765 lines
20 KiB
C
765 lines
20 KiB
C
/*
|
|
* 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/osdep.h"
|
|
#include "qemu-common.h"
|
|
#include "qemu/iov.h"
|
|
#include "qemu/sockets.h"
|
|
#include "qemu/cutils.h"
|
|
|
|
size_t iov_from_buf_full(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_full(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)
|
|
{
|
|
#ifdef 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, const struct iovec *_iov, unsigned iov_cnt,
|
|
size_t offset, size_t bytes,
|
|
bool do_send)
|
|
{
|
|
ssize_t total = 0;
|
|
ssize_t ret;
|
|
size_t orig_len, tail;
|
|
unsigned niov;
|
|
struct iovec *local_iov, *iov;
|
|
|
|
if (bytes <= 0) {
|
|
return 0;
|
|
}
|
|
|
|
local_iov = g_new0(struct iovec, iov_cnt);
|
|
iov_copy(local_iov, iov_cnt, _iov, iov_cnt, offset, bytes);
|
|
offset = 0;
|
|
iov = local_iov;
|
|
|
|
while (bytes > 0) {
|
|
/* Find the start position, skipping `offset' bytes:
|
|
* first, skip all full-sized vector elements, */
|
|
for (niov = 0; niov < iov_cnt && offset >= iov[niov].iov_len; ++niov) {
|
|
offset -= iov[niov].iov_len;
|
|
}
|
|
|
|
/* niov == iov_cnt would only be valid if bytes == 0, which
|
|
* we already ruled out in the loop condition. */
|
|
assert(niov < iov_cnt);
|
|
iov += niov;
|
|
iov_cnt -= niov;
|
|
|
|
if (offset) {
|
|
/* second, skip `offset' bytes from the (now) first element,
|
|
* undo it on exit */
|
|
iov[0].iov_base += offset;
|
|
iov[0].iov_len -= offset;
|
|
}
|
|
/* Find the end position skipping `bytes' bytes: */
|
|
/* first, skip all full-sized elements */
|
|
tail = bytes;
|
|
for (niov = 0; niov < iov_cnt && iov[niov].iov_len <= tail; ++niov) {
|
|
tail -= iov[niov].iov_len;
|
|
}
|
|
if (tail) {
|
|
/* second, fixup the last element, and remember the original
|
|
* length */
|
|
assert(niov < iov_cnt);
|
|
assert(iov[niov].iov_len > tail);
|
|
orig_len = iov[niov].iov_len;
|
|
iov[niov++].iov_len = tail;
|
|
ret = do_send_recv(sockfd, iov, niov, do_send);
|
|
/* Undo the changes above before checking for errors */
|
|
iov[niov-1].iov_len = orig_len;
|
|
} else {
|
|
ret = do_send_recv(sockfd, iov, niov, do_send);
|
|
}
|
|
if (offset) {
|
|
iov[0].iov_base -= offset;
|
|
iov[0].iov_len += offset;
|
|
}
|
|
|
|
if (ret < 0) {
|
|
assert(errno != EINTR);
|
|
g_free(local_iov);
|
|
if (errno == EAGAIN && total > 0) {
|
|
return total;
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
if (ret == 0 && !do_send) {
|
|
/* recv returns 0 when the peer has performed an orderly
|
|
* shutdown. */
|
|
break;
|
|
}
|
|
|
|
/* Prepare for the next iteration */
|
|
offset += ret;
|
|
total += ret;
|
|
bytes -= ret;
|
|
}
|
|
|
|
g_free(local_iov);
|
|
return total;
|
|
}
|
|
|
|
|
|
void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
|
|
FILE *fp, const char *prefix, size_t limit)
|
|
{
|
|
int v;
|
|
size_t size = 0;
|
|
char *buf;
|
|
|
|
for (v = 0; v < iov_cnt; v++) {
|
|
size += iov[v].iov_len;
|
|
}
|
|
size = size > limit ? limit : size;
|
|
buf = g_malloc(size);
|
|
iov_to_buf(iov, iov_cnt, 0, buf, size);
|
|
qemu_hexdump(fp, prefix, buf, size);
|
|
g_free(buf);
|
|
}
|
|
|
|
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 && (offset || 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_new(struct iovec, alloc_hint);
|
|
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_renew(struct iovec, qiov->iov, qiov->nalloc);
|
|
}
|
|
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.
