discussion - feasibility to integrate `https://wicg.github.io/file-system-access/`

[kaizhu256]

a serious limitation of downstream libraries like sql.js is inability to persist largish databases (e.g. 1gb) to local filesystem.

that might finally be overcome with newly proposed https://wicg.github.io/file-system-access (note spec's motivation appears mainly saving data in web-editors and ides). they have an experimental demo here

feasibility question - what additional spec read/write features are needed to integrate emscripten with file-system-access?

spec's current read/write capabilities are (from what i gather):

read

• await FileSystemHandle.file() // method returns blob/file object

write

• await FileSystemWritableFileStream.write(data)
• await FileSystemWritableFileStream.write({ type: "write", data: data })
• await FileSystemWritableFileStream.write({ type: "write", position: position, data: data })
• await FileSystemWritableFileStream.write({ type: "seek", position: position })
• await FileSystemWritableFileStream.write({ type: "truncate", size: size })

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[sbc100]

@tlively is this the same thing you are working on with wasmfs+opfs?

[tlively]

Very related, but the API in the OP accesses and stores data to the user's file system rather than a private file system as in OPFS.

[ProgrammerIn-wonderland]

Very related, but the API in the OP accesses and stores data to the user's file system rather than a private file system as in OPFS.

tested, you can replace the let root = await navigator.storage.getDirectory(); in the compiled output with

        let root;
        await new Promise((res, rej) => {
          const button = document.createElement("button")
          button.onclick = async () => {
            root = await window.showDirectoryPicker({mode:"readwrite"});
            res();
          }
          button.textContent = "Click me to proceed";
          document.body.appendChild(button);
        })

and it works fine, the emscripten code can access the local files. The button is created because showDirectoryPicker can only be run as a result of user interaction