The inotify userspace API for reading events is quite horrible, so it is useful to wrap it in a more friendly API to avoid duplicating code across many users in QEMU.
Signed-off-by: Daniel P. Berrangé <berra...@redhat.com> --- MAINTAINERS | 6 ++ include/qemu/inotify.h | 49 +++++++++++++++ util/Makefile.objs | 1 + util/inotify.c | 138 +++++++++++++++++++++++++++++++++++++++++ 4 files changed, 194 insertions(+) create mode 100644 include/qemu/inotify.h create mode 100644 util/inotify.c diff --git a/MAINTAINERS b/MAINTAINERS index 41cd3736a9..3610479af7 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1766,6 +1766,12 @@ F: include/qemu/sockets.h F: util/qemu-sockets.c F: qapi/sockets.json +Inotify +M: Daniel P. Berrange <berra...@redhat.com> +S: Odd fixes +F: util/inotify.c +F: include/qemu/inotify.h + Throttling infrastructure M: Alberto Garcia <be...@igalia.com> S: Supported diff --git a/include/qemu/inotify.h b/include/qemu/inotify.h new file mode 100644 index 0000000000..d78d04c5bb --- /dev/null +++ b/include/qemu/inotify.h @@ -0,0 +1,49 @@ +/* + * QEMU inotify helper + * + * Copyright (c) 2018 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, see <http://www.gnu.org/licenses/>. + * + */ + +#ifndef QEMU_INOTIFY_H +#define QEMU_INOTIFY_H + +#include "qemu-common.h" +#ifdef CONFIG_INOTIFY1 +#include <sys/inotify.h> +#endif + + +typedef struct QInotify QInotify; + +typedef void (*QInotifyHandler)(int wd, + uint32_t mask, + const char *name, + void *opaque); + +QInotify *qemu_inotify_new(QInotifyHandler cb, + void *opaque, + GDestroyNotify ffcb, + Error **errp); + +void qemu_inotify_free(QInotify *in); + +int qemu_inotify_add_watch(QInotify *in, + const char *path, + uint32_t mask, + Error **errp); + +#endif /* QEMU_INOTIFY_H */ diff --git a/util/Makefile.objs b/util/Makefile.objs index e1c3fed4dc..4c1b44d019 100644 --- a/util/Makefile.objs +++ b/util/Makefile.objs @@ -48,4 +48,5 @@ util-obj-y += range.o util-obj-y += stats64.o util-obj-y += systemd.o util-obj-y += iova-tree.o +util-obj-y += inotify.o util-obj-$(CONFIG_LINUX) += vfio-helpers.o diff --git a/util/inotify.c b/util/inotify.c new file mode 100644 index 0000000000..dd9c194bea --- /dev/null +++ b/util/inotify.c @@ -0,0 +1,138 @@ +/* + * QEMU inotify helper + * + * Copyright (c) 2018 Red Hat, Inc. + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2 of the License, or (at your option) any later version. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, see <http://www.gnu.org/licenses/>. + * + */ + +#include "qemu/osdep.h" +#include "qemu/inotify.h" +#include "qemu/main-loop.h" +#include "qemu/error-report.h" +#include "qapi/error.h" + +struct QInotify { + int fd; + QInotifyHandler cb; + void *opaque; + GDestroyNotify ffcb; +}; + +#ifdef CONFIG_INOTIFY1 +static void qemu_inotify_watch(void *arg) +{ + QInotify *in = arg; + char buf[4096] + __attribute__ ((aligned(__alignof__(struct inotify_event)))); + int used = 0; + int len = read(in->fd, buf, sizeof(buf)); + + if (len < 0) { + if (errno != EAGAIN) { + error_report("Failure monitoring inotify FD, disabling events"); + goto error; + } + + /* no more events right now */ + return; + } + + /* Loop over all events in the buffer */ + while (used < len) { + struct inotify_event *ev = + (struct inotify_event *)buf + used; + + in->cb(ev->wd, ev->mask, ev->name, in->opaque); + + used += sizeof(struct inotify_event) + ev->len; + } + + return; + + error: + qemu_set_fd_handler(in->fd, NULL, NULL, NULL); + close(in->fd); + in->fd = -1; +} +#endif + +QInotify *qemu_inotify_new(QInotifyHandler cb, + void *opaque, + GDestroyNotify ffcb, + Error **errp) +{ +#ifdef CONFIG_INOTIFY1 + QInotify *in = g_new0(QInotify, 1); + + in->fd = inotify_init1(IN_NONBLOCK); + if (in->fd == -1) { + error_setg_errno(errp, errno, + "Unable to initialize inotify"); + g_free(in); + return NULL; + } + in->cb = cb; + in->opaque = opaque; + in->ffcb = ffcb; + + qemu_set_fd_handler(in->fd, qemu_inotify_watch, NULL, in); + + return in; +#else + error_setg(errp, "Inotify not available on this platform"); + return NULL; +#endif + +} + + +void qemu_inotify_free(QInotify *in) +{ + if (!in) { + return; + } + + if (in->ffcb) { + in->ffcb(in->opaque); + } + + if (in->fd != -1) { + qemu_set_fd_handler(in->fd, NULL, NULL, NULL); + close(in->fd); + g_free(in); + } +} + + +int qemu_inotify_add_watch(QInotify *in, + const char *path, + uint32_t mask, + Error **errp) +{ +#ifdef CONFIG_INOTIFY1 + int rv; + rv = inotify_add_watch(in->fd, path, mask); + if (rv < 0) { + error_setg_errno(errp, errno, "Unable to watch '%s'", path); + return -1; + } + + return rv; +#else + error_setg(errp, "Inotify not available on this platform"); + return -1; +#endif +} -- 2.17.0
