basic index file checksum verification (#293)

Author: Byron

Diff for: git-index/Cargo.toml

@@ -30,7 +30,7 @@ internal-testing-to-avoid-being-run-by-cargo-test-all = []
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-git-features = { version = "^0.19.1", path = "../git-features", features = ["rustsha1"] }
+git-features = { version = "^0.19.1", path = "../git-features", features = ["rustsha1", "progress"] }
 git-hash = { version = "^0.9.1", path = "../git-hash" }
 git-bitmap = { version = "^0.0.1", path = "../git-bitmap" }
 

Diff for: git-index/src/access.rs

@@ -0,0 +1,26 @@
+use crate::{extension, Entry, State, Version};
+
+impl State {
+    pub fn version(&self) -> Version {
+        self.version
+    }
+
+    pub fn entries(&self) -> &[Entry] {
+        &self.entries
+    }
+    pub fn tree(&self) -> Option<&extension::Tree> {
+        self.tree.as_ref()
+    }
+    pub fn link(&self) -> Option<&extension::Link> {
+        self.link.as_ref()
+    }
+    pub fn resolve_undo(&self) -> Option<&extension::resolve_undo::Paths> {
+        self.resolve_undo.as_ref()
+    }
+    pub fn untracked(&self) -> Option<&extension::UntrackedCache> {
+        self.untracked.as_ref()
+    }
+    pub fn fs_monitor(&self) -> Option<&extension::FsMonitor> {
+        self.fs_monitor.as_ref()
+    }
+}

Diff for: git-index/src/file.rs

@@ -64,3 +64,45 @@ pub mod init {
         }
     }
 }
+
+mod verify {
+    use crate::File;
+    use std::sync::atomic::AtomicBool;
+
+    pub mod error {
+        use quick_error::quick_error;
+
+        quick_error! {
+            #[derive(Debug)]
+            pub enum Error {
+                Io(err: std::io::Error) {
+                    display("Could not read index file to generate hash")
+                    source(err)
+                    from()
+                }
+                ChecksumMismatch { actual: git_hash::ObjectId, expected: git_hash::ObjectId }{
+                    display("Index checksum should have been {}, but was {}", expected, actual)
+                }
+            }
+        }
+    }
+    pub use error::Error;
+
+    impl File {
+        pub fn verify_integrity(&self) -> Result<(), Error> {
+            let num_bytes_to_hash = self.path.metadata()?.len() - self.checksum.as_bytes().len() as u64;
+            let should_interrupt = AtomicBool::new(false);
+            let actual = git_features::hash::bytes_of_file(
+                &self.path,
+                num_bytes_to_hash as usize,
+                self.checksum.kind(),
+                &mut git_features::progress::Discard,
+                &should_interrupt,
+            )?;
+            (actual == self.checksum).then(|| ()).ok_or(Error::ChecksumMismatch {
+                actual,
+                expected: self.checksum,
+            })
+        }
+    }
+}

Diff for: git-index/src/lib.rs

@@ -11,34 +11,7 @@ pub mod extension;
 
 pub mod entry;
 
-mod access {
-    use crate::{extension, Entry, State, Version};
-
-    impl State {
-        pub fn version(&self) -> Version {
-            self.version
-        }
-
-        pub fn entries(&self) -> &[Entry] {
-            &self.entries
-        }
-        pub fn tree(&self) -> Option<&extension::Tree> {
-            self.tree.as_ref()
-        }
-        pub fn link(&self) -> Option<&extension::Link> {
-            self.link.as_ref()
-        }
-        pub fn resolve_undo(&self) -> Option<&extension::resolve_undo::Paths> {
-            self.resolve_undo.as_ref()
-        }
-        pub fn untracked(&self) -> Option<&extension::UntrackedCache> {
-            self.untracked.as_ref()
-        }
-        pub fn fs_monitor(&self) -> Option<&extension::FsMonitor> {
-            self.fs_monitor.as_ref()
-        }
-    }
-}
+mod access;
 
 pub mod decode;
 

Diff for: git-index/tests/index/file/mod.rs

@@ -7,13 +7,19 @@ mod init {
 
     fn loose_file(name: &str) -> git_index::File {
         let path = git_testtools::fixture_path(Path::new("loose_index").join(name).with_extension("git-index"));
-        git_index::File::at(path, git_index::decode::Options::default()).unwrap()
+        let file = git_index::File::at(path, git_index::decode::Options::default()).unwrap();
+        file.verify_integrity().unwrap();
+        file
     }
     fn file(name: &str) -> git_index::File {
-        git_index::File::at(crate::fixture_path(name), git_index::decode::Options::default()).unwrap()
+        let file = git_index::File::at(crate::fixture_path(name), git_index::decode::Options::default()).unwrap();
+        file.verify_integrity().unwrap();
+        file
     }
     fn file_opt(name: &str, opts: git_index::decode::Options) -> git_index::File {
-        git_index::File::at(crate::fixture_path(name), opts).unwrap()
+        let file = git_index::File::at(crate::fixture_path(name), opts).unwrap();
+        file.verify_integrity().unwrap();
+        file
     }
 
     #[test]