pack multi-index info subcommand (#301)

README.md

@@ -35,9 +35,13 @@ Please see _'Development Status'_ for a listing of all crates and their capabili
       * [x] **create** - create a pack from given objects or tips of the commit graph.
       * [ ] **send** - create a pack and send it using the pack protocol to stdout, similar to 'git-upload-pack', 
             for consumption by **pack-receive** or _git-receive-pack_
-      * **index**
-      * [x] [create](https://asciinema.org/a/352941) - create an index file by streaming a pack file as done during clone
-          * [x] support for thin packs (as needed for fetch/pull)
+      - **multi-index**
+          * [x] **info** - print information about the file
+          * [x] **create** - create a multi-index from pack indices
+          * [x] **verify** - check the file for consistency
+      - **index**
+          * [x] [create](https://asciinema.org/a/352941) - create an index file by streaming a pack file as done during clone
+             * [x] support for thin packs (as needed for fetch/pull)
     * **commit-graph**
       * [x] **verify** - assure that a commit-graph is consistent
     * **repository**

gitoxide-core/src/pack/multi_index.rs

@@ -1,5 +1,6 @@
 use std::{io::BufWriter, path::PathBuf, sync::atomic::AtomicBool};
 
+use crate::OutputFormat;
 use git_repository as git;
 use git_repository::Progress;
 
@@ -32,3 +33,38 @@ pub fn create(
     out.into_inner()?.commit()?;
     Ok(())
 }
+
+mod info {
+    use std::path::PathBuf;
+
+    #[cfg_attr(feature = "serde1", derive(serde::Serialize))]
+    pub struct Statistics {
+        pub path: PathBuf,
+        pub num_objects: u32,
+        pub index_names: Vec<PathBuf>,
+        pub object_hash: String,
+    }
+}
+
+pub fn info(
+    multi_index_path: PathBuf,
+    format: OutputFormat,
+    out: impl std::io::Write,
+    mut err: impl std::io::Write,
+) -> anyhow::Result<()> {
+    let file = git::odb::pack::multi_index::File::at(&multi_index_path)?;
+    if format == OutputFormat::Human {
+        writeln!(err, "Defaulting to JSON as human format isn't implemented").ok();
+    }
+    #[cfg(feature = "serde1")]
+    serde_json::to_writer_pretty(
+        out,
+        &info::Statistics {
+            path: multi_index_path,
+            num_objects: file.num_objects(),
+            index_names: file.index_names().to_vec(),
+            object_hash: file.object_hash().to_string(),
+        },
+    )?;
+    Ok(())
+}

gitoxide-core/src/repository/tree.rs

@@ -120,8 +120,8 @@ pub fn info(
     treeish: Option<&str>,
     extended: bool,
     format: OutputFormat,
-    out: &mut dyn io::Write,
-    err: &mut dyn io::Write,
+    out: impl io::Write,
+    mut err: impl io::Write,
 ) -> anyhow::Result<()> {
     if format == OutputFormat::Human {
         writeln!(err, "Only JSON is implemented - using that instead")?;
@@ -148,7 +148,7 @@ pub fn entries(
     recursive: bool,
     extended: bool,
     format: OutputFormat,
-    out: &mut dyn io::Write,
+    mut out: impl io::Write,
 ) -> anyhow::Result<()> {
     if format != OutputFormat::Human {
         bail!("Only human output format is supported at the moment");
@@ -158,13 +158,13 @@ pub fn entries(
     let tree = treeish_to_tree(treeish, &repo)?;
 
     if recursive {
-        let mut delegate = entries::Traverse::new(extended.then(|| &repo), out.into());
+        let mut delegate = entries::Traverse::new(extended.then(|| &repo), Some(&mut out));
         tree.traverse().breadthfirst(&mut delegate)?;
     } else {
         for entry in tree.iter() {
             let entry = entry?;
             format_entry(
-                &mut *out,
+                &mut out,
                 &entry.inner,
                 entry.inner.filename,
                 extended

src/plumbing/main.rs

@@ -378,6 +378,14 @@ pub fn main() -> Result<()> {
             )
             .map(|_| ()),
             pack::Subcommands::MultiIndex(multi_index::Platform { multi_index_path, cmd }) => match cmd {
+                pack::multi_index::Subcommands::Info => prepare_and_run(
+                    "pack-multi-index-info",
+                    verbose,
+                    progress,
+                    progress_keep_open,
+                    core::pack::multi_index::PROGRESS_RANGE,
+                    move |_progress, out, err| core::pack::multi_index::info(multi_index_path, format, out, err),
+                ),
                 pack::multi_index::Subcommands::Verify => prepare_and_run(
                     "pack-multi-index-verify",
                     verbose,

src/plumbing/options.rs

@@ -257,7 +257,7 @@ pub mod pack {
         #[derive(Debug, clap::Parser)]
         pub struct Platform {
             /// The path to the index file.
-            #[clap(short = 'i', long, default_value = ".git/objects/packs/multi-pack-index")]
+            #[clap(short = 'i', long, default_value = ".git/objects/pack/multi-pack-index")]
             pub multi_index_path: PathBuf,
 
             /// Subcommands
@@ -267,6 +267,8 @@ pub mod pack {
 
         #[derive(Debug, clap::Subcommand)]
         pub enum Subcommands {
+            /// Print general information about a multi-index file
+            Info,
             /// Verify a multi-index quickly without inspecting objects themselves
             Verify,
             /// Create a multi-pack index from one or more pack index files, overwriting possibloy existing files.