From b750101eb236130cf056c675997decbac904cc49 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 17:35:18 +0200 Subject: Adding upstream version 252.22. Signed-off-by: Daniel Baumann --- src/libudev/libudev-monitor.c | 309 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 309 insertions(+) create mode 100644 src/libudev/libudev-monitor.c (limited to 'src/libudev/libudev-monitor.c') diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c new file mode 100644 index 0000000..d7c931d --- /dev/null +++ b/src/libudev/libudev-monitor.c @@ -0,0 +1,309 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include +#include + +#include "libudev.h" + +#include "alloc-util.h" +#include "device-monitor-private.h" +#include "device-private.h" +#include "device-util.h" +#include "io-util.h" +#include "libudev-device-internal.h" +#include "string-util.h" + +/** + * SECTION:libudev-monitor + * @short_description: device event source + * + * Connects to a device event source. + */ + +/** + * udev_monitor: + * + * Opaque object handling an event source. + */ +struct udev_monitor { + struct udev *udev; + unsigned n_ref; + sd_device_monitor *monitor; +}; + +static MonitorNetlinkGroup monitor_netlink_group_from_string(const char *name) { + if (!name) + return MONITOR_GROUP_NONE; + if (streq(name, "udev")) + return MONITOR_GROUP_UDEV; + if (streq(name, "kernel")) + return MONITOR_GROUP_KERNEL; + return _MONITOR_NETLINK_GROUP_INVALID; +} + +/** + * udev_monitor_new_from_netlink: + * @udev: udev library context + * @name: name of event source + * + * Create new udev monitor and connect to a specified event + * source. Valid sources identifiers are "udev" and "kernel". + * + * Applications should usually not connect directly to the + * "kernel" events, because the devices might not be usable + * at that time, before udev has configured them, and created + * device nodes. Accessing devices at the same time as udev, + * might result in unpredictable behavior. The "udev" events + * are sent out after udev has finished its event processing, + * all rules have been processed, and needed device nodes are + * created. + * + * The initial refcount is 1, and needs to be decremented to + * release the resources of the udev monitor. + * + * Returns: a new udev monitor, or #NULL, in case of an error + **/ +_public_ struct udev_monitor *udev_monitor_new_from_netlink(struct udev *udev, const char *name) { + _cleanup_(sd_device_monitor_unrefp) sd_device_monitor *m = NULL; + struct udev_monitor *udev_monitor; + MonitorNetlinkGroup g; + int r; + + g = monitor_netlink_group_from_string(name); + if (g < 0) + return_with_errno(NULL, EINVAL); + + r = device_monitor_new_full(&m, g, -1); + if (r < 0) + return_with_errno(NULL, r); + + udev_monitor = new(struct udev_monitor, 1); + if (!udev_monitor) + return_with_errno(NULL, ENOMEM); + + *udev_monitor = (struct udev_monitor) { + .udev = udev, + .n_ref = 1, + .monitor = TAKE_PTR(m), + }; + + return udev_monitor; +} + +/** + * udev_monitor_filter_update: + * @udev_monitor: monitor + * + * Update the installed socket filter. This is only needed, + * if the filter was removed or changed. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_update(struct udev_monitor *udev_monitor) { + assert_return(udev_monitor, -EINVAL); + + return sd_device_monitor_filter_update(udev_monitor->monitor); +} + +/** + * udev_monitor_enable_receiving: + * @udev_monitor: the monitor which should receive events + * + * Binds the @udev_monitor socket to the event source. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_enable_receiving(struct udev_monitor *udev_monitor) { + assert_return(udev_monitor, -EINVAL); + + return device_monitor_enable_receiving(udev_monitor->monitor); +} + +/** + * udev_monitor_set_receive_buffer_size: + * @udev_monitor: the monitor which should receive events + * @size: the size in bytes + * + * Set the size of the kernel socket buffer. This call needs the + * appropriate privileges to succeed. + * + * Returns: 0 on success, otherwise -1 on error. + */ +_public_ int udev_monitor_set_receive_buffer_size(struct udev_monitor *udev_monitor, int size) { + assert_return(udev_monitor, -EINVAL); + + return sd_device_monitor_set_receive_buffer_size(udev_monitor->monitor, (size_t) size); +} + +static struct udev_monitor *udev_monitor_free(struct udev_monitor *udev_monitor) { + assert(udev_monitor); + + sd_device_monitor_unref(udev_monitor->monitor); + return mfree(udev_monitor); +} + +/** + * udev_monitor_ref: + * @udev_monitor: udev monitor + * + * Take a reference of a udev monitor. + * + * Returns: