feat(cpio): add rust argument parsing library from crosvm

Crosvm's rust argument library is very small and simple, while still
providing helpful functionality. It will be consumed by dracut-cpio in a
subsequent commit.

The unmodified, BSD licensed argument.rs source is lifted as-is from
https://chromium.googlesource.com/chromiumos/platform/crosvm
(release-R92-13982.B b6ae6517aeef9ae1e3a39c55b52f9ac6de8edb31).
The one-line crosvm.rs wrapper is needed to ensure that crosvm::argument
imports continue to work.

Signed-off-by: David Disseldorp <ddiss@suse.de>

4 files changed, 586 insertions, 0 deletions

diff --git a/src/dracut-cpio/third_party/crosvm/Cargo.toml b/src/dracut-cpio/third_party/crosvm/Cargo.toml
new file mode 100644
index 00000000..a56ff2db
--- /dev/null
+++ b/src/dracut-cpio/third_party/crosvm/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "crosvm"
+version = "0.1.0"
+authors = ["The Chromium OS Authors"]
+edition = "2018"
+
+[lib]
+path = "crosvm.rs"
diff --git a/src/dracut-cpio/third_party/crosvm/LICENSE b/src/dracut-cpio/third_party/crosvm/LICENSE
new file mode 100644
index 00000000..8bafca30
--- /dev/null
+++ b/src/dracut-cpio/third_party/crosvm/LICENSE
@@ -0,0 +1,27 @@
+// Copyright 2017 The Chromium OS Authors. All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//    * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//    * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//    * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/src/dracut-cpio/third_party/crosvm/argument.rs b/src/dracut-cpio/third_party/crosvm/argument.rs
new file mode 100644
index 00000000..64be1822
--- /dev/null
+++ b/src/dracut-cpio/third_party/crosvm/argument.rs
@@ -0,0 +1,549 @@
+// Copyright 2017 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+//! Handles argument parsing.
+//!
+//! # Example
+//!
+//! ```
+//! # use crosvm::argument::{Argument, Error, print_help, set_arguments};
+//! # let args: std::slice::Iter<String> = [].iter();
+//! let arguments = &[
+//!     Argument::positional("FILES", "files to operate on"),
+//!     Argument::short_value('p', "program", "PROGRAM", "Program to apply to each file"),
+//!     Argument::short_value('c', "cpus", "N", "Number of CPUs to use. (default: 1)"),
+//!     Argument::flag("unmount", "Unmount the root"),
+//!     Argument::short_flag('h', "help", "Print help message."),
+//! ];
+//!
+//! let match_res = set_arguments(args, arguments, |name, value| {
+//!     match name {
+//!         "" => println!("positional arg! {}", value.unwrap()),
+//!         "program" => println!("gonna use program {}", value.unwrap()),
+//!         "cpus" => {
+//!             let v: u32 = value.unwrap().parse().map_err(|_| {
+//!                 Error::InvalidValue {
+//!                     value: value.unwrap().to_owned(),
+//!                     expected: String::from("this value for `cpus` needs to be integer"),
+//!                 }
+//!             })?;
+//!         }
+//!         "unmount" => println!("gonna unmount"),
+//!         "help" => return Err(Error::PrintHelp),
+//!         _ => unreachable!(),
+//!     }
+//!     unreachable!();
+//! });
+//!
+//! match match_res {
+//!     Ok(_) => println!("running with settings"),
+//!     Err(Error::PrintHelp) => print_help("best_program", "FILES", arguments),
+//!     Err(e) => println!("{}", e),
+//! }
+//! ```
+
+use std::fmt::{self, Display};
+use std::result;
+
+/// An error with argument parsing.
+#[derive(Debug)]
+pub enum Error {
+    /// There was a syntax error with the argument.
+    Syntax(String),
+    /// The argument's name is unused.
+    UnknownArgument(String),
+    /// The argument was required.
+    ExpectedArgument(String),
+    /// The argument's given value is invalid.
