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-- $Id: testes/cstack.lua $
-- See Copyright Notice in file all.lua
local debug = require "debug"
print"testing C-stack overflow detection"
local origlimit = debug.setCstacklimit(400)
print("current stack limit: " .. origlimit)
debug.setCstacklimit(origlimit)
-- Segmentation faults in these tests probably result from a C-stack
-- overflow. To avoid these errors, recompile Lua with a smaller
-- value for the constant 'LUAI_MAXCCALLS' or else ensure a larger
-- stack for the program.
local function checkerror (msg, f, ...)
local s, err = pcall(f, ...)
assert(not s and string.find(err, msg))
end
local count
local back = string.rep("\b", 8)
local function progress ()
count = count + 1
local n = string.format("%-8d", count)
io.stderr:write(back, n)
end
do print("testing simple recursion:")
count = 0
local function foo ()
progress()
foo()
end
checkerror("stack overflow", foo)
print("\tfinal count: ", count)
end
do print("testing stack overflow in message handling")
count = 0
local function loop (x, y, z)
progress()
return 1 + loop(x, y, z)
end
local res, msg = xpcall(loop, loop)
assert(msg == "error in error handling")
print("\tfinal count: ", count)
end
-- bug since 2.5 (C-stack overflow in recursion inside pattern matching)
do print("testing recursion inside pattern matching")
local function f (size)
local s = string.rep("a", size)
local p = string.rep(".?", size)
return string.match(s, p)
end
local m = f(80)
assert(#m == 80)
checkerror("too complex", f, 200000)
end
do print("testing stack-overflow in recursive 'gsub'")
count = 0
local function foo ()
progress()
string.gsub("a", ".", foo)
end
checkerror("stack overflow", foo)
print("\tfinal count: ", count)
print("testing stack-overflow in recursive 'gsub' with metatables")
count = 0
local t = setmetatable({}, {__index = foo})
foo = function ()
count = count + 1
progress(count)
string.gsub("a", ".", t)
end
checkerror("stack overflow", foo)
print("\tfinal count: ", count)
end
do print("testing changes in C-stack limit")
assert(not debug.setCstacklimit(0)) -- limit too small
assert(not debug.setCstacklimit(50000)) -- limit too large
local co = coroutine.wrap (function ()
return debug.setCstacklimit(400)
end)
assert(co() == false) -- cannot change C stack inside coroutine
local n
local function foo () n = n + 1; foo () end
local function check ()
n = 0
pcall(foo)
return n
end
assert(debug.setCstacklimit(400) == origlimit)
local lim400 = check()
-- a very low limit (given that the several calls to arive here)
local lowlimit = 38
assert(debug.setCstacklimit(lowlimit) == 400)
assert(check() < lowlimit - 30)
assert(debug.setCstacklimit(600) == lowlimit)
local lim600 = check()
assert(lim600 == lim400 + 200)
-- 'setCstacklimit' works inside protected calls. (The new stack
-- limit is kept when 'pcall' returns.)
assert(pcall(function ()
assert(debug.setCstacklimit(400) == 600)
assert(check() <= lim400)
end))
assert(check() == lim400)
assert(debug.setCstacklimit(origlimit) == 400) -- restore original limit
end
print'OK'
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