-.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
+.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\"
+.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
-.\"
+.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
-.\"
+.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
-.\" License.
+.\" %%%LICENSE_END
+.\"
.\" Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faith@cs.unc.edu)
-.\" FIXME Many more values for 'name' are supported, some of which
-.\" are documented under 'info confstr'.
-.\" See <bits/confname.h> for the rest.
-.\" These should all be added to this page.
-.\" See also the SUSv3 specification of confstr()
-.TH CONFSTR 3 1993-04-17 "GNU" "Linux Programmer's Manual"
+.\"
+.\" FIXME Many more values for 'name' are supported, some of which
+.\" are documented under 'info confstr'.
+.\" See <bits/confname.h> for the rest.
+.\" These should all be added to this page.
+.\" See also the POSIX.1-2001 specification of confstr()
+.\"
+.TH CONFSTR 3 2019-03-06 "GNU" "Linux Programmer's Manual"
.SH NAME
confstr \- get configuration dependent string variables
.SH SYNOPSIS
.nf
-.B #define _POSIX_C_SOURCE 2
-or
-.B #define _XOPEN_SOURCE
-.nl
.B #include <unistd.h>
-.sp
+.PP
.BI "size_t confstr(int " "name" ", char *" buf ", size_t " len );
.fi
+.PP
+.in -4n
+Feature Test Macro Requirements for glibc (see
+.BR feature_test_macros (7)):
+.in
+.PP
+.BR confstr ():
+_POSIX_C_SOURCE\ >=\ 2 || _XOPEN_SOURCE
.SH DESCRIPTION
.BR confstr ()
gets the value of configuration-dependent string variables.
.TP
.BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)"
A string which identifies the GNU C library version on this system
-(e.g, "glibc 2.3.4").
+(e.g., "glibc 2.3.4").
.TP
.BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)"
A string which identifies the POSIX implementation supplied by this
-C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").
+C library (e.g., "NPTL 2.3.4" or "linuxthreads-0.10").
.TP
.B _CS_PATH
A value for the
.PP
If
.I buf
-is not NULL and
+is not NULL and
.I len
is not zero,
.BR confstr ()
.I buf
truncated to
.I len \- 1
-characters if necessary, with a null character as termination.
+bytes if necessary, with a null byte (\(aq\e0\(aq) as terminator.
This can be detected by comparing the return value of
.BR confstr ()
against
is NULL,
.BR confstr ()
just returns the value as defined below.
-.SH "RETURN VALUE"
+.SH RETURN VALUE
If
.I name
-does not correspond to a valid configuration variable,
+is a valid configuration variable,
+.BR confstr ()
+returns the number of bytes (including the terminating null byte)
+that would be required to hold the entire value of that variable.
+This value may be greater than
+.IR len ,
+which means that the value in
+.I buf
+is truncated.
+.PP
+If
+.I name
+is a valid configuration variable,
+but that variable does not have a value, then
.BR confstr ()
returns 0.
-.SH EXAMPLES
-The following code fragment determines the path where to find
-the POSIX.2 system utilities:
-.br
-.nf
-.in 10
-
-char *pathbuf; size_t n;
-
-n = confstr(_CS_PATH,NULL,(size_t)0);
-if ((pathbuf = malloc(n)) == NULL) abort();
-confstr(_CS_PATH, pathbuf, n);
-.SH ERRORS
-If the value of
+If
.I name
-is invalid,
+does not correspond to a valid configuration variable,
+.BR confstr ()
+returns 0, and
.I errno
is set to
.BR EINVAL .
-.SH "CONFORMING TO"
-proposed POSIX.2
-.SH BUGS
-POSIX.2 is not yet an approved standard; the information in this
-manpage is subject to change.
-.SH "SEE ALSO"
+.SH ERRORS
+.TP
+.B EINVAL
+The value of
+.I name
+is invalid.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lb lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR confstr ()
+T} Thread safety MT-Safe
+.TE
+.SH CONFORMING TO
+POSIX.1-2001, POSIX.1-2008.
+.SH EXAMPLE
+The following code fragment determines the path where to find
+the POSIX.2 system utilities:
+.PP
+.in +4n
+.EX
+char *pathbuf;
+size_t n;
+
+n = confstr(_CS_PATH, NULL, (size_t) 0);
+pathbuf = malloc(n);
+if (pathbuf == NULL)
+ abort();
+confstr(_CS_PATH, pathbuf, n);
+.EE
+.in
+.SH SEE ALSO
+.BR getconf (1),
.BR sh (1),
.BR exec (3),
+.BR fpathconf (3),
+.BR pathconf (3),
+.BR sysconf (3),
.BR system (3)
projects / thirdparty / man-pages.git / blobdiff