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Diffstat (limited to 'man3/confstr.3')
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diff --git a/man3/confstr.3 b/man3/confstr.3 new file mode 100644 index 0000000..5efd862 --- /dev/null +++ b/man3/confstr.3 @@ -0,0 +1,157 @@ +'\" t +.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.\" 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 libc 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 2023-07-20 "Linux man-pages 6.05.01" +.SH NAME +confstr \- get configuration dependent string variables +.SH LIBRARY +Standard C library +.RI ( libc ", " \-lc ) +.SH SYNOPSIS +.nf +.B #include <unistd.h> +.PP +.BI "size_t confstr(int " "name" ", char " buf [. size "], size_t " size ); +.fi +.PP +.RS -4 +Feature Test Macro Requirements for glibc (see +.BR feature_test_macros (7)): +.RE +.PP +.BR confstr (): +.nf + _POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE +.fi +.SH DESCRIPTION +.BR confstr () +gets the value of configuration-dependent string variables. +.PP +The +.I name +argument is the system variable to be queried. +The following variables are supported: +.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"). +.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"). +.TP +.B _CS_PATH +A value for the +.B PATH +variable which indicates where all the POSIX.2 standard utilities can +be found. +.PP +If +.I buf +is not NULL and +.I size +is not zero, +.BR confstr () +copies the value of the string to +.I buf +truncated to +.I size \- 1 +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 +.IR size . +.PP +If +.I size +is zero and +.I buf +is NULL, +.BR confstr () +just returns the value as defined below. +.SH RETURN VALUE +If +.I name +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 size , +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. +If +.I name +does not correspond to a valid configuration variable, +.BR confstr () +returns 0, and +.I errno +is set to +.BR EINVAL . +.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; +lbx lb lb +l l l. +Interface Attribute Value +T{ +.na +.nh +.BR confstr () +T} Thread safety MT-Safe +.TE +.sp 1 +.SH STANDARDS +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001. +.SH EXAMPLES +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) |