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Handle newlines in hidutil list column values
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@rossmacarthur
rossmacarthur committed Aug 14, 2023
1 parent 24b3a1f commit 5f04860
Showing 1 changed file with 191 additions and 58 deletions.
249 changes: 191 additions & 58 deletions src/hid.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,67 +15,73 @@ pub struct Device {
pub name: String,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum Kind {
Service,
Device,
}

/// List available HID devices.
pub fn list() -> Result<Vec<Device>> {
let mut devices = Vec::new();
let output = process::Command::new("hidutil").arg("list").output_text()?;
let mut iter = output.lines();

let mut kind = Kind::Device;
let mut h = "";
let mut h_indices: Option<Vec<Option<usize>>> = None;

while let Some(line) = iter.next() {
match line {
"" => {}
"Services:" | "Devices:" => {
kind = match line {
"Services:" => Kind::Service,
"Devices:" => Kind::Device,
_ => unreachable!(),
};
h = iter.next().context("expected header")?;
h_indices = Some(
split_whitespace_indices(h)
.map(Some)
.chain([None])
.collect(),
);
}
line => {
if kind != Kind::Device {
continue;
let devices = parse_hidutil_output(&output).context("failed to parse `hidutil list` output")?;
Ok(devices)
}

fn parse_hidutil_output(mut output: &str) -> Result<Vec<Device>> {
let mut devices = Vec::new();

// first find the header and skip past it
const HEADER: &str = "Devices:\n";
let start = output.find(HEADER).context("expected 'Devices:'")? + HEADER.len();
output = &output[start..];

// then parse the indices of the header
let line = output
.find('\n')
.map(|i| &output[..i])
.context("expected header")?;
let indices: Vec<_> = split_whitespace_indices(line)
.map(|(header, i)| Some((header.trim(), i)))
.chain([None])
.collect();

// now skip over the header
output = &output[line.len() + 1..];

while !output.is_empty() {
let mut line_end = 0;

// parse the line into a map of header -> value using the header
// indices to know where columns start and end, for the last column
// we simply find the next newline
let map: HashMap<_, _> = indices
.windows(2)
.map(|w| match *w {
[Some((header, m)), Some((_, n))] => {
let value = output[m..n].trim();
(header, value)
}
[Some((header, m)), None] => {
line_end = output[m..]
.find('\n')
.map(|i| m + i + 1)
.unwrap_or(output.len());
let value = output[m..line_end].trim();
(header, value)
}
_ => unreachable!(),
})
.collect();

let indices = h_indices.as_deref().unwrap().windows(2);
let map: HashMap<_, _> = indices
.map(|w| match *w {
[Some(m), Some(n)] => (h[m..n].trim(), line[m..n].trim()),
[Some(m), None] => (h[m..].trim(), line[m..].trim()),
_ => unreachable!(),
})
.collect();

let name = match parse_maybe(map["Product"]) {
Some(name) => name,
None => continue,
};
let vendor_id = hex::parse(map["VendorID"])?;
let product_id = hex::parse(map["ProductID"])?;

devices.push(Device {
vendor_id,
product_id,
name,
});
}
}
output = &output[line_end..];

let name = match parse_maybe(map["Product"]) {
Some(name) => name.replace('\n', " "),
None => continue,
};
let vendor_id = hex::parse(map["VendorID"])?;
let product_id = hex::parse(map["ProductID"])?;

devices.push(Device {
vendor_id,
product_id,
name,
});
}

devices.sort();
Expand Down Expand Up @@ -144,7 +150,134 @@ fn parse_maybe(s: &str) -> Option<String> {
}
}

fn split_whitespace_indices(s: &str) -> impl Iterator<Item = usize> + '_ {
fn split_whitespace_indices(s: &str) -> impl Iterator<Item = (&str, usize)> + '_ {
let addr = |s: &str| s.as_ptr() as usize;
s.split_whitespace().map(move |sub| (addr(sub) - addr(s)))
s.split_whitespace()
.map(move |sub| (sub, (addr(sub) - addr(s))))
}

#[cfg(test)]
mod tests {
use super::*;

#[test]
fn test_parse_hidutil_output_empty() {
let output = r#"Devices:
VendorID ProductID Product
"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(devices, Vec::new());
}

#[test]
fn test_parse_hidutil_output_preamble() {
let output = r#"
Services:
VendorID ProductID LocationID UsagePage Usage RegistryID Transport Class
Devices:
VendorID ProductID Product
"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(devices, Vec::new());
}

#[test]
fn test_parse_hidutil_output_basic() {
let output = r#"Devices:
VendorID ProductID Product Built-In
0x0 0x0 BTM (null)
"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(
devices,
vec![Device {
vendor_id: 0,
product_id: 0,
name: "BTM".to_owned()
},]
);
}

#[test]
fn test_parse_hidutil_output_no_trailing_newline() {
let output = r#"Devices:
VendorID ProductID Product Built-In
0x0 0x0 BTM (null)"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(
devices,
vec![Device {
vendor_id: 0,
product_id: 0,
name: "BTM".to_owned()
},]
);
}

#[test]
fn test_parse_hidutil_output_null_product() {
let output = r#"Devices:
VendorID ProductID Product Built-In
0x0 0x0 (null) (null)"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(devices, vec![]);
}

#[test]
fn test_parse_hidutil_output_wide() {
let output = r#"Devices:
VendorID ProductID Product Built-In
0x0 0x0 BTM (null)
0x5ac 0x8600 TouchBarUserDevice 1
"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(
devices,
vec![
Device {
vendor_id: 0,
product_id: 0,
name: "BTM".to_owned()
},
Device {
vendor_id: 0x5ac,
product_id: 0x8600,
name: "TouchBarUserDevice".to_owned()
}
]
);
}

#[test]
fn test_parse_hidutil_output_newline() {
let output = r#"Devices:
VendorID ProductID Product Built-In
0x0 0x0 BTM (null)
0x5ac 0x8600 TouchBar
UserDevice 1
0x6ac 0x9600 Made Up 1
"#;
let devices = parse_hidutil_output(output).unwrap();
assert_eq!(
devices,
vec![
Device {
vendor_id: 0,
product_id: 0,
name: "BTM".to_owned()
},
Device {
vendor_id: 0x5ac,
product_id: 0x8600,
name: "TouchBar UserDevice".to_owned()
},
Device {
vendor_id: 0x6ac,
product_id: 0x9600,
name: "Made Up".to_owned(),
}
]
);
}
}

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