ioctl_fslabel - get or set a filesystem label
#include <linux/fs.h> /* Definition of *FSLABEL* constants */
#include <sys/ioctl.h>
int ioctl(int fd, FS_IOC_GETFSLABEL, char label[FSLABEL_MAX]);
int ioctl(int fd, FS_IOC_SETFSLABEL, char label[FSLABEL_MAX]);
If a filesystem supports online label manipulation, these ioctl(2)
operations can be used to get or set the filesystem label for the filesystem
on which fd resides. The FS_IOC_SETFSLABEL operation requires
privilege (CAP_SYS_ADMIN).
On success zero is returned. On error, -1 is returned, and errno is set
to indicate the error.
Possible errors include (but are not limited to) the following:
- EFAULT
- label references an inaccessible memory area.
- EINVAL
- The specified label exceeds the maximum label length for the
filesystem.
- ENOTTY
- This can appear if the filesystem does not support online label
manipulation.
- EPERM
- The calling process does not have sufficient permissions to set the
label.
These ioctl(2) operations first appeared in Linux 4.18. They were
previously known as BTRFS_IOC_GET_FSLABEL and
BTRFS_IOC_SET_FSLABEL and were private to Btrfs.
This API is Linux-specific.
The maximum string length for this interface is FSLABEL_MAX, including
the terminating null byte ('\0'). Filesystems have differing maximum label
lengths, which may or may not include the terminating null. The string
provided to FS_IOC_SETFSLABEL must always be null-terminated, and the
string returned by FS_IOC_GETFSLABEL will always be null-terminated.
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