g_uevent_device_new 代码举例

以下是一个简单的 g_uevent_device_new 函数实现的示例代码：

#include <glib.h>
#include <gio/gio.h>

#define UEVENT_BUFFER_SIZE 2048

typedef struct _GUeventDevice GUeventDevice;

struct _GUeventDevice {
    GObject parent_instance;

    gchar *syspath;
    gchar *subsystem;
    gchar *devtype;
    gchar **filters;
    GRegex **regex_filters;
    guint n_filters;

    GIOChannel *io_channel;
    guint io_watch_id;
    gchar io_buffer[UEVENT_BUFFER_SIZE];
};

G_DEFINE_TYPE(GUeventDevice, g_uevent_device, G_TYPE_OBJECT);

static gboolean
g_uevent_device_io_watch_callback(GIOChannel *channel, GIOCondition condition,
                                  gpointer user_data)
{
    GUeventDevice *self = G_UEVENT_DEVICE(user_data);

    if (condition & G_IO_IN) {
        gsize bytes_read = 0;
        gsize io_buffer_size = sizeof(self->io_buffer) - 1;

        if (g_io_channel_read_chars(channel, self->io_buffer, io_buffer_size,
                                     &bytes_read, NULL) != G_IO_ERROR_NONE) {
            g_warning("Failed to read from uevent device");
            return G_SOURCE_REMOVE;
        }

        /* Null-terminate the read buffer */
        self->io_buffer[bytes_read] = '\0';

        /* Process the uevent messages in the buffer */
        gchar *line_start = self->io_buffer;
        gchar *line_end = NULL;

        while ((line_end = strchr(line_start, '\n'))) {
            *line_end = '\0';
            gchar **kv_pairs = g_strsplit(line_start, "=", -1);

            /* Process the key-value pairs in the uevent message */
            for (guint i = 0; kv_pairs[i]; i += 2) {
                gchar *key = kv_pairs[i];
                gchar *value = kv_pairs[i + 1];

                /* Filter out the key-value pairs that don't match any of the
                   regex filters */
                gboolean filter_match = FALSE;

                for (guint j = 0; j < self->n_filters; j++) {
                    if (g_regex_match(self->regex_filters[j], key, 0, NULL)) {
                        filter_match = TRUE;
                        break;
                    }
                }

                if (!filter_match) {
                    continue;
                }

                g_message("Received uevent message: %s=%s", key, value);
            }

            g_strfreev(kv_pairs);
            line_start = line_end + 1;
        }
    }

    return G_SOURCE_CONTINUE;
}

static void
g_uevent_device_init(GUeventDevice *self)
{
    self->syspath = NULL;
    self->subsystem = NULL;
    self->devtype = NULL;
    self->filters = NULL;
    self->regex_filters = NULL;
    self->n_filters = 0;
    self->io_channel = NULL;
    self->io_watch_id = 0;
}

static void
g_uevent_device_class_init(GUeventDeviceClass *klass)
{
    GObjectClass *object_class = G_OBJECT_CLASS(klass);

    object_class->finalize = (GObjectFinalizeFunc) g_free;
}

GUeventDevice *
g_uevent_device_new(const gchar *syspath, const gchar *subsystem,
                    const gchar *devtype, gchar **filters)
{
    GUeventDevice *self = g_object_new(G_TYPE_UEVENT_DEVICE, NULL);

    self->syspath = g_strdup(syspath);
    self->subsystem = g_strdup(subsystem);
    self->devtype = g_strdup(devtype);
    self->filters = g_strdupv(filters);

    /* Compile the regex filters */
    for (guint i = 0; self->filters[i]; i++) {
        GRegex *regex_filter = g_regex_new(self->filters[i], 0, 0, NULL);

        if (!regex_filter) {
            g_warning("Failed to compile regex filter: %s", self->filters[i]);
            continue;
        }

        self->regex_filters = g_realloc(self->regex_filters,
                                        (self->n_filters + 1) * sizeof(GRegex *));
        self->regex_filters[self->n_filters++] = regex_filter;
    }

    /* Open the uevent device file */
    gchar *uevent_path = g_build_filename(self->syspath, "uevent", NULL);
    GError *error = NULL;

    self->io_channel = g_io_channel_new_file(uevent_path, "r", &error);

    if (!self->io_channel) {
        g_warning("Failed to open uevent device: %s", error->message);
        g_error_free(error);
        g_object_unref(self);
        return NULL;
    }

    /* Add a watch for the IO channel */
    self->io_watch_id = g_io_add_watch(self->io_channel, G_IO_IN,
                                       g_uevent_device_io_watch_callback, self);

    g_free(uevent_path);

    return self;
}

这个示例代码演示了如何使用 GLib 和 GIO 库来创建一个 GUeventDevice 对象，该对象可以通过监听 Linux 内核的 uevent 消息来获取设备事件。GUeventDevice 对象可以指定一些过滤器，以只接收特定的 uevent 消息。在对象的销毁期间，将释放所有内存和资源。