_be64(QEMUFile *f)
{
    uint64_t v;
    v = (uint64_t)qemu_get_be32(f) << 32;
    v |= qemu_get_be32(f);
    return v;
}