rewrite iov_send_recv() and move it to iov.c
Make it much more understandable, add a missing iov_cnt argument (number of iovs in the iov), and add comments to it. The new implementation has been extensively tested by splitting a large buffer into many small randomly-sized chunks, sending it over socket to another, slow process and verifying the receiving data is the same. Also add a unit test for iov_send_recv(), sending/ receiving data between two processes over a socketpair using random vectors and random sizes. Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Michael Tokarev
parent
2fc8ae1dd7
commit
25e5e4c7e9
83
cutils.c
83
cutils.c
@ -375,86 +375,3 @@ int qemu_parse_fd(const char *param)
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}
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return fd;
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}
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ssize_t iov_send_recv(int sockfd, struct iovec *iov,
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size_t offset, size_t bytes,
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bool do_sendv)
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{
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int iovlen;
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ssize_t ret;
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size_t diff;
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struct iovec *last_iov;
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/* last_iov is inclusive, so count from one. */
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iovlen = 1;
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last_iov = iov;
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bytes += offset;
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while (last_iov->iov_len < bytes) {
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bytes -= last_iov->iov_len;
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last_iov++;
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iovlen++;
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}
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diff = last_iov->iov_len - bytes;
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last_iov->iov_len -= diff;
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while (iov->iov_len <= offset) {
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offset -= iov->iov_len;
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iov++;
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iovlen--;
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}
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iov->iov_base = (char *) iov->iov_base + offset;
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iov->iov_len -= offset;
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{
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#if defined CONFIG_IOVEC && defined CONFIG_POSIX
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struct msghdr msg;
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memset(&msg, 0, sizeof(msg));
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msg.msg_iov = iov;
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msg.msg_iovlen = iovlen;
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do {
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if (do_sendv) {
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ret = sendmsg(sockfd, &msg, 0);
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} else {
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ret = recvmsg(sockfd, &msg, 0);
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}
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} while (ret == -1 && errno == EINTR);
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#else
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struct iovec *p = iov;
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ret = 0;
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while (iovlen > 0) {
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int rc;
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if (do_sendv) {
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rc = send(sockfd, p->iov_base, p->iov_len, 0);
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} else {
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rc = qemu_recv(sockfd, p->iov_base, p->iov_len, 0);
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}
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if (rc == -1) {
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if (errno == EINTR) {
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continue;
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}
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if (ret == 0) {
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ret = -1;
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}
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break;
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}
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if (rc == 0) {
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break;
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}
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ret += rc;
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iovlen--, p++;
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}
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#endif
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}
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/* Undo the changes above */
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iov->iov_base = (char *) iov->iov_base - offset;
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iov->iov_len += offset;
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last_iov->iov_len += diff;
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return ret;
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}
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103
iov.c
103
iov.c
@ -18,6 +18,14 @@
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#include "iov.h"
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#ifdef _WIN32
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# include <windows.h>
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# include <winsock2.h>
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#else
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# include <sys/types.h>
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# include <sys/socket.h>
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#endif
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size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
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size_t offset, const void *buf, size_t bytes)
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{
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@ -87,6 +95,101 @@ size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt)
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return len;
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}
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/* helper function for iov_send_recv() */
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static ssize_t
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do_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send)
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{
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#if defined CONFIG_IOVEC && defined CONFIG_POSIX
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ssize_t ret;
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struct msghdr msg;
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memset(&msg, 0, sizeof(msg));
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msg.msg_iov = iov;
