[PATCH 1/2] devfs: Add symlink support
Sascha Hauer
s.hauer at pengutronix.de
Wed Dec 16 01:47:21 PST 2015
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
commands/devinfo.c | 7 +++--
fs/devfs-core.c | 76 ++++++++++++++++++++++++++++++++++++++++++++----------
fs/devfs.c | 27 ++++++++++++++++++-
include/driver.h | 5 ++++
4 files changed, 99 insertions(+), 16 deletions(-)
diff --git a/commands/devinfo.c b/commands/devinfo.c
index 3c9d6a6..c78efcb 100644
--- a/commands/devinfo.c
+++ b/commands/devinfo.c
@@ -21,7 +21,7 @@
static int do_devinfo_subtree(struct device_d *dev, int depth)
{
struct device_d *child;
- struct cdev *cdev;
+ struct cdev *cdev, *cdevl;
int i;
for (i = 0; i < depth; i++)
@@ -33,11 +33,14 @@ static int do_devinfo_subtree(struct device_d *dev, int depth)
list_for_each_entry(cdev, &dev->cdevs, devices_list) {
for (i = 0; i < depth + 1; i++)
printf(" ");
- printf("`-- 0x%08llx-0x%08llx (%10s): /dev/%s\n",
+ printf("`-- 0x%08llx-0x%08llx (%10s): /dev/%s",
cdev->offset,
cdev->offset + cdev->size - 1,
size_human_readable(cdev->size),
cdev->name);
+ list_for_each_entry(cdevl, &cdev->links, link_entry)
+ printf(", %s", cdevl->name);
+ printf("\n");
}
} else {
printf("\n");
diff --git a/fs/devfs-core.c b/fs/devfs-core.c
index 2541ea3..640a134 100644
--- a/fs/devfs-core.c
+++ b/fs/devfs-core.c
@@ -46,7 +46,18 @@ int devfs_partition_complete(struct string_list *sl, char *instr)
}
#endif
-struct cdev *cdev_by_name(const char *filename)
+struct cdev *cdev_readlink(struct cdev *cdev)
+{
+ if (cdev->link)
+ cdev = cdev->link;
+
+ /* links to links are not allowed */
+ BUG_ON(cdev->link);
+
+ return cdev;
+}
+
+struct cdev *lcdev_by_name(const char *filename)
{
struct cdev *cdev;
@@ -57,6 +68,17 @@ struct cdev *cdev_by_name(const char *filename)
return NULL;
}
+struct cdev *cdev_by_name(const char *filename)
+{
+ struct cdev *cdev;
+
+ cdev = lcdev_by_name(filename);
+ if (!cdev)
+ return NULL;
+
+ return cdev_readlink(cdev);
+}
+
struct cdev *cdev_by_device_node(struct device_node *node)
{
struct cdev *cdev;
@@ -65,7 +87,7 @@ struct cdev *cdev_by_device_node(struct device_node *node)
if (!cdev->device_node)
continue;
if (cdev->device_node == node)
- return cdev;
+ return cdev_readlink(cdev);
}
return NULL;
}
@@ -111,14 +133,6 @@ int cdev_find_free_index(const char *basename)
return -EBUSY; /* all indexes are used */
}
-int cdev_do_open(struct cdev *cdev, unsigned long flags)
-{
- if (cdev->ops->open)
- return cdev->ops->open(cdev, flags);
-
- return 0;
-}
-
struct cdev *cdev_open(const char *name, unsigned long flags)
{
struct cdev *cdev;
@@ -131,9 +145,11 @@ struct cdev *cdev_open(const char *name, unsigned long flags)
if (!cdev)
return NULL;
- ret = cdev_do_open(cdev, flags);
- if (ret)
- return NULL;
+ if (cdev->ops->open) {
+ ret = cdev->ops->open(cdev, flags);
+ if (ret)
+ return NULL;
+ }
return cdev;
}
@@ -259,6 +275,8 @@ int devfs_create(struct cdev *new)
if (cdev)
return -EEXIST;
+ INIT_LIST_HEAD(&new->links);
+
list_add_tail(&new->list, &cdev_list);
if (new->dev)
list_add_tail(&new->devices_list, &new->dev->cdevs);
@@ -266,15 +284,47 @@ int devfs_create(struct cdev *new)
return 0;
}
+int devfs_create_link(struct cdev *cdev, const char *name)
+{
+ struct cdev *new;
+
+ if (cdev_by_name(name))
+ return -EEXIST;
+
+ /*
+ * Create a link to the real cdev instead of creating
+ * a link to a link.
