[tarantool-patches] [PATCH tarantool v2 4/4] test/luajit-tap: Add table_chain_bug_LuaJIT_494.test.lua

[Cyrill Gorcunov <gorcunov@gmail.com>]

Backport of openresty/luajit2-test-suite
commit ce2c916d5582914edeb9499f487d9fa812632c5c

To test hash chain bug.

Part-of #4171
---
 .../table_chain_bug_LuaJIT_494.test.lua       | 178 ++++++++++++++++++
 1 file changed, 178 insertions(+)
 create mode 100755 test/luajit-tap/table_chain_bug_LuaJIT_494.test.lua

diff --git a/test/luajit-tap/table_chain_bug_LuaJIT_494.test.lua b/test/luajit-tap/table_chain_bug_LuaJIT_494.test.lua
new file mode 100755
index 000000000..06c0f0d29
--- /dev/null
+++ b/test/luajit-tap/table_chain_bug_LuaJIT_494.test.lua
@@ -0,0 +1,178 @@
+#!/usr/bin/env tarantool
+
+tap = require('tap')
+
+test = tap.test("494")
+test:plan(1)
+
+-- Test file to demonstrate Lua table hash chain bugs discussed in
+--     https://github.com/LuaJIT/LuaJIT/issues/494
+-- Credit: prepared by Peter Cawley here with minor edits:
+--     https://gist.github.com/corsix/1fc9b13a2dd5f3659417b62dd54d4500
+
+--- Plumbing
+ffi = require"ffi"
+ffi.cdef"char* strstr(const char*, const char*)"
+strstr = ffi.C.strstr
+cast = ffi.cast
+str_hash_offset = cast("uint32_t*", strstr("*", ""))[-2] == 1 and 3 or 2
+function str_hash(s)
+    return cast("uint32_t*", strstr(s, "")) - str_hash_offset
+end
+table_new = require"table.new"
+
+--- Prepare some objects
+victims = {}
+orig_hash = {}
+for c in ("abcdef"):gmatch"." do
+    v = c .. "{09add58a-13a4-44e0-a52c-d44d0f9b2b95}"
+    victims[c] = v
+    orig_hash[c] = str_hash(v)[0]
+end
+collectgarbage()
+
+do --- Basic version of the problem
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d, all with a as primary
+    t[victims.a] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, and d's primary to c
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 5
+    str_hash(victims.d)[0] = 6
+    t[victims.c] = true
+    t[victims.d] = true
+    -- Insert something with b as primary
+    str_hash(victims.e)[0] = 5
+    t[victims.e] = true
+    -- Check for consistency
+    for c in ("abcde"):gmatch"." do
+        assert(t[victims[c]], c)
+    end
+end
+collectgarbage()
+
+do --- Just `mn != freenode` can lead to infinite loops
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d, all with a as primary
+    t[victims.a] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, and d's primary to d
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 5
+    str_hash(victims.d)[0] = 7
+    t[victims.c] = true
+    t[victims.d] = true
+    -- Insert something with b as primary
+    str_hash(victims.e)[0] = 5
+    t[victims.e] = true
+    -- Insert something with d as primary (infinite lookup loop)
+    str_hash(victims.f)[0] = 7
+    t[victims.f] = true
+end
+collectgarbage()
+
+do --- Just `mn != nn` can lead to infinite loops
+    for k, v in pairs(victims) do
+        str_hash(v)[0] = 0
+    end
+    t = table_new(0, 8)
+    -- Make chain a -> b -> c -> d -> e, all with a as primary
+    t[victims.a] = true
+    t[victims.e] = true
+    t[victims.d] = true
+    t[victims.c] = true
+    t[victims.b] = true
+    -- Change c's primary to b, d's primary to d, and e's primary to d
+    t[victims.e] = nil
+    t[victims.d] = nil
+    t[victims.c] = nil
+    str_hash(victims.c)[0] = 4
+    str_hash(victims.d)[0] = 6
+    str_hash(victims.e)[0] = 6
+    t[victims.c] = true
+    t[victims.d] = true
+    t[victims.e] = true
+    -- Insert something with b as primary (infinite rechaining loop)
+    str_hash(victims.f)[0] = 4
+    t[victims.f] = true
+end
+
+for i = 0, 10 do --- Non-strings can need rechaining too
+    collectgarbage()
+
+    k = tonumber((("0x%xp-1074"):format(i)))
+    str_hash(victims.a)[0] = 0
+    str_hash(victims.b)[0] = 0
+    t = table_new(0, 4)
+    -- a -> b, both with a as primary
+    t[victims.a] = true
+    t[victims.b] = true
+    -- Change b's primary to b
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 3
+    t[victims.b] = true
+    -- Might get a -> b -> k, with k's primary as b
+    t[k] = true
+    -- Change b's primary to a
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 0
+    t[victims.b] = true
+    -- Insert something with b as primary
+    str_hash(victims.c)[0] = 3
+    t[victims.c] = true
+    -- Check for consistency
+    assert(t[k], i)
+end
+
+for i = 0, 10 do --- Non-strings can be moved to freenode
+    collectgarbage()
+
+    k = false
+    str_hash(victims.a)[0] = 0
+    str_hash(victims.b)[0] = 0
+    t = table_new(0, 4)
+    -- a -> k -> b, all with a as primary
+    t[victims.a] = true
+    t[victims.b] = true
+    t[k] = true
+    -- Change b's primary to k
+    t[victims.b] = nil
+    str_hash(victims.b)[0] = 2
+    t[victims.b] = true
+    -- Insert a non-string with primary of k
+    t[tonumber((("0x%xp-1074"):format(i)))] = true
+    -- Check for consistency
+    assert(t[victims.b], i)
+end
+collectgarbage()
+
+do --- Do not forget to advance freenode in the not-string case
+    t = table_new(0, 4)
+    -- Chain of colliding numbers
+    t[0x0p-1074] = true
+    t[0x4p-1074] = true
+    t[0x8p-1074] = true
+    -- Steal middle node of the chain to be a main node (infinite walking loop)
+    t[0x2p-1074] = true
+end
+collectgarbage()
+
+--- Restore interpreter invariants, just in case
+for c, v in pairs(victims) do
+    str_hash(v)[0] = orig_hash[c]
+end
+
+test:ok("PASS")
-- 
2.20.1