PROCESSENTRY32 szExeFile usage

[scatrunner]

I couldn't find an example on how to “correctly” convert Foundation::CHAR slices like szExeFile from ProcessEntry32 to a string.

My current solution looks like this

let mut buf = Vec::with_capacity(260);
for c in process_entry.szExeFile.iter() {
    if c.0 == 0 {
        break;
    }

    buf.push(c.0 as char);
}

let process_name: String = String::from_iter(buf);

Is there a better solution for this or another preferred/intended way on how we should handle these?

[tim-weis]

Questions about the use of the windows and windows-sys crates are best delegated to Stack Overflow.

As for the specific question: You shouldn't be using Foundation::CHAR here at all. Process32First returns strings encoded as ANSI (CP_ACP by default). That can quickly turn into sequences of bytes that do not represent valid UTF-8, and String::from_iter will respond with a panic!.

Instead, call Process32FirstW, which will populate a PROCESSENTRY32W structure. You can now convert the &[u16] into an OsString, if you so choose, or keep a 'raw' Vec<u16> around.

Rust just doesn't offer a convenient way to represent strings as used by Windows (UTF-16, but not necessarily well-formed). String handling is always going to feel unnatural with Rust on Windows: You'll either have lots of OsStrings, lots of fallible operations, or lots of opportunities for panic!s.

[rylev]

Note: there are some suggestions for making this marginally better in #1848. Please give your feedback there as we try to make string handling a little less painful.

[kennykerr]

Here's an example for a similar API: #1837 (comment)