mirror of https://github.com/mkerrisk/man-pages
192 lines
5.7 KiB
Plaintext
192 lines
5.7 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
|
|
.TH "GETPWUID" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
|
|
.\" getpwuid
|
|
.SH NAME
|
|
getpwuid, getpwuid_r \- search user database for a user ID
|
|
.SH SYNOPSIS
|
|
.LP
|
|
\fB#include <pwd.h>
|
|
.br
|
|
.sp
|
|
struct passwd *getpwuid(uid_t\fP \fIuid\fP\fB);
|
|
.br
|
|
\fP
|
|
.LP
|
|
\fBint getpwuid_r(uid_t\fP \fIuid\fP\fB, struct passwd *\fP\fIpwd\fP\fB,
|
|
char
|
|
*\fP\fIbuffer\fP\fB,
|
|
.br
|
|
\ \ \ \ \ \ size_t\fP \fIbufsize\fP\fB, struct passwd **\fP\fIresult\fP\fB);
|
|
\fP
|
|
\fB
|
|
.br
|
|
\fP
|
|
.SH DESCRIPTION
|
|
.LP
|
|
The \fIgetpwuid\fP() function shall search the user database for an
|
|
entry with a matching \fIuid\fP.
|
|
.LP
|
|
The \fIgetpwuid\fP() function need not be reentrant. A function that
|
|
is not required to be reentrant is not required to be
|
|
thread-safe.
|
|
.LP
|
|
Applications wishing to check for error situations should set \fIerrno\fP
|
|
to 0 before calling \fIgetpwuid\fP(). If
|
|
\fIgetpwuid\fP() returns a null pointer and \fIerrno\fP is set to
|
|
non-zero, an error occurred.
|
|
.LP
|
|
The \fIgetpwuid_r\fP() function shall update the \fBpasswd\fP structure
|
|
pointed to by \fIpwd\fP and store a pointer to that
|
|
structure at the location pointed to by \fIresult\fP. The structure
|
|
shall contain an entry from the user database with a matching
|
|
\fIuid\fP. Storage referenced by the structure is allocated from the
|
|
memory provided with the \fIbuffer\fP parameter, which is
|
|
\fIbufsize\fP bytes in size. The maximum size needed for this buffer
|
|
can be determined with the {_SC_GETPW_R_SIZE_MAX} \fIsysconf\fP()
|
|
parameter. A NULL pointer shall be returned at the location pointed
|
|
to by
|
|
\fIresult\fP on error or if the requested entry is not found.
|
|
.SH RETURN VALUE
|
|
.LP
|
|
The \fIgetpwuid\fP() function shall return a pointer to a \fBstruct
|
|
passwd\fP with the structure as defined in \fI<pwd.h>\fP with a matching
|
|
entry if found. A null pointer shall be returned if the requested
|
|
entry is not found, or an error occurs. On error, \fIerrno\fP shall
|
|
be set to indicate the error.
|
|
.LP
|
|
The return value may point to a static area which is overwritten by
|
|
a subsequent call to \fIgetpwent\fP(), \fIgetpwnam\fP(), or
|
|
\fIgetpwuid\fP().
|
|
.LP
|
|
If successful, the \fIgetpwuid_r\fP() function shall return zero;
|
|
otherwise, an error number shall be returned to indicate the
|
|
error.
|
|
.SH ERRORS
|
|
.LP
|
|
The \fIgetpwuid\fP() and \fIgetpwuid_r\fP() functions may fail if:
|
|
.TP 7
|
|
.B EIO
|
|
An I/O error has occurred.
|
|
.TP 7
|
|
.B EINTR
|
|
A signal was caught during \fIgetpwuid\fP().
|
|
.TP 7
|
|
.B EMFILE
|
|
{OPEN_MAX} file descriptors are currently open in the calling process.
|
|
.TP 7
|
|
.B ENFILE
|
|
The maximum allowable number of files is currently open in the system.
|
|
.sp
|
|
.LP
|
|
The \fIgetpwuid_r\fP() function may fail if:
|
|
.TP 7
|
|
.B ERANGE
|
|
Insufficient storage was supplied via \fIbuffer\fP and \fIbufsize\fP
|
|
to contain the data to be referenced by the resulting
|
|
\fBpasswd\fP structure.
|
|
.sp
|
|
.LP
|
|
\fIThe following sections are informative.\fP
|
|
.SH EXAMPLES
|
|
.SS Getting an Entry for the Root User
|
|
.LP
|
|
The following example gets the user database entry for the user with
|
|
user ID 0 (root).
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#include <sys/types.h>
|
|
#include <pwd.h>
|
|
\&...
|
|
uid_t id = 0;
|
|
struct passwd *pwd;
|
|
.sp
|
|
|
|
pwd = getpwuid(id);
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.SS Finding the Name for the Effective User ID
|
|
.LP
|
|
The following example defines \fIpws\fP as a pointer to a structure
|
|
of type \fBpasswd\fP, which is used to store the structure
|
|
pointer returned by the call to the \fIgetpwuid\fP() function. The
|
|
\fIgeteuid\fP()
|
|
function shall return the effective user ID of the calling process;
|
|
this is used as the search criteria for the \fIgetpwuid\fP()
|
|
function. The call to \fIgetpwuid\fP() shall return a pointer to the
|
|
structure containing that user ID value.
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <pwd.h>
|
|
\&...
|
|
struct passwd *pws;
|
|
pws = getpwuid(geteuid());
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.SS Finding an Entry in the User Database
|
|
.LP
|
|
The following example uses \fIgetpwuid\fP() to search the user database
|
|
for a user ID that was previously stored in a
|
|
\fBstat\fP structure, then prints out the user name if it is found.
|
|
If the user is not found, the program prints the numeric value
|
|
of the user ID for the entry.
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#include <sys/types.h>
|
|
#include <pwd.h>
|
|
#include <stdio.h>
|
|
\&...
|
|
struct stat statbuf;
|
|
struct passwd *pwd;
|
|
\&...
|
|
if ((pwd = getpwuid(statbuf.st_uid)) != NULL)
|
|
printf(" %-8.8s", pwd->pw_name);
|
|
else
|
|
printf(" %-8d", statbuf.st_uid);
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.SH APPLICATION USAGE
|
|
.LP
|
|
Three names associated with the current process can be determined:
|
|
\fIgetpwuid\fP( \fIgeteuid\fP()) returns the name associated with
|
|
the effective user ID of the process; \fIgetlogin\fP() returns the
|
|
name associated with the current login activity; and
|
|
\fIgetpwuid\fP( \fIgetuid\fP()) returns the name associated with the
|
|
real user ID of the
|
|
process.
|
|
.LP
|
|
The \fIgetpwuid_r\fP() function is thread-safe and returns values
|
|
in a user-supplied buffer instead of possibly using a static
|
|
data area that may be overwritten by each call.
|
|
.SH RATIONALE
|
|
.LP
|
|
None.
|
|
.SH FUTURE DIRECTIONS
|
|
.LP
|
|
None.
|
|
.SH SEE ALSO
|
|
.LP
|
|
\fIgetpwnam\fP() , \fIgeteuid\fP() , \fIgetuid\fP() , \fIgetlogin\fP()
|
|
, the Base Definitions volume of
|
|
IEEE\ Std\ 1003.1-2001, \fI<limits.h>\fP, \fI<pwd.h>\fP, \fI<sys/types.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 .
|