Auto merge of #1275 - JOE1994:move_string_helpers, r=RalfJung

move OsStr helpers to a separate file

Moved OsStr read/write functions from `src/helpers.rs` to `src/shims/os_str.rs`, in order to keep `src/helpers.rs` from bloating too much.

Author: bors

src/helpers.rs

@@ -1,13 +1,5 @@
-use std::ffi::{OsStr, OsString};
-use std::path::{Path, PathBuf};
-use std::{iter, mem};
 use std::convert::TryFrom;
-use std::borrow::Cow;
-
-#[cfg(unix)]
-use std::os::unix::ffi::{OsStrExt, OsStringExt};
-#[cfg(windows)]
-use std::os::windows::ffi::{OsStrExt, OsStringExt};
+use std::mem;
 
 use rustc::mir;
 use rustc::ty::{
@@ -463,237 +455,6 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
         }
     }
-
-    /// Helper function to read an OsString from a null-terminated sequence of bytes, which is what
-    /// the Unix APIs usually handle.
-    fn read_os_str_from_c_str<'a>(&'a self, scalar: Scalar<Tag>) -> InterpResult<'tcx, &'a OsStr>
-    where
-        'tcx: 'a,
-        'mir: 'a,
-    {
-        #[cfg(unix)]
-        fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
-            Ok(OsStr::from_bytes(bytes))
-        }
-        #[cfg(not(unix))]
-        fn bytes_to_os_str<'tcx, 'a>(bytes: &'a [u8]) -> InterpResult<'tcx, &'a OsStr> {
-            let s = std::str::from_utf8(bytes)
-                .map_err(|_| err_unsup_format!("{:?} is not a valid utf-8 string", bytes))?;
-            Ok(OsStr::new(s))
-        }
-
-        let this = self.eval_context_ref();
-        let bytes = this.memory.read_c_str(scalar)?;
-        bytes_to_os_str(bytes)
-    }
-
-    /// Helper function to read an OsString from a 0x0000-terminated sequence of u16,
-    /// which is what the Windows APIs usually handle.
-    fn read_os_str_from_wide_str<'a>(&'a self, scalar: Scalar<Tag>) -> InterpResult<'tcx, OsString>
-    where
-        'tcx: 'a,
-        'mir: 'a,
-    {
-        #[cfg(windows)]
-        pub fn u16vec_to_osstring<'tcx, 'a>(u16_vec: Vec<u16>) -> InterpResult<'tcx, OsString> {
-            Ok(OsString::from_wide(&u16_vec[..]))
-        }
-        #[cfg(not(windows))]
-        pub fn u16vec_to_osstring<'tcx, 'a>(u16_vec: Vec<u16>) -> InterpResult<'tcx, OsString> {
-            let s = String::from_utf16(&u16_vec[..])
-                .map_err(|_| err_unsup_format!("{:?} is not a valid utf-16 string", u16_vec))?;
-            Ok(s.into())
-        }
-
-        let u16_vec = self.eval_context_ref().memory.read_wide_str(scalar)?;
-        u16vec_to_osstring(u16_vec)
-    }
-
-    /// Helper function to write an OsStr as a null-terminated sequence of bytes, which is what
-    /// the Unix APIs usually handle. This function returns `Ok((false, length))` without trying
-    /// to write if `size` is not large enough to fit the contents of `os_string` plus a null
-    /// terminator. It returns `Ok((true, length))` if the writing process was successful. The
-    /// string length returned does not include the null terminator.
-    fn write_os_str_to_c_str(
-        &mut self,
-        os_str: &OsStr,
-        scalar: Scalar<Tag>,
-        size: u64,
-    ) -> InterpResult<'tcx, (bool, u64)> {
-        #[cfg(unix)]
-        fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
-            Ok(os_str.as_bytes())
-        }
-        #[cfg(not(unix))]
-        fn os_str_to_bytes<'tcx, 'a>(os_str: &'a OsStr) -> InterpResult<'tcx, &'a [u8]> {
-            // On non-unix platforms the best we can do to transform bytes from/to OS strings is to do the
-            // intermediate transformation into strings. Which invalidates non-utf8 paths that are actually
-            // valid.
-            os_str
-                .to_str()
-                .map(|s| s.as_bytes())
-                .ok_or_else(|| err_unsup_format!("{:?} is not a valid utf-8 string", os_str).into())
-        }
-
-        let bytes = os_str_to_bytes(os_str)?;
