Vendor things

third-party/vendor/backtrace/src/symbolize/gimli/mmap_windows.rs

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+use super::super::super::windows::*;
+use super::mystd::fs::File;
+use super::mystd::os::windows::prelude::*;
+use core::ops::Deref;
+use core::ptr;
+use core::slice;
+
+pub struct Mmap {
+    // keep the file alive to prevent it from being deleted which would cause
+    // us to read bad data.
+    _file: File,
+    ptr: *mut c_void,
+    len: usize,
+}
+
+impl Mmap {
+    pub unsafe fn map(file: &File, len: usize) -> Option<Mmap> {
+        let file = file.try_clone().ok()?;
+        let mapping = CreateFileMappingA(
+            file.as_raw_handle() as *mut _,
+            ptr::null_mut(),
+            PAGE_READONLY,
+            0,
+            0,
+            ptr::null(),
+        );
+        if mapping.is_null() {
+            return None;
+        }
+        let ptr = MapViewOfFile(mapping, FILE_MAP_READ, 0, 0, len);
+        CloseHandle(mapping);
+        if ptr.is_null() {
+            return None;
+        }
+        Some(Mmap {
+            _file: file,
+            ptr,
+            len,
+        })
+    }
+}
+impl Deref for Mmap {
+    type Target = [u8];
+
+    fn deref(&self) -> &[u8] {
+        unsafe { slice::from_raw_parts(self.ptr as *const u8, self.len) }
+    }
+}
+
+impl Drop for Mmap {
+    fn drop(&mut self) {
+        unsafe {
+            let r = UnmapViewOfFile(self.ptr);
+            debug_assert!(r != 0);
+        }
+    }
+}