man-pages/man3p/getutxid.3p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "ENDUTXENT" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" endutxent 
.SH NAME
endutxent, getutxent, getutxid, getutxline, pututxline, setutxent
\- user accounting database functions
.SH SYNOPSIS
.LP
\fB#include <utmpx.h>
.br
.sp
void endutxent(void);
.br
struct utmpx *getutxent(void);
.br
struct utmpx *getutxid(const struct utmpx *\fP\fIid\fP\fB);
.br
struct utmpx *getutxline(const struct utmpx *\fP\fIline\fP\fB);
.br
struct utmpx *pututxline(const struct utmpx *\fP\fIutmpx\fP\fB);
.br
void setutxent(void); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
These functions shall provide access to the user accounting database.
.LP
The \fIgetutxent\fP() function shall read the next entry from the
user accounting database. If the database is not already
open, it shall open it. If it reaches the end of the database, it
shall fail.
.LP
The \fIgetutxid\fP() function shall search forward from the current
point in the database. If the \fIut_type\fP value of the
\fButmpx\fP structure pointed to by \fIid\fP is BOOT_TIME, OLD_TIME,
or NEW_TIME, then it shall stop when it finds an entry with
a matching \fIut_type\fP value. If the \fIut_type\fP value is INIT_PROCESS,
LOGIN_PROCESS, USER_PROCESS, or DEAD_PROCESS, then it
shall stop when it finds an entry whose type is one of these four
and whose \fIut_id\fP member matches the \fIut_id\fP member of
the \fButmpx\fP structure pointed to by \fIid\fP. If the end of the
database is reached without a match, \fIgetutxid\fP() shall
fail.
.LP
The \fIgetutxline\fP() function shall search forward from the current
point in the database until it finds an entry of the type
LOGIN_PROCESS or USER_PROCESS which also has a \fIut_line\fP value
matching that in the \fButmpx\fP structure pointed to by
\fIline\fP. If the end of the database is reached without a match,
\fIgetutxline\fP() shall fail.
.LP
The \fIgetutxid\fP() or \fIgetutxline\fP() function may cache data.
For this reason, to use \fIgetutxline\fP() to search for
multiple occurrences, the application shall zero out the static data
after each success, or \fIgetutxline\fP() may return a
pointer to the same \fButmpx\fP structure.
.LP
There is one exception to the rule about clearing the structure before
further reads are done. The implicit read done by
\fIpututxline\fP() (if it finds that it is not already at the correct
place in the user accounting database) shall not modify the
static structure returned by \fIgetutxent\fP(), \fIgetutxid\fP(),
or \fIgetutxline\fP(), if the application has modified this
structure and passed the pointer back to \fIpututxline\fP().
.LP
For all entries that match a request, the \fIut_type\fP member indicates
the type of the entry. Other members of the entry
shall contain meaningful data based on the value of the \fIut_type\fP
member as follows:
.TS C
center; l lw(40).
\fBut_type Member\fP	T{
.na
\fBOther Members with Meaningful Data\fP
.ad
T}
EMPTY	T{
.na
No others
.ad
T}
BOOT_TIME	T{
.na
\fIut_tv\fP
.ad
T}
OLD_TIME	T{
.na
\fIut_tv\fP
.ad
T}
NEW_TIME	T{
.na
\fIut_tv\fP
.ad
T}
USER_PROCESS	T{
.na
\fIut_id\fP, \fIut_user\fP (login name of the user), \fIut_line\fP, \fIut_pid\fP, \fIut_tv\fP
.ad
T}
INIT_PROCESS	T{
.na
\fIut_id\fP, \fIut_pid\fP, \fIut_tv\fP
.ad
T}
LOGIN_PROCESS	T{
.na
\fIut_id\fP, \fIut_user\fP (implementation-defined name of the login process), \fIut_pid\fP, \fIut_tv\fP
.ad
T}
DEAD_PROCESS	T{
.na
\fIut_id\fP, \fIut_pid\fP, \fIut_tv\fP
.ad
T}
.TE
.LP
An implementation that provides extended security controls may impose
implementation-defined restrictions on accessing the user
accounting database. In particular, the system may deny the existence
of some or all of the user accounting database entries
associated with users other than the caller.
.LP
If the process has appropriate privileges, the \fIpututxline\fP()
function shall write out the structure into the user
accounting database. It shall use \fIgetutxid\fP() to search for a
record that satisfies the request. If this search succeeds,
then the entry shall be replaced. Otherwise, a new entry shall be
made at the end of the user accounting database.
.LP
The \fIendutxent\fP() function shall close the user accounting database.
.LP
The \fIsetutxent\fP() function shall reset the input to the beginning
of the database. This should be done before each search
for a new entry if it is desired that the entire database be examined.
.LP
These functions need not be reentrant. A function that is not required
to be reentrant is not required to be thread-safe.
.SH RETURN VALUE
.LP
Upon successful completion, \fIgetutxent\fP(), \fIgetutxid\fP(), and
\fIgetutxline\fP() shall return a pointer to a
\fButmpx\fP structure containing a copy of the requested entry in
the user accounting database. Otherwise, a null pointer shall be
returned.
.LP
The return value may point to a static area which is overwritten by
a subsequent call to \fIgetutxid\fP() or
\fIgetutxline\fP().
.LP
Upon successful completion, \fIpututxline\fP() shall return a pointer
to a \fButmpx\fP structure containing a copy of the
entry added to the user accounting database. Otherwise, a null pointer
shall be returned.
.LP
The \fIendutxent\fP() and \fIsetutxent\fP() functions shall not return
a value.
.SH ERRORS
.LP
No errors are defined for the \fIendutxent\fP(), \fIgetutxent\fP(),
\fIgetutxid\fP(), \fIgetutxline\fP(), and
\fIsetutxent\fP() functions.
.LP
The \fIpututxline\fP() function may fail if:
.TP 7
.B EPERM
The process does not have appropriate privileges.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
The sizes of the arrays in the structure can be found using the \fIsizeof\fP
operator.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
The Base Definitions volume of IEEE\ Std\ 1003.1-2001, \fI<utmpx.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .