Mailing List Archive

Add some helpers to hypfs.c to support dynamic directories with a
numerical id as name.

The dynamic directory is based on a template specified by the user
allowing to use specific access functions and having a predefined
set of entries in the directory.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- use macro for length of entry name (Jan Beulich)
- const attributes (Jan Beulich)
- use template name as format string (Jan Beulich)
- add hypfs_dynid_entry_size() helper (Jan Beulich)
- expect dyndir data having been allocated by enter() callback

V3:
- add a specific enter() callback returning the template pointer
- add data field to struct hypfs_dyndir_id
- rename hypfs_gen_dyndir_entry_id() (Jan Beulich)
- add comments regarding generated names to be kept in sync (Jan Beulich)

Signed-off-by: Juergen Gross <jgross@suse.com>
---
xen/common/hypfs.c | 98 +++++++++++++++++++++++++++++++++++++++++
xen/include/xen/hypfs.h | 18 ++++++++
2 files changed, 116 insertions(+)

diff --git a/xen/common/hypfs.c b/xen/common/hypfs.c
index 8faf65cea0..087c63b92f 100644
--- a/xen/common/hypfs.c
+++ b/xen/common/hypfs.c
@@ -356,6 +356,104 @@ unsigned int hypfs_getsize(const struct hypfs_entry *entry)
return entry->size;
}

+/*
+ * Fill the direntry for a dynamically generated directory. Especially the
+ * generated name needs to be kept in sync with hypfs_gen_dyndir_id_entry().
+ */
+int hypfs_read_dyndir_id_entry(const struct hypfs_entry_dir *template,
+ unsigned int id, bool is_last,
+ XEN_GUEST_HANDLE_PARAM(void) *uaddr)
+{
+ struct xen_hypfs_dirlistentry direntry;
+ char name[HYPFS_DYNDIR_ID_NAMELEN];
+ unsigned int e_namelen, e_len;
+
+ e_namelen = snprintf(name, sizeof(name), template->e.name, id);
+ e_len = DIRENTRY_SIZE(e_namelen);
+ direntry.e.pad = 0;
+ direntry.e.type = template->e.type;
+ direntry.e.encoding = template->e.encoding;
+ direntry.e.content_len = template->e.funcs->getsize(&template->e);
+ direntry.e.max_write_len = template->e.max_size;
+ direntry.off_next = is_last ? 0 : e_len;
+ if ( copy_to_guest(*uaddr, &direntry, 1) )
+ return -EFAULT;
+ if ( copy_to_guest_offset(*uaddr, DIRENTRY_NAME_OFF, name,
+ e_namelen + 1) )
+ return -EFAULT;
+
+ guest_handle_add_offset(*uaddr, e_len);
+
+ return 0;
+}
+
+static const struct hypfs_entry *hypfs_dyndir_enter(
+ const struct hypfs_entry *entry)
+{
+ const struct hypfs_dyndir_id *data;
+
+ data = hypfs_get_dyndata();
+
+ /* Use template with original enter function. */
+ return data->template->e.funcs->enter(&data->template->e);
+}
+
+static struct hypfs_entry *hypfs_dyndir_findentry(
+ const struct hypfs_entry_dir *dir, const char *name, unsigned int name_len)
+{
+ const struct hypfs_dyndir_id *data;
+
+ data = hypfs_get_dyndata();
+
+ /* Use template with original findentry function. */
+ return data->template->e.funcs->findentry(data->template, name, name_len);
+}
+
+static int hypfs_read_dyndir(const struct hypfs_entry *entry,
+ XEN_GUEST_HANDLE_PARAM(void) uaddr)
+{
+ const struct hypfs_dyndir_id *data;
+
+ data = hypfs_get_dyndata();
+
+ /* Use template with original read function. */
+ return data->template->e.funcs->read(&data->template->e, uaddr);
+}
+
+/*
+ * Fill dyndata with a dynamically generated directory based on a template
+ * and a numerical id.
+ * Needs to be kept in sync with hypfs_read_dyndir_id_entry() regarding the
+ * name generated.
+ */
+struct hypfs_entry *hypfs_gen_dyndir_id_entry(
+ const struct hypfs_entry_dir *template, unsigned int id, void *data)
+{
+ struct hypfs_dyndir_id *dyndata;
+
+ dyndata = hypfs_get_dyndata();
+
+ dyndata->template = template;
+ dyndata->id = id;
+ dyndata->data = data;
+ snprintf(dyndata->name, sizeof(dyndata->name), template->e.name, id);
+ dyndata->dir = *template;
+ dyndata->dir.e.name = dyndata->name;
+ dyndata->dir.e.funcs = &dyndata->funcs;
+ dyndata->funcs = *template->e.funcs;
+ dyndata->funcs.enter = hypfs_dyndir_enter;
+ dyndata->funcs.findentry = hypfs_dyndir_findentry;
+ dyndata->funcs.read = hypfs_read_dyndir;
+
+ return &dyndata->dir.e;
+}
+
+unsigned int hypfs_dynid_entry_size(const struct hypfs_entry *template,
+ unsigned int id)
+{
+ return DIRENTRY_SIZE(snprintf(NULL, 0, template->name, id));
+}
+
int hypfs_read_dir(const struct hypfs_entry *entry,
XEN_GUEST_HANDLE_PARAM(void) uaddr)
{
diff --git a/xen/include/xen/hypfs.h b/xen/include/xen/hypfs.h
index 4c469cbeb4..34073faff8 100644
--- a/xen/include/xen/hypfs.h
+++ b/xen/include/xen/hypfs.h
@@ -76,6 +76,17 @@ struct hypfs_entry_dir {
struct list_head dirlist;
};

+struct hypfs_dyndir_id {
+ struct hypfs_entry_dir dir; /* Modified copy of template. */
+ struct hypfs_funcs funcs; /* Dynamic functions. */
+ const struct hypfs_entry_dir *template; /* Template used. */
+#define HYPFS_DYNDIR_ID_NAMELEN 12
+ char name[HYPFS_DYNDIR_ID_NAMELEN]; /* Name of hypfs entry. */
+
+ unsigned int id; /* Numerical id. */
+ void *data; /* Data associated with id. */
+};
+
#define HYPFS_DIR_INIT_FUNC(var, nam, fn) \
struct hypfs_entry_dir __read_mostly var = { \
.e.type = XEN_HYPFS_TYPE_DIR, \
@@ -186,6 +197,13 @@ void *hypfs_alloc_dyndata_size(unsigned long size);
#define hypfs_alloc_dyndata(type) (type *)hypfs_alloc_dyndata_size(sizeof(type))
void *hypfs_get_dyndata(void);
void hypfs_free_dyndata(void);
+int hypfs_read_dyndir_id_entry(const struct hypfs_entry_dir *template,
+ unsigned int id, bool is_last,
+ XEN_GUEST_HANDLE_PARAM(void) *uaddr);
+struct hypfs_entry *hypfs_gen_dyndir_id_entry(
+ const struct hypfs_entry_dir *template, unsigned int id, void *data);
+unsigned int hypfs_dynid_entry_size(const struct hypfs_entry *template,
+ unsigned int id);
#endif

#endif /* __XEN_HYPFS_H__ */
--
2.26.2