args.rs.html -- source
Description: Source to the Rust file `src/libstd/sys/unix/args.rs`.
Keywords: rust, rustlang, rust-lang

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    //! Global initialization and retrieval of command line arguments.
    //!
    //! On some platforms these are stored during runtime startup,
    //! and on some they are retrieved from the system on demand.

    #![allow(dead_code)] // runtime init functions not used during testing

    use crate::ffi::OsString;
    use crate::marker::PhantomData;
    use crate::vec;

    /// One-time global initialization.
    pub unsafe fn init(argc: isize, argv: *const *const u8) {
        imp::init(argc, argv)
    }

    /// One-time global cleanup.
    pub unsafe fn cleanup() {
        imp::cleanup()
    }

    /// Returns the command line arguments
    pub fn args() -> Args {
        imp::args()
    }

    pub struct Args {
        iter: vec::IntoIter<OsString>,
        _dont_send_or_sync_me: PhantomData<*mut ()>,
    }

    impl Args {
        pub fn inner_debug(&self) -> &[OsString] {
            self.iter.as_slice()
        }
    }

    impl Iterator for Args {
        type Item = OsString;
        fn next(&mut self) -> Option<OsString> {
            self.iter.next()
        }
        fn size_hint(&self) -> (usize, Option<usize>) {
            self.iter.size_hint()
        }
    }

    impl ExactSizeIterator for Args {
        fn len(&self) -> usize {
            self.iter.len()
        }
    }

    impl DoubleEndedIterator for Args {
        fn next_back(&mut self) -> Option<OsString> {
            self.iter.next_back()
        }
    }

    #[cfg(any(
        target_os = "linux",
        target_os = "android",
        target_os = "freebsd",
        target_os = "dragonfly",
        target_os = "netbsd",
        target_os = "openbsd",
        target_os = "solaris",
        target_os = "illumos",
        target_os = "emscripten",
        target_os = "haiku",
        target_os = "l4re",
        target_os = "fuchsia",
        target_os = "redox"
    ))]
    mod imp {
        use super::Args;
        use crate::ffi::{CStr, OsString};
        use crate::marker::PhantomData;
        use crate::os::unix::prelude::*;
        use crate::ptr;
        use crate::sync::atomic::{AtomicIsize, AtomicPtr, Ordering};

        use crate::sys_common::mutex::Mutex;

        static ARGC: AtomicIsize = AtomicIsize::new(0);
        static ARGV: AtomicPtr<*const u8> = AtomicPtr::new(ptr::null_mut());
        // We never call `ENV_LOCK.init()`, so it is UB to attempt to
        // acquire this mutex reentrantly!
        static LOCK: Mutex = Mutex::new();

        unsafe fn really_init(argc: isize, argv: *const *const u8) {
            let _guard = LOCK.lock();
            ARGC.store(argc, Ordering::Relaxed);
            ARGV.store(argv as *mut _, Ordering::Relaxed);
        }

        #[inline(always)]
        pub unsafe fn init(_argc: isize, _argv: *const *const u8) {
            // On Linux-GNU, we rely on `ARGV_INIT_ARRAY` below to initialize
            // `ARGC` and `ARGV`. But in Miri that does not actually happen so we
            // still initialize here.
            #[cfg(any(miri, not(all(target_os = "linux", target_env = "gnu"))))]
            really_init(_argc, _argv);
        }

        /// glibc passes argc, argv, and envp to functions in .init_array, as a non-standard extension.
        /// This allows `std::env::args` to work even in a `cdylib`, as it does on macOS and Windows.
        #[cfg(all(target_os = "linux", target_env = "gnu"))]
        #[used]
        #[link_section = ".init_array.00099"]
        static ARGV_INIT_ARRAY: extern "C" fn(
            crate::os::raw::c_int,
            *const *const u8,
            *const *const u8,
        ) = {
            extern "C" fn init_wrapper(
                argc: crate::os::raw::c_int,
                argv: *const *const u8,
                _envp: *const *const u8,
            ) {
                unsafe {
                    really_init(argc as isize, argv);
                }
            }
            init_wrapper
        };

        pub unsafe fn cleanup() {
            let _guard = LOCK.lock();
            ARGC.store(0, Ordering::Relaxed);
            ARGV.store(ptr::null_mut(), Ordering::Relaxed);
        }

        pub fn args() -> Args {
            Args { iter: clone().into_iter(), _dont_send_or_sync_me: PhantomData }
        }

        fn clone() -> Vec<OsString> {
            unsafe {
                let _guard = LOCK.lock();
                let argc = ARGC.load(Ordering::Relaxed);
                let argv = ARGV.load(Ordering::Relaxed);
                (0..argc)
                    .map(|i| {
                        let cstr = CStr::from_ptr(*argv.offset(i) as *const libc::c_char);
                        OsStringExt::from_vec(cstr.to_bytes().to_vec())
                    })
                    .collect()
            }
        }
    }

