STATFS(2) System Calls Manual STATFS(2)

statfs — get file system statistics

Standard C Library (libc, -lc)

#include <sys/param.h>
#include <sys/mount.h>

int
statfs(const char *path, struct statfs *buf);

int
fstatfs(int fd, struct statfs *buf);

The () system call returns information about a mounted file system. The path argument is the path name of any file within the mounted file system. The buf argument is a pointer to a statfs structure defined as follows:

typedef struct fsid { int32_t val[2]; } fsid_t; /* file system id type */

/*
 * filesystem statistics
 */

#define	MFSNAMELEN	16		/* length of type name including null */
#define	MNAMELEN	1024		/* size of on/from name bufs */
#define	STATFS_VERSION	0x20140518	/* current version number */

struct statfs {
uint32_t f_version;		/* structure version number */
uint32_t f_type;		/* type of filesystem */
uint64_t f_flags;		/* copy of mount exported flags */
uint64_t f_bsize;		/* filesystem fragment size */
uint64_t f_iosize;		/* optimal transfer block size */
uint64_t f_blocks;		/* total data blocks in filesystem */
uint64_t f_bfree;		/* free blocks in filesystem */
int64_t	 f_bavail;		/* free blocks avail to non-superuser */
uint64_t f_files;		/* total file nodes in filesystem */
int64_t	 f_ffree;		/* free nodes avail to non-superuser */
uint64_t f_syncwrites;		/* count of sync writes since mount */
uint64_t f_asyncwrites;		/* count of async writes since mount */
uint64_t f_syncreads;		/* count of sync reads since mount */
uint64_t f_asyncreads;		/* count of async reads since mount */
uint64_t f_spare[10];		/* unused spare */
uint32_t f_namemax;		/* maximum filename length */
uid_t	  f_owner;		/* user that mounted the filesystem */
fsid_t	  f_fsid;		/* filesystem id */
char	  f_charspare[80];	    /* spare string space */
char	  f_fstypename[MFSNAMELEN]; /* filesystem type name */
char	  f_mntfromname[MNAMELEN];  /* mounted filesystem */
char	  f_mntonname[MNAMELEN];    /* directory on which mounted */
};

The flags that may be returned include:

The file system is mounted read-only; Even the super-user may not write on it.
Files may not be executed from the file system.
Setuid and setgid bits on files are not honored when they are executed.
All I/O to the file system is done synchronously.
No file system I/O is done synchronously.
Soft updates being done (see ffs(7)).
Journaling with gjournal is enabled (see gjournal(8)).
Special handling of SUID bit on directories.
Union with underlying file system.
Symbolic links are not followed.
Read clustering is disabled.
Write clustering is disabled.
Mandatory Access Control (MAC) support for individual objects (see mac(4)).
Access Control List (ACL) support enabled.
The file system resides locally.
The file system has quotas enabled on it.
Identifies the root file system.
The file system is exported read-only.
Updating of file access times is disabled.
The file system has been mounted by a user.
The file system is exported for both reading and writing.
The file system is exported for both reading and writing to any Internet host.
The file system maps all remote accesses to the anonymous user.
The file system is exported with Kerberos uid mapping.
The file system is exported publicly (WebNFS).

Fields that are undefined for a particular file system are set to -1. The () system call returns the same information about an open file referenced by descriptor fd.

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

The statfs() system call fails if one or more of the following are true:

[]
A component of the path prefix of path is not a directory.
[]
The length of a component of path exceeds 255 characters, or the length of path exceeds 1023 characters.
[]
The file referred to by path does not exist.
[]
Search permission is denied for a component of the path prefix of path.
[]
Too many symbolic links were encountered in translating path.
[]
The buf or path argument points to an invalid address.
[]
An I/O error occurred while reading from or writing to the file system.
[]
Corrupted data was detected while reading from the file system.

The fstatfs() system call fails if one or more of the following are true:

[]
The fd argument is not a valid open file descriptor.
[]
The buf argument points to an invalid address.
[]
An I/O error occurred while reading from or writing to the file system.
[]
Corrupted data was detected while reading from the file system.

fhstatfs(2), getfsstat(2)

The statfs() system call first appeared in 4.4BSD.

March 30, 2020 Debian