the passed udev monitor + **/ + +/** + * udev_monitor_unref: + * @udev_monitor: udev monitor + * + * Drop a reference of a udev monitor. If the refcount reaches zero, + * the bound socket will be closed, and the resources of the monitor + * will be released. + * + * Returns: #NULL + **/ +DEFINE_PUBLIC_TRIVIAL_REF_UNREF_FUNC(struct udev_monitor, udev_monitor, udev_monitor_free); + +/** + * udev_monitor_get_udev: + * @udev_monitor: udev monitor + * + * Retrieve the udev library context the monitor was created with. + * + * Returns: the udev library context + **/ +_public_ struct udev *udev_monitor_get_udev(struct udev_monitor *udev_monitor) { + assert_return(udev_monitor, NULL); + + return udev_monitor->udev; +} + +/** + * udev_monitor_get_fd: + * @udev_monitor: udev monitor + * + * Retrieve the socket file descriptor associated with the monitor. + * + * Returns: the socket file descriptor + **/ +_public_ int udev_monitor_get_fd(struct udev_monitor *udev_monitor) { + assert_return(udev_monitor, -EINVAL); + + return device_monitor_get_fd(udev_monitor->monitor); +} + +static int udev_monitor_receive_sd_device(struct udev_monitor *udev_monitor, sd_device **ret) { + int r; + + assert(udev_monitor); + assert(ret); + + for (;;) { + /* r == 0 means a device is received but it does not pass the current filter. */ + r = device_monitor_receive_device(udev_monitor->monitor, ret); + if (r != 0) + return r; + + for (;;) { + /* Wait for next message */ + r = fd_wait_for_event(device_monitor_get_fd(udev_monitor->monitor), POLLIN, 0); + if (r == -EINTR) + continue; + if (r < 0) + return r; + if (r == 0) + return -EAGAIN; + + /* Receive next message */ + break; + } + } +} + +/** + * udev_monitor_receive_device: + * @udev_monitor: udev monitor + * + * Receive data from the udev monitor socket, allocate a new udev + * device, fill in the received data, and return the device. + * + * Only socket connections with uid=0 are accepted. + * + * The monitor socket is by default set to NONBLOCK. A variant of poll() on + * the file descriptor returned by udev_monitor_get_fd() should to be used to + * wake up when new devices arrive, or alternatively the file descriptor + * switched into blocking mode. + * + * The initial refcount is 1, and needs to be decremented to + * release the resources of the udev device. + * + * Returns: a new udev device, or #NULL, in case of an error + **/ +_public_ struct udev_device *udev_monitor_receive_device(struct udev_monitor *udev_monitor) { + _cleanup_(sd_device_unrefp) sd_device *device = NULL; + int r; + + assert_return(udev_monitor, NULL); + + r = udev_monitor_receive_sd_device(udev_monitor, &device); + if (r < 0) + return_with_errno(NULL, r); + + return udev_device_new(udev_monitor->udev, device); +} + +/** + * udev_monitor_filter_add_match_subsystem_devtype: + * @udev_monitor: the monitor + * @subsystem: the subsystem value to match the incoming devices against + * @devtype: the devtype value to match the incoming devices against + * + * This filter is efficiently executed inside the kernel, and libudev subscribers + * will usually not be woken up for devices which do not match. + * + * The filter must be installed before the monitor is switched to listening mode. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_add_match_subsystem_devtype(struct udev_monitor *udev_monitor, const char *subsystem, const char *devtype) { + int r; + + assert_return(udev_monitor, -EINVAL); + + r = sd_device_monitor_filter_add_match_subsystem_devtype(udev_monitor->monitor, subsystem, devtype); + return r < 0 ? r : 0; +} + +/** + * udev_monitor_filter_add_match_tag: + * @udev_monitor: the monitor + * @tag: the name of a tag + * + * This filter is efficiently executed inside the kernel, and libudev subscribers + * will usually not be woken up for devices which do not match. + * + * The filter must be installed before the monitor is switched to listening mode. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_add_match_tag(struct udev_monitor *udev_monitor, const char *tag) { + int r; + + assert_return(udev_monitor, -EINVAL); + + r = sd_device_monitor_filter_add_match_tag(udev_monitor->monitor, tag); + return r < 0 ? r : 0; +} + +/** + * udev_monitor_filter_remove: + * @udev_monitor: monitor + * + * Remove all filters from monitor. + * + * Returns: 0 on success, otherwise a negative error value. + */ +_public_ int udev_monitor_filter_remove(struct udev_monitor *udev_monitor) { + assert_return(udev_monitor, -EINVAL); + + return sd_device_monitor_filter_remove(udev_monitor->monitor); +} -- cgit v1.2.3