wasmtime | A fast and secure runtime for WebAssembly | Binary Executable Format library

 by   bytecodealliance Rust Version: dev License: Apache-2.0

kandi X-RAY | wasmtime Summary

kandi X-RAY | wasmtime Summary

wasmtime is a Rust library typically used in Programming Style, Binary Executable Format applications. wasmtime has no bugs, it has a Permissive License and it has medium support. However wasmtime has 14 vulnerabilities. You can download it from GitHub.

A fast and secure runtime for WebAssembly

            kandi-support Support

              wasmtime has a medium active ecosystem.
              It has 12421 star(s) with 1010 fork(s). There are 180 watchers for this library.
              There were 10 major release(s) in the last 12 months.
              There are 517 open issues and 1325 have been closed. On average issues are closed in 91 days. There are 65 open pull requests and 0 closed requests.
              It has a neutral sentiment in the developer community.
              The latest version of wasmtime is dev

            kandi-Quality Quality

              wasmtime has 0 bugs and 0 code smells.

            kandi-Security Security

              wasmtime has 14 vulnerability issues reported (3 critical, 6 high, 5 medium, 0 low).
              wasmtime code analysis shows 0 unresolved vulnerabilities.
              There are 0 security hotspots that need review.

            kandi-License License

              wasmtime is licensed under the Apache-2.0 License. This license is Permissive.
              Permissive licenses have the least restrictions, and you can use them in most projects.

            kandi-Reuse Reuse

              wasmtime releases are available to install and integrate.
              Installation instructions, examples and code snippets are available.

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            wasmtime Key Features

            No Key Features are available at this moment for wasmtime.

            wasmtime Examples and Code Snippets

            No Code Snippets are available at this moment for wasmtime.

            Community Discussions


            WASM from Rust not returning the expected types
            Asked 2022-Jan-18 at 09:48

            Hey @all I was playing with WebAssembly Studio and created an empty Rust project.

            In my Rust code, I'm returning the pointer and the length for my "Hello World" string. Compiling worked fine, but I was expecting the resulting WASM to have a function returning two i32. But I found a function taking one i32 and returning nothing.

            1. Why is the function not having the signature fn () -> (i32,i32) ?

            2. How am I supposed to extract the two values from the WASM module? (Using Rust-wasmtime)

            Below you can find the code snippets I'm talking about. Thanks in advance!



            Answered 2022-Jan-18 at 09:48

            WebAssembly got the ability to return multiple values just recently. The compiler used doesn't seem to support this yet or doesn't use it for compatibility reasons, i.e. for runtimes that don't know this feature yet.

            Therefore, the compiler rewrites the code as follows:

            Source https://stackoverflow.com/questions/70641080


            Is there a way to inspect a wasm module for imports
            Asked 2021-Oct-27 at 06:30

            Let me explain a little bit about what I'm doing. I have an application that I'm embedding a wasm engine (specifically wasmtime) and writing the wasm in Rust. The target is not a browser so I'm not using wasm-bindgen. I'm trying to import two functions from the host environment. I've gotten it to work but with a bit of a hack and I'd like to remove the hack. Here's the problem I'm having. I've been able to figure out how to get Rust to generate the import statements in the wasm output. The problem is that if those functions aren't used the import statements in the wasm aren't included. Wasmtime seem to require that the number of imports passed to the wasm instance match the number of import statements. Makes sense that if the wasm module is expecting imports it's a problem if you don't provide them. The problem is, it's also an error if you provide imports and they're not used.

            So I see two ways to fix that, either I need to figure out how to get Rust to include the import statements even if they're not used (right now the hack is to call the functions but ignore the results and it's basically a no-op) or to find a way to introspect the wasm an figure out what kind of imports it's expecting and only pass what it's asking for.

            My question is is that the correct approach and if so how do you do that?



            Answered 2021-Oct-27 at 06:30

            You can convert between .wasm (binary format) and .wat (textual format) with the The WebAssembly Binary Toolkit. It is open source. Maybe it can help you to extract the needed imports programmatically.

            The proper way, should be that your host environment gives you the import requirements before you initialize the instance. The Module gives you the imports. See the "Instance variables". You get that in between the module loading and the creation of the instance that itself needs these imports.

