GETMNTENT(3C) Standard C Library Functions GETMNTENT(3C)
NAME
getmntent, getmntany, getextmntent, hasmntopt, putmntent, resetmnttab -
get mounted device information
SYNOPSIS
#include <stdio.h>
#include <sys/mnttab.h>
int getmntent(
FILE *fp,
struct mnttab *mp);
int getmntany(
FILE *fp,
struct mnttab *mp,
struct mnttab *mpref);
int getextmntent(
FILE *fp,
struct extmnttab *mp,
int len);
char *hasmntopt(
struct mnttab *mnt,
char *opt);
int putmntent(
FILE *iop,
struct mnttab *mp);
void resetmnttab(
FILE *fp);
DESCRIPTION
getmntent() and
getmntany() The
getmntent() and
getmntany() functions each fill in the structure
pointed to by
mp with the broken-out fields of a line in the
mnttab file.
Each line read from the file contains a
mnttab structure, which is
defined in the <
sys/mnttab.h> header. The structure contains the
following members, which correspond to the broken-out fields from a line
in
/etc/mnttab (see
mnttab(5)).
char *mnt_special; /* name of mounted resource */
char *mnt_mountp; /* mount point */
char *mnt_fstype; /* type of file system mounted */
char *mnt_mntopts; /* options for this mount */
char *mnt_time; /* time file system mounted */
Fields with no actual content in
/etc/mnttab are represented in the file
as "-". To clearly distinguish empty fields,
getmntent() set the
corresponding field in
mp to
NULL.
Each
getmntent() call causes a new line to be read from the
mnttab file.
Successive calls can be used to search the entire list. The
getmntany() function searches the file referenced by
fp until a match is found
between a line in the file and
mpref. A match occurs if all non-null
entries in
mpref match the corresponding fields in the file. These
functions do not open, close, or rewind the file.
getextmntent() The
getextmntent() function is an extended version of the
getmntent() function that returns, in addition to the information that
getmntent() returns, the major and minor number of the mounted resource to which the
line in
mnttab corresponds. The
getextmntent() function also fills in the
extmntent structure defined in the <
sys/mnttab.h> header. For
getextmntent() to function properly, it must be notified when the
mnttab file has been reopened or rewound since a previous
getextmntent() call.
This notification is accomplished by calling
resetmnttab(). Otherwise, it
behaves exactly as
getmntent() described above
The data pointed to by the
mnttab structure members are stored in a
static area and must be copied to be saved between successive calls.
hasmntopt() The
hasmntopt() function scans the
mnt_mntopts member of the
mnttab structure
mnt for a substring that matches
opt. It returns the address of
the substring if a match is found; otherwise it returns
0. Substrings are
delimited by commas and the end of the
mnt_mntopts string.
putmntent() The
putmntent() function is obsolete and no longer has any effect.
Entries appear in
mnttab as a side effect of a
mount(2) call. The
function name is still defined for transition purposes.
resetmnttab() The
resetmnttab() function notifies
getextmntent() to reload from the
kernel the device information that corresponds to the new snapshot of the
mnttab information (see
mnttab(5)). Subsequent
getextmntent() calls then
return correct
extmnttab information. This function should be called
whenever the
mnttab file is either rewound or closed and reopened before
any calls are made to
getextmntent().
RETURN VALUES
getmntent() and
getmntany() If the next entry is successfully read by
getmntent() or a match is found
with
getmntany(),
0 is returned. If an
EOF is encountered on reading,
these functions return
-1. If an error is encountered, a value greater
than 0 is returned. The following error values are defined in
<sys/mnttab.h>:
MNT_TOOLONG A line in the file exceeded the internal buffer size of
MNT_LINE_MAX.
MNT_TOOMANY A line in the file contains too many fields.
MNT_TOOFEW A line in the file contains too few fields.
hasmntopt() Upon successful completion,
hasmntopt() returns the address of the
substring if a match is found. Otherwise, it returns
0.
putmntent() The
putmntent() is obsolete and always returns
-1.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+---------------+-----------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------+
|MT-Level | Safe |
+---------------+-----------------+
SEE ALSO
mount(2),
mnttab(5),
attributes(7) March 22, 2004
GETMNTENT(3C)