fsctl(2) [opendarwin man page]
FSCTL(2) BSD System Calls Manual FSCTL(2) NAME
fsctl -- control filesystems SYNOPSIS
#include <sys/attr.h> #include <sys/ioctl.h> int fsctl(const char *path, unsigned long request, void *data, unsigned long options); DESCRIPTION
The fsctl() function manipulates the filesystem controlling mounted volumes. In particular, many filesystem-specific operating characteris- tics of mounted filesystems may be controlled with fsctl() requests. fsctl() requests can also be used to extract filesystem-specific infor- mation for a mounted volumes. path is the path name of any file within the mounted filesystem. An fsctl request has encoded in it whether the argument is an ``in'' parameter or ``out'' parameter, and the size of the argument data in bytes. Values for request are entirely filesystem-specific except for the following, defined in <sys/fsctl.h>: FSGETMOUNTINFOSIZE /* Return size of mount info data */ Macros and defines used in specifying an fsctl request are the same as for ioctl() requests and are located in the file <sys/ioccom.h>. options may specify special flags for the processing of the fsctl() call. The options are specified by or'ing the option values. The only option currently defined is #define FSOPT_NOFOLLOW 0x00000001 /* Don't follow symlinks */ which is interpreted by the fsctl() call to prevent following of symlinks. The options argument is passed to the filesystem, which may define and handle additional options bit values. RETURN VALUES
If an error has occurred, a value of -1 is returned and errno is set to indicate the error. ERRORS
fsctl() will fail if: [ENOTDIR] A component of the path prefix is not a directory. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters. [ENOENT] The named file does not exist. [EACCES] Search permission is denied for a component of the path prefix. [ELOOP] Too many symbolic links were encountered in translating the pathname. [EFAULT] path or data points to an invalid address. [EIO] An I/O error occurred while reading from or writing to the file system. [EINVAL] request or data is not valid. SEE ALSO
ioctl(2), getattrlist(2), setattrlist(2) HISTORY
The fsctl() function call appeared in Mac OS X version 10.0. Mac OS X January 14, 2003 Mac OS X
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MOUNT(2) BSD System Calls Manual MOUNT(2) NAME
mount, unmount -- mount or dismount a filesystem SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> int mount(const char *type, const char *dir, int flags, void *data); int unmount(const char *dir, int flags); DESCRIPTION
The mount() function grafts a filesystem object onto the system file tree at the point dir. The argument data describes the filesystem object to be mounted. The argument type tells the kernel how to interpret data (See type below). The contents of the filesystem become available through the new mount point dir. Any files in dir at the time of a successful mount are swept under the carpet so to speak, and are unavailable until the filesystem is unmounted. The following flags may be specified to suppress default semantics which affect filesystem access. MNT_RDONLY The filesystem should be treated as read-only; Even the super-user may not write on it. MNT_NOEXEC Do not allow files to be executed from the filesystem. MNT_NOSUID Do not honor setuid or setgid bits on files when executing them. MNT_NODEV Do not interpret special files on the filesystem. MNT_UNION Union with underlying filesystem instead of obscuring it. MNT_SYNCHRONOUS All I/O to the filesystem should be done synchronously. The flag MNT_UPDATE indicates that the mount command is being applied to an already mounted filesystem. This allows the mount flags to be changed without requiring that the filesystem be unmounted and remounted. Some filesystems may not allow all flags to be changed. For exam- ple, most filesystems will not allow a change from read-write to read-only. The flag MNT_RELOAD causes the vfs subsystem to update its data structures pertaining to the specified already mounted filesystem. The type argument defines the type of the filesystem. Data is a pointer to a structure that contains the type specific arguments to mount. The format for these argument structures is described in the manual page for each filesystem. The umount() function call disassociates the filesystem from the specified mount point dir. The flags argument may specify MNT_FORCE to specify that the filesystem should be forcibly unmounted even if files are still active. Active special devices continue to work, but any further accesses to any other active files result in errors even if the filesystem is later remounted. RETURN VALUES
The mount() returns the value 0 if the mount was successful, otherwise -1 is returned and the variable errno is set to indicate the error. Umount returns the value 0 if the umount succeeded; otherwise -1 is returned and the variable errno is set to indicate the error. ERRORS
Mount() will fail when one of the following occurs: [EPERM] The caller is not the super-user, and the device-node and the mountpoint do not have adequate ownership and permissions. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters. [ELOOP] Too many symbolic links were encountered in translating a pathname. [ENOENT] A component of dir does not exist. [ENOTDIR] A component of name is not a directory, or a path prefix of special is not a directory. [EINVAL] A pathname contains a character with the high-order bit set. [EBUSY] Another process currently holds a reference to dir. [EFAULT] Dir points outside the process's allocated address space. Umount may fail with one of the following errors: [EPERM] The caller is not the super-user, and the mount() was not done by the user. [ENOTDIR] A component of the path is not a directory. [EINVAL] The pathname contains a character with the high-order bit set. [ENAMETOOLONG] A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters. [ELOOP] Too many symbolic links were encountered in translating the pathname. [EINVAL] The requested directory is not in the mount table. [EBUSY] A process is holding a reference to a file located on the filesystem. [EIO] An I/O error occurred while writing cached filesystem information. [EFAULT] Dir points outside the process's allocated address space. SEE ALSO
mount(8), umount(8), BUGS
Some of the error codes need translation to more obvious messages. HISTORY
Mount() and umount() function calls appeared in Version 6 AT&T UNIX. 4th Berkeley Distribution December 11, 1993 4th Berkeley Distribution