diff options
Diffstat (limited to 'extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c')
| -rw-r--r-- | extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c | 304 |
1 files changed, 300 insertions, 4 deletions
diff --git a/extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c b/extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c index d5b3e127297..35dbf576f0e 100644 --- a/extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c +++ b/extras/vcl-ldpreload/src/libvcl-ldpreload/vcom.c @@ -19,6 +19,7 @@ #include <pthread.h> #include <time.h> #include <stdarg.h> +#include <sys/resource.h> #include <libvcl-ldpreload/vcom_socket_wrapper.h> #include <libvcl-ldpreload/vcom.h> @@ -2940,24 +2941,319 @@ epoll_pwait (int __epfd, struct epoll_event *__events, This function is a cancellation point and therefore not marked with __THROW. */ + int vcom_poll (struct pollfd *__fds, nfds_t __nfds, int __timeout) { + int rv = 0; + pid_t pid = getpid (); + + struct rlimit nofile_limit; + struct pollfd vcom_fds[MAX_POLL_NFDS_DEFAULT]; + nfds_t fds_idx = 0; + + /* actual set of file descriptors to be monitored */ + nfds_t libc_nfds = 0; + nfds_t vcom_nfds = 0; + + /* ready file descriptors + * + * number of structures which have nonzero revents fields + * in other words, descriptors with events or errors reported. + * */ + /* after call to libc_poll () */ + int rlibc_nfds = 0; + /* after call to vcom_socket_poll () */ + int rvcom_nfds = 0; + + + /* timeout value in units of timespec */ + struct timespec timeout_ts; + struct timespec start_time, now, end_time; + + + /* get start_time */ + rv = clock_gettime (CLOCK_MONOTONIC, &start_time); + if (rv == -1) + { + rv = -errno; + goto poll_done; + } + + /* set timeout_ts & end_time */ + if (__timeout >= 0) + { + /* set timeout_ts */ + timeout_ts.tv_sec = __timeout / MSEC_PER_SEC; + timeout_ts.tv_nsec = (__timeout % MSEC_PER_SEC) * NSEC_PER_MSEC; + set_normalized_timespec (&timeout_ts, + timeout_ts.tv_sec, timeout_ts.tv_nsec); + /* set end_time */ + if (__timeout) + { + end_time = timespec_add (start_time, timeout_ts); + } + else + { + end_time = start_time; + } + } + if (vcom_init () != 0) { - return -1; + rv = -1; + goto poll_done; } - return -EOPNOTSUPP; + /* validate __fds */ + if (!__fds) + { + rv = -EFAULT; + goto poll_done; + } + + /* validate __nfds */ + /*TBD: call getrlimit once when vcl-ldpreload library is init */ + rv = getrlimit (RLIMIT_NOFILE, &nofile_limit); + if (rv != 0) + { + rv = -errno; + goto poll_done; + } + if (__nfds >= nofile_limit.rlim_cur || __nfds < 0) + { + rv = -EINVAL; + goto poll_done; + } + + /* + * for the POC, it's fair to assume that nfds is less than 1024 + * */ + if (__nfds >= MAX_POLL_NFDS_DEFAULT) + { + rv = -EINVAL; + goto poll_done; + } + + /* set revents field (output parameter) + * to zero + * */ + for (fds_idx = 0; fds_idx < __nfds; fds_idx++) + { + __fds[fds_idx].revents = 0; + } + +#if 0 + /* set revents field (output parameter) + * to zero for user ignored fds + * */ + for (fds_idx = 0; fds_idx < __nfds; fds_idx++) + { + /* + * if negative fd, ignore events field + * and set output parameter (revents field) to zero */ + if (__fds[fds_idx].fd < 0) + { + __fds[fds_idx].revents = 0; + } + } +#endif + + /* + * 00. prepare __fds and vcom_fds for polling + * copy __fds to vcom_fds + * 01. negate all except libc fds in __fds, + * ignore user negated fds + * 02. negate all except vcom_fds in vocm fds, + * ignore user negated fds + * ignore fd 0 by setting it to negative number + * */ + memcpy (vcom_fds, __fds, sizeof (*__fds) * __nfds); + libc_nfds = 0; + vcom_nfds = 0; + for (fds_idx = 0; fds_idx < __nfds; fds_idx++) + { + /* ignore negative fds */ + if (__fds[fds_idx].fd < 0) + { + continue; + } + + /* + * 00. ignore vcom fds in __fds + * 01. ignore libc fds in vcom_fds, + * ignore fd 0 by setting it to negative number. + * as