-        // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required null
-        // terminator to memory using the `ptr` pointer would cause an out-of-bounds access.
-        let string_length = u64::try_from(bytes.len()).unwrap();
-        if size <= string_length {
-            return Ok((false, string_length));
-        }
-        self.eval_context_mut()
-            .memory
-            .write_bytes(scalar, bytes.iter().copied().chain(iter::once(0u8)))?;
-        Ok((true, string_length))
-    }
-
-    /// Helper function to write an OsStr as a 0x0000-terminated u16-sequence, which is what
-    /// the Windows APIs usually handle. This function returns `Ok((false, length))` without trying
-    /// to write if `size` is not large enough to fit the contents of `os_string` plus a null
-    /// terminator. It returns `Ok((true, length))` if the writing process was successful. The
-    /// string length returned does not include the null terminator.
-    fn write_os_str_to_wide_str(
-        &mut self,
-        os_str: &OsStr,
-        scalar: Scalar<Tag>,
-        size: u64,
-    ) -> InterpResult<'tcx, (bool, u64)> {
-        #[cfg(windows)]
-        fn os_str_to_u16vec<'tcx>(os_str: &OsStr) -> InterpResult<'tcx, Vec<u16>> {
-            Ok(os_str.encode_wide().collect())
-        }
-        #[cfg(not(windows))]
-        fn os_str_to_u16vec<'tcx>(os_str: &OsStr) -> InterpResult<'tcx, Vec<u16>> {
-            // On non-Windows platforms the best we can do to transform Vec<u16> from/to OS strings is to do the
-            // intermediate transformation into strings. Which invalidates non-utf8 paths that are actually
-            // valid.
-            os_str
-                .to_str()
-                .map(|s| s.encode_utf16().collect())
-                .ok_or_else(|| err_unsup_format!("{:?} is not a valid utf-8 string", os_str).into())
-        }
-
-        let u16_vec = os_str_to_u16vec(os_str)?;
-        // If `size` is smaller or equal than `bytes.len()`, writing `bytes` plus the required
-        // 0x0000 terminator to memory would cause an out-of-bounds access.
-        let string_length = u64::try_from(u16_vec.len()).unwrap();
-        if size <= string_length {
-            return Ok((false, string_length));
-        }
-
-        // Store the UTF-16 string.
-        self.eval_context_mut()
-            .memory
-            .write_u16s(scalar, u16_vec.into_iter().chain(iter::once(0x0000)))?;
-        Ok((true, string_length))
-    }
-
-    /// Allocate enough memory to store the given `OsStr` as a null-terminated sequence of bytes.
-    fn alloc_os_str_as_c_str(
-        &mut self,
-        os_str: &OsStr,
-        memkind: MemoryKind<MiriMemoryKind>,
-    ) -> Pointer<Tag> {
-        let size = u64::try_from(os_str.len()).unwrap().checked_add(1).unwrap(); // Make space for `0` terminator.
-        let this = self.eval_context_mut();
-
-        let arg_type = this.tcx.mk_array(this.tcx.types.u8, size);
-        let arg_place = this.allocate(this.layout_of(arg_type).unwrap(), memkind);
-        assert!(self.write_os_str_to_c_str(os_str, arg_place.ptr, size).unwrap().0);
-        arg_place.ptr.assert_ptr()
-    }
-
-    /// Allocate enough memory to store the given `OsStr` as a null-terminated sequence of `u16`.
-    fn alloc_os_str_as_wide_str(
-        &mut self,
-        os_str: &OsStr,
-        memkind: MemoryKind<MiriMemoryKind>,
-    ) -> Pointer<Tag> {
-        let size = u64::try_from(os_str.len()).unwrap().checked_add(1).unwrap(); // Make space for `0x0000` terminator.
-        let this = self.eval_context_mut();
-
-        let arg_type = this.tcx.mk_array(this.tcx.types.u16, size);
-        let arg_place = this.allocate(this.layout_of(arg_type).unwrap(), memkind);
-        assert!(self.write_os_str_to_wide_str(os_str, arg_place.ptr, size).unwrap().0);
-        arg_place.ptr.assert_ptr()
-    }
-
