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*** empty log message ***
This commit is contained in:
David L. Leskovec
parent
d9691ab277
commit
6ca76333f3
@ -1,3 +1,8 @@
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Thu May 9 00:07:34 PST 2008 David L. Leskovec <dlesko@linux.vnet.ibm.com>
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* src/lxc_driver.c: use epoll in tty process to avoid consuming the
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cpu when the slave side disconnects
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Thu May 8 10:36:11 EST 2008 Daniel P. Berrange <berrange@redhat.com>
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* HACKING: Added notes on string/memory/buffer internal APIs
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172
src/lxc_driver.c
172
src/lxc_driver.c
@ -26,9 +26,10 @@
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#ifdef WITH_LXC
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#include <fcntl.h>
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#include <poll.h>
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#include <sys/epoll.h>
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#include <sched.h>
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#include <sys/utsname.h>
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#include <stdbool.h>
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#include <string.h>
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#include <sys/types.h>
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#include <termios.h>
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@ -552,7 +553,7 @@ static int lxcSetupContainerTty(virConnectPtr conn,
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int rc = -1;
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char tempTtyName[PATH_MAX];
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*ttymaster = posix_openpt(O_RDWR|O_NOCTTY);
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*ttymaster = posix_openpt(O_RDWR|O_NOCTTY|O_NONBLOCK);
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if (*ttymaster < 0) {
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lxcError(conn, NULL, VIR_ERR_INTERNAL_ERROR,
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_("posix_openpt failed: %s"), strerror(errno));
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@ -592,76 +593,156 @@ cleanup:
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return rc;
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}
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/**
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* lxcFdForward:
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* @readFd: file descriptor to read
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* @writeFd: file desriptor to write
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*
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* Reads 1 byte of data from readFd and writes to writeFd.
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*
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* Returns 0 on success, EAGAIN if returned on read, or -1 in case of error
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*/
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static int lxcFdForward(int readFd, int writeFd)
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{
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int rc = -1;
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char buf[2];
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if (1 != (saferead(readFd, buf, 1))) {
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if (EAGAIN == errno) {
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rc = EAGAIN;
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goto cleanup;
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}
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("read of fd %d failed: %s"), readFd, strerror(errno));
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goto cleanup;
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}
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if (1 != (safewrite(writeFd, buf, 1))) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("write to fd %d failed: %s"), writeFd, strerror(errno));
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goto cleanup;
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}
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rc = 0;
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cleanup:
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return rc;
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}
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typedef struct _lxcTtyForwardFd_t {
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int fd;
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bool active;
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} lxcTtyForwardFd_t;
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/**
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* lxcTtyForward:
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* @fd1: Open fd
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* @fd1: Open fd
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*
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* Forwards traffic between fds. Data read from fd1 will be written to fd2
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* Data read from fd2 will be written to fd1. This process loops forever.
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* This process loops forever.
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* This uses epoll in edge triggered mode to avoid a hard loop on POLLHUP
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* events when the user disconnects the virsh console via ctrl-]
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*
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* Returns 0 on success or -1 in case of error
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*/
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static int lxcTtyForward(int fd1, int fd2)
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{
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int rc = -1;
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int i;
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char buf[2];
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struct pollfd fds[2];
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int numFds = 0;
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int epollFd;
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struct epoll_event epollEvent;
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int numEvents;
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int numActive = 0;
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lxcTtyForwardFd_t fdArray[2];
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int timeout = -1;
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int curFdOff = 0;
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int writeFdOff = 0;
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if (0 <= fd1) {
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fds[numFds].fd = fd1;
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fds[numFds].events = POLLIN;
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++numFds;
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fdArray[0].fd = fd1;
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fdArray[0].active = false;
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fdArray[1].fd = fd2;
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fdArray[1].active = false;
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/* create the epoll fild descriptor */
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epollFd = epoll_create(2);
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if (0 > epollFd) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("epoll_create(2) failed: %s"), strerror(errno));
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goto cleanup;
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}
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if (0 <= fd2) {
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fds[numFds].fd = fd2;
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fds[numFds].events = POLLIN;
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++numFds;
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/* add the file descriptors the epoll fd */
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memset(&epollEvent, 0x00, sizeof(epollEvent));
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epollEvent.events = EPOLLIN|EPOLLET; /* edge triggered */
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epollEvent.data.fd = fd1;
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epollEvent.data.u32 = 0; /* fdArray position */
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if (0 > epoll_ctl(epollFd, EPOLL_CTL_ADD, fd1, &epollEvent)) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("epoll_ctl(fd1) failed: %s"), strerror(errno));
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goto cleanup;
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}
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if (0 == numFds) {
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DEBUG0("No fds to monitor, return");
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epollEvent.data.fd = fd2;
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epollEvent.data.u32 = 1; /* fdArray position */
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if (0 > epoll_ctl(epollFd, EPOLL_CTL_ADD, fd2, &epollEvent)) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("epoll_ctl(fd2) failed: %s"), strerror(errno));
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goto cleanup;
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}
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while (1) {
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if ((rc = poll(fds, numFds, -1)) <= 0) {
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/* if active fd's, return if no events, else wait forever */
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timeout = (numActive > 0) ? 0 : -1;
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numEvents = epoll_wait(epollFd, &epollEvent, 1, timeout);
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if (0 < numEvents) {
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if (epollEvent.events & EPOLLIN) {
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curFdOff = epollEvent.data.u32;
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if (!fdArray[curFdOff].active) {
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fdArray[curFdOff].active = true;
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++numActive;
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}
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if ((0 == rc) || (errno == EINTR) || (errno == EAGAIN)) {
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} else if (epollEvent.events & EPOLLHUP) {
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DEBUG("EPOLLHUP from fd %d", epollEvent.data.fd);
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continue;
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} else {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("error event %d"), epollEvent.events);
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goto cleanup;
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}
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} else if (0 == numEvents) {
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if (2 == numActive) {
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/* both fds active, toggle between the two */
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curFdOff ^= 1;
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} else {
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/* only one active, if current is active, use it, else it */
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/* must be the other one (ie. curFd just went inactive) */
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curFdOff = fdArray[curFdOff].active ? curFdOff : curFdOff ^ 1;
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}
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} else {
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if (EINTR == errno) {
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continue;
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}
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/* error */
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("poll returned error: %s"), strerror(errno));
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_("epoll_wait() failed: %s"), strerror(errno));
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goto cleanup;
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}
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for (i = 0; i < numFds; ++i) {
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if (!fds[i].revents) {
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continue;
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}
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if (fds[i].revents & POLLIN) {
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if (1 != (saferead(fds[i].fd, buf, 1))) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("read of fd %d failed: %s"), i,
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strerror(errno));
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goto cleanup;
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}
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if (1 < numFds) {
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if (1 != (safewrite(fds[i ^ 1].fd, buf, 1))) {
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lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
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_("write to fd %d failed: %s"), i,
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strerror(errno));
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goto cleanup;
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}
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}
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if (0 < numActive) {
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writeFdOff = curFdOff ^ 1;
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rc = lxcFdForward(fdArray[curFdOff].fd, fdArray[writeFdOff].fd);
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if (EAGAIN == rc) {
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/* this fd no longer has data, set it as inactive */
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--numActive;
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fdArray[curFdOff].active = false;
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} else if (-1 == rc) {
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goto cleanup;
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}
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}
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@ -671,7 +752,10 @@ static int lxcTtyForward(int fd1, int fd2)
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rc = 0;
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cleanup:
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return rc;
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close(fd1);
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close(fd2);
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close(epollFd);
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exit(rc);
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}
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/**
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