+ */
+ cdev = cdev_readlink(cdev);
+
+ new = xzalloc(sizeof(*new));
+ new->name = xstrdup(name);
+ new->link = cdev;
+ INIT_LIST_HEAD(&new->links);
+ list_add_tail(&new->list, &cdev_list);
+ list_add_tail(&new->link_entry, &cdev->links);
+
+ return 0;
+}
+
int devfs_remove(struct cdev *cdev)
{
+ struct cdev *c, *tmp;
+
if (cdev->open)
return -EBUSY;
list_del(&cdev->list);
+
if (cdev->dev)
list_del(&cdev->devices_list);
+ list_for_each_entry_safe(c, tmp, &cdev->links, link_entry)
+ devfs_remove(c);
+
+ if (cdev->link)
+ free(cdev);
+
return 0;
}
diff --git a/fs/devfs.c b/fs/devfs.c
index 5c96682..0b8d4fd 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -212,12 +212,18 @@ static int devfs_stat(struct device_d *_dev, const char *filename, struct stat *
{
struct cdev *cdev;
- cdev = cdev_by_name(filename + 1);
+ cdev = lcdev_by_name(filename + 1);
if (!cdev)
return -ENOENT;
s->st_mode = S_IFCHR;
s->st_size = cdev->size;
+
+ if (cdev->link)
+ s->st_mode |= S_IFLNK;
+
+ cdev = cdev_readlink(cdev);
+
if (cdev->ops->write)
s->st_mode |= S_IWUSR;
if (cdev->ops->read)
@@ -242,6 +248,24 @@ static void devfs_delete(struct device_d *dev)
{
}
+static int devfs_readlink(struct device_d *dev, const char *pathname,
+ char *buf, size_t bufsz)
+{
+ struct cdev *cdev;
+
+ cdev = cdev_by_name(pathname + 1);
+ if (!cdev)
+ return -ENOENT;
+
+ while (cdev->link)
+ cdev = cdev->link;
+
+ bufsz = min(bufsz, strlen(cdev->name));
+ memcpy(buf, cdev->name, bufsz);
+
+ return 0;
+}
+
static struct fs_driver_d devfs_driver = {
.read = devfs_read,
.write = devfs_write,
@@ -258,6 +282,7 @@ static struct fs_driver_d devfs_driver = {
.erase = devfs_erase,
.protect = devfs_protect,
.memmap = devfs_memmap,
+ .readlink = devfs_readlink,
.flags = FS_DRIVER_NO_DEV,
.drv = {
.probe = devfs_probe,
diff --git a/include/driver.h b/include/driver.h
index 046dd90..31c6734 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -450,13 +450,18 @@ struct cdev {
int open;
struct mtd_info *mtd;
u8 dos_partition_type;
+ struct cdev *link;
+ struct list_head link_entry, links;
};
int devfs_create(struct cdev *);
+int devfs_create_link(struct cdev *, const char *name);
int devfs_remove(struct cdev *);
int cdev_find_free_index(const char *);
struct cdev *device_find_partition(struct device_d *dev, const char *name);
struct cdev *cdev_by_name(const char *filename);
+struct cdev *lcdev_by_name(const char *filename);
+struct cdev *cdev_readlink(struct cdev *cdev);
struct cdev *cdev_by_device_node(struct device_node *node);
struct cdev *cdev_open(const char *name, unsigned long flags);
int cdev_do_open(struct cdev *, unsigned long flags);
--
2.6.2
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