-    /// Read a null-terminated sequence of bytes, and perform path separator conversion if needed.
-    fn read_path_from_c_str<'a>(&'a self, scalar: Scalar<Tag>) -> InterpResult<'tcx, Cow<'a, Path>>
-    where
-        'tcx: 'a,
-        'mir: 'a,
-    {
-        let this = self.eval_context_ref();
-        let os_str = this.read_os_str_from_c_str(scalar)?;
-
-        #[cfg(windows)]
-        return Ok(if this.tcx.sess.target.target.target_os == "windows" {
-            // Windows-on-Windows, all fine.
-            Cow::Borrowed(Path::new(os_str))
-        } else {
-            // Unix target, Windows host. Need to convert target '/' to host '\'.
-            let converted = os_str
-                .encode_wide()
-                .map(|wchar| if wchar == '/' as u16 { '\\' as u16 } else { wchar })
-                .collect::<Vec<_>>();
-            Cow::Owned(PathBuf::from(OsString::from_wide(&converted)))
-        });
-        #[cfg(unix)]
-        return Ok(if this.tcx.sess.target.target.target_os == "windows" {
-            // Windows target, Unix host. Need to convert target '\' to host '/'.
-            let converted = os_str
-                .as_bytes()
-                .iter()
-                .map(|&wchar| if wchar == '/' as u8 { '\\' as u8 } else { wchar })
-                .collect::<Vec<_>>();
-            Cow::Owned(PathBuf::from(OsString::from_vec(converted)))
-        } else {
-            // Unix-on-Unix, all is fine.
-            Cow::Borrowed(Path::new(os_str))
-        });
-    }
-
-    /// Write a Path to the machine memory, adjusting path separators if needed.
-    fn write_path_to_c_str(
-        &mut self,
-        path: &Path,
-        scalar: Scalar<Tag>,
-        size: u64,
-    ) -> InterpResult<'tcx, (bool, u64)> {
-        let this = self.eval_context_mut();
-
-        #[cfg(windows)]
-        let os_str = if this.tcx.sess.target.target.target_os == "windows" {
-            // Windows-on-Windows, all fine.
-            Cow::Borrowed(path.as_os_str())
-        } else {
-            // Unix target, Windows host. Need to convert host '\\' to target '/'.
-            let converted = path
-                .as_os_str()
-                .encode_wide()
-                .map(|wchar| if wchar == '\\' as u16 { '/' as u16 } else { wchar })
-                .collect::<Vec<_>>();
-            Cow::Owned(OsString::from_wide(&converted))
-        };
-        #[cfg(unix)]
-        let os_str = if this.tcx.sess.target.target.target_os == "windows" {
-            // Windows target, Unix host. Need to convert host '/' to target '\'.
-            let converted = path
-                .as_os_str()
-                .as_bytes()
-                .iter()
-                .map(|&wchar| if wchar == '/' as u8 { '\\' as u8 } else { wchar })
-                .collect::<Vec<_>>();
-            Cow::Owned(OsString::from_vec(converted))
-        } else {
-            // Unix-on-Unix, all is fine.
-            Cow::Borrowed(path.as_os_str())
-        };
-
-        this.write_os_str_to_c_str(&os_str, scalar, size)
-    }
 }
 
 pub fn immty_from_int_checked<'tcx>(

src/lib.rs

@@ -41,6 +41,7 @@ pub use crate::shims::env::{EnvVars, EvalContextExt as EnvEvalContextExt};
 pub use crate::shims::foreign_items::EvalContextExt as ForeignItemsEvalContextExt;
 pub use crate::shims::fs::{DirHandler, EvalContextExt as FileEvalContextExt, FileHandler};
 pub use crate::shims::intrinsics::EvalContextExt as IntrinsicsEvalContextExt;
+pub use crate::shims::os_str::EvalContextExt as OsStrEvalContextExt;
 pub use crate::shims::panic::{CatchUnwindData, EvalContextExt as PanicEvalContextExt};
 pub use crate::shims::time::EvalContextExt as TimeEvalContextExt;
 pub use crate::shims::tls::{EvalContextExt as TlsEvalContextExt, TlsData};

src/shims/mod.rs

@@ -3,6 +3,7 @@ pub mod env;
 pub mod foreign_items;
 pub mod fs;
 pub mod intrinsics;
+pub mod os_str;
 pub mod panic;
 pub mod time;
 pub mod tls;