refactor: minimize deserialize_newtype_struct

Also update example because we do not change fdt binary anymore. Signed-off-by: Woshiluo Luo <[email protected]>
rustsbi · Nov 18, 2024 · 6913268 · 6913268
1 parent c4574b4
commit 6913268
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Showing 5 changed files with 38 additions and 171 deletions.
diff --git a/examples/qemu-virt.rs b/examples/qemu-virt.rs
@@ -142,7 +142,7 @@ fn main() -> Result<(), Error> {
 
         // 解析过程中，设备树的内容被修改了。
         // 因此若要以其他方式再次访问设备树，先将这次解析的结果释放。
-        assert_ne!(slice, RAW_DEVICE_TREE);
+        //        assert_ne!(slice, RAW_DEVICE_TREE);
     }
     // 释放后，内存会恢复原状。
     assert_eq!(slice, RAW_DEVICE_TREE);

diff --git a/src/de_mut/cursor.rs b/src/de_mut/cursor.rs
@@ -246,16 +246,6 @@ impl PropCursor {
             ))
         }
     }
-
-    pub fn operate_on(&self, dtb: RefDtb<'_>, f: impl FnOnce(&mut [u8])) {
-        if let [_, len_data, _, data @ ..] = &mut dtb.borrow_mut().structure[self.0..] {
-            f(unsafe {
-                core::slice::from_raw_parts_mut(data.as_mut_ptr() as _, len_data.as_usize())
-            });
-        } else {
-            todo!()
-        }
-    }
 }
 
 #[derive(Debug)]

diff --git a/src/de_mut/data.rs b/src/de_mut/data.rs
@@ -239,37 +239,7 @@ impl<'de> de::Deserializer<'de> for &mut ValueDeserializer<'de> {
         if name == super::VALUE_DESERIALIZER_NAME {
             return visitor.visit_newtype_struct(self);
         }
-        match self.cursor {
-            ValueCursor::Prop(_, cursor) => match name {
-                "StrSeq" => {
-                    let inner = super::str_seq::Inner {
-                        dtb: self.dtb,
-                        cursor,
-                    };
-                    visitor.visit_borrowed_bytes(unsafe {
-                        core::slice::from_raw_parts(
-                            &inner as *const _ as *const u8,
-                            core::mem::size_of_val(&inner),
-                        )
-                    })
-                }
-                "Reg" => {
-                    let inner = super::reg::Inner {
-                        dtb: self.dtb,
-                        reg: self.reg,
-                        cursor,
-                    };
-                    visitor.visit_borrowed_bytes(unsafe {
-                        core::slice::from_raw_parts(
-                            &inner as *const _ as *const u8,
-                            core::mem::size_of_val(&inner),
-                        )
-                    })
-                }
-                _ => visitor.visit_newtype_struct(self),
-            },
-            ValueCursor::Body(_) => visitor.visit_newtype_struct(self),
-        }
+        unreachable!("unknown newtype struct");
     }
 
     fn deserialize_seq<V>(self, visitor: V) -> Result<V::Value, Self::Error>

diff --git a/src/de_mut/reg.rs b/src/de_mut/reg.rs
@@ -1,6 +1,6 @@
-use super::{PropCursor, RefDtb, StructureBlock, BLOCK_LEN};
-use core::{fmt::Debug, marker::PhantomData, mem::MaybeUninit, ops::Range};
-use serde::{de, Deserialize};
+use super::{PropCursor, RefDtb, StructureBlock, ValueCursor, BLOCK_LEN};
+use core::{fmt::Debug, ops::Range};
+use serde::Deserialize;
 
 /// 节点地址空间。
 pub struct Reg<'de>(Inner<'de>);
@@ -40,58 +40,24 @@ impl<'de> Deserialize<'de> for Reg<'_> {
     where
         D: serde::Deserializer<'de>,
     {
-        struct Visitor<'de, 'b> {
-            marker: PhantomData<Reg<'b>>,
-            lifetime: PhantomData<&'de ()>,
-        }
-        impl<'de, 'b> de::Visitor<'de> for Visitor<'de, 'b> {
-            type Value = Reg<'b>;
-
-            fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
-                write!(formatter, "struct Reg")
-            }
+        let value_deserialzer = super::ValueDeserializer::deserialize(deserializer)?;
 
-            fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                // 结构体转为内存切片，然后拷贝过来
-                if v.len() == core::mem::size_of::<Self::Value>() {
-                    Ok(Self::Value::from_raw_parts(v.as_ptr()))
-                } else {
-                    Err(E::invalid_length(
-                        v.len(),
-                        &"`Reg` is copied with wrong size.",
-                    ))
+        let inner = Inner {
+            dtb: value_deserialzer.dtb,
+            reg: value_deserialzer.reg,
+            cursor: match value_deserialzer.cursor {
+                ValueCursor::Prop(_, cursor) => cursor,
+                _ => {
+                    unreachable!("Reg Deserialize should only be called by prop cursor")
                 }
-            }
-        }
-
-        serde::Deserializer::deserialize_newtype_struct(
-            deserializer,
-            "Reg",
-            Visitor {
-                marker: PhantomData,
-                lifetime: PhantomData,
             },
-        )
+        };
+
+        Ok(Self(inner))
     }
 }
 
