From 0bb4ebb47e05fb3b57f0d405be5e9186971ad339 Mon Sep 17 00:00:00 2001
From: Owen Shepherd <owen.shepherd@e43.eu>
Date: Wed, 15 Aug 2012 00:40:43 +0100
Subject: [PATCH] Documentation for errno.h and errno

---
 man/errno.3   |  66 +++++++++++++++++++++++++++++
 man/errno.h.3 | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 180 insertions(+)
 create mode 100644 man/errno.3
 create mode 100644 man/errno.h.3

diff --git a/man/errno.3 b/man/errno.3
new file mode 100644
index 0000000..da54640
--- /dev/null
+++ b/man/errno.3
@@ -0,0 +1,66 @@
+.\" This file is part of the Public Domain C Library (PDCLib).
+.\" Permission is granted to use, modify, and / or redistribute at will.
+.\"
+.Dd
+.Dt ERRNO 3
+.Os
+
+.Sh NAME
+.Nm errno
+.Nd library error result
+
+.Sh SYNOPSIS
+.In errno.h
+.Pp
+.Sy #define errno <object of thread local storage duration>
+.\"
+.Sh DESCRIPTION
+The header
+.In errno.h
+defines the name
+.Va errno
+to refer to an object of thread local storage duration. It is undefined whether
+or not 
+.Va errno
+refers to a preprocessor symbol or not.
+.\"
+.Pp
+At program startup, the runtime shall initialize
+.Va errno
+to contain the value zero (the initial value in other threads is undefined). It 
+is guaranteed that no function provided by the C standard library shall set the 
+value of 
+.Va errno
+to zero; therefore, for functions which do not have a unique return value for
+indicating error, it is possible to determine whether an error occured by 
+setting
+.Va errno
+to zero before the call, then after the call seeing if an error value has been
+stored into 
+.Va errno.
+.Pp
+.Bf Sy
+Note that it is valid for any function which is not described as explicitly 
+setting 
+.Va errno 
+to set it to a non-zero value. Checking for a non-zero value is only valid with
+functions which are defined to modify 
+.Va errno .
+.Ef
+.\"
+.Pp
+In some historical versions of the POSIX standard, the prescribed method of 
+using errno was to define
+.Va extern int errno .
+This is no longer supported by the POSIX or C standards, and will not work on 
+the majority of implementations, including this one.
+
+.Sh SEE ALSO
+.Xr errno.h 3
+.Xr abort 3
+.Xr assert 3
+\"
+.Sh STANDARDS
+Conforming to
+.St -isoC-90 ,
+.St -isoC-99 .
\ No newline at end of file
diff --git a/man/errno.h.3 b/man/errno.h.3
new file mode 100644
index 0000000..a754d80
--- /dev/null
+++ b/man/errno.h.3
@@ -0,0 +1,114 @@
+.\" This file is part of the Public Domain C Library (PDCLib).
+.\" Permission is granted to use, modify, and / or redistribute at will.
+.\"
+.Dd
+.Dt ERRNO.H 3
+.Os
+.\"
+.Sh NAME
+.Nm errno.h
+.Nd error results
+.\"
+.Sh SYNOPSIS
+.In errno.h
+.\"
+.Sh DESCRIPTION
+The header defines the value
+.Dv errno
+to be an lvalue of thread-local storage duration.
+.\"
+.Pp
+From the ISO C standard, the following error code constants are defined:
+.Bl -tag -compact
+.It ERANGE
+indicating a value is out of range
+.It EDOM
+indicating that a value is outside the domain of the current function
+.It EILSEQ
+indicating an invalid character sequence
+.El
+.\"
+.Pp
+From the ISO C++ 2011 standard, the following error code constants are defined:
+.Bl -tag -compact
+.It E2BIG
+.It ECONNRESET
+.It EISCONN
+.It ENOENT
+.It ENOTRECOVERABLE
+.It EROFS
+.It EACCES
+.It EDEADLK
+.It EISDIR
+.It ENOEXEC
+.It ENOTSOCK
+.It ESPIPE
+.It EADDRINUSE
+.It EDESTADDRREQ
+.It ELOOP
+.It ENOLCK
+.It ENOTSUP
+.It ESRCH
+.It EADDRNOTAVAIL
+.It EMFILE
+.It ENOLINK
+.It ENOTTY
+.It ETIME
+.It EAFNOSUPPORT
+.It EEXIST
+.It EMLINK
+.It ENOMEM
+.It ENXIO
+.It ETIMEDOUT
+.It EAGAIN
+.It EFAULT
+.It EMSGSIZE
+.It ENOMSG
+.It EOPNOTSUPP
+.It ETXTBSY
+.It EALREADY
+.It EFBIG
+.It ENAMETOOLONG
+.It ENOPROTOOPT
+.It EOVERFLOW
+.It EWOULDBLOCK
+(which may have the same value as 
+.Ev EAGAIN )
+.It EBADF
+.It EHOSTUNREACH
+.It ENETDOWN
+.It ENOSPC
+.It EOWNERDEAD
+.It EXDEV
+.It EBADMSG
+.It EIDRM
+.It ENETRESET
+.It ENOSR
+.It EPERM
+.It EBUSY
+.It ENETUNREACH
+.It ENOSTR
+.It EPIPE
+.It ECANCELED
+.It EINPROGRESS
+.It ENFILE
+.It ENOSYS
+.It EPROTO
+.It ECHILD
+.It EINTR
+.It ENOBUFS
+.It ENOTCONN
+.It EPROTONOSUPPORT
+.It ECONNABORTED
+.It EINVAL
+.It ENODATA
+.It ENOTDIR
+.It EPROTOTYPE
+.El
+.Sh SEE ALSO
+.Xr errno 3
+.Sh STANDARDS
+Conforming to
+.St -isoC-90 ,
+.St -isoC-99 , 
+ISO/IEC 14882:2011 "ISO C++ 11"
\ No newline at end of file
-- 
2.40.0