getmnt.2

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)getmnt.2	2.3	5/19/87
.TH getmnt 2
.SH Name
getmnt \- get information about mounted file systems
.SH Syntax
.B #include <sys/types.h>
.br
.B #include <sys/param.h>
.br
.B #include <sys/mount.h>
.PP
.B getmnt(\fIstart, buffer, nbytes, mode, path\fB)
.br
.B int \fI*start\fB;
.br
.B struct fs_data  \fI*buffer\fB;
.br
.B int	\fInbytes, mode\fB;	
.br
.B char	 \fI*path\fP;
.SH Description
.NXR "getmnt system call"
.NXR "file system" "getting information on mounted"
The
.PN getmnt
system call retrieves information about mounted file systems.
.PP
The
.I mode
argument is one of the following:
.PN STAT_ONE ,
.PN NOSTAT_ONE ,
.PN STAT_MANY ,
or
.PN NOSTAT_MANY .
.PP
If
.I mode
is
.PN  STAT_ONE
or
.PN NOSTAT_ONE ,
then
.I path
is the name of a single file system for which information is desired,
.I start
and
.I nbytes
are ignored,
and
.I buffer
is assumed to be large enough to hold one
.PN fs_data
structure.
.PP
If
.I mode
is
.PN STAT_MANY
or
.PN NOSTAT_MANY ,
then
.I path
is ignored.
The
.I start
argument is the current logical location within the internal system
mount table and must be initially set to
.PN 0 .
The 
.I start
argument is updated to reflect the current logical
location within the system mount table,
allowing successive executions of
.PN getmnt
to retrieve information about all the mounted file systems.
The
.I nbytes
argument defines the size of
.IR buffer ,
into which the file system information is returned.
Buffer sizes must be a multiple of 
.PN "sizeof(struct fs_data)"
bytes.
Larger buffer sizes allow information about multiple file systems
to be returned.
.PP
If
.I mode
is
.PN NOSTAT_ONE
or
.PN NOSTAT_MANY ,
then dynamic
.PN fs_data
information (the number of free inodes and the number of free blocks)
could be out of date,
but these calls are guaranteed to return.
The file system information in memory is not updated.
.\" The 
.\" .I start
.\" argument is set to 0 when information about all file
.\" systems has been retrieved.
.PP
If
.I mode
is
.PN STAT_ONE
or
.PN STAT_MANY ,
then the file system information in memory is updated.
However,
if the server of any file system for which information is being
retrieved is down,
then these calls will hang until the server responds.
.PP
When information about multiple file
systems is returned,
it is stored within consecutive 
.I buffer
locations. 
The information for each file system is described by the structure
.PN fs_data:
.EX 0
struct fs_data {
	struct	fs_data_req	fd_req;	/* required data */
	u_int	fd_spare[113];		/* spare */
};	/* 2560 bytes */

struct fs_data_req {    /* required part for all file systems */
	u_int	flags;    /* how mounted */
	u_int	mtsize;   /* max transfer size in bytes */
	u_int	otsize;   /* optimal transfer size in bytes */
	u_int	bsize;    /* fs block size in bytes for vm code */
	u_int	fstype;   /* see ../h/fs_types.h  */
	u_int	gtot;     /* total number of gnodes */
	u_int	gfree;    /* # of free gnodes */
	u_int	btot;     /* total number of 1K blocks */
	u_int	bfree;    /* # of free 1K blocks */
	u_int	bfreen;   /* user consumable 1K blocks */
	u_int	pgthresh; /* min size in bytes before paging*/
	int	uid;      /* uid that mounted me */
	dev_t	dev;      /* major/minor of fs */
	dev_t	pad;      /* alignment: dev_t is a short*/
	char	devname[MAXPATHLEN + 4];  /* name of dev */
	char	path[MAXPATHLEN + 4];     /* name of mount point */
}
.EE
.SH Return Values
.PP
Upon successful completion, a value indicating the number of
.PN fs_data
structures stored in
.I buffer
is returned.
If the file system is not mounted (\fImode\fR is
.PN STAT_ONE
or
.PN NOSTAT_ONE )
or there are no more file systems
in the mount table (\fImode\fR is
.PN STAT_MANY
or
.PN NOSTAT_MANY ),
.PN 0
is returned.
Otherwise,
.PN \-1
is returned and the global variable
.I errno
is set to indicate the error.
.SH Diagnostics
.TP 18
[ENOTDIR]
A component of the path prefix of
.I path
is not a directory.
.TP
[EINVAL]
Invalid argument.
.TP
[ENAMETOOLONG]
The length of a component of
.I path
exceeds 255 characters,
or the length of
.I path
exceeds 1023 characters.
.TP
[ENOENT]
The file referred to by
.I path
does not exist.
.TP
[EACCESS]
Search permission is denied for a component of the path prefix of
.IR path .
.TP
[ELOOP]
Too many symbolic links were encountered in translating
.IR path .
.TP
[EFAULT]
Either
.I buffer
or
.I start
causes an illegal address to be referenced.
.TP
[EIO]
An I/O error occurred while reading from the file system.
.SH See Also
gfsi(5)