    #[cfg(any(target_os = "macos", target_os = "ios"))]
    mod imp {
        use super::Args;
        use crate::ffi::CStr;
        use crate::marker::PhantomData;

        pub unsafe fn init(_argc: isize, _argv: *const *const u8) {}

        pub fn cleanup() {}

        #[cfg(target_os = "macos")]
        pub fn args() -> Args {
            use crate::os::unix::prelude::*;
            extern "C" {
                // These functions are in crt_externs.h.
                fn _NSGetArgc() -> *mut libc::c_int;
                fn _NSGetArgv() -> *mut *mut *mut libc::c_char;
            }

            let vec = unsafe {
                let (argc, argv) =
                    (*_NSGetArgc() as isize, *_NSGetArgv() as *const *const libc::c_char);
                (0..argc as isize)
                    .map(|i| {
                        let bytes = CStr::from_ptr(*argv.offset(i)).to_bytes().to_vec();
                        OsStringExt::from_vec(bytes)
                    })
                    .collect::<Vec<_>>()
            };
            Args { iter: vec.into_iter(), _dont_send_or_sync_me: PhantomData }
        }

        // As _NSGetArgc and _NSGetArgv aren't mentioned in iOS docs
        // and use underscores in their names - they're most probably
        // are considered private and therefore should be avoided
        // Here is another way to get arguments using Objective C
        // runtime
        //
        // In general it looks like:
        // res = Vec::new()
        // let args = [[NSProcessInfo processInfo] arguments]
        // for i in (0..[args count])
        //      res.push([args objectAtIndex:i])
        // res
        #[cfg(target_os = "ios")]
        pub fn args() -> Args {
            use crate::ffi::OsString;
            use crate::mem;
            use crate::str;

            extern "C" {
                fn sel_registerName(name: *const libc::c_uchar) -> Sel;
                fn objc_getClass(class_name: *const libc::c_uchar) -> NsId;
            }

            #[cfg(target_arch = "aarch64")]
            extern "C" {
                fn objc_msgSend(obj: NsId, sel: Sel) -> NsId;
                #[cfg_attr(not(bootstrap), allow(clashing_extern_declarations))]
                #[link_name = "objc_msgSend"]
                fn objc_msgSend_ul(obj: NsId, sel: Sel, i: libc::c_ulong) -> NsId;
            }

            #[cfg(not(target_arch = "aarch64"))]
            extern "C" {
                fn objc_msgSend(obj: NsId, sel: Sel, ...) -> NsId;
                #[cfg_attr(not(bootstrap), allow(clashing_extern_declarations))]
                #[link_name = "objc_msgSend"]
                fn objc_msgSend_ul(obj: NsId, sel: Sel, ...) -> NsId;
            }

            type Sel = *const libc::c_void;
            type NsId = *const libc::c_void;

            let mut res = Vec::new();

            unsafe {
                let process_info_sel = sel_registerName("processInfo\0".as_ptr());
                let arguments_sel = sel_registerName("arguments\0".as_ptr());
                let utf8_sel = sel_registerName("UTF8String\0".as_ptr());
                let count_sel = sel_registerName("count\0".as_ptr());
                let object_at_sel = sel_registerName("objectAtIndex:\0".as_ptr());

                let klass = objc_getClass("NSProcessInfo\0".as_ptr());
                let info = objc_msgSend(klass, process_info_sel);
                let args = objc_msgSend(info, arguments_sel);

                let cnt: usize = mem::transmute(objc_msgSend(args, count_sel));
                for i in 0..cnt {
                    let tmp = objc_msgSend_ul(args, object_at_sel, i as libc::c_ulong);
                    let utf_c_str: *const libc::c_char = mem::transmute(objc_msgSend(tmp, utf8_sel));
                    let bytes = CStr::from_ptr(utf_c_str).to_bytes();
                    res.push(OsString::from(str::from_utf8(bytes).unwrap()))
                }
            }

            Args { iter: res.into_iter(), _dont_send_or_sync_me: PhantomData }
        }
    }