Provide world Git identity, reflog fallback, object inspection, and which (T73)

userland/exec-tools/src/which.rs

@@ -0,0 +1,39 @@
+//! Resolve tool names through PATH, with the same .wasm fallback as the host.
+use std::path::Path;
+fn main() {
+    let mut args = std::env::args().skip(1).peekable();
+    let all = args.peek().is_some_and(|arg| arg == "-a");
+    if all {
+        args.next();
+    }
+    let names: Vec<_> = args.collect();
+    if names.is_empty() || names.iter().any(|name| name.starts_with('-')) {
+        eprintln!("usage: which [-a] <name>...");
+        std::process::exit(2);
+    }
+    let path = std::env::var("PATH").unwrap_or_else(|_| "/usr/local/bin:/bin".into());
+    let mut missing = false;
+    for name in names {
+        let paths: Vec<_> = if name.contains('/') {
+            vec![name.clone()]
+        } else {
+            path.split(':')
+                .map(|dir| Path::new(dir).join(&name).to_string_lossy().into_owned())
+                .collect()
+        };
+        let mut found = false;
+        'search: for path in paths {
+            for candidate in [path.clone(), format!("{path}.wasm")] {
+                if std::fs::metadata(&candidate).is_ok_and(|metadata| metadata.is_file()) {
+                    println!("{candidate}");
+                    found = true;
+                    if !all {
+                        break 'search;
+                    }
+                }
+            }
+        }
+        missing |= !found;
+    }
+    std::process::exit(i32::from(missing));
+}