1 files changed, 180 insertions, 0 deletions

diff --git a/src/lib/libc/stdlib/getenv.3 b/src/lib/libc/stdlib/getenv.3
new file mode 100644
index 0000000000..9da27ec11c
--- /dev/null
+++ b/src/lib/libc/stdlib/getenv.3
@@ -0,0 +1,180 @@
+.\" Copyright (c) 1988, 1991, 1993
+.\"    The Regents of the University of California.  All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"     $OpenBSD: getenv.3,v 1.16 2011/04/27 13:40:15 otto Exp $
+.\"
+.Dd $Mdocdate: April 27 2011 $
+.Dt GETENV 3
+.Os
+.Sh NAME
+.Nm getenv ,
+.Nm putenv ,
+.Nm setenv ,
+.Nm unsetenv
+.Nd environment variable functions
+.Sh SYNOPSIS
+.Fd #include <stdlib.h>
+.Ft char *
+.Fn getenv "const char *name"
+.Ft int
+.Fn setenv "const char *name" "const char *value" "int overwrite"
+.Ft int
+.Fn putenv "char *string"
+.Ft int
+.Fn unsetenv "const char *name"
+.Sh DESCRIPTION
+These functions set, unset, and fetch environment variables from the host
+.Em environment list .
+For compatibility with differing environment conventions, the given argument
+.Fa name
+may be appended with an equal sign
+.Dq Li \&=
+followed by zero or more characters,
+and
+.Fa value
+may be prepended with an equal sign.
+.Pp
+The
+.Fn getenv
+function obtains the current value of the environment variable
+.Fa name .
+If the variable
+.Fa name
+is not in the current environment, a null pointer is returned.
+.Pp
+The
+.Fn setenv
+function inserts or resets the environment variable
+.Fa name
+in the current environment list.
+If the variable
+.Fa name
+does not exist in the list, it is inserted with the given
+.Fa value .
+If the variable does exist, the argument
+.Fa overwrite
+is tested; if
+.Fa overwrite
+is zero, the variable is not reset, otherwise it is reset to the given
+.Fa value .
+.Pp
+The
+.Fn putenv
+function takes an argument of the form
+.Ar name Ns = Ns Ar value .
+The memory pointed to by
+.Ar string
+becomes part of the environment and must not be deallocated by the caller.
+If the variable already exists, it will be overwritten.
+A common source of bugs is to pass a
+.Ar string
+argument that is a locally scoped string buffer.
+This will result in corruption of the environment after leaving
+the scope in which the variable is defined.
+For this reason, the
+.Fn setenv
+function is preferred over
+.Fn putenv .
+.Pp
+The
+.Fn unsetenv
+function deletes all instances of the variable name pointed to by
+.Fa name
+from the list.
+.Sh RETURN VALUES
+These functions
+return zero if successful; otherwise the global variable
+.Va errno
+is set to indicate the error and \-1 is returned.
+.Pp
+If
+.Fn getenv
+is successful, the string returned should be considered read-only.
+.Sh ERRORS
+.Bl -tag -width Er
+.It Bq Er EINVAL
+The
+.Fn setenv
+or
+.Fn unsetenv
+function was passed a
+.Ar name
+containing an
+.Sq =
+character.
+.Pp
+The
+.Fn unsetenv
+function was passed an empty
+.Ar name
+or a NULL pointer.
+.Pp
+The
+.Fn putenv
+function was passed a
+.Ar string
+that did not contain an
+.Sq =
+character.
+.It Bq Er ENOMEM
+The
+.Fn setenv
+or
+.Fn putenv
+function failed because it was unable to allocate memory for the environment.
+.El
+.Sh SEE ALSO
+.Xr csh 1 ,
+.Xr sh 1 ,
+.Xr execve 2 ,
+.Xr environ 7
+.Sh STANDARDS
+The
+.Fn getenv
+function conforms to
+.St -ansiC .
+.Sh HISTORY
+The function
+.Fn getenv
+appeared in
+.At v7
+and
+.Bx 3 .
+The functions
+.Fn setenv
+and
+.Fn unsetenv
+appeared in
+.Bx 4.3 Tahoe .
+The
+.Fn putenv
+function appeared in
+.Bx 4.3 Reno .