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# Copyright (C) 2013, 2016 Patrick "P. J." McDermott
#
# This file is part of libsh.
#
# libsh is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# libsh is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with libsh. If not, see
# <http://www.gnu.org/licenses/>.
# Shells and the file descriptors they reserve for the user:
# * Debian Almquist Shell
# - The shell doesn't understand any file descriptor greater than 9.
# - File descriptors starting at 10 are used for I/O redirection.
# * BusyBox ash
# - File descriptors starting at 10 are used for job control and I/O
# redirection.
# * GNU Bash:
# - GNU Readline uses file descriptor 255 in interactive shells.
# - File descriptors starting at 10 are used for I/O redirection.
# * MirOS Korn Shell
# - File descriptors starting at either 10 or 24 are used for the shell's
# tty_fd and shl_dbg_fd.
# * Solaris ksh
# - The shell doesn't understand any file descriptor greater than 9.
static fd_min=3
static fd_max=9
static fd_3_set=false
static fd_4_set=false
static fd_5_set=false
static fd_6_set=false
static fd_7_set=false
static fd_8_set=false
static fd_9_set=false
fd=0
fopen(string path, string mode)
{
local mode_r=
local mode_w=
local i=
local f=
case "${mode}" in
'r') mode_r=true mode_w=false mode='<' ;;
'r+') mode_r=true mode_w=true mode='<>';;
'w') mode_r=false mode_w=true mode='>' ;;
'a') mode_r=false mode_w=true mode='>>';;
*) return ${EINVAL};;
esac
# Find first available file descriptor.
i=${fd_min}
while [ ${i} -le ${fd_max} ]; do
if ! $(eval "printf '%s' \${fd_${i}_set}"); then
f=${i}
break
fi
i=$(($i + 1))
done
if [ "x${f}" = 'x' ]; then
return ${EMFILE}
fi
# Check file mode and existence.
if ${mode_r} && ! [ -r "${path}" ]; then
return ${EACCES}
fi
if ${mode_w} && ! [ -w "${path}" ]; then
return ${EACCES}
fi
if ! [ -e "${path}" ]; then
return ${ENOENT}
fi
if [ -d "${path}" ]; then
return ${EISDIR}
fi
if ! eval "exec ${f}${mode}'${path}'" 2>/dev/null; then
return ${EUNK}
fi
eval "fd_${f}_set=true"
fd="${f}"
return 0
}
fclose(int f)
{
local f=${1}
# Make sure the file descriptor is valid and open.
if [ ${f} -lt ${fd_min} ] || [ ${f} -gt ${fd_max} ]; then
return ${EINVAL}
fi
if $(eval "printf '%s' \${fd_${i}_set}"); then
return ${EBADF}
fi
eval "exec ${f}>&-"
unset "fd_${f}"
return 0
}
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