aboutsummaryrefslogtreecommitdiff
path: root/util/iov.c
blob: c0f5c566185c22828c8ec100435c949630b49e82 (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
/*
 * Helpers for getting linearized buffers from iov / filling buffers into iovs
 *
 * Copyright IBM, Corp. 2007, 2008
 * Copyright (C) 2010 Red Hat, Inc.
 *
 * Author(s):
 *  Anthony Liguori <aliguori@us.ibm.com>
 *  Amit Shah <amit.shah@redhat.com>
 *  Michael Tokarev <mjt@tls.msk.ru>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.  See
 * the COPYING file in the top-level directory.
 *
 * Contributions after 2012-01-13 are licensed under the terms of the
 * GNU GPL, version 2 or (at your option) any later version.
 */

#include "qemu/iov.h"

#ifdef _WIN32
# include <windows.h>
# include <winsock2.h>
#else
# include <sys/types.h>
# include <sys/socket.h>
#endif

size_t iov_from_buf(const struct iovec *iov, unsigned int iov_cnt,
                    size_t offset, const void *buf, size_t bytes)
{
    size_t done;
    unsigned int i;
    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
        if (offset < iov[i].iov_len) {
            size_t len = MIN(iov[i].iov_len - offset, bytes - done);
            memcpy(iov[i].iov_base + offset, buf + done, len);
            done += len;
            offset = 0;
        } else {
            offset -= iov[i].iov_len;
        }
    }
    assert(offset == 0);
    return done;
}

size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
                  size_t offset, void *buf, size_t bytes)
{
    size_t done;
    unsigned int i;
    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
        if (offset < iov[i].iov_len) {
            size_t len = MIN(iov[i].iov_len - offset, bytes - done);
            memcpy(buf + done, iov[i].iov_base + offset, len);
            done += len;
            offset = 0;
        } else {
            offset -= iov[i].iov_len;
        }
    }
    assert(offset == 0);
    return done;
}

size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
                  size_t offset, int fillc, size_t bytes)
{
    size_t done;
    unsigned int i;
    for (i = 0, done = 0; (offset || done < bytes) && i < iov_cnt; i++) {
        if (offset < iov[i].iov_len) {
            size_t len = MIN(iov[i].iov_len - offset, bytes - done);
            memset(iov[i].iov_base + offset, fillc, len);
            done += len;
            offset = 0;
        } else {
            offset -= iov[i].iov_len;
        }
    }
    assert(offset == 0);
    return done;
}

size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
{
    size_t len;
    unsigned int i;

    len = 0;
    for (i = 0; i < iov_cnt; i++) {
        len += iov[i].iov_len;
    }
    return len;
}

/* helper function for iov_send_recv() */
static ssize_t
do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send)
{
#if defined CONFIG_IOVEC && defined CONFIG_POSIX
    ssize_t ret;
    struct msghdr msg;
    memset(&msg, 0, sizeof(msg));
    msg.msg_iov = iov;
    msg.msg_iovlen = iov_cnt;
    do {
        ret = do_send
            ? sendmsg(sockfd, &msg, 0)
            : recvmsg(sockfd, &msg, 0);
    } while (ret < 0 && errno == EINTR);
    return ret;
#else
    /* else send piece-by-piece */
    /*XXX Note: windows has WSASend() and WSARecv() */
    unsigned i = 0;
    ssize_t ret = 0;
    while (i < iov_cnt) {
        ssize_t r = do_send
            ? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0)
            : recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0);
        if (r > 0) {
            ret += r;
        } else if (!r) {
            break;
        } else if (errno == EINTR) {
            continue;
        } else {
            /* else it is some "other" error,
             * only return if there was no data processed. */
            if (ret == 0) {
                ret = -1;
            }
            break;
        }
        i++;
    }
    return ret;
#endif
}

ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
                      size_t offset, size_t bytes,
                      bool do_send)
{
    ssize_t ret;
    unsigned si, ei;            /* start and end indexes */
    if (bytes == 0) {
        /* Catch the do-nothing case early, as otherwise we will pass an
         * empty iovec to sendmsg/recvmsg(), and not all implementations
         * accept this.
         */
        return 0;
    }