fd 0 cannot be ignored. + */ + if (is_vcom_socket_fd (__fds[fds_idx].fd) || + is_vcom_epfd (__fds[fds_idx].fd)) + { + __fds[fds_idx].fd = -__fds[fds_idx].fd; + vcom_nfds++; + } + else + { + libc_nfds++; + /* ignore fd 0 by setting it to negative number */ + if (!vcom_fds[fds_idx].fd) + { + vcom_fds[fds_idx].fd = -1; + } + vcom_fds[fds_idx].fd = -vcom_fds[fds_idx].fd; + } + } + + /* + * polling loop + * + * poll on libc fds and vcom fds + * + * specifying a timeout of zero causes libc_poll() and + * vcom_socket_poll() to return immediately, even if no + * file descriptors are ready + * */ + do + { + rlibc_nfds = 0; + rvcom_nfds = 0; + + /* + * timeout parameter for libc_poll () set to zero + * to poll on libc fds + * */ + + /* poll on libc fds */ + if (libc_nfds) + { + /* + * a timeout of zero causes libc_poll() + * to return immediately + * */ + rlibc_nfds = libc_poll (__fds, __nfds, 0); + if (VCOM_DEBUG > 0) + fprintf (stderr, + "[%d] poll libc: " + "'%04d'='%08lu'\n", pid, rlibc_nfds, __nfds); + + if (rlibc_nfds < 0) + { + rv = -errno; + goto poll_done_update_nfds; + } + } + + /* + * timeout parameter for vcom_socket_poll () set to zero + * to poll on vcom fds + * */ + + /* poll on vcom fds */ + if (vcom_nfds) + { + /* + * a timeout of zero causes vcom_socket_poll() + * to return immediately + * */ + rvcom_nfds = vcom_socket_poll (vcom_fds, __nfds, 0); + if (VCOM_DEBUG > 0) + fprintf (stderr, + "[%d] poll vcom: " + "'%04d'='%08lu'\n", pid, rvcom_nfds, __nfds); + if (rvcom_nfds < 0) + { + rv = rvcom_nfds; + goto poll_done_update_nfds; + } + } + + /* check if any file descriptors changed status */ + if ((libc_nfds && rlibc_nfds > 0) || (vcom_nfds && rvcom_nfds > 0)) + { + /* something interesting happened */ + rv = rlibc_nfds + rvcom_nfds; + goto poll_done_update_nfds; + } + + rv = clock_gettime (CLOCK_MONOTONIC, &now); + if (rv == -1) + { + rv = -errno; + goto poll_done_update_nfds; + } + } + + /* block indefinitely || timeout elapsed */ + while ((__timeout < 0) || timespec_compare (&now, &end_time) < 0); + + /* timeout expired before anything interesting happened */ + rv = 0; + +poll_done_update_nfds: + for (fds_idx = 0; fds_idx < __nfds; fds_idx++) + { + /* ignore negative fds in vcom_fds + * 00. user negated fds + * 01. libc fds + * */ + if (vcom_fds[fds_idx].fd < 0) + { + continue; + } + + /* from here on handle positive vcom fds */ + /* + * restore vcom fds to positive number in __fds + * and update revents in __fds with the events + * that actually occurred in vcom fds + * */ + __fds[fds_idx].fd = -__fds[fds_idx].fd; + if (rvcom_nfds) + { + __fds[fds_idx].revents = vcom_fds[fds_idx].revents; + } + } + +poll_done: + if (VCOM_DEBUG > 0) + fprintf (stderr, "[%d] vpoll: " "'%04d'='%08lu'\n", pid, rv, __nfds); + return rv; } +/* + * 00. The field __fds[i].fd contains a file descriptor for an + * open file. + * If this field is negative, then the corresponding + * events field is ignored and the revents field returns zero. + * The field __fds[i].events is an input parameter. + * The field __fds[i].revents is an output parameter. + * 01. Specifying a negative value in timeout + * means an infinite timeout. + * Specifying a timeout of zero causes poll() to return + * immediately, even if no file descriptors are ready. + * + * NOTE: observed __nfds is less than 128 from kubecon strace files + */ + + int poll (struct pollfd *__fds, nfds_t __nfds, int __timeout) { int rv = 0; + pid_t pid = getpid (); - errno = EOPNOTSUPP; - rv = -1; + + if (VCOM_DEBUG > 0) + fprintf (stderr, "[%d] poll1: " "'%04d'='%08lu, %d, 0x%x'\n", + pid, rv, __nfds, __fds[0].fd, __fds[0].events); + rv = vcom_poll (__fds, __nfds, __timeout); + if (VCOM_DEBUG > 0) + fprintf (stderr, "[%d] poll2: " "'%04d'='%08lu, %d, 0x%x'\n", + pid, rv, __nfds, __fds[0].fd, __fds[0].revents); + if (rv < 0) + { + errno = -rv; + return -1; + } return rv; } |