+    InvalidValue { value: String, expected: String },
+    /// The argument was already given and none more are expected.
+    TooManyArguments(String),
+    /// The argument expects a value.
+    ExpectedValue(String),
+    /// The argument does not expect a value.
+    UnexpectedValue(String),
+    /// The help information was requested
+    PrintHelp,
+}
+
+impl Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        use self::Error::*;
+
+        match self {
+            Syntax(s) => write!(f, "syntax error: {}", s),
+            UnknownArgument(s) => write!(f, "unknown argument: {}", s),
+            ExpectedArgument(s) => write!(f, "expected argument: {}", s),
+            InvalidValue { value, expected } => {
+                write!(f, "invalid value {:?}: {}", value, expected)
+            }
+            TooManyArguments(s) => write!(f, "too many arguments: {}", s),
+            ExpectedValue(s) => write!(f, "expected parameter value: {}", s),
+            UnexpectedValue(s) => write!(f, "unexpected parameter value: {}", s),
+            PrintHelp => write!(f, "help was requested"),
+        }
+    }
+}
+
+/// Result of a argument parsing.
+pub type Result<T> = result::Result<T, Error>;
+
+#[derive(Debug, PartialEq)]
+pub enum ArgumentValueMode {
+    /// Specifies that an argument requires a value and that an error should be generated if
+    /// no value is provided during parsing.
+    Required,
+
+    /// Specifies that an argument does not allow a value and that an error should be returned
+    /// if a value is provided during parsing.
+    Disallowed,
+
+    /// Specifies that an argument may have a value during parsing but is not required to.
+    Optional,
+}
+
+/// Information about an argument expected from the command line.
+///
+/// # Examples
+///
+/// To indicate a flag style argument:
+///
+/// ```
+/// # use crosvm::argument::Argument;
+/// Argument::short_flag('f', "flag", "enable awesome mode");
+/// ```
+///
+/// To indicate a parameter style argument that expects a value:
+///
+/// ```
+/// # use crosvm::argument::Argument;
+/// // "VALUE" and "NETMASK" are placeholder values displayed in the help message for these
+/// // arguments.
+/// Argument::short_value('v', "val", "VALUE", "how much do you value this usage information");
+/// Argument::value("netmask", "NETMASK", "hides your netface");
+/// ```
+///
+/// To indicate an argument with no short version:
+///
+/// ```
+/// # use crosvm::argument::Argument;
+/// Argument::flag("verbose", "this option is hard to type quickly");
+/// ```
+///
+/// To indicate a positional argument:
+///
+/// ```
+/// # use crosvm::argument::Argument;
+/// Argument::positional("VALUES", "these are positional arguments");
+/// ```
+pub struct Argument {
+    /// The name of the value to display in the usage information.
+    pub value: Option<&'static str>,
+    /// Specifies how values should be handled for this this argument.
+    pub value_mode: ArgumentValueMode,
+    /// Optional single character shortened argument name.
+    pub short: Option<char>,
+    /// The long name of this argument.
+    pub long: &'static str,
+    /// Helpfuly usage information for this argument to display to the user.
