Added filesystem access example #55
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Thanks @JayJamieson for the PR
However, when you build Reactor modules, we typically have an If we put all of the code inside 1: The fact that we are using the |
README.md
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| Next we need to setup the runtime to make filesystem APIs available, we do this by calling `__wasm_call_ctors()` exported method in a WASM `_initialize` hook. | ||
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| ```go | ||
| package main | ||
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| import ( | ||
| "os" | ||
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| "github.com/extism/go-pdk" | ||
| ) | ||
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| //export __wasm_call_ctors | ||
| func __wasm_call_ctors() | ||
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| //export _initialize | ||
| func _initialize() { | ||
| __wasm_call_ctors() | ||
| } | ||
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| //export write_file | ||
| func writeFile() int32 { | ||
| input := pdk.Input() | ||
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| err := pluginMain("/mnt/wasm.txt", input) | ||
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| if err != nil { | ||
| pdk.Log(pdk.LogTrace, err.Error()) | ||
| return 1 | ||
| } | ||
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| return 0 | ||
| } | ||
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| func pluginMain(filename string, data []byte) error { | ||
| pdk.Log(pdk.LogInfo, "Writing following data to disk: "+string(data)) | ||
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| // Write to the file, will be created if it doesn't exist | ||
| err := os.WriteFile(filename, data, 0644) | ||
| if err != nil { | ||
| return err | ||
| } | ||
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| return nil | ||
| } | ||
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| func main() {} | ||
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| ``` |
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I think it's a little confusing to have PDK code in this repo. This SDK can run lots of languages and documenting how to enable WASI is more the concern of the PDK readme. So maybe this could move to the go-pdk if it's not already documented there?
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We should maybe just have a note that the plug-in needs to be built to a WASI target or something.
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Hmmm I did consider if this should be in the sdk repo. I can move this to the PDF repo easy enough.
I think a link from the PDK back to the SDK repo section covering file access will make discoverability good, what do you think?
| } | ||
| ``` | ||
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| > *Note*: In order for filesystem APIs to work the plugin needs to be compiled with WASI target. Source code for the plugin can be found [here](https://github.com/extism/go-pdk/blob/main/example/fs/main.go) and is written in Go, but it could be written in any of our PDK languages. |
Adds a filesystem access example to
README.md.I'm a little unsure what
__wasm_call_ctors()and_initialize()do and may need a better worded explanation as part of the example. My assumption is that it initializes some needed runtime APIs needed for filesystem access.Let me know of any adjustments needed.