GETFSSTAT(2) | System Calls Manual | GETFSSTAT(2)

# NAME

`getfsstat` — get list of all mounted file systems

# SYNOPSIS

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

int
`getfsstat`(struct statfs *buf, size_t bufsize, int flags);

# DESCRIPTION

`getfsstat`() returns information about all mounted file systems. buf is a pointer to an array of statfs(2) structures 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 */
    };

The buffer is filled with an array of statfs structures, one for each mounted file system up to the size specified by bufsize.

If buf is `NULL`, `getfsstat`() returns just the number of mounted file systems.

Normally flags should be specified as `MNT_WAIT`. If flags is set to `MNT_NOWAIT`, `getfsstat`() will return the information it has available without requesting an update from each file system. Thus, some of the information will be out of date, but `getfsstat`() will not block waiting for information from a file system that is unable to respond. If no flags are provided, `MNT_WAIT` is assumed.

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

# RETURN VALUES

Upon successful completion, the number of statfs structures is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.

# ERRORS

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

[`EFAULT`]
  buf points to an invalid address.
[`EIO`]
  An I/O error occurred while reading from or writing to the file system.

# SEE ALSO

statfs(2), fstab(5), mount(8)

# HISTORY

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

July 30, 2022 | Debian