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Use ID numbers in lieu of allocations for DIR*

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This commit is contained in:
David Cook 2020-02-16 14:49:48 -06:00
parent 89cbe0ae56
commit dd00e5830f
1 changed files with 38 additions and 27 deletions
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65
src/shims/fs.rs
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@ -204,19 +204,39 @@ trait EvalContextExtPrivate<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, '
}
}
#[derive(Debug, Default)]
#[derive(Debug)]
pub struct DirHandler {
/// Directory iterators used to emulate libc "directory streams", as used in opendir, readdir,
/// and closedir.
///
/// When opendir is called, a new allocation is made, a directory iterator is created on the
/// host for the target directory, and an entry is stored in this hash map, indexed by a
/// pointer to the allocation which represents the directory stream. When readdir is called,
/// the directory stream pointer is used to look up the corresponding ReadDir iterator from
/// this HashMap, and information from the next directory entry is returned. When closedir is
/// called, the ReadDir iterator is removed from this HashMap, and the allocation that
/// represented the directory stream is deallocated.
streams: HashMap<Pointer<Tag>, ReadDir>,
/// When opendir is called, a directory iterator is created on the host for the target
/// directory, and an entry is stored in this hash map, indexed by an ID which represents
/// the directory stream. When readdir is called, the directory stream ID is used to look up
/// the corresponding ReadDir iterator from this HashMap, and information from the next
/// directory entry is returned. When closedir is called, the ReadDir iterator is removed from
/// this HashMap.
streams: HashMap<u64, ReadDir>,
/// ID number to be used by the next call to opendir
next_id: u64,
}
impl DirHandler {
fn insert_new(&mut self, read_dir: ReadDir) -> u64 {
let id = self.next_id;
self.next_id += 1;
self.streams.insert(id, read_dir).unwrap_none();
id
}
}
impl Default for DirHandler {
fn default() -> DirHandler {
DirHandler {
streams: HashMap::new(),
// Skip 0 as an ID, because it looks like a null pointer to libc
next_id: 1,
}
}
}
impl<'mir, 'tcx> EvalContextExt<'mir, 'tcx> for crate::MiriEvalContext<'mir, 'tcx> {}
@ -838,20 +858,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
match result {
Ok(dir_iter) => {
let size = 1;
let kind = MiriMemoryKind::Env;
let align = this.min_align(size, kind);
let dir_ptr = this.memory.allocate(Size::from_bytes(size), align, kind.into());
let prev = this
.machine
.dir_handler
.streams
.insert(dir_ptr, dir_iter);
if let Some(_) = prev {
panic!("The pointer allocated for opendir was already registered by a previous call to opendir")
} else {
Ok(Scalar::Ptr(dir_ptr))
}
let id = this.machine.dir_handler.insert_new(dir_iter);
// The libc API for opendir says that this method returns a pointer to an opaque
// structure, but we are returning an ID number. Thus, pass it as a scalar of
// pointer width.
Ok(Scalar::from_int(id, this.pointer_size()))
}
Err(e) => {
this.set_last_error_from_io_error(e)?;
@ -870,7 +882,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.check_no_isolation("readdir64_r")?;
let dirp = this.force_ptr(this.read_scalar(dirp_op)?.not_undef()?)?;
let dirp = this.read_scalar(dirp_op)?.to_machine_usize(this)?;
let entry_ptr = this.force_ptr(this.read_scalar(entry_op)?.not_undef()?)?;
let dirent64_layout = this.libc_ty_layout("dirent64")?;
@ -946,7 +958,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.check_no_isolation("readdir_r")?;
let dirp = this.force_ptr(this.read_scalar(dirp_op)?.not_undef()?)?;
let dirp = this.read_scalar(dirp_op)?.to_machine_usize(this)?;
let entry_ptr = this.force_ptr(this.read_scalar(entry_op)?.not_undef()?)?;
let dirent_layout = this.libc_ty_layout("dirent")?;
@ -1020,11 +1032,10 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
this.check_no_isolation("closedir")?;
let dirp = this.force_ptr(this.read_scalar(dirp_op)?.not_undef()?)?;
let dirp = this.read_scalar(dirp_op)?.to_machine_usize(this)?;
if let Some(dir_iter) = this.machine.dir_handler.streams.remove(&dirp) {
drop(dir_iter);
this.memory.deallocate(dirp, None, MiriMemoryKind::Env.into())?;
Ok(0)
} else {
this.handle_not_found()