From 42a09339204915c15cf5a539418e05e5a74eb0bd Mon Sep 17 00:00:00 2001
From: Niklas Fiekas <niklas.fiekas@backscattering.de>
Date: Wed, 27 Mar 2024 20:18:35 +0100
Subject: [PATCH 1/2] relax uid restriction in fuzzer after #32

---
 fuzz/src/lib.rs | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/fuzz/src/lib.rs b/fuzz/src/lib.rs
index 80c98d3..0dae460 100644
--- a/fuzz/src/lib.rs
+++ b/fuzz/src/lib.rs
@@ -94,11 +94,16 @@ impl Arbitrary<'_> for Timestamp {
     }
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, Arbitrary)]
 struct Uid(u32);
 
-impl Arbitrary<'_> for Uid {
-    fn arbitrary(u: &mut Unstructured<'_>) -> arbitrary::Result<Self> {
-        u.int_in_range(0..=999_999).map(Uid) // TODO: Deal with entire range (#29)
+impl PartialEq for Uid {
+    fn eq(&self, other: &Uid) -> bool {
+        truncated_ascii(self.0.to_string(), 6) == truncated_ascii(other.0.to_string(), 6)
     }
 }
+
+fn truncated_ascii(mut ascii: String, width: usize) -> String {
+    ascii.truncate(width);
+    ascii
+}

From d265dd1b8b6bfeea8adc6f0c8cf93ec649dfb7e5 Mon Sep 17 00:00:00 2001
From: Niklas Fiekas <niklas.fiekas@backscattering.de>
Date: Wed, 27 Mar 2024 20:36:46 +0100
Subject: [PATCH 2/2] cap more field sizes and relax fuzzer

---
 fuzz/src/lib.rs | 28 ++++++++++++++--------------
 src/header.rs   | 21 +++++++++++++++------
 2 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/fuzz/src/lib.rs b/fuzz/src/lib.rs
index 0dae460..ee4733a 100644
--- a/fuzz/src/lib.rs
+++ b/fuzz/src/lib.rs
@@ -1,4 +1,5 @@
 use arbitrary::{Arbitrary, Unstructured};
+use std::cmp::min;
 
 #[derive(Clone, Default, Debug, Eq, PartialEq, Arbitrary)]
 pub struct Model {
@@ -76,21 +77,21 @@ impl Arbitrary<'_> for Identifier {
     }
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, Arbitrary)]
 struct Mode(u32);
 
-impl Arbitrary<'_> for Mode {
-    fn arbitrary(u: &mut Unstructured<'_>) -> arbitrary::Result<Self> {
-        u32::arbitrary(u).map(|v| Mode(v & 0o7777))
+impl PartialEq for Mode {
+    fn eq(&self, other: &Mode) -> bool {
+        self.0 & 0o7777_7777 == other.0 & 0o7777_7777
     }
 }
 
-#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+#[derive(Copy, Clone, Debug, Eq, Arbitrary)]
 struct Timestamp(u64);
 
-impl Arbitrary<'_> for Timestamp {
-    fn arbitrary(u: &mut Unstructured<'_>) -> arbitrary::Result<Self> {
-        u.int_in_range(0..=999_999_999_999).map(Timestamp) // TODO: Deal with entire range
+impl PartialEq for Timestamp {
+    fn eq(&self, other: &Timestamp) -> bool {
+        min(self.0, 999_999_999_999) == min(other.0, 999_999_999_999)
     }
 }
 
@@ -99,11 +100,10 @@ struct Uid(u32);
 
 impl PartialEq for Uid {
     fn eq(&self, other: &Uid) -> bool {
-        truncated_ascii(self.0.to_string(), 6) == truncated_ascii(other.0.to_string(), 6)
+        let mut left = self.0.to_string();
+        left.truncate(6);
+        let mut right = other.0.to_string();
+        right.truncate(6);
+        left == right
     }
 }
-
-fn truncated_ascii(mut ascii: String, width: usize) -> String {
-    ascii.truncate(width);
-    ascii
-}
diff --git a/src/header.rs b/src/header.rs
index 9d9d556..1d1cc46 100644
--- a/src/header.rs
+++ b/src/header.rs
@@ -1,3 +1,4 @@
+use std::cmp::min;
 use std::collections::HashMap;
 use std::fs::Metadata;
 use std::io::{self, Error, ErrorKind, Read, Result, Write};
@@ -244,10 +245,10 @@ impl Header {
                 writer,
                 "#1/{:<13}{:<12}{:<6.6}{:<6.6}{:<8o}{:<10}`",
                 padded_length,
-                self.mtime,
+                cap_mtime(self.mtime),
                 self.uid.to_string(),
                 self.gid.to_string(),
-                self.mode,
+                cap_mode(self.mode),
                 self.size + padded_length as u64
             )?;
             writer.write_all(&self.identifier)?;
@@ -258,10 +259,10 @@ impl Header {
             writeln!(
                 writer,
                 "{:<12}{:<6.6}{:<6.6}{:<8o}{:<10}`",
-                self.mtime,
+                cap_mtime(self.mtime),
                 self.uid.to_string(),
                 self.gid.to_string(),
-                self.mode,
+                cap_mode(self.mode),
                 self.size
             )?;
         }
@@ -287,16 +288,24 @@ impl Header {
         writeln!(
             writer,
             "{:<12}{:<6.6}{:<6.6}{:<8o}{:<10}`",
-            self.mtime,
+            cap_mtime(self.mtime),
             self.uid.to_string(),
             self.gid.to_string(),
-            self.mode,
+            cap_mode(self.mode),
             self.size
         )?;
         Ok(())
     }
 }
 
+fn cap_mtime(mtime: u64) -> u64 {
+    min(mtime, 999_999_999_999) // Closest representable timestamp
+}
+
+fn cap_mode(mode: u32) -> u32 {
+    mode & 0o7777_7777 // Preserve as many bits as possible
+}
+
 fn parse_number(field_name: &str, bytes: &[u8], radix: u32) -> Result<u64> {
     if let Ok(string) = str::from_utf8(bytes) {
         if let Ok(value) = u64::from_str_radix(string.trim_end(), radix) {