prepare full 'verify' implementation

git-odb/src/pack/data/decode.rs

@@ -363,6 +363,10 @@ impl File {
         // FIXME(Performance) If delta-chains are uneven, we know we will have to copy bytes over here
         // Instead we could use a different start buffer, to naturally end up with the result in the
         // right one.
+        // However, this is a bit more complicated than just that - you have to deal with the base
+        // object, which should also be placed in the second buffer right away. You don't have that
+        // control/knowledge for out-of-pack bases, so this is a special case to deal with, too.
+        // Maybe these invariants can be represented in the type system though.
         if chain.len() % 2 == 1 {
             // this seems inverted, but remember: we swapped the buffers on the last iteration
             target_buf[..last_result_size].copy_from_slice(&source_buf[..last_result_size]);

gitoxide-core/src/pack/explode.rs

@@ -2,11 +2,7 @@ use anyhow::{anyhow, Result};
 use git_features::progress::{self, Progress};
 use git_object::{owned, HashKind};
 use git_odb::{loose, pack, Write};
-use std::{
-    fs,
-    io::{self, Read},
-    path::{Path, PathBuf},
-};
+use std::{fs, io::Read, path::Path};
 
 #[derive(PartialEq, Debug)]
 pub enum SafetyCheck {
@@ -79,8 +75,11 @@ quick_error! {
         ObjectEncodeMismatch(kind: git_object::Kind, actual: owned::Id, expected: owned::Id) {
             display("{} object {} wasn't re-encoded without change - new hash is {}", kind, expected, actual)
         }
-        RemoveFile(err: io::Error, index: PathBuf, data: PathBuf) {
-            display("Failed to delete pack index file at '{} or data file at '{}'", index.display(), data.display())
+        WrittenFileMissing(id: owned::Id) {
+            display("The recently written file for loose object {} could not be found", id)
+        }
+        WrittenFileCorrupt(err: loose::db::locate::Error, id: owned::Id) {
+            display("The recently written file for loose object {} cold not be read", id)
             source(err)
         }
     }
@@ -124,10 +123,12 @@ impl OutputWriter {
     }
 }
 
+#[derive(Default)]
 pub struct Context {
     pub thread_limit: Option<usize>,
     pub delete_pack: bool,
     pub sink_compress: bool,
+    pub verify: bool,
 }
 
 pub fn pack_or_pack_index<P>(
@@ -139,6 +140,7 @@ pub fn pack_or_pack_index<P>(
         thread_limit,
         delete_pack,
         sink_compress,
+        verify,
     }: Context,
 ) -> Result<()>
 where
@@ -183,22 +185,34 @@ where
         {
             let object_path = object_path.map(|p| p.as_ref().to_owned());
             move || {
-            let out = OutputWriter::new(object_path.clone(), sink_compress);
-            move |object_kind, buf, index_entry, _entry_stats, progress| {
-                let written_id = out
-                    .write_buf(object_kind, buf, HashKind::Sha1)
-                    .map_err(|err| Error::Write(Box::new(err) as Box<dyn std::error::Error + Send + Sync>, object_kind, index_entry.oid))
-                    .map_err(|err| Box::new(err) as Box<dyn std::error::Error + Send + Sync>)?;
-                if written_id != index_entry.oid {
-                   if let git_object::Kind::Tree = object_kind {
-                       progress.info(format!("The tree in pack named {} was written as {} due to modes 100664 and 100640 rewritten as 100644.", index_entry.oid, written_id));
-                   } else {
-                       return Err(Box::new(Error::ObjectEncodeMismatch(object_kind, index_entry.oid, written_id)))
-                   }
+                let out = OutputWriter::new(object_path.clone(), sink_compress);
+                let object_verifier = if verify {
+                    object_path.as_ref().map(|p| loose::Db::at(p))
+                } else {
+                    None
+                };
+                move |object_kind, buf, index_entry, _entry_stats, progress| {
+                    let written_id = out
+                        .write_buf(object_kind, buf, HashKind::Sha1)
+                        .map_err(|err| Error::Write(Box::new(err) as Box<dyn std::error::Error + Send + Sync>, object_kind, index_entry.oid))
+                        .map_err(|err| Box::new(err) as Box<dyn std::error::Error + Send + Sync>)?;
+                    if written_id != index_entry.oid {
+                       if let git_object::Kind::Tree = object_kind {
+                           progress.info(format!("The tree in pack named {} was written as {} due to modes 100664 and 100640 rewritten as 100644.", index_entry.oid, written_id));
+                       } else {
+                           return Err(Box::new(Error::ObjectEncodeMismatch(object_kind, index_entry.oid, written_id)))
+                       }
+                    }
+                    if let Some(verifier) = object_verifier.as_ref() {
+                        let obj = verifier.locate(written_id.to_borrowed())
+                                            .ok_or_else(|| Error::WrittenFileMissing(written_id))?
+                                            .map_err(|err| Error::WrittenFileCorrupt(err, written_id))?;
+                        // obj.checksum_matches(written_id);
+                    }
+                    Ok(())
                 }
-                Ok(())
             }
-        }},
+        },
         pack::cache::DecodeEntryLRU::default,
     ).map(|(_,_,c)|progress::DoOrDiscard::from(c)).with_context(|| "Failed to explode the entire pack - some loose objects may have been created nonetheless")?;
 
