Standard C Library Functions getutent(3C)
NAME
getutent, getutid, getutline, pututline, setutent, endutent,
utmpname - user accounting database functions
SYNOPSIS
#include
struct utmp *getutent(void);
struct utmp *getutid(const struct utmp *id);
struct utmp *getutline(const struct utmp *line);
struct utmp *pututline(const struct utmp *utmp);
void setutent(void);
void endutent(void);
int utmpname(const char *file);
DESCRIPTION
These functions provide access to the user accounting data-
base, utmp. Entries in the database are described by the
definitions and data structures in .
The utmp structure contains the following members:
char utuser[8]; /* user login name */
char utid[4]; /* /sbin/inittab id */
/* (usually line #) */
char utline[12]; /* device name (console, lnxx) */
short utpid; /* process id */
short uttype; /* type of entry */
struct exitstatus utexit; /* exit status of a process */
/* marked as DEADPROCES */
timet uttime; /* time entry was made */
The structure exitstatus includes the following members:
short etermination; /* termination status */
short eexit; /* exit status */
SunOS 5.11 Last change: 27 Oct 1998 1
Standard C Library Functions getutent(3C)
getutent()
The getutent() function reads in the next entry from a utmp
database. If the database is not already open, it opens it.
If it reaches the end of the database, it fails.
getutid()
The getutid() function searches forward from the current
point in the utmp database until it finds an entry with a
uttype matching id->uttype if the type specified is
RUNLVL, BOTIME, DOWNTIME, OLDTIME, or NEWTIME. If the
type specified in id is INITPROCES, LOGINPROCES,
USERPROCES, or DEADPROCES, then getutid() will return a
pointer to the first entry whose type is one of these four
and whose utid member matches id->utid. If the end of
database is reached without a match, it fails.
getutline()
The getutline() function searches forward from the current
point in the utmp database until it finds an entry of the
type LOGINPROCES or utline string matching the line-
>utline string. If the end of database is reached without a
match, it fails.
pututline()
The pututline() function writes the supplied utmp structure
into the utmp database. It uses getutid() to search forward
for the proper place if it finds that it is not already at
the proper place. It is expected that normally the user of
pututline() will have searched for the proper entry using
one of the these functions. If so, pututline() will not
search. If pututline() does not find a matching slot for
the new entry, it will add a new entry to the end of the
database. It returns a pointer to the utmp structure. When
called by a non-root user, pututline() invokes a setuid()
root program to verify and write the entry, since the utmp
database is normally writable only by root. In this event,
the utname member must correspond to the actual user name
associated with the process; the uttype member must be
either USERPROCES or DEADPROCES; and the utline member
must be a device special file and be writable by the user.
setutent()
The setutent() function resets the input stream to the
beginning. This reset should be done before each search for
a new entry if it is desired that the entire database be
examined.
endutent()
The endutent() function closes the currently open database.
utmpname()
SunOS 5.11 Last change: 27 Oct 1998 2
Standard C Library Functions getutent(3C)
The utmpname() function allows the user to change the name
of the database file examined to another file. If the file
does not exist, this will not be apparent until the first
attempt to reference the file is made. The utmpname() func-
tion does not open the file but closes the old file if it is
currently open and saves the new file name.
RETURN VALUES
A null pointer is returned upon failure to read, whether for
permissions or having reached the end of file, or upon
failure to write. If the file name given is longer than 79
characters, utmpname() returns 0. Otherwise, it returns 1.
USAGE
These functions use buffered standard I/O for input, but
pututline() uses an unbuffered non-standard write to avoid
race conditions between processes trying to modify the utmp
and wtmp databases.
Applications should not access the utmp and wtmp databases
directly, but should use these functions to ensure that
these databases are maintained consistently. Using these
functions, however, may cause applications to fail if user
accounting data cannot be represented properly in the utmp
structure (for example, on a system where PIDs can exceed
32767). Use the functions described on the getutxent(3C)
manual page instead.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
MT-Level Unsafe
SEE ALSO
getutxent(3C), ttyslot(3C), utmpx(4), attributes(5)
NOTES
The most current entry is saved in a static structure. Mul-
tiple accesses require that it be copied before further
accesses are made. On each call to either getutid() or
getutline(), the function examines the static structure
before performing more I/O. If the contents of the static
structure match what it is searching for, it looks no
SunOS 5.11 Last change: 27 Oct 1998 3
Standard C Library Functions getutent(3C)
further. For this reason, to use getutline() to search for
multiple occurrences, it would be necessary to zero out the
static area after each success, or getutline() would just
return the same structure over and over again. There is one
exception to the rule about emptying the structure before
further reads are done. The implicit read done by putut-
line() (if it finds that it is not already at the correct
place in the file) will not hurt the contents of the static
structure returned by the getutent(), getutid() or getut-
line() functions, if the user has just modified those con-
tents and passed the pointer back to pututline().
SunOS 5.11 Last change: 27 Oct 1998 4
|