|
|
*/
|
|
size_t 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;
|
|
|
|
if (!sbytes) {
|
|
return 0;
|
|
}
|
|
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 */
|
|
|
|
return done;
|
|
}
|
|
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
/*
|
|
* qiov_find_iov
|
|
*
|
|
* Return pointer to iovec structure, where byte at @offset in original vector
|
|
* @iov exactly is.
|
|
* Set @remaining_offset to be offset inside that iovec to the same byte.
|
|
*/
|
|
static struct iovec *iov_skip_offset(struct iovec *iov, size_t offset,
|
|
size_t *remaining_offset)
|
|
{
|
|
while (offset > 0 && offset >= iov->iov_len) {
|
|
offset -= iov->iov_len;
|
|
iov++;
|
|
}
|
|
*remaining_offset = offset;
|
|
|
|
return iov;
|
|
}
|
|
|
|
/*
|
|
* qiov_slice
|
|
*
|
|
* Find subarray of iovec's, containing requested range. @head would
|
|
* be offset in first iov (returned by the function), @tail would be
|
|
* count of extra bytes in last iovec (returned iov + @niov - 1).
|
|
*/
|
|
static struct iovec *qiov_slice(QEMUIOVector *qiov,
|
|
size_t offset, size_t len,
|
|
size_t *head, size_t *tail, int *niov)
|
|
{
|
|
struct iovec *iov, *end_iov;
|
|
|
|
assert(offset + len <= qiov->size);
|
|
|
|
iov = iov_skip_offset(qiov->iov, offset, head);
|
|
end_iov = iov_skip_offset(iov, *head + len, tail);
|
|
|
|
if (*tail > 0) {
|
|
assert(*tail < end_iov->iov_len);
|
|
*tail = end_iov->iov_len - *tail;
|
|
end_iov++;
|
|
}
|
|
|
|
*niov = end_iov - iov;
|
|
|
|
return iov;
|
|
}
|
|
|
|
int qemu_iovec_subvec_niov(QEMUIOVector *qiov, size_t offset, size_t len)
|
|
{
|
|
size_t head, tail;
|
|
int niov;
|
|
|
|
qiov_slice(qiov, offset, len, &head, &tail, &niov);
|
|
|
|
return niov;
|
|
}
|
|
|
|
/*
|
|
* Compile new iovec, combining @head_buf buffer, sub-qiov of @mid_qiov,
|
|
* and @tail_buf buffer into new qiov.
|
|
*/
|
|
int qemu_iovec_init_extended(
|
|
QEMUIOVector *qiov,
|
|
void *head_buf, size_t head_len,
|
|
QEMUIOVector *mid_qiov, size_t mid_offset, size_t mid_len,
|
|
void *tail_buf, size_t tail_len)
|
|
{
|
|
size_t mid_head, mid_tail;
|
|
int total_niov, mid_niov = 0;
|
|
struct iovec *p, *mid_iov = NULL;
|
|
|
|
assert(mid_qiov->niov <= IOV_MAX);
|
|
|
|
if (SIZE_MAX - head_len < mid_len ||
|
|
SIZE_MAX - head_len - mid_len < tail_len)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (mid_len) {
|
|
mid_iov = qiov_slice(mid_qiov, mid_offset, mid_len,
|
|
&mid_head, &mid_tail, &mid_niov);
|
|
}
|
|
|
|
total_niov = !!head_len + mid_niov + !!tail_len;
|
|
if (total_niov > IOV_MAX) {
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (total_niov == 1) {
|
|
qemu_iovec_init_buf(qiov, NULL, 0);
|
|
p = &qiov->local_iov;
|
|
} else {
|
|
qiov->niov = qiov->nalloc = total_niov;
|
|
qiov->size = head_len + mid_len + tail_len;
|
|
p = qiov->iov = g_new(struct iovec, qiov->niov);
|
|
}
|
|
|
|
if (head_len) {
|
|
p->iov_base = head_buf;
|
|
p->iov_len = head_len;
|
|
p++;
|
|
}
|
|
|
|
assert(!mid_niov == !mid_len);
|
|
if (mid_niov) {
|
|
memcpy(p, mid_iov, mid_niov * sizeof(*p));
|
|
p[0].iov_base = (uint8_t *)p[0].iov_base + mid_head;
|
|
p[0].iov_len -= mid_head;
|
|
p[mid_niov - 1].iov_len -= mid_tail;
|
|
p += mid_niov;
|
|
}
|
|
|
|
if (tail_len) {
|
|
p->iov_base = tail_buf;
|
|
p->iov_len = tail_len;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Check if the contents of subrange of qiov data is all zeroes.
