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skynet-webportal/docker/nginx/libs/utils.lua

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local _M = {}
-- utility function for checking if table is empty
function _M.is_table_empty(check)
-- bind next to local variable to achieve ultimate efficiency
-- https://stackoverflow.com/a/1252776
local next = next
return next(check) == nil
end
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-- extract full cookie name and value by its name from cookie string
-- note: name matcher argument is a pattern so you will need to escape
-- any special characters, read more https://www.lua.org/pil/20.2.html
function _M.extract_cookie(cookie_string, name_matcher)
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-- nil cookie string safeguard
if cookie_string == nil then
return nil
end
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local start, stop = string.find(cookie_string, name_matcher .. "=[^;]+")
if start then
return string.sub(cookie_string, start, stop)
end
return nil
end
-- extract just the cookie value by its name from cookie string
-- note: name matcher argument is a pattern so you will need to escape
-- any special characters, read more https://www.lua.org/pil/20.2.html
function _M.extract_cookie_value(cookie_string, name_matcher)
local cookie = _M.extract_cookie(cookie_string, name_matcher)
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if cookie == nil then
return nil
end
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local value_start = string.find(cookie, "=") + 1
return string.sub(cookie, value_start)
end
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-- utility function that builds on os.getenv to get environment variable value
-- * will always return nil for both unset and empty env vars
-- * parse "boolean": "true" and "1" as true, "false" and "0" as false, throws for others
-- * parse "integer": any numerical string gets converted, otherwise returns nil
function _M.getenv(name, parse)
local value = os.getenv(name)
-- treat empty string value as nil to simplify comparisons
if value == nil or value == "" then
return nil
end
-- do not parse the value
if parse == nil then
return value
end
-- try to parse as boolean
if parse == "boolean" then
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if string.lower(value) == "true" or value == "1" then
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return true
end
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if string.lower(value) == "false" or value == "0" then
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return false
end
error("utils.getenv: Parsing value '" .. tostring(value) .. "' to boolean is not supported")
end
-- try to parse as integer
if parse == "integer" then
return tonumber(value)
end
error("utils.getenv: Parsing to '" .. parse .. "' is not supported")
end
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return _M