+    pub help: &'static str,
+}
+
+impl Argument {
+    pub fn positional(value: &'static str, help: &'static str) -> Argument {
+        Argument {
+            value: Some(value),
+            value_mode: ArgumentValueMode::Required,
+            short: None,
+            long: "",
+            help,
+        }
+    }
+
+    pub fn value(long: &'static str, value: &'static str, help: &'static str) -> Argument {
+        Argument {
+            value: Some(value),
+            value_mode: ArgumentValueMode::Required,
+            short: None,
+            long,
+            help,
+        }
+    }
+
+    pub fn short_value(
+        short: char,
+        long: &'static str,
+        value: &'static str,
+        help: &'static str,
+    ) -> Argument {
+        Argument {
+            value: Some(value),
+            value_mode: ArgumentValueMode::Required,
+            short: Some(short),
+            long,
+            help,
+        }
+    }
+
+    pub fn flag(long: &'static str, help: &'static str) -> Argument {
+        Argument {
+            value: None,
+            value_mode: ArgumentValueMode::Disallowed,
+            short: None,
+            long,
+            help,
+        }
+    }
+
+    pub fn short_flag(short: char, long: &'static str, help: &'static str) -> Argument {
+        Argument {
+            value: None,
+            value_mode: ArgumentValueMode::Disallowed,
+            short: Some(short),
+            long,
+            help,
+        }
+    }
+
+    pub fn flag_or_value(long: &'static str, value: &'static str, help: &'static str) -> Argument {
+        Argument {
+            value: Some(value),
+            value_mode: ArgumentValueMode::Optional,
+            short: None,
+            long,
+            help,
+        }
+    }
+}
+
+fn parse_arguments<I, R, F>(args: I, mut f: F) -> Result<()>
+where
+    I: Iterator<Item = R>,
+    R: AsRef<str>,
+    F: FnMut(&str, Option<&str>) -> Result<()>,
+{
+    enum State {
+        // Initial state at the start and after finishing a single argument/value.
+        Top,
+        // The remaining arguments are all positional.
+        Positional,
+        // The next string is the value for the argument `name`.
+        Value { name: String },
+    }
+    let mut s = State::Top;
+    for arg in args {
+        let arg = arg.as_ref();
+        loop {
+            let mut arg_consumed = true;
+            s = match s {
+                State::Top => {
+                    if arg == "--" {
+                        State::Positional
+                    } else if arg.starts_with("--") {
+                        let param = arg.trim_start_matches('-');
+                        if param.contains('=') {
+                            let mut iter = param.splitn(2, '=');
+                            let name = iter.next().unwrap();
+                            let value = iter.next().unwrap();
+                            if name.is_empty() {
+                                return Err(Error::Syntax(
+                                    "expected parameter name before `=`".to_owned(),
+                                ));
+                            }
+                            if value.is_empty() {
+                                return Err(Error::Syntax(
+                                    "expected parameter value after `=`".to_owned(),
+                                ));
+                            }
+                            f(name, Some(value))?;
+                            State::Top
+                        } else {
+                            State::Value {
+                                name: param.to_owned(),
+                            }
+                        }
+                    } else if arg.starts_with('-') {
+                        if arg.len() == 1 {
+                            return Err(Error::Syntax(
+                                "expected argument short name after `-`".to_owned(),
+                            ));
+                        }
+                        let name = &arg[1..2];
+                        let value = if arg.len() > 2 { Some(&arg[2..]) } else { None };
+                        if let Err(e) = f(name, value) {
+                            if let Error::ExpectedValue(_) = e {
+                                State::Value {
+                                    name: name.to_owned(),
+                                }
+                            } else {
+                                return Err(e);
+                            }
+                        } else {
+                            State::Top
+                        }
+                    } else {
+                        f("", Some(&arg))?;
+                        State::Positional
+                    }
+                }
+                State::Positional => {
+                    f("", Some(&arg))?;
+                    State::Positional
+                }
+                State::Value { name } => {
+                    if arg.starts_with('-') {
+                        arg_consumed = false;
+                        f(&name, None)?;
+                    } else if let Err(e) = f(&name, Some(&arg)) {
+                        arg_consumed = false;
+                        f(&name, None).map_err(|_| e)?;
+                    }
+                    State::Top
+                }
+            };
+
+            if arg_consumed {
+                break;
+            }
+        }
+    }
+
+    // If we ran out of arguments while parsing the last parameter, which may be either a
+    // value parameter or a flag, try to parse it as a flag. This will produce "missing value"
+    // error if the parameter is in fact a value parameter, which is the desired outcome.
+    match s {
+        State::Value { name } => f(&name, None),
+        _ => Ok(()),
+    }
+}
+
+/// Parses the given `args` against the list of know arguments `arg_list` and calls `f` with each
+/// present argument and value if required.
+///
+/// This function guarantees that only valid long argument names from `arg_list` are sent to the
+/// callback `f`. It is also guaranteed that if an arg requires a value (i.e.
