#!/bin/sh
##########################################################################
# Title      :  errno - show messages to system errors
# Author     :  Heiner Steven <heiner.steven@odn.de>
# Date       :  1995-07-19
# Requires   :  xargs
# Category   :  Programming
# SCCS-Id.   :  @(#) errno  1.5 03/11/04
##########################################################################
# Description
#    -  Searches the systems "errno.h" include file, and extracts all
#   error numbers with descriptions
#    -  The processed ERRNO-table will be cached for faster lookup
#
# Note
#    o  Needs the following non-standard programs or features:
#       xargs, "find ... -follow"
##########################################################################

PN=`basename "$0"`          # Program name
VER='1.5'

: ${NAWK:=nawk}
: ${GREP:=grep}

Errnos=/tmp/$PN.cache           # "database" with errnos

Usage () {
    echo "$PN - print name and description of error codes, $VER (stv '95)
usage: $PN {number|name|regex} [...]
   or  $PN -l
    -l      list all error codes
    number  system error number, i.e. 10
    name    system error name, i.e. EPERM
    regex   string to 'grep' for" >&2
    exit 1
}

Msg () {
    for i
    do echo "$PN: $i" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

# Check arguments before setting them
getopt hl "$@" > /dev/null 2>&1 || Usage
set -- `getopt hl "$@"`
while [ $# -gt 0 ]
do
    case "$1" in
    -l) set -- '.'; break;; # List all errnos
    --) shift; break;;
    -h) Usage;;
    -*) Usage;;
    *)  break;;         # First argument
    esac
    shift
done

[ $# -lt 1 ] && Usage

[ -s "$Errnos" ] || {
    echo >&2 "creating errno table (will be cached for faster lookup)..."
    umask 000               # Everybody may read and write
    : ${INCLUDE=/usr/include}
    find `echo "$INCLUDE" | tr : ' '`   \
            -follow         \
        -type f -name 'errno*.h' -print |
    sort -u |

    # Create "database" of errno values in the following format:
    #   2   ENOENT  No such file or directory
    xargs $NAWK '
    # Example:
    # #define ENOENT          2    /* No such file or directory */
    ($1 == "#define") && ($2 ~ /^E[A-Z][A-Z]*$/) && (NF >= 3) {
        # $2=name, $3=errno
        Desc = ""
        for ( i=4; i<=NF; i++ ) {
        if ( $i == "/*" || $i == "*/" ) continue;
        # Remove comment delimiters from description:
        #   "/*Not owner*/" -> "Not owner"
        if ( $i ~ /^\/\*/ ) {
            sub (/\/\*[     ]*/, "", $i)
        } else if ( $i ~ /\*\/$/ ) {
            sub (/[     ]*\*\/$/, "", $i)
        }
        if ( Desc == "" )
            Desc = $i
        else
            Desc = Desc " " $i
        }
        print $3 "  " $2 "  " Desc
    }
    ' > "$Errnos" || exit   # awk will print error message
    [ -s "$Errnos" ] || Fatal "could not find include file(s)"
}

# Search "database" for given strings
for i
do
    case "$i" in
    E[A-Z]*) Col=2;;    # Symbolic name given
    *[!0-9]*)       # No number: just grep for pattern
        $GREP -i "$i" "$Errnos"
        continue;;
    *)  Col=1;;     # This seems to be a number
    esac
    $NAWK '$'$Col' == "'$i'"' "$Errnos"
done