statfs(2) - Useful Manual Pages

NAME

statfs, statfs64, fstatfs, fstatfs64 — get file system statistics

SYNOPSIS

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

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

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

TRANSITIONAL SYNOPSIS (NOW DEPRECATED)

int
statfs64(const char *path, struct statfs64 *buf);

int
fstatfs64(int fd, struct statfs64 *buf);

The statfs() routine returns information about a mounted file system. The path argument is the path name of any file or directory within the mounted file system. The buf argument is a pointer to a statfs structure. When the macro _DARWIN_FEATURE_64_BIT_INODE is not defined (see stat(2) for more information on this macro), the statfs structure is defined as:

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

#define MFSNAMELEN      15 /* length of fs type name, not inc. nul */
#define MNAMELEN        90 /* length of buffer for returned name */

struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is NOT defined */
    short   f_otype;	/* type of file system (reserved: zero) */
    short   f_oflags;	/* copy of mount flags (reserved: zero) */
    long    f_bsize;	/* fundamental file system block size */
    long    f_iosize;	/* optimal transfer block size */
    long    f_blocks;	/* total data blocks in file system */
    long    f_bfree;	/* free blocks in fs */
    long    f_bavail;	/* free blocks avail to non-superuser */
    long    f_files;	/* total file nodes in file system */
    long    f_ffree;	/* free file nodes in fs */
    fsid_t  f_fsid;	/* file system id */
    uid_t   f_owner;	/* user that mounted the file system */
    short   f_reserved1;	/* reserved for future use */
    short   f_type;	/* type of file system (reserved) */
    long    f_flags;	/* copy of mount flags */
    long    f_reserved2[2];	/* reserved for future use */
    char    f_fstypename[MFSNAMELEN]; /* fs type name */
    char    f_mntonname[MNAMELEN];    /* directory on which mounted */
    char    f_mntfromname[MNAMELEN];  /* mounted file system */
    char    f_reserved3;	/* reserved for future use */
    long    f_reserved4[4];	/* reserved for future use */
};

However, when the macro _DARWIN_FEATURE_64_BIT_INODE is defined, the statfs structure is defined as:

#define MFSTYPENAMELEN  16 /* length of fs type name including null */
#define MAXPATHLEN      1024
#define MNAMELEN        MAXPATHLEN

struct statfs { /* when _DARWIN_FEATURE_64_BIT_INODE is defined */
    uint32_t    f_bsize;        /* fundamental file system block size */
    int32_t     f_iosize;       /* optimal transfer block size */
    uint64_t    f_blocks;       /* total data blocks in file system */
    uint64_t    f_bfree;        /* free blocks in fs */
    uint64_t    f_bavail;       /* free blocks avail to non-superuser */
    uint64_t    f_files;        /* total file nodes in file system */
    uint64_t    f_ffree;        /* free file nodes in fs */
    fsid_t      f_fsid;         /* file system id */
    uid_t       f_owner;        /* user that mounted the filesystem */
    uint32_t    f_type;         /* type of filesystem */
    uint32_t    f_flags;        /* copy of mount exported flags */
    uint32_t    f_fssubtype;    /* fs sub-type (flavor) */
    char        f_fstypename[MFSTYPENAMELEN];   /* fs type name */
    char        f_mntonname[MAXPATHLEN];        /* directory on which mounted */
    char        f_mntfromname[MAXPATHLEN];      /* mounted filesystem */
    uint32_t    f_reserved[8];  /* For future use */
};

Note that the f_fstypename, f_mntonname, and f_mntfromname fields are also wider in this variant.

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

FLAGS

These are some of the flags that may be present in the f_flags field.

MNT_RDONLY: A read-only filesystem
MNT_SYNCHRONOUS: File system is written to synchronously
MNT_NOEXEC: Can't exec from filesystem
MNT_NOSUID: Setuid bits are not honored on this filesystem
MNT_NODEV: Don't interpret special files
MNT_UNION: Union with underlying filesysten
MNT_ASYNC: File system written to asynchronously
MNT_EXPORTED: File system is exported
MNT_LOCAL: File system is stored locally
MNT_QUOTA: Quotas are enabled on this file system
MNT_ROOTFS: This file system is the root of the file system
MNT_DOVOLFS: File system supports volfs
MNT_DONTBROWSE: File system is not appropriate path to user data
MNT_UNKNOWNPERMISSIONS: VFS will ignore ownership information on filesystem objects
MNT_AUTOMOUNTED: File system was mounted by automounter
MNT_JOURNALED: File system is journaled
MNT_DEFWRITE: File system should defer writes
MNT_MULTILABEL: MAC support for individual labels
MNT_CPROTECT: File system supports per-file encrypted data protection

CAVEATS

In Mac OS X versions before 10.4, f_iosize is 4096. On these older systems, use MAXBSIZE instead.

RETURN VALUES

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

ERRORS

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

[ENOTDIR]: A component of the path prefix of Path is not a directory.
[ENAMETOOLONG]: The length of a component of path exceeds {NAME_MAX} characters, or the length of path exceeds {PATH_MAX} characters.
[ENOENT]: The file or directory referred to by path does not exist.
[EACCES]: Search permission is denied for a component of the path prefix of path.
[ELOOP]: Too many symbolic links were encountered in translating path.
[EFAULT]: Buf or path points to an invalid address.
[EIO]: An I/O error occurred while reading from or writing to the file system.

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

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

TRANSITIONAL DESCRIPTION (NOW DEPRECATED)

The statfs64 and fstatfs64 routines are equivalent to their corresponding non-64-suffixed routine, when 64-bit inodes are in effect. They were added before there was support for the symbol variants, and so are now deprecated. Instead of using these, set the _DARWIN_USE_64_BIT_INODE macro before including header files to force 64-bit inode support.

The statfs64 structure used by these deprecated routines is the same as the statfs structure when 64-bit inodes are in effect (see above).

HISTORY

The statfs() function first appeared in 4.4BSD. The statfs64() and fstatfs64() first appeared in Max OS X 10.5 (Leopard) and are now deprecated in favor of the corresponding symbol variants.

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