+/// `arg.value.is_some()`), the value will be `Some` in the callbacks arguments. If the callback
+/// returns `Err`, this function will end parsing and return that `Err`.
+///
+/// See the [module level](index.html) example for a usage example.
+pub fn set_arguments<I, R, F>(args: I, arg_list: &[Argument], mut f: F) -> Result<()>
+where
+    I: Iterator<Item = R>,
+    R: AsRef<str>,
+    F: FnMut(&str, Option<&str>) -> Result<()>,
+{
+    parse_arguments(args, |name, value| {
+        let mut matches = None;
+        for arg in arg_list {
+            if let Some(short) = arg.short {
+                if name.len() == 1 && name.starts_with(short) {
+                    if value.is_some() != arg.value.is_some() {
+                        return Err(Error::ExpectedValue(short.to_string()));
+                    }
+                    matches = Some(arg.long);
+                }
+            }
+            if matches.is_none() && arg.long == name {
+                if value.is_none() && arg.value_mode == ArgumentValueMode::Required {
+                    return Err(Error::ExpectedValue(arg.long.to_owned()));
+                }
+                if value.is_some() && arg.value_mode == ArgumentValueMode::Disallowed {
+                    return Err(Error::UnexpectedValue(arg.long.to_owned()));
+                }
+                matches = Some(arg.long);
+            }
+        }
+        match matches {
+            Some(long) => f(long, value),
+            None => Err(Error::UnknownArgument(name.to_owned())),
+        }
+    })
+}
+
+/// Prints command line usage information to stdout.
+///
+/// Usage information is printed according to the help fields in `args` with a leading usage line.
+/// The usage line is of the format "`program_name` \[ARGUMENTS\] `required_arg`".
+pub fn print_help(program_name: &str, required_arg: &str, args: &[Argument]) {
+    println!(
+        "Usage: {} {}{}\n",
+        program_name,
+        if args.is_empty() { "" } else { "[ARGUMENTS] " },
+        required_arg
+    );
+    if args.is_empty() {
+        return;
+    }
+    println!("Argument{}:", if args.len() > 1 { "s" } else { "" });
+    for arg in args {
+        match arg.short {
+            Some(s) => print!(" -{}, ", s),
+            None => print!("     "),
+        }
+        if arg.long.is_empty() {
+            print!("  ");
+        } else {
+            print!("--");
+        }
+        print!("{:<12}", arg.long);
+        if let Some(v) = arg.value {
+            if arg.long.is_empty() {
+                print!(" ");
+            } else {
+                print!("=");
+            }
+            print!("{:<10}", v);
+        } else {
+            print!("{:<11}", "");
+        }
+        println!("{}", arg.help);
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn request_help() {
+        let arguments = [Argument::short_flag('h', "help", "Print help message.")];
+
+        let match_res = set_arguments(["-h"].iter(), &arguments[..], |name, _| {
+            match name {
+                "help" => return Err(Error::PrintHelp),
+                _ => unreachable!(),
+            };
+        });
+        match match_res {
+            Err(Error::PrintHelp) => {}
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn mixed_args() {
+        let arguments = [
+            Argument::positional("FILES", "files to operate on"),
+            Argument::short_value('p', "program", "PROGRAM", "Program to apply to each file"),
+            Argument::short_value('c', "cpus", "N", "Number of CPUs to use. (default: 1)"),
+            Argument::flag("unmount", "Unmount the root"),
+            Argument::short_flag('h', "help", "Print help message."),
+        ];
+
+        let mut unmount = false;
+        let match_res = set_arguments(
+            ["--cpus", "3", "--program", "hello", "--unmount", "file"].iter(),
+            &arguments[..],
+            |name, value| {
+                match name {
+                    "" => assert_eq!(value.unwrap(), "file"),
+                    "program" => assert_eq!(value.unwrap(), "hello"),
+                    "cpus" => {
+                        let c: u32 = value.unwrap().parse().map_err(|_| Error::InvalidValue {
+                            value: value.unwrap().to_owned(),