    /* Find the start position, skipping `offset' bytes:
     * first, skip all full-sized vector elements, */
    for (si = 0; si < iov_cnt && offset >= iov[si].iov_len; ++si) {
        offset -= iov[si].iov_len;
    }
    if (offset) {
        assert(si < iov_cnt);
        /* second, skip `offset' bytes from the (now) first element,
         * undo it on exit */
        iov[si].iov_base += offset;
        iov[si].iov_len -= offset;
    }
    /* Find the end position skipping `bytes' bytes: */
    /* first, skip all full-sized elements */
    for (ei = si; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) {
        bytes -= iov[ei].iov_len;
    }
    if (bytes) {
        /* second, fixup the last element, and remember
         * the length we've cut from the end of it in `bytes' */
        size_t tail;
        assert(ei < iov_cnt);
        assert(iov[ei].iov_len > bytes);
        tail = iov[ei].iov_len - bytes;
        iov[ei].iov_len = bytes;
        bytes = tail;  /* bytes is now equal to the tail size */
        ++ei;
    }

    ret = do_send_recv(sockfd, iov + si, ei - si, do_send);

    /* Undo the changes above */
    if (offset) {
        iov[si].iov_base -= offset;
        iov[si].iov_len += offset;
    }
    if (bytes) {
        iov[ei-1].iov_len += bytes;
    }

    return ret;
}


void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
                 FILE *fp, const char *prefix, size_t limit)
{
    unsigned int i, v, b;
    uint8_t *c;

    c = iov[0].iov_base;
    for (i = 0, v = 0, b = 0; b < limit; i++, b++) {
        if (i == iov[v].iov_len) {
            i = 0; v++;
            if (v == iov_cnt) {
                break;
            }
            c = iov[v].iov_base;
        }
        if ((b % 16) == 0) {
            fprintf(fp, "%s: %04x:", prefix, b);
        }
        if ((b % 4) == 0) {
            fprintf(fp, " ");
        }
        fprintf(fp, " %02x", c[i]);
        if ((b % 16) == 15) {
            fprintf(fp, "\n");
        }
    }
    if ((b % 16) != 0) {
        fprintf(fp, "\n");
    }
}

unsigned iov_copy(struct iovec *dst_iov, unsigned int dst_iov_cnt,
                 const struct iovec *iov, unsigned int iov_cnt,
                 size_t offset, size_t bytes)
{
    size_t len;
    unsigned int i, j;
    for (i = 0, j = 0; i < iov_cnt && j < dst_iov_cnt && bytes; i++) {
        if (offset >= iov[i].iov_len) {
            offset -= iov[i].iov_len;
            continue;
        }
        len = MIN(bytes, iov[i].iov_len - offset);

        dst_iov[j].iov_base = iov[i].iov_base + offset;
        dst_iov[j].iov_len = len;
        j++;
        bytes -= len;
        offset = 0;
    }
    assert(offset == 0);
    return j;
}

/* io vectors */

void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
{
    qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec));
    qiov->niov = 0;
    qiov->nalloc = alloc_hint;
    qiov->size = 0;
}

void qemu_iovec_init_external(QEMUIOVector *qiov, struct iovec *iov, int niov)
{
    int i;

    qiov->iov = iov;
    qiov->niov = niov;
    qiov->nalloc = -1;
    qiov->size = 0;
    for (i = 0; i < niov; i++)
        qiov->size += iov[i].iov_len;
}

void qemu_iovec_add(QEMUIOVector *qiov, void *base, size_t len)
{
    assert(qiov->nalloc != -1);

    if (qiov->niov == qiov->nalloc) {
        qiov->nalloc = 2 * qiov->nalloc + 1;
        qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec));
    }
    qiov->iov[qiov->niov].iov_base = base;
    qiov->iov[qiov->niov].iov_len = len;
    qiov->size += len;
    ++qiov->niov;
}