 impl Reg<'_> {
-    fn from_raw_parts(ptr: *const u8) -> Self {
-        // 直接从指针拷贝
-        unsafe {
-            let mut res = MaybeUninit::<Self>::uninit();
-            core::ptr::copy_nonoverlapping(
-                ptr,
-                res.as_mut_ptr() as *mut _,
-                core::mem::size_of::<Self>(),
-            );
-            res.assume_init()
-        }
-    }
-
     pub fn iter(&self) -> RegIter {
         RegIter {
             data: self.0.cursor.data_on(self.0.dtb),

diff --git a/src/de_mut/str_seq.rs b/src/de_mut/str_seq.rs
@@ -1,6 +1,6 @@
-use super::{PropCursor, RefDtb};
-use core::{fmt::Debug, marker::PhantomData, mem::MaybeUninit};
-use serde::{de, Deserialize};
+use super::{PropCursor, RefDtb, ValueCursor};
+use core::fmt::Debug;
+use serde::Deserialize;
 
 /// 一组 '\0' 分隔字符串的映射。
 ///
@@ -31,70 +31,23 @@ impl<'de> Deserialize<'de> for StrSeq<'_> {
     where
         D: serde::Deserializer<'de>,
     {
-        struct Visitor<'de, 'b> {
-            marker: PhantomData<StrSeq<'b>>,
-            lifetime: PhantomData<&'de ()>,
-        }
-        impl<'de, 'b> de::Visitor<'de> for Visitor<'de, 'b> {
-            type Value = StrSeq<'b>;
-
-            fn expecting(&self, formatter: &mut core::fmt::Formatter) -> core::fmt::Result {
-                write!(formatter, "struct StrSeq")
-            }
+        let value_deserialzer = super::ValueDeserializer::deserialize(deserializer)?;
 
-            fn visit_borrowed_bytes<E>(self, v: &'de [u8]) -> Result<Self::Value, E>
-            where
-                E: de::Error,
-            {
-                // 结构体转为内存切片，然后拷贝过来
-                if v.len() == core::mem::size_of::<Self::Value>() {
-                    Ok(Self::Value::from_raw_parts(v.as_ptr()))
-                } else {
-                    Err(E::invalid_length(
-                        v.len(),
-                        &"`StrSeq` is copied with wrong size.",
-                    ))
+        let inner = Inner {
+            dtb: value_deserialzer.dtb,
+            cursor: match value_deserialzer.cursor {
+                ValueCursor::Prop(_, cursor) => cursor,
+                _ => {
+                    unreachable!("Reg Deserialize should only be called by prop cursor")
                 }
-            }
-        }
-
-        serde::Deserializer::deserialize_newtype_struct(
-            deserializer,
-            "StrSeq",
-            Visitor {
-                marker: PhantomData,
-                lifetime: PhantomData,
             },
-        )
+        };
+
+        Ok(Self(inner))
     }
 }
 
 impl StrSeq<'_> {
-    fn from_raw_parts(ptr: *const u8) -> Self {
-        // 直接从指针拷贝
-        let res = unsafe {
-            let mut res = MaybeUninit::<Self>::uninit();
-            core::ptr::copy_nonoverlapping(
-                ptr,
-                res.as_mut_ptr() as *mut _,
-                core::mem::size_of::<Self>(),
-            );
-            res.assume_init()
-        };
-        // 初始化
-        res.0.cursor.operate_on(res.0.dtb, |data| {
-            let mut i = data.len() - 1;
-            for j in (0..data.len() - 1).rev() {
-                if data[j] == b'\0' {
-                    data[i] = (i - j - 1) as _;
-                    i = j;
-                }
-            }
-            data[i] = i as u8;
-        });
-        res
-    }
-
     /// 构造一个可访问每个字符串的迭代器。
     pub fn iter(&self) -> StrSeqIter {
         StrSeqIter {
@@ -125,27 +78,15 @@ impl<'de> Iterator for StrSeqIter<'de> {
         if self.data.is_empty() {
             None
         } else {
-            let len = *self.data.last().unwrap() as usize;
-            let (a, b) = self.data.split_at(self.data.len() - len - 1);
-            self.data = a;
-            Some(unsafe { core::str::from_utf8_unchecked(&b[..len]) })
+            let pos = self
+                .data
+                .iter()
+                .position(|&x| x == b'\0')
+                .unwrap_or(self.data.len());
+            let (a, b) = self.data.split_at(pos + 1);
+            self.data = b;
+            // Remove \0 at end
+            Some(unsafe { core::str::from_utf8_unchecked(&a[..a.len() - 1]) })
         }
     }
 }
-
-impl Drop for StrSeq<'_> {
-    fn drop(&mut self) {
-        self.0.cursor.operate_on(self.0.dtb, |data| {
-            let mut idx = data.len() - 1;
-            loop {
-                let len = data[idx] as usize;
-                data[idx] = 0;
-                if idx > len {
-                    idx -= len + 1;
-                } else {
-                    break;
-                }
-            }
-        })
-    }
-}