+                            expected: String::from("this value for `cpus` needs to be integer"),
+                        })?;
+                        assert_eq!(c, 3);
+                    }
+                    "unmount" => unmount = true,
+                    "help" => return Err(Error::PrintHelp),
+                    _ => unreachable!(),
+                };
+                Ok(())
+            },
+        );
+        assert!(match_res.is_ok());
+        assert!(unmount);
+    }
+
+    #[test]
+    fn name_value_pair() {
+        let arguments = [Argument::short_value(
+            'c',
+            "cpus",
+            "N",
+            "Number of CPUs to use. (default: 1)",
+        )];
+        let match_res = set_arguments(
+            ["-c", "5", "--cpus", "5", "-c5", "--cpus=5"].iter(),
+            &arguments[..],
+            |name, value| {
+                assert_eq!(name, "cpus");
+                assert_eq!(value, Some("5"));
+                Ok(())
+            },
+        );
+        assert!(match_res.is_ok());
+        let not_match_res = set_arguments(
+            ["-c", "5", "--cpus"].iter(),
+            &arguments[..],
+            |name, value| {
+                assert_eq!(name, "cpus");
+                assert_eq!(value, Some("5"));
+                Ok(())
+            },
+        );
+        assert!(not_match_res.is_err());
+    }
+
+    #[test]
+    fn flag_or_value() {
+        let run_case = |args| -> Option<String> {
+            let arguments = [
+                Argument::positional("FILES", "files to operate on"),
+                Argument::flag_or_value("gpu", "[2D|3D]", "Enable or configure gpu"),
+                Argument::flag("foo", "Enable foo."),
+                Argument::value("bar", "stuff", "Configure bar."),
+            ];
+
+            let mut gpu_value: Option<String> = None;
+            let match_res =
+                set_arguments(args, &arguments[..], |name: &str, value: Option<&str>| {
+                    match name {
+                        "" => assert_eq!(value.unwrap(), "file1"),
+                        "foo" => assert!(value.is_none()),
+                        "bar" => assert_eq!(value.unwrap(), "stuff"),
+                        "gpu" => match value {
+                            Some(v) => match v {
+                                "2D" | "3D" => {
+                                    gpu_value = Some(v.to_string());
+                                }
+                                _ => {
+                                    return Err(Error::InvalidValue {
+                                        value: v.to_string(),
+                                        expected: String::from("2D or 3D"),
+                                    })
+                                }
+                            },
+                            None => {
+                                gpu_value = None;
+                            }
+                        },
+                        _ => unreachable!(),
+                    };
+                    Ok(())
+                });
+
+            assert!(match_res.is_ok());
+            gpu_value
+        };
+
+        // Used as flag and followed by positional
+        assert_eq!(run_case(["--gpu", "file1"].iter()), None);
+        // Used as flag and followed by flag
+        assert_eq!(run_case(["--gpu", "--foo", "file1",].iter()), None);
+        // Used as flag and followed by value
+        assert_eq!(run_case(["--gpu", "--bar=stuff", "file1"].iter()), None);
+
+        // Used as value and followed by positional
+        assert_eq!(run_case(["--gpu=2D", "file1"].iter()).unwrap(), "2D");
+        // Used as value and followed by flag
+        assert_eq!(run_case(["--gpu=2D", "--foo"].iter()).unwrap(), "2D");
+        // Used as value and followed by value
+        assert_eq!(
+            run_case(["--gpu=2D", "--bar=stuff", "file1"].iter()).unwrap(),
+            "2D"
+        );
+    }
+}
diff --git a/src/dracut-cpio/third_party/crosvm/crosvm.rs b/src/dracut-cpio/third_party/crosvm/crosvm.rs
new file mode 100644
index 00000000..ddccbfee
--- /dev/null
+++ b/src/dracut-cpio/third_party/crosvm/crosvm.rs
@@ -0,0 +1,2 @@
+// ensure that existing crosvm::argument imports work without modification...
+pub mod argument;