/*
 * Concatenates (partial) iovecs from src_iov to the end of dst.
 * It starts copying after skipping `soffset' bytes at the
 * beginning of src and adds individual vectors from src to
 * dst copies up to `sbytes' bytes total, or up to the end
 * of src_iov if it comes first.  This way, it is okay to specify
 * very large value for `sbytes' to indicate "up to the end
 * of src".
 * Only vector pointers are processed, not the actual data buffers.
 */
void qemu_iovec_concat_iov(QEMUIOVector *dst,
                           struct iovec *src_iov, unsigned int src_cnt,
                           size_t soffset, size_t sbytes)
{
    int i;
    size_t done;
    assert(dst->nalloc != -1);
    for (i = 0, done = 0; done < sbytes && i < src_cnt; i++) {
        if (soffset < src_iov[i].iov_len) {
            size_t len = MIN(src_iov[i].iov_len - soffset, sbytes - done);
            qemu_iovec_add(dst, src_iov[i].iov_base + soffset, len);
            done += len;
            soffset = 0;
        } else {
            soffset -= src_iov[i].iov_len;
        }
    }
    assert(soffset == 0); /* offset beyond end of src */
}

/*
 * Concatenates (partial) iovecs from src to the end of dst.
 * It starts copying after skipping `soffset' bytes at the
 * beginning of src and adds individual vectors from src to
 * dst copies up to `sbytes' bytes total, or up to the end
 * of src if it comes first.  This way, it is okay to specify
 * very large value for `sbytes' to indicate "up to the end
 * of src".
 * Only vector pointers are processed, not the actual data buffers.
 */
void qemu_iovec_concat(QEMUIOVector *dst,
                       QEMUIOVector *src, size_t soffset, size_t sbytes)
{
    qemu_iovec_concat_iov(dst, src->iov, src->niov, soffset, sbytes);
}

void qemu_iovec_destroy(QEMUIOVector *qiov)
{
    assert(qiov->nalloc != -1);

    qemu_iovec_reset(qiov);
    g_free(qiov->iov);
    qiov->nalloc = 0;
    qiov->iov = NULL;
}

void qemu_iovec_reset(QEMUIOVector *qiov)
{
    assert(qiov->nalloc != -1);

    qiov->niov = 0;
    qiov->size = 0;
}

size_t qemu_iovec_to_buf(QEMUIOVector *qiov, size_t offset,
                         void *buf, size_t bytes)
{
    return iov_to_buf(qiov->iov, qiov->niov, offset, buf, bytes);
}

size_t qemu_iovec_from_buf(QEMUIOVector *qiov, size_t offset,
                           const void *buf, size_t bytes)
{
    return iov_from_buf(qiov->iov, qiov->niov, offset, buf, bytes);
}

size_t qemu_iovec_memset(QEMUIOVector *qiov, size_t offset,
                         int fillc, size_t bytes)
{
    return iov_memset(qiov->iov, qiov->niov, offset, fillc, bytes);
}

size_t iov_discard_front(struct iovec **iov, unsigned int *iov_cnt,
                         size_t bytes)
{
    size_t total = 0;
    struct iovec *cur;

    for (cur = *iov; *iov_cnt > 0; cur++) {
        if (cur->iov_len > bytes) {
            cur->iov_base += bytes;
            cur->iov_len -= bytes;
            total += bytes;
            break;
        }

        bytes -= cur->iov_len;
        total += cur->iov_len;
        *iov_cnt -= 1;
    }

    *iov = cur;
    return total;
}

size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
                        size_t bytes)
{
    size_t total = 0;
    struct iovec *cur;

    if (*iov_cnt == 0) {
        return 0;
    }

    cur = iov + (*iov_cnt - 1);

    while (*iov_cnt > 0) {
        if (cur->iov_len > bytes) {
            cur->iov_len -= bytes;
            total += bytes;
            break;
        }

        bytes -= cur->iov_len;
        total += cur->iov_len;
        cur--;
        *iov_cnt -= 1;
    }

    return total;
}