Introduce CmdArgs for argument parsing in Rust

native/src/base/cstr.rs

@@ -300,6 +300,13 @@ impl Utf8CStr {
         }
     }
 
+    pub unsafe fn from_raw_parts<'a>(ptr: *const c_char, len: usize) -> &'a Utf8CStr {
+        unsafe {
+            let bytes = slice::from_raw_parts(ptr.cast(), len);
+            Self::from_bytes_unchecked(bytes)
+        }
+    }
+
     #[inline(always)]
     pub fn as_bytes_with_nul(&self) -> &[u8] {
         &self.0

native/src/base/misc.rs

@@ -1,13 +1,16 @@
-use crate::{StrErr, Utf8CStr, ffi};
+use crate::{Utf8CStr, cstr, ffi};
 use argh::EarlyExit;
 use libc::c_char;
-use std::fmt::Arguments;
-use std::io::Write;
-use std::mem::ManuallyDrop;
-use std::process::exit;
-use std::sync::Arc;
-use std::sync::atomic::{AtomicPtr, Ordering};
-use std::{fmt, slice, str};
+use std::{
+    fmt,
+    fmt::Arguments,
+    io::Write,
+    mem::ManuallyDrop,
+    process::exit,
+    slice, str,
+    sync::Arc,
+    sync::atomic::{AtomicPtr, Ordering},
+};
 
 pub fn errno() -> &'static mut i32 {
     unsafe { &mut *libc::__errno() }
@@ -76,15 +79,6 @@ impl<T: AsMut<[u8]> + ?Sized> MutBytesExt for T {
     }
 }
 
-// SAFETY: libc guarantees argc and argv are properly setup and are static
-#[allow(clippy::not_unsafe_ptr_arg_deref)]
-pub fn map_args(argc: i32, argv: *const *const c_char) -> Result<Vec<&'static str>, StrErr> {
-    unsafe { slice::from_raw_parts(argv, argc as usize) }
-        .iter()
-        .map(|s| unsafe { Utf8CStr::from_ptr(*s) }.map(|s| s.as_str()))
-        .collect()
-}
-
 pub trait EarlyExitExt<T> {
     fn on_early_exit<F: FnOnce()>(self, print_help_msg: F) -> T;
 }
@@ -227,3 +221,35 @@ impl Chunker {
         chunk
     }
 }
+
+pub struct CmdArgs(pub Vec<&'static str>);
+
+impl CmdArgs {
+    #[allow(clippy::not_unsafe_ptr_arg_deref)]
+    pub fn new(argc: i32, argv: *const *const c_char) -> CmdArgs {
+        CmdArgs(
+            // SAFETY: libc guarantees argc and argv are properly setup and are static
+            unsafe { slice::from_raw_parts(argv, argc as usize) }
+                .iter()
+                .map(|s| unsafe { Utf8CStr::from_ptr(*s) })
+                .map(|r| r.unwrap_or(cstr!("<invalid>")))
+                .map(Utf8CStr::as_str)
+                .collect(),
+        )
+    }
+
+    pub fn as_slice(&self) -> &[&'static str] {
+        self.0.as_slice()
+    }
+
+    pub fn iter(&self) -> slice::Iter<'_, &'static str> {
+        self.0.iter()
+    }
+
+    pub fn cstr_iter(&self) -> impl Iterator<Item = &'static Utf8CStr> {
+        // SAFETY: libc guarantees null terminated strings
+        self.0
+            .iter()
+            .map(|s| unsafe { Utf8CStr::from_raw_parts(s.as_ptr().cast(), s.len() + 1) })
+    }
+}

native/src/boot/cli.rs

@@ -7,8 +7,8 @@ use crate::payload::extract_boot_from_payload;
 use crate::sign::sha1_hash;
 use argh::FromArgs;
 use base::{
-    EarlyExitExt, LoggedResult, MappedFile, ResultExt, Utf8CStr, cmdline_logging, cstr,
-    libc::umask, log_err, map_args,
+    CmdArgs, EarlyExitExt, LoggedResult, MappedFile, ResultExt, Utf8CStr, cmdline_logging, cstr,
+    libc::umask, log_err,
 };
 use std::ffi::c_char;
 use std::str::FromStr;
@@ -264,7 +264,7 @@ pub extern "C" fn main(argc: i32, argv: *const *const c_char, _envp: *const *con
     cmdline_logging();
     unsafe { umask(0) };
     let res: LoggedResult<()> = try {
-        let mut cmds = map_args(argc, argv)?;
+        let mut cmds = CmdArgs::new(argc, argv).0;
         if argc < 2 {
             print_usage(cmds.first().unwrap_or(&"magiskboot"));
             return 1;

native/src/sepolicy/cli.rs

@@ -2,8 +2,8 @@ use crate::ffi::SePolicy;
 use crate::statement::format_statement_help;
 use argh::FromArgs;
 use base::{
-    EarlyExitExt, FmtAdaptor, LoggedResult, Utf8CStr, cmdline_logging, cstr, libc::umask, log_err,
-    map_args,
+    CmdArgs, EarlyExitExt, FmtAdaptor, LoggedResult, Utf8CStr, cmdline_logging, cstr, libc::umask,
+    log_err,
 };
 use std::ffi::c_char;
 use std::io::stderr;
@@ -79,7 +79,8 @@ pub unsafe extern "C" fn main(
     }
 
     let res: LoggedResult<()> = try {
-        let cmds = map_args(argc, argv)?;
+        let cmds = CmdArgs::new(argc, argv);
+        let cmds = cmds.as_slice();
         if argc < 2 {
             print_usage(cmds.first().unwrap_or(&"magiskpolicy"));
             return 1;