fix: stack overflow in table.concat function #526
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The previous implementation of tableConcat was pushing all values and
separators onto the Lua stack before concatenating them, which caused
stack overflow with large tables.
This fix changes the implementation to build the result string
incrementally rather than pushing all values onto the stack first,
preventing stack overflow with large tables.
Example that would previously fail but now works correctly:
```
package main
import "github.com/yuin/gopher-lua"
func main() {
var L *lua.LState
var err error
L = lua.NewState()
defer L.Close()
err = L.DoString(`
local t = {}
for i = 1, 10000 do
t[i] = tostring(i)
end
local s = table.concat(t, ',')
`)
if err != nil {
println(err.Error())
}
}
```
tul
reviewed
Mar 12, 2025
| } | ||
| } | ||
| L.Push(stringConcat(L, L.GetTop()-retbottom, L.reg.Top()-1)) | ||
| L.Push(LString(result)) |
There was a problem hiding this comment.
Worth considering go lang string builder? https://pkg.go.dev/strings#Builder ?
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Fix: Stack Overflow in table.concat Function
This PR fixes a stack overflow issue in the
table.concatfunction when working with large tables.Problem
The previous implementation of
tableConcatpushed all values and separators onto the Lua stack before concatenating them. This approach caused stack overflow errors when dealing with large tables.Solution
This fix changes the implementation to build the result string incrementally rather than pushing all values onto the stack first. Instead of accumulating items on the stack, we now:
Testing
The fix has been verified with large tables that previously caused stack overflow. For example, this test case now works correctly:
This example would previously fail with a stack overflow error but now executes successfully.