test: improve greedy fuzzing

bluurryy · Sep 3, 2024 · 9680036 · 9680036
1 parent 9b8ff03
commit 9680036
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Showing 6 changed files with 90 additions and 8 deletions.
diff --git a/crates/fuzzing-support/src/bump_greedy_down.rs b/crates/fuzzing-support/src/bump_greedy_down.rs
@@ -1,10 +1,10 @@
 use arbitrary::Arbitrary;
 
-use crate::{from_bump_scope, FuzzBumpProps};
+use crate::{from_bump_scope, FuzzBumpGreedyProps};
 
 #[derive(Debug, Arbitrary)]
 pub struct Fuzz {
-    props: FuzzBumpProps,
+    props: FuzzBumpGreedyProps,
 }
 
 impl Fuzz {

diff --git a/crates/fuzzing-support/src/bump_greedy_up.rs b/crates/fuzzing-support/src/bump_greedy_up.rs
@@ -1,10 +1,10 @@
 use arbitrary::Arbitrary;
 
-use crate::{from_bump_scope, FuzzBumpProps};
+use crate::{from_bump_scope, FuzzBumpGreedyProps};
 
 #[derive(Debug, Arbitrary)]
 pub struct Fuzz {
-    props: FuzzBumpProps,
+    props: FuzzBumpGreedyProps,
 }
 
 impl Fuzz {

diff --git a/crates/fuzzing-support/src/from_bump_scope/bumping.rs b/crates/fuzzing-support/src/from_bump_scope/bumping.rs
@@ -230,9 +230,10 @@ pub(crate) fn bump_greedy_up(
         min_align,
         align_is_const,
         size_is_const: _,
-        size_is_multiple_of_align: _,
+        size_is_multiple_of_align,
     }: BumpProps,
 ) -> Option<Range<usize>> {
+    debug_assert!(size_is_multiple_of_align);
     debug_assert!(start <= end);
     debug_assert!(end % MIN_CHUNK_ALIGN == 0);
 
@@ -281,9 +282,10 @@ pub(crate) fn bump_greedy_down(
         min_align,
         align_is_const,
         size_is_const: _,
-        size_is_multiple_of_align: _,
+        size_is_multiple_of_align,
     }: BumpProps,
 ) -> Option<Range<usize>> {
+    debug_assert!(size_is_multiple_of_align);
     debug_assert!(start <= end);
 
     if align_is_const && layout.align() <= min_align {

diff --git a/crates/fuzzing-support/src/lib.rs b/crates/fuzzing-support/src/lib.rs
@@ -235,6 +235,83 @@ impl FuzzBumpProps {
     }
 }
 
+#[derive(Debug, Clone, Copy)]
+pub(crate) struct FuzzBumpGreedyProps {
+    pub(crate) start: usize,
+    pub(crate) end: usize,
+    pub(crate) layout: Layout,
+    pub(crate) min_align: usize,
+    pub(crate) align_is_const: bool,
+}
+
+impl<'a> Arbitrary<'a> for FuzzBumpGreedyProps {
+    fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
+        let (mut start, mut end) = u.arbitrary()?;
+
+        if end < start {
+            swap(&mut start, &mut end);
+        }
+
+        start = align(start);
+        end = align(end);
+
+        let layout = {
+            let size: usize = u.arbitrary()?;
+            let align_pow2 = u.int_in_range(0..=10)?;
+            let align = 1 << align_pow2;
+            Layout::from_size_align(
+                size.checked_mul(align).ok_or_else(|| arbitrary::Error::IncorrectFormat)?,
+                align,
+            )
+            .map_err(|_| arbitrary::Error::IncorrectFormat)?
+        };
+
+        let min_align = *u.choose(&[1, 2, 4, 8, 16])?;
+
+        Ok(Self {
+            start,
+            end,
+            layout,
+            min_align,
+            align_is_const: u.arbitrary()?,
+        })
+    }
+}
+
+impl FuzzBumpGreedyProps {
+    fn for_up(mut self) -> Self {
+        self.start = down_align(self.start, self.min_align);
+        self
+    }
+
+    fn for_down(mut self) -> Self {
+        self.end = down_align(self.end, self.min_align);
+        self
+    }
+}
+
+impl FuzzBumpGreedyProps {
+    fn to(self) -> from_bump_scope::bumping::BumpProps {
+        let Self {
+            start,
+            end,
+            layout,
+            min_align,
+            align_is_const,
+        } = self;
+
+        from_bump_scope::bumping::BumpProps {
+            start,
+            end,
+            layout,
+            min_align,
+            align_is_const,
+            size_is_const: false,
+            size_is_multiple_of_align: layout.size() % layout.align() == 0,
+        }
+    }
+}
+
 #[inline(always)]
 fn down_align(addr: usize, align: usize) -> usize {
     debug_assert!(align.is_power_of_two());

diff --git a/src/bumping.rs b/src/bumping.rs
@@ -230,9 +230,10 @@ pub(crate) fn bump_greedy_up(
         min_align,
         align_is_const,
         size_is_const: _,
-        size_is_multiple_of_align: _,
+        size_is_multiple_of_align,
     }: BumpProps,
 ) -> Option<Range<usize>> {
+    debug_assert!(size_is_multiple_of_align);
     debug_assert!(start <= end);
     debug_assert!(end % MIN_CHUNK_ALIGN == 0);
 
@@ -281,9 +282,10 @@ pub(crate) fn bump_greedy_down(
         min_align,
         align_is_const,
         size_is_const: _,
-        size_is_multiple_of_align: _,
+        size_is_multiple_of_align,
     }: BumpProps,
 ) -> Option<Range<usize>> {
+    debug_assert!(size_is_multiple_of_align);
     debug_assert!(start <= end);
 
     if align_is_const && layout.align() <= min_align {

diff --git a/src/chunk_raw.rs b/src/chunk_raw.rs
@@ -254,6 +254,7 @@ impl<const UP: bool, A> RawChunk<UP, A> {
     ///
     /// - `range.start` and `range.end` are aligned.
     /// - `layout.size` must not be zero
+    /// - `layout.size` must be a multiple of `layout.align`
     ///
     /// [`MutBumpVec`]: crate::MutBumpVec
     /// [`into_slice`]: crate::MutBumpVec::into_slice