            Source https://stackoverflow.com/questions/69726917


            Addition with Rust and Webassembly
            Asked 2021-Sep-03 at 20:35

            Given I want to sum the first n terms of a series 1,2,3,.. with the following function in Rust



            Answered 2021-Sep-03 at 20:35

            It seems to be because wasm does not support native u64 as a type, only the signed variants (notably, i64), which is why it's using i64 as the type for the arithmetic operations. Since this then overflows a 64-bit integer (the correct output is n * (n+1) / 2, or 50000000005000000000, you're getting a negative value due to the overflow, which is then getting printed to console. This is due to a lack of type support in wasm.

            Just for reference, a Σ n=0 to N := (N * (N+1) / 2, which I use from here on out since it's much faster computationally, and correct for our purposes.

            The result, 50000000005000000000, takes ~65.4 bits in memory to accurately represent in memory, which is why you get wrapping behavior for x86_64 and wasm, just the types it wraps to are different.

            Using NumPy, we can clearly confirm this:

            Source https://stackoverflow.com/questions/69050143


            Is it possible to access a WebAssembly instance's exported memory from one of the host functions it imports in JavaScript?
            Asked 2021-Sep-01 at 13:15

            I've been handwriting some WebAssembly modules to learn how they work. Right now I'm trying to understand how imports and exports work, and how to perform IO.

            The module is as follows:



            Answered 2021-Sep-01 at 13:15

            At least in Javascript you can do something like

            Source https://stackoverflow.com/questions/69003106


            host can choose which system calls pass to each webassembly module
            Asked 2021-Apr-08 at 06:42

            part of the talk of Lin Clark in https://hacks.mozilla.org/2019/03/standardizing-wasi-a-webassembly-system-interface/:

            It also gives us sandboxing because the host can choose which wasi-core functions to pass in — so, which system calls to allow — on a program-by-program basis. This preserves security.

            she says host can choose which system calls pass to each wasm module. for example read() system call passes to module A and write() system call to module B.

            is it implemented in wasmtime or lucet or other runtimes? or is it just a dream without implementation in real world?



            Answered 2021-Apr-08 at 06:42

            Yes it is implemented in all runtimes implementing wasi. The reason is that this feature is related to import/export mechanism of WebAssembly.

            Source https://stackoverflow.com/questions/66949040


            How do I call a Rust function from Go with a string as a parameter?
            Asked 2021-Jan-20 at 11:00

            I have been trying to pass a string to a Rust function (compiled to Wasm), however for what I understood, right now there is no way to pass strings directy, because the "str" is not a type in the "FFI world" (at least that's what the rust compiler is saying): = help: consider using `*const u8` and a length instead

            So what I did was changing the function to this form (instead of using a simple &str type):



            Answered 2021-Jan-20 at 11:00

            Took me a little to understand exactly how the wasmtime Go-package worked, but in the end I resolved my problem doing this:

            Source https://stackoverflow.com/questions/65778901


            Creating callback function with closure on a parameter, without "may outlive borrowed value" or "this closure implements `FnOnce`, not `Fn`"
            Asked 2020-Nov-27 at 18:32

            I would like to create a callback function that has access to the argument instanceContext, but I am not sure how to fix the code. The failing code is instanceContext.instances.len().

            I have tried using lifetimes, move, Rc, Arc, Box, RefCell, but nothing seems to work.

            The goal is to have multiple Instances which will have callbacks that will make it possible for one Instance to call/modify another Instance, through the InstanceContext.

            During my experimentation I've been getting the following errors:

            • may outlive borrowed value
            • borrowed value does not live long enough
            • closure is FnOnce because it moves the variable
            • this closure implements FnOnce, not Fn


            Answered 2020-Nov-27 at 18:32

            You don't provide the compiler error message or an actual reproduction case so it's hard to know whether the diagnostic achieved by just thinking about things is the correct one, but to me it looks like this would be the solution:

            Source https://stackoverflow.com/questions/65041598


            How to call WASI functions directly in C using wasi-sdk (import module problem)
            Asked 2020-Jul-25 at 07:33

            I'm trying to call a WASI function (fd_write) directly in a C program using wasi-sdk. This is the the library (lib.c):



            Answered 2020-Jul-25 at 07:33

            Community Discussions, Code Snippets contain sources that include Stack Exchange Network


            No vulnerabilities reported

            Install wasmtime

            The Wasmtime CLI can be installed on Linux and macOS with a small install script:. Windows or otherwise interested users can download installers and binaries directly from the GitHub Releases page.


            You can use Wasmtime from a variety of different languages through embeddings of the implementation:.
            Find more information at:

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