lsfd: (refactor) make the way to handle character devices extensible

Signed-off-by: Masatake YAMATO <yamato@redhat.com>

diff --git a/misc-utils/lsfd-cdev.c b/misc-utils/lsfd-cdev.c
index 6ba0d15edddfca1dac9591ce9aa7bee2afe5afa6..73e7784ecea95a5f912d8e95fda6e15a58555306 100644 (file)
--- a/misc-utils/lsfd-cdev.c
+++ b/misc-utils/lsfd-cdev.c
@@ -36,6 +36,23 @@ struct miscdev {
 struct cdev {
        struct file file;
        const char *devdrv;
+       const struct cdev_ops *cdev_ops;
+       void *cdev_data;
+};
+
+struct cdev_ops {
+       const struct cdev_ops *parent;
+       bool (*probe)(const struct cdev *);
+       char * (*get_name)(struct cdev *);
+       bool (*fill_column)(struct proc *,
+                           struct cdev *,
+                           struct libscols_line *,
+                           int,
+                           size_t,
+                           char **);
+       void (*init)(const struct cdev *);
+       void (*free)(const struct cdev *);
+       int (*handle_fdinfo)(struct cdev *, const char *, const char *);
 };
 
 static bool cdev_fill_column(struct proc *proc __attribute__((__unused__)),
@@ -45,10 +62,18 @@ static bool cdev_fill_column(struct proc *proc __attribute__((__unused__)),
                             size_t column_index)
 {
        struct cdev *cdev = (struct cdev *)file;
+       const struct cdev_ops *ops = cdev->cdev_ops;
        char *str = NULL;
        const char *miscdev;
 
        switch(column_id) {
+       case COL_NAME:
+               if (cdev->cdev_ops->get_name) {
+                       str = cdev->cdev_ops->get_name(cdev);
+                       if (str)
+                               break;
+               }
+               return false;
        case COL_TYPE:
                if (scols_line_set_data(ln, column_index, "CHR"))
                        err(EXIT_FAILURE, _("failed to add output data"));
@@ -96,9 +121,17 @@ static bool cdev_fill_column(struct proc *proc __attribute__((__unused__)),
                          minor(file->stat.st_rdev));
                break;
        default:
+               while (ops) {
+                       if (ops->fill_column
+                           && ops->fill_column(proc, cdev, ln,
+                                               column_id, column_index, &str))
+                               goto out;
+                       ops = ops->parent;
+               }
                return false;
        }
 
+ out:
        if (!str)
                err(EXIT_FAILURE, _("failed to add output data"));
        if (scols_line_refer_data(ln, column_index, str))
@@ -170,9 +203,64 @@ const char *get_miscdev(unsigned long minor)
        return NULL;
 }
 
+/*
+ * generic (fallback implementation)
+ */
+static bool cdev_generic_probe(const struct cdev *cdev __attribute__((__unused__))) {
+       return true;
+}
+
+static struct cdev_ops cdev_generic_ops = {
+       .probe = cdev_generic_probe,
+};
+
+
+static const struct cdev_ops *cdev_ops[] = {
+       &cdev_generic_ops                 /* This must be at the end. */
+};
+
+static const struct cdev_ops *cdev_probe(const struct cdev *cdev)
+{
+       const struct cdev_ops *r = NULL;
+
+       for (size_t i = 0; i < ARRAY_SIZE(cdev_ops); i++) {
+               if (cdev_ops[i]->probe(cdev)) {
+                       r = cdev_ops[i];
+                       break;
+               }
+       }
+
+       assert(r);
+       return r;
+}
+
 static void init_cdev_content(struct file *file)
 {
-       ((struct cdev *)file)->devdrv = get_chrdrv(major(file->stat.st_rdev));
+       struct cdev *cdev = (struct cdev *)file;
+
+       cdev->devdrv = get_chrdrv(major(file->stat.st_rdev));
+
+       cdev->cdev_data = NULL;
+       cdev->cdev_ops = cdev_probe(cdev);
+       if (cdev->cdev_ops->init)
+               cdev->cdev_ops->init(cdev);
+}
+
+static void free_cdev_content(struct file *file)
+{
+       struct cdev *cdev = (struct cdev *)file;
+
+       if (cdev->cdev_ops->free)
+               cdev->cdev_ops->free(cdev);
+}
+
+static int cdev_handle_fdinfo(struct file *file, const char *key, const char *value)
+{
+       struct cdev *cdev = (struct cdev *)file;
+
+       if (cdev->cdev_ops->handle_fdinfo)
+               return cdev->cdev_ops->handle_fdinfo(cdev, key, value);
+       return 0;               /* Should be handled in parents */
 }
 
 const struct file_class cdev_class = {
@@ -182,5 +270,6 @@ const struct file_class cdev_class = {
        .finalize_class = cdev_class_finalize,
        .fill_column = cdev_fill_column,
        .initialize_content = init_cdev_content,
-       .free_content = NULL,
+       .free_content = free_cdev_content,
+       .handle_fdinfo = cdev_handle_fdinfo,
 };