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msg.msg_iovlen = iov_cnt;
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do {
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ret = do_send
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? sendmsg(sockfd, &msg, 0)
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: recvmsg(sockfd, &msg, 0);
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} while (ret < 0 && errno == EINTR);
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return ret;
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#else
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/* else send piece-by-piece */
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/*XXX Note: windows has WSASend() and WSARecv() */
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unsigned i;
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size_t count = 0;
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for (i = 0; i < iov_cnt; ++i) {
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ssize_t r = do_send
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? send(sockfd, iov[i].iov_base, iov[i].iov_len, 0)
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: recv(sockfd, iov[i].iov_base, iov[i].iov_len, 0);
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if (r > 0) {
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ret += r;
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} else if (!r) {
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break;
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} else if (errno == EINTR) {
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continue;
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} else {
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/* else it is some "other" error,
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* only return if there was no data processed. */
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if (ret == 0) {
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return -1;
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}
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break;
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}
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}
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return count;
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#endif
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}
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ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
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size_t offset, size_t bytes,
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bool do_send)
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{
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ssize_t ret;
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unsigned si, ei; /* start and end indexes */
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/* Find the start position, skipping `offset' bytes:
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* first, skip all full-sized vector elements, */
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for (si = 0; si < iov_cnt && offset >= iov[si].iov_len; ++si) {
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offset -= iov[si].iov_len;
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}
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if (offset) {
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assert(si < iov_cnt);
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/* second, skip `offset' bytes from the (now) first element,
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* undo it on exit */
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iov[si].iov_base += offset;
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iov[si].iov_len -= offset;
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}
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/* Find the end position skipping `bytes' bytes: */
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/* first, skip all full-sized elements */
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for (ei = si; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) {
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bytes -= iov[ei].iov_len;
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}
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if (bytes) {
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/* second, fixup the last element, and remember
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* the length we've cut from the end of it in `bytes' */
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size_t tail;
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assert(ei < iov_cnt);
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assert(iov[ei].iov_len > bytes);
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tail = iov[ei].iov_len - bytes;
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iov[ei].iov_len = bytes;
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bytes = tail; /* bytes is now equal to the tail size */
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++ei;
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}
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ret = do_send_recv(sockfd, iov + si, ei - si, do_send);
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/* Undo the changes above */
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if (offset) {
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iov[si].iov_base -= offset;
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iov[si].iov_len += offset;
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}
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if (bytes) {
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iov[ei-1].iov_len += bytes;
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}
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return ret;
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}
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void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
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FILE *fp, const char *prefix, size_t limit)
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{
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15
iov.h
15
iov.h
@ -60,7 +60,7 @@ size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
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* `offset' bytes in the beginning of iovec buffer are skipped and
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* next `bytes' bytes are used, which must be within data of iovec.
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*
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* r = iov_send_recv(sockfd, iov, offset, bytes, true);
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* r = iov_send_recv(sockfd, iov, iovcnt, offset, bytes, true);
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*
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* is logically equivalent to
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*
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@ -68,13 +68,16 @@ size_t iov_memset(const struct iovec *iov, const unsigned int iov_cnt,
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* iov_to_buf(iov, iovcnt, offset, buf, bytes);
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* r = send(sockfd, buf, bytes, 0);
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* free(buf);
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*
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* For iov_send_recv() _whole_ area being sent or received
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* should be within the iovec, not only beginning of it.