|
|
*/
|
|
bool qemu_iovec_is_zero(QEMUIOVector *qiov, size_t offset, size_t bytes)
|
|
{
|
|
struct iovec *iov;
|
|
size_t current_offset;
|
|
|
|
assert(offset + bytes <= qiov->size);
|
|
|
|
iov = iov_skip_offset(qiov->iov, offset, ¤t_offset);
|
|
|
|
while (bytes) {
|
|
uint8_t *base = (uint8_t *)iov->iov_base + current_offset;
|
|
size_t len = MIN(iov->iov_len - current_offset, bytes);
|
|
|
|
if (!buffer_is_zero(base, len)) {
|
|
return false;
|
|
}
|
|
|
|
current_offset = 0;
|
|
bytes -= len;
|
|
iov++;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
void qemu_iovec_init_slice(QEMUIOVector *qiov, QEMUIOVector *source,
|
|
size_t offset, size_t len)
|
|
{
|
|
int ret;
|
|
|
|
assert(source->size >= len);
|
|
assert(source->size - len >= offset);
|
|
|
|
/* We shrink the request, so we can't overflow neither size_t nor MAX_IOV */
|
|
ret = qemu_iovec_init_extended(qiov, NULL, 0, source, offset, len, NULL, 0);
|
|
assert(ret == 0);
|
|
}
|
|
|
|
void qemu_iovec_destroy(QEMUIOVector *qiov)
|
|
{
|
|
if (qiov->nalloc != -1) {
|
|
g_free(qiov->iov);
|
|
}
|
|
|
|
memset(qiov, 0, sizeof(*qiov));
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
/**
|
|
* Check that I/O vector contents are identical
|
|
*
|
|
* The IO vectors must have the same structure (same length of all parts).
|
|
* A typical usage is to compare vectors created with qemu_iovec_clone().
|
|
*
|
|
* @a: I/O vector
|
|
* @b: I/O vector
|
|
* @ret: Offset to first mismatching byte or -1 if match
|
|
*/
|
|
ssize_t qemu_iovec_compare(QEMUIOVector *a, QEMUIOVector *b)
|
|
{
|
|
int i;
|
|
ssize_t offset = 0;
|
|
|
|
assert(a->niov == b->niov);
|
|
for (i = 0; i < a->niov; i++) {
|
|
size_t len = 0;
|
|
uint8_t *p = (uint8_t *)a->iov[i].iov_base;
|
|
uint8_t *q = (uint8_t *)b->iov[i].iov_base;
|
|
|
|
assert(a->iov[i].iov_len == b->iov[i].iov_len);
|
|
while (len < a->iov[i].iov_len && *p++ == *q++) {
|
|
len++;
|
|
}
|
|
|
|
offset += len;
|
|
|
|
if (len != a->iov[i].iov_len) {
|
|
return offset;
|
|
}
|
|
}
|
|
return -1;
|
|
}
|
|
|
|
typedef struct {
|
|
int src_index;
|
|
struct iovec *src_iov;
|
|
void *dest_base;
|
|
} IOVectorSortElem;
|
|
|
|
static int sortelem_cmp_src_base(const void *a, const void *b)
|
|
{
|
|
const IOVectorSortElem *elem_a = a;
|
|
const IOVectorSortElem *elem_b = b;
|
|
|
|
/* Don't overflow */
|
|
if (elem_a->src_iov->iov_base < elem_b->src_iov->iov_base) {
|
|
return -1;
|
|
} else if (elem_a->src_iov->iov_base > elem_b->src_iov->iov_base) {
|
|
return 1;
|
|
} else {
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
static int sortelem_cmp_src_index(const void *a, const void *b)
|
|
{
|
|
const IOVectorSortElem *elem_a = a;
|
|
const IOVectorSortElem *elem_b = b;
|
|
|
|
return elem_a->src_index - elem_b->src_index;
|
|
}
|
|
|
|
/**
|
|
* Copy contents of I/O vector
|
|
*
|
|
* The relative relationships of overlapping iovecs are preserved. This is
|
|
* necessary to ensure identical semantics in the cloned I/O vector.