@@ -208,7 +222,13 @@ where
     if delete_pack {
         fs::remove_file(&index_path)
             .and_then(|_| fs::remove_file(&data_path))
-            .map_err(|err| Error::RemoveFile(err, index_path.clone(), data_path.clone()))?;
+            .with_context(|| {
+                format!(
+                    "Failed to delete pack index file at '{} or data file at '{}'",
+                    index_path.display(),
+                    data_path.display()
+                )
+            })?;
         progress.info(format!(
             "Removed '{}' and '{}'",
             index_path.display(),

src/plumbing/lean.rs

@@ -34,6 +34,12 @@ mod options {
     #[derive(FromArgs, PartialEq, Debug)]
     #[argh(subcommand, name = "pack-explode")]
     pub struct PackExplode {
+        #[argh(switch)]
+        /// read written objects back and assert they match their source. Fail the operation otherwise.
+        ///
+        /// Only relevant if an object directory is set.
+        pub verify: bool,
+
         /// delete the pack and index file after the operation is successful
         #[argh(switch)]
         pub delete_pack: bool,
@@ -147,6 +153,7 @@ pub fn main() -> Result<()> {
             sink_compress,
             object_path,
             verbose,
+            verify,
             check,
             delete_pack,
         }) => {
@@ -160,6 +167,7 @@ pub fn main() -> Result<()> {
                     thread_limit,
                     delete_pack,
                     sink_compress,
+                    verify,
                 },
             )
         }

src/plumbing/pretty.rs

@@ -30,7 +30,13 @@ mod options {
         /// Verify the integrity of a pack or index file
         #[structopt(setting = AppSettings::ColoredHelp)]
         PackExplode {
-            /// Delete the pack and index file after the operation is successful
+            #[structopt(long, requires("object_path"))]
+            /// Read written objects back and assert they match their source. Fail the operation otherwise.
+            ///
+            /// Only relevant if an object directory is set.
+            verify: bool,
+
+            /// delete the pack and index file after the operation is successful
             #[structopt(long)]
             delete_pack: bool,
 
@@ -48,7 +54,7 @@ mod options {
             /// This helps to determine overhead related to compression. If unset, the sink will
             /// only create hashes from bytes, which is usually limited by the speed at which input
             /// can be obtained.
-            #[structopt(long)]
+            #[structopt(long, conflicts_with("object_path"))]
             sink_compress: bool,
 
             /// Display verbose messages and progress information
@@ -236,6 +242,7 @@ pub fn main() -> Result<()> {
             delete_pack,
             pack_path,
             object_path,
+            verify,
         } => prepare_and_run(
             "pack-explode",
             verbose,
@@ -251,6 +258,7 @@ pub fn main() -> Result<()> {
                         thread_limit,
                         delete_pack,
                         sink_compress,
+                        verify,
                     },
                 )
             },

tasks.md

@@ -40,7 +40,7 @@
         * [x] to disk
      * [x] progress
      * [x] option to compress sink input too
-     * [ ] unrelated: see if delta-decode buffer optimization can work easily
+     * [x] unrelated: see if delta-decode buffer optimization can work easily
      * [ ] --verify
      * [ ] statistics
 

tests/stateless-journey.sh

@@ -72,7 +72,7 @@ title "CLI ${kind}"
           (with "and all safety checks"
             it "does not explode the file at all" && {
               WITH_SNAPSHOT="$snapshot/plumbing-broken-pack-explode-delete-pack-to-sink-failure" \
-              expect_run $WITH_FAILURE "$exe_plumbing" pack-explode --check all --delete-pack "${PACK_FILE}.pack"
+              expect_run $WITH_FAILURE "$exe_plumbing" pack-explode --sink-compress --check all --delete-pack "${PACK_FILE}.pack"
             }
 
             it "did not touch index or pack file" && {
@@ -84,8 +84,8 @@ title "CLI ${kind}"
           (with "and no safety checks at all (and an output directory)"
             it "does explode the file" && {
               WITH_SNAPSHOT="$snapshot/plumbing-broken-pack-explode-delete-pack-to-sink-skip-checks-success" \
-              expect_run $SUCCESSFULLY "$exe_plumbing" pack-explode --check skip-file-and-object-checksum-and-no-abort-on-decode \
-                                        --delete-pack --sink-compress "${PACK_FILE}.pack" .
+              expect_run $SUCCESSFULLY "$exe_plumbing" pack-explode --verify --check skip-file-and-object-checksum-and-no-abort-on-decode \
+                                        --delete-pack "${PACK_FILE}.pack" .
             }
 
             it "removes the original files" && {