lualoader: Support variable substitution in env var settings

We support both of the following cases of substitution:

bar="y"
foo="${bar}"
foo="$bar"

The latter substitution syntax is, of course, not recommended- all
punctuation must be considered potential variable names, and we do not go
through the effort of searching the different combinations of, for instance,
"$x.y.z" to determine if the variable is $x, $x.y, or $x.y.z.

This is not officially documented as supported, but it has worked in
forthloader for what is most likely a long time as `evaluate` is used to
process the right hand side of the assignment.
This commit is contained in:
kevans 2018-06-10 02:36:38 +00:00
parent d00bc0730a
commit a7456ee91a

View File

@ -102,6 +102,25 @@ local function setKey(key, name, value)
modules[key][name] = value
end
-- Escapes the named value for use as a literal in a replacement pattern.
-- e.g. dhcp.host-name gets turned into dhcp%.host%-name to remove the special
-- meaning.
local function escapeName(name)
return name:gsub("([%p])", "%%%1")
end
local function processEnvVar(value)
for name in value:gmatch("${([^}]+)}") do
local replacement = loader.getenv(name) or ""
value = value:gsub("${" .. escapeName(name) .. "}", replacement)
end
for name in value:gmatch("$([%w%p]+)%s*") do
local replacement = loader.getenv(name) or ""
value = value:gsub("$" .. escapeName(name), replacement)
end
return value
end
local pattern_table = {
{
str = "^%s*(#.*)",
@ -172,7 +191,7 @@ local pattern_table = {
{
str = "^%s*([%w%p]+)%s*=%s*\"([%w%s%p]-)\"%s*(.*)",
process = function(k, v)
if setEnv(k, v) ~= 0 then
if setEnv(k, processEnvVar(v)) ~= 0 then
print(MSG_FAILSETENV:format(k, v))
end
end,
@ -181,7 +200,7 @@ local pattern_table = {
{
str = "^%s*([%w%p]+)%s*=%s*(%d+)%s*(.*)",
process = function(k, v)
if setEnv(k, v) ~= 0 then
if setEnv(k, processEnvVar(v)) ~= 0 then
print(MSG_FAILSETENV:format(k, tostring(v)))
end
end,