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# Functions for setting and substituting variables
#
# Copyright (C) 2012, 2014 Patrick "P. J." McDermott
#
# This file is part of the ProteanOS Development Kit.
#
# The ProteanOS Development Kit is free software: you can redistribute
# it and/or modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# The ProteanOS Development Kit 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 General Public License
# along with the ProteanOS Development Kit. If not, see
# <http://www.gnu.org/licenses/>.
substvars_max_depth=50
set_substvar()
{
local name="${1}"
local value="${2}"
# Convert variable name to lower case and validate.
name="$(printf '%s\n' "${name}" | tr 'A-Z-' 'a-z_')"
case "${name:- }" in
*[!a-z0-9_]*)
warn "$(get_msg 'substvar_invalid')" "${name}"
return 1
;;
esac
# Trim leading and trailing newline characters from value.
value="$(printf '%s\n' "${value}" | sed -n '
H; # Store each input line in the hold space.
${ # At the last line of input:
g; # Restore the hold space into the pattern space.
s/^[\n]*//; # Remove leading newline characters.
s/[\n]*$//; # Remove trailing newline characters.
p; # Print the results.
};
')"
# Escape single quotes in value.
value="$(printf '%s\n' "${value}" | sed "s/'/'\\\\''/g")"
eval "substvar_${name}='${value}'"
return 0
}
substvars()
{
local string="${1}"
local depth=
local lhs=
local name=
local rhs=
local old_rhs=
local value=
# Logic inspired by that of dpkg's Dpkg::Substvars::substvars()
# subroutine.
depth=0
while :; do
lhs="${string%%\$\{*}"
if [ ${#lhs} -eq ${#string} ]; then
# No "${" was found.
break
fi
string="${string#*\$\{}"
name="${string%%\}*}"
rhs="${string#*\}}"
if [ ${#rhs} -lt ${#old_rhs} ]; then
# Reset the nesting counter if we've advanced the right
# side of the matched space.
depth=0
fi
if [ ${depth} -ge ${substvars_max_depth} ]; then
# Warn of possible recursion.
warn "$(get_msg 'substvar_deep_nesting')"
return 1
fi
old_rhs="${rhs}"
# Perform the substitution.
name="$(printf '%s\n' "${name}" | tr 'A-Z-' 'a-z_')"
value="$(eval "printf '%s\n' \"\${substvar_${name}}\"")"
string="${lhs}${value}${rhs}"
depth=$((${depth} + 1))
done
printf '%s\n' "${string}"
return 0
}
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