228bda9fb3
Summary: Filter out gas linter error checks for fmt.Fprintf commands. This required defining a custom linter around gas that additionally included the offending code. Notes: Gas format, without piping it through gometalinter, gives output like this: $ gas -fmt=csv geth/jail/console/console.go geth/jail/console/console.go,21,Errors unhandled.,LOW,HIGH,"fmt.Fprintf(w, ""%s: %s"", consoleEventName, formatForConsole(fn.ArgumentList))" Gometalinter, by default, does not grab the line of code when it filters gas errors. To resolve this, I created a wrapper around gas (I wasn't sure what to call this "gas wrapper", I opted for gasv2, open to other names). The first part of the regular expression was taken directly from gometalinter (see https://github.com/alecthomas/gometalinter/blob/master/linters.go#L236), and I then appended ,\".*\" to additionally grab the line of code of the offending line. Lastly, I excluded ".*Errors unhandled.*fmt.Fprintf.*" to filter out only fmt.Fprintf errors around omitted errors. Also as a result of this change, gas lint output will now include the offending code. Closes #590 |
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.. | ||
console | ||
internal | ||
README.md | ||
cell.go | ||
cell_test.go | ||
doc.go | ||
handlers.go | ||
handlers_test.go | ||
jail.go | ||
jail_test.go |
README.md
jail
jail - jailed environment for executing JS code.
Download:
go get github.com/status-im/status-go/geth/jail
jail - jailed environment for executing JS code.
Package jail implements "jailed" environment for executing arbitrary JavaScript code using Otto JS interpreter (https://github.com/robertkrimen/otto).
Jail create multiple Cells, one cell per status client chat. Each cell runs own Otto virtual machine and lives forever, but that may change in the future.
+----------------------------------------------+
| Jail |
+----------------------------------------------+
+---------+ +---------+ +---------+ +---------+
| Cell | | Cell | | Cell | | Cell |
|ChatID 1 | |ChatID 2 | |ChatID 3 | |ChatID N |
|+-------+| |+-------+| |+-------+| |+-------+|
||Otto VM|| ||Otto VM|| ||Otto VM|| ||Otto VM||
|+-------+| |+-------+| |+-------+| |+-------+|
|| Loop || || Loop || || Loop || || Loop ||
++-------++ ++-------++ ++-------++ ++-------++
Cells
Each Cell object embeds *VM from 'jail/vm' for concurrency safe wrapper around *otto.VM functions. This is important when dealing with setTimeout and Fetch API functions (see below).
Get and Set
(*VM).Get/Set functions provide transparent and concurrently safe wrappers for Otto VM Get and Set functions respectively. See Otto documentation for usage examples: https://godoc.org/github.com/robertkrimen/otto
Call and Run
(*VM).Call/Run functions allows executing arbitrary JS in the cell. They're also
wrappers around Otto VM functions of the same name. Run
accepts raw JS strings for execution while Call
takes a JS function name (defined in VM) and parameters.
Timeouts and intervals support
Default Otto VM interpreter doesn't support setTimeout() / setInterval() JS functions, because they're not part of ECMA-262 spec, but properties of the window object in browser.
We add support for them using own implementation of Event Loop, heavily based on ottoext package. See loop/fetch/promise packages under jail/internal/.
Each cell starts a new loop in a separate goroutine, registers functions for setTimeout / setInterval calls and associate them with this loop. All JS code executed as callback to setTimeout/setInterval will be handled by this loop.
For example, following code:
cell.Run(`setTimeout(function(){ value = "42" }, 2000);`)
will execute setTimeout and return immediately, but callback function will be executed after 2 seconds in the loop that was started upon current cell.
In order to capture response one may use following approach:
err = cell.Set("__captureResponse", func(val string) otto.Value {
fmt.Println("Captured response from callback:", val)
return otto.UndefinedValue()
})
cell.Run(`setTimeout(function(){ __captureResponse("OK") }, 2000);`)
Fetch support
Fetch API is implemented in a similar way using the same loop. When Cell is created, corresponding handlers are registered within VM and associated event loop.
Due to asynchronous nature of Fetch API, the following code will return immediately:
cell.Run(`fetch('http://example.com/').then(function(data) { ... })`)
and callback function in a promise will be executed in a event loop in the background. Thus, it's user responsibility to register a corresponding callback function before:
cell.Set("__captureSuccess", func(res otto.Value) { ... })
cell.Run(`fetch('http://example.com').then(function(r) {
return r.text()
}).then(function(data) {
// user code
__captureSuccess(data)
}))
Automatically generated by autoreadme on 2018.02.08