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STATFS(2) System Calls Manual STATFS(2)

statfs, fstatfs — get file system statistics

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

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

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

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

typedef struct { int32_t val[2]; } fsid_t;

#define MFSNAMELEN   16 /* length of fs type name, including nul */
#define MNAMELEN     90	/* length of buffer for returned name */

struct statfs {
    u_int32_t	f_flags;	/* copy of mount flags */
    u_int32_t	f_bsize;	/* file system block size */
    u_int32_t	f_iosize;	/* optimal transfer block size */

				/* unit is f_bsize */
    u_int64_t	f_blocks;	/* total data blocks in file system */
    u_int64_t	f_bfree;	/* free blocks in fs */
    int64_t	f_bavail;	/* free blocks avail to non-superuser */

    u_int64_t	f_files;	/* total file nodes in file system */
    u_int64_t	f_ffree;	/* free file nodes in fs */
    int64_t	f_favail;	/* free file nodes avail to non-root */

    u_int64_t	f_syncwrites;	/* count of sync writes since mount */
    u_int64_t	f_syncreads;	/* count of sync reads since mount */
    u_int64_t	f_asyncwrites;	/* count of async writes since mount */
    u_int64_t	f_asyncreads;	/* count of async reads since mount */

    fsid_t	f_fsid;		/* file system id */
    u_int32_t	f_namemax;	/* maximum filename length */
    uid_t	f_owner;	/* user that mounted the file system */
    u_int64_t	f_ctime;	/* last mount [-u] time */

    char f_fstypename[MFSNAMELEN]; /* fs type name */
    char f_mntonname[MNAMELEN];    /* directory on which mounted */
    char f_mntfromname[MNAMELEN];  /* mounted file system */
    char f_mntfromspec[MNAMELEN];  /* special for mount request */
    union mount_info mount_info;   /* per-filesystem mount options */
};

() returns the same information about an open file referenced by descriptor fd.

Note that f_fsid will be empty unless the user is the superuser.

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.

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

[]
A component of the path prefix of path is not a directory.
[]
A component of a pathname exceeded NAME_MAX characters, or an entire pathname (including the terminating NUL) exceeded PATH_MAX bytes.
[]
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.
[]
buf or path points to an invalid address.
[]
An I/O error occurred while reading from or writing to the file system.

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

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

df(1), getfsstat(2), mount(2), stat(2)

The statfs() function first appeared in 4.3BSD-Reno.

July 30, 2022 openbsd