|
|
*/
|
|
void qemu_iovec_clone(QEMUIOVector *dest, const QEMUIOVector *src, void *buf)
|
|
{
|
|
IOVectorSortElem sortelems[src->niov];
|
|
void *last_end;
|
|
int i;
|
|
|
|
/* Sort by source iovecs by base address */
|
|
for (i = 0; i < src->niov; i++) {
|
|
sortelems[i].src_index = i;
|
|
sortelems[i].src_iov = &src->iov[i];
|
|
}
|
|
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_base);
|
|
|
|
/* Allocate buffer space taking into account overlapping iovecs */
|
|
last_end = NULL;
|
|
for (i = 0; i < src->niov; i++) {
|
|
struct iovec *cur = sortelems[i].src_iov;
|
|
ptrdiff_t rewind = 0;
|
|
|
|
/* Detect overlap */
|
|
if (last_end && last_end > cur->iov_base) {
|
|
rewind = last_end - cur->iov_base;
|
|
}
|
|
|
|
sortelems[i].dest_base = buf - rewind;
|
|
buf += cur->iov_len - MIN(rewind, cur->iov_len);
|
|
last_end = MAX(cur->iov_base + cur->iov_len, last_end);
|
|
}
|
|
|
|
/* Sort by source iovec index and build destination iovec */
|
|
qsort(sortelems, src->niov, sizeof(sortelems[0]), sortelem_cmp_src_index);
|
|
for (i = 0; i < src->niov; i++) {
|
|
qemu_iovec_add(dest, sortelems[i].dest_base, src->iov[i].iov_len);
|
|
}
|
|
}
|
|
|
|
void iov_discard_undo(IOVDiscardUndo *undo)
|
|
{
|
|
/* Restore original iovec if it was modified */
|
|
if (undo->modified_iov) {
|
|
*undo->modified_iov = undo->orig;
|
|
}
|
|
}
|
|
|
|
size_t iov_discard_front_undoable(struct iovec **iov,
|
|
unsigned int *iov_cnt,
|
|
size_t bytes,
|
|
IOVDiscardUndo *undo)
|
|
{
|
|
size_t total = 0;
|
|
struct iovec *cur;
|
|
|
|
if (undo) {
|
|
undo->modified_iov = NULL;
|
|
}
|
|
|
|
for (cur = *iov; *iov_cnt > 0; cur++) {
|
|
if (cur->iov_len > bytes) {
|
|
if (undo) {
|
|
undo->modified_iov = cur;
|
|
undo->orig = *cur;
|
|
}
|
|
|
|
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_front(struct iovec **iov, unsigned int *iov_cnt,
|
|
size_t bytes)
|
|
{
|
|
return iov_discard_front_undoable(iov, iov_cnt, bytes, NULL);
|
|
}
|
|
|
|
size_t iov_discard_back_undoable(struct iovec *iov,
|
|
unsigned int *iov_cnt,
|
|
size_t bytes,
|
|
IOVDiscardUndo *undo)
|
|
{
|
|
size_t total = 0;
|
|
struct iovec *cur;
|
|
|
|
if (undo) {
|
|
undo->modified_iov = NULL;
|
|
}
|
|
|
|
if (*iov_cnt == 0) {
|
|
return 0;
|
|
}
|
|
|
|
cur = iov + (*iov_cnt - 1);
|
|
|
|
while (*iov_cnt > 0) {
|
|
if (cur->iov_len > bytes) {
|
|
if (undo) {
|
|
undo->modified_iov = cur;
|
|
undo->orig = *cur;
|
|
}
|
|
|
|
cur->iov_len -= bytes;
|
|
total += bytes;
|
|
break;
|
|
}
|
|
|
|
bytes -= cur->iov_len;
|
|
total += cur->iov_len;
|
|
cur--;
|
|
*iov_cnt -= 1;
|
|
}
|
|
|
|
return total;
|
|
}
|
|
|
|
size_t iov_discard_back(struct iovec *iov, unsigned int *iov_cnt,
|
|
size_t bytes)
|
|
{
|
|
return iov_discard_back_undoable(iov, iov_cnt, bytes, NULL);
|
|
}
|
|
|
|
void qemu_iovec_discard_back(QEMUIOVector *qiov, size_t bytes)
|
|
{
|
|
size_t total;
|
|
unsigned int niov = qiov->niov;
|
|
|
|
assert(qiov->size >= bytes);
|
|
total = iov_discard_back(qiov->iov, &niov, bytes);
|
|
assert(total == bytes);
|
|
|
|
qiov->niov = niov;
|
|
qiov->size -= bytes;
|
|
}
|