Get filesystem information, given a file descriptor
#include <sys/statvfs.h> int fstatvfs( int fildes, struct statvfs *buf ); int fstatvfs64( int fildes, struct statvfs64 *buf );
- The descriptor for a file that resides on the filesystem that you want to get information about.
- A pointer to a buffer where the function can store information about the filesystem; see below.
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The fstatvfs() function returns a generic superblock describing a filesystem; you can use it to get information about mounted filesystems. The fstatvfs64() function is a 64-bit version of fstatvfs(). The statvfs() and statvfs64() functions are similar, but they take a path name instead of a file descriptor.
The fildes argument is an open file descriptor, obtained from a successful call to open(), creat(), dup(), fcntl(), or pipe(), for a file that resides on that filesystem. The filesystem type is known to the operating system. Read, write, or execute permission for the named file isn't required.
The buf argument is a pointer to a statvfs or statvfs64 structure that's filled by the function. It contains at least:
- unsigned long f_bsize
- The preferred filesystem blocksize.
- unsigned long f_frsize
- The fundamental filesystem blocksize (if supported)
- fsblkcnt_t f_blocks
- The total number of blocks on the filesystem, in units of f_frsize.
- fsblkcnt_t f_bfree
- The total number of free blocks.
- fsblkcnt_t f_bavail
- The number of free blocks available to a nonsuperuser.
- fsfilcnt_t f_files
- The total number of file nodes (inodes).
- fsfilcnt_t f_ffree
- The total number of free file nodes.
- fsfilcnt_t f_favail
- The number of inodes available to a nonsuperuser.
- unsigned long f_fsid
- The filesystem ID (currently the device ID).
- char f_basetype
- The type of the target filesystem, as a null-terminated string.
- unsigned long f_flag
- A bitmask of flags; the function can set these flags (the
_MOUNT_* and ST_* bits are equivalent):
_MOUNT_* ST_* Meaning _MOUNT_READONLY ST_RDONLY The filesystem is read-only. _MOUNT_NOEXEC ST_NOEXEC The filesystem doesn't permit the loading of executables. _MOUNT_NOSUID ST_NOSUID The filesystem doesn't support setuid() and setgid() semantics. _MOUNT_NOCREAT ST_NOCREAT You can't create files on the filesystem. _MOUNT_OFF32 ST_OFF32 The off_t type is limited to 32 bits. _MOUNT_NOATIME ST_NOATIME The filesystem doesn't support the logging of file access times.
- unsigned long f_namemax
- The maximum filename length.
The values returned for f_files, f_ffree, and f_favail depend on the filesystem:
- An error occurred (errno is set).
- The fildes argument isn't an open file descriptor.
- The buf argument points to an illegal address.
- A signal was caught during execution.
- An I/O error occurred while reading the filesystem.
- One of the values to be returned can't be represented correctly in the structure pointed to by buf.