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*/
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ssize_t iov_send_recv(int sockfd, struct iovec *iov,
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ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt,
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size_t offset, size_t bytes, bool do_send);
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#define iov_recv(sockfd, iov, offset, bytes) \
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iov_send_recv(sockfd, iov, offset, bytes, false)
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#define iov_send(sockfd, iov, offset, bytes) \
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iov_send_recv(sockfd, iov, offset, bytes, true)
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#define iov_recv(sockfd, iov, iov_cnt, offset, bytes) \
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iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, false)
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#define iov_send(sockfd, iov, iov_cnt, offset, bytes) \
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iov_send_recv(sockfd, iov, iov_cnt, offset, bytes, true)
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/**
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* Produce a text hexdump of iovec `iov' with `iov_cnt' number of elements
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@ -34,7 +34,7 @@ qemu_co_sendv_recvv(int sockfd, struct iovec *iov, unsigned iov_cnt,
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size_t done = 0;
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ssize_t ret;
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while (done < bytes) {
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ret = iov_send_recv(sockfd, iov,
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ret = iov_send_recv(sockfd, iov, iov_cnt,
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offset + done, bytes - done, do_send);
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if (ret > 0) {
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done += ret;
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107
tests/test-iov.c
107
tests/test-iov.c
@ -1,6 +1,7 @@
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#include <glib.h>
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#include "qemu-common.h"
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#include "iov.h"
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#include "qemu_socket.h"
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/* create a randomly-sized iovec with random vectors */
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static void iov_random(struct iovec **iovp, unsigned *iov_cntp)
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@ -144,10 +145,116 @@ static void test_to_from_buf(void)
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}
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}
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static void test_io(void)
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{
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#ifndef _WIN32
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/* socketpair(PF_UNIX) which does not exist on windows */
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int sv[2];
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int r;
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unsigned i, j, k, s, t;
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fd_set fds;
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unsigned niov;
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struct iovec *iov, *siov;
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unsigned char *buf;
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size_t sz;
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iov_random(&iov, &niov);
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sz = iov_size(iov, niov);
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buf = g_malloc(sz);
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for (i = 0; i < sz; ++i) {
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buf[i] = i & 255;
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}
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iov_from_buf(iov, niov, 0, buf, sz);
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siov = g_malloc(sizeof(*iov) * niov);
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memcpy(siov, iov, sizeof(*iov) * niov);
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if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) < 0) {
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perror("socketpair");
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exit(1);
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}
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FD_ZERO(&fds);
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t = 0;
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if (fork() == 0) {
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/* writer */
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close(sv[0]);
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FD_SET(sv[1], &fds);
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fcntl(sv[1], F_SETFL, O_RDWR|O_NONBLOCK);
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r = g_test_rand_int_range(sz / 2, sz);
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setsockopt(sv[1], SOL_SOCKET, SO_SNDBUF, &r, sizeof(r));
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for (i = 0; i <= sz; ++i) {
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for (j = i; j <= sz; ++j) {
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k = i;
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do {
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s = g_test_rand_int_range(0, j - k + 1);
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r = iov_send(sv[1], iov, niov, k, s);
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g_assert(memcmp(iov, siov, sizeof(*iov)*niov) == 0);
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if (r >= 0) {
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k += r;
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t += r;
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usleep(g_test_rand_int_range(0, 30));
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} else if (errno == EAGAIN) {
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select(sv[1]+1, NULL, &fds, NULL, NULL);
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continue;
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} else {
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perror("send");
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exit(1);
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}
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} while(k < j);
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}
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}
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exit(0);
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} else {
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/* reader & verifier */
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close(sv[1]);
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FD_SET(sv[0], &fds);
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fcntl(sv[0], F_SETFL, O_RDWR|O_NONBLOCK);
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r = g_test_rand_int_range(sz / 2, sz);
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setsockopt(sv[0], SOL_SOCKET, SO_RCVBUF, &r, sizeof(r));
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usleep(500000);
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for (i = 0; i <= sz; ++i) {
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for (j = i; j <= sz; ++j) {
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k = i;
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iov_memset(iov, niov, 0, 0xff, -1);
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do {
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s = g_test_rand_int_range(0, j - k + 1);
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r = iov_recv(sv[0], iov, niov, k, s);
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g_assert(memcmp(iov, siov, sizeof(*iov)*niov) == 0);
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if (r > 0) {
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k += r;
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t += r;
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} else if (!r) {
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if (s) {
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break;
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}
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} else if (errno == EAGAIN) {
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select(sv[0]+1, &fds, NULL, NULL, NULL);
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continue;
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} else {
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perror("recv");
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exit(1);
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}
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} while(k < j);
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test_iov_bytes(iov, niov, i, j - i);
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}
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}
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}
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#endif
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}
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int main(int argc, char **argv)
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{
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g_test_init(&argc, &argv, NULL);
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g_test_rand_int();
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g_test_add_func("/basic/iov/from-to-buf", test_to_from_buf);
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g_test_add_func("/basic/iov/io", test_io);
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return g_test_run();
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}
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