Store all args in the unsupported Command implementation

library/std/src/sys/pal/unsupported/process.rs

@@ -1,7 +1,6 @@
-use crate::ffi::OsStr;
+use crate::ffi::{OsStr, OsString};
 use crate::fmt;
 use crate::io;
-use crate::marker::PhantomData;
 use crate::num::NonZero;
 use crate::path::Path;
 use crate::sys::fs::File;
@@ -16,7 +15,14 @@ pub use crate::ffi::OsString as EnvKey;
 ////////////////////////////////////////////////////////////////////////////////
 
 pub struct Command {
+    program: OsString,
+    args: Vec<OsString>,
     env: CommandEnv,
+
+    cwd: Option<OsString>,
+    stdin: Option<Stdio>,
+    stdout: Option<Stdio>,
+    stderr: Option<Stdio>,
 }
 
 // passed back to std::process with the pipes connected to the child, if any
@@ -27,47 +33,70 @@ pub struct StdioPipes {
     pub stderr: Option<AnonPipe>,
 }
 
-// FIXME: This should be a unit struct, so we can always construct it
-// The value here should be never used, since we cannot spawn processes.
+#[derive(Debug)]
 pub enum Stdio {
     Inherit,
     Null,
     MakePipe,
+    ParentStdout,
+    ParentStderr,
+    #[allow(dead_code)] // This variant exists only for the Debug impl
+    InheritFile(File),
 }
 
 impl Command {
-    pub fn new(_program: &OsStr) -> Command {
-        Command { env: Default::default() }
+    pub fn new(program: &OsStr) -> Command {
+        Command {
+            program: program.to_owned(),
+            args: vec![program.to_owned()],
+            env: Default::default(),
+            cwd: None,
+            stdin: None,
+            stdout: None,
+            stderr: None,
+        }
     }
 
-    pub fn arg(&mut self, _arg: &OsStr) {}
+    pub fn arg(&mut self, arg: &OsStr) {
+        self.args.push(arg.to_owned());
+    }
 
     pub fn env_mut(&mut self) -> &mut CommandEnv {
         &mut self.env
     }
 
-    pub fn cwd(&mut self, _dir: &OsStr) {}
+    pub fn cwd(&mut self, dir: &OsStr) {
+        self.cwd = Some(dir.to_owned());
+    }
 
-    pub fn stdin(&mut self, _stdin: Stdio) {}
+    pub fn stdin(&mut self, stdin: Stdio) {
+        self.stdin = Some(stdin);
+    }
 
-    pub fn stdout(&mut self, _stdout: Stdio) {}
+    pub fn stdout(&mut self, stdout: Stdio) {
+        self.stdout = Some(stdout);
+    }
 
-    pub fn stderr(&mut self, _stderr: Stdio) {}
+    pub fn stderr(&mut self, stderr: Stdio) {
+        self.stderr = Some(stderr);
+    }
 
     pub fn get_program(&self) -> &OsStr {
-        panic!("unsupported")
+        &self.program
     }
 
     pub fn get_args(&self) -> CommandArgs<'_> {
-        CommandArgs { _p: PhantomData }
+        let mut iter = self.args.iter();
+        iter.next();
+        CommandArgs { iter }
     }
 
     pub fn get_envs(&self) -> CommandEnvs<'_> {
         self.env.iter()
     }
 
     pub fn get_current_dir(&self) -> Option<&Path> {
-        None
+        self.cwd.as_ref().map(|cs| Path::new(cs))
     }
 
     pub fn spawn(
@@ -91,31 +120,83 @@ impl From<AnonPipe> for Stdio {
 
 impl From<io::Stdout> for Stdio {
     fn from(_: io::Stdout) -> Stdio {
-        // FIXME: This is wrong.
-        // Instead, the Stdio we have here should be a unit struct.
-        panic!("unsupported")
+        Stdio::ParentStdout
     }
 }
 
 impl From<io::Stderr> for Stdio {
     fn from(_: io::Stderr) -> Stdio {
-        // FIXME: This is wrong.
-        // Instead, the Stdio we have here should be a unit struct.
-        panic!("unsupported")
+        Stdio::ParentStderr
     }
 }
 
 impl From<File> for Stdio {
-    fn from(_file: File) -> Stdio {
-        // FIXME: This is wrong.
-        // Instead, the Stdio we have here should be a unit struct.
-        panic!("unsupported")
+    fn from(file: File) -> Stdio {
+        Stdio::InheritFile(file)
     }
 }
 
 impl fmt::Debug for Command {
-    fn fmt(&self, _f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        Ok(())
+    // show all attributes
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if f.alternate() {
+            let mut debug_command = f.debug_struct("Command");
+            debug_command.field("program", &self.program).field("args", &self.args);
+            if !self.env.is_unchanged() {
+                debug_command.field("env", &self.env);
+            }
+
+            if self.cwd.is_some() {
+                debug_command.field("cwd", &self.cwd);
+            }
+
+            if self.stdin.is_some() {
+                debug_command.field("stdin", &self.stdin);
+            }
+            if self.stdout.is_some() {
+                debug_command.field("stdout", &self.stdout);
+            }
+            if self.stderr.is_some() {
+                debug_command.field("stderr", &self.stderr);
+            }
+
+            debug_command.finish()
+        } else {
+            if let Some(ref cwd) = self.cwd {
+                write!(f, "cd {cwd:?} && ")?;
+            }
+            if self.env.does_clear() {
+                write!(f, "env -i ")?;
+                // Altered env vars will be printed next, that should exactly work as expected.
+            } else {
+                // Removed env vars need the command to be wrapped in `env`.
+                let mut any_removed = false;
+                for (key, value_opt) in self.get_envs() {
+                    if value_opt.is_none() {
+                        if !any_removed {
+                            write!(f, "env ")?;
+                            any_removed = true;
+                        }
+                        write!(f, "-u {} ", key.to_string_lossy())?;
+                    }
+                }
+            }
+            // Altered env vars can just be added in front of the program.
+            for (key, value_opt) in self.get_envs() {
+                if let Some(value) = value_opt {
+                    write!(f, "{}={value:?} ", key.to_string_lossy())?;
+                }
+            }
+            if self.program != self.args[0] {
+                write!(f, "[{:?}] ", self.program)?;
+            }
+            write!(f, "{:?}", self.args[0])?;
+
+            for arg in &self.args[1..] {
+                write!(f, " {:?}", arg)?;
+            }
+            Ok(())
+        }
     }
 }
 
@@ -217,23 +298,30 @@ impl Process {
 }
 
 pub struct CommandArgs<'a> {
-    _p: PhantomData<&'a ()>,
+    iter: crate::slice::Iter<'a, OsString>,
 }
 
 impl<'a> Iterator for CommandArgs<'a> {
     type Item = &'a OsStr;
     fn next(&mut self) -> Option<&'a OsStr> {
-        None
+        self.iter.next().map(|os| &**os)
     }
     fn size_hint(&self) -> (usize, Option<usize>) {
-        (0, Some(0))
+        self.iter.size_hint()
     }
 }
 
-impl<'a> ExactSizeIterator for CommandArgs<'a> {}
+impl<'a> ExactSizeIterator for CommandArgs<'a> {
+    fn len(&self) -> usize {
+        self.iter.len()
+    }
+    fn is_empty(&self) -> bool {
+        self.iter.is_empty()
+    }
+}
 
 impl<'a> fmt::Debug for CommandArgs<'a> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.debug_list().finish()
+        f.debug_list().entries(self.iter.clone()).finish()
     }
 }