feat: create a blob object

Cargo.lock

@@ -64,6 +64,15 @@ version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34ac096ce696dc2fcabef30516bb13c0a68a11d30131d3df6f04711467681b04"
 
+[[package]]
+name = "block-buffer"
+version = "0.10.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3078c7629b62d3f0439517fa394996acacc5cbc91c5a20d8c658e77abd503a71"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "cfg-if"
 version = "1.0.0"
@@ -116,6 +125,15 @@ version = "1.0.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5b63caa9aa9397e2d9480a9b13673856c78d8ac123288526c37d7839f2a86990"
 
+[[package]]
+name = "cpufeatures"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "59ed5838eebb26a2bb2e58f6d5b5316989ae9d08bab10e0e6d103e656d1b0280"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "crc32fast"
 version = "1.4.2"
@@ -125,6 +143,26 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "crypto-common"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bfb12502f3fc46cca1bb51ac28df9d618d813cdc3d2f25b9fe775a34af26bb3"
+dependencies = [
+ "generic-array",
+ "typenum",
+]
+
+[[package]]
+name = "digest"
+version = "0.10.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
+dependencies = [
+ "block-buffer",
+ "crypto-common",
+]
+
 [[package]]
 name = "flate2"
 version = "1.0.35"
@@ -135,6 +173,16 @@ dependencies = [
  "miniz_oxide",
 ]
 
+[[package]]
+name = "generic-array"
+version = "0.14.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "85649ca51fd72272d7821adaf274ad91c288277713d9c18820d8499a7ff69e9a"
+dependencies = [
+ "typenum",
+ "version_check",
+]
+
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -153,6 +201,12 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "libc"
+version = "0.2.169"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b5aba8db14291edd000dfcc4d620c7ebfb122c613afb886ca8803fa4e128a20a"
+
 [[package]]
 name = "mg"
 version = "0.1.0"
@@ -161,6 +215,7 @@ dependencies = [
  "clap",
  "flate2",
  "hex",
+ "sha1",
  "thiserror",
 ]
 
@@ -197,6 +252,17 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "sha1"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e3bf829a2d51ab4a5ddf1352d8470c140cadc8301b2ae1789db023f01cedd6ba"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "digest",
+]
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -234,6 +300,12 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "typenum"
+version = "1.17.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "42ff0bf0c66b8238c6f3b578df37d0b7848e55df8577b3f74f92a69acceeb825"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.16"
@@ -246,6 +318,12 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "version_check"
+version = "0.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0b928f33d975fc6ad9f86c8f283853ad26bdd5b10b7f1542aa2fa15e2289105a"
+
 [[package]]
 name = "windows-sys"
 version = "0.59.0"

Cargo.toml

@@ -8,4 +8,5 @@ anyhow = "1.0.95"
 clap = { version = "4.5.27", features = ["derive", "string"] }
 flate2 = "1.0.35"
 hex = "0.4.3"
+sha1 = "0.10.6"
 thiserror = "2.0.11"

src/main.rs

@@ -10,6 +10,7 @@ mod kind;
 mod object;
 
 use crate::object::read_object;
+use crate::object::write_object;
 
 #[derive(Parser)]
 #[command(name = "mg", about = "A simple git clone")]
@@ -31,6 +32,11 @@ enum Command {
         /// The object to display
         hash: String,
     },
+    /// Write a blob object
+    WriteBlob {
+        /// The file to write
+        file: PathBuf,
+    },
 }
 
 fn default_init_path() -> PathBuf {
@@ -61,9 +67,13 @@ fn main() -> Result<(), Error> {
             Err(e) => eprintln!("Failed to initialize repository: {}", e),
         },
         Command::CatFile { hash } => match read_object(&path, &hash) {
-            Ok(mut obj) => println!("{}", obj.string()?),
+            Ok(mut obj) => print!("{}", obj.string()?),
             Err(e) => eprintln!("Failed to read object: {}", e),
         },
+        Command::WriteBlob { file } => match write_object(&path, &file) {
+            Ok(hash) => println!("{}", hash),
+            Err(e) => eprintln!("Failed to write object: {}", e),
+        },
     }
 
     Ok(())

src/object.rs

@@ -1,7 +1,14 @@
-use anyhow::{Context, Result};
-use std::{fs::File, io::BufRead, path::Path};
-
 use crate::{error::RuntimeError, kind::Kind};
+use anyhow::{anyhow, Context, Result};
+use flate2::{write::ZlibEncoder, Compression};
+use sha1::{Digest, Sha1};
+use std::io::Write;
+use std::{
+    fs::{create_dir, File},
+    io::{copy, BufRead},
+    os::unix::fs::MetadataExt,
+    path::Path,
+};
 
 #[derive(Debug)]
 pub struct Object<Reader> {
@@ -61,6 +68,60 @@ pub fn read_object(path: &Path, object: &str) -> Result<Object<impl BufRead>> {
     })
 }
 
+fn is_path_in_repo(repo_path: &Path, file_path: &Path) -> Result<bool> {
+    // Convert both paths to absolute paths
+    let repo_canonical = repo_path.canonicalize()?;
+    let file_canonical = match file_path.canonicalize() {
+        Ok(path) => path,
+        Err(_) => return Ok(false),
+    };
+
+    // Check if file_path starts with repo_path
+    Ok(file_canonical.starts_with(repo_canonical))
+}
+
+pub fn hash_file(file: &Path) -> Result<String> {
+    let fd = File::open(file).context("opening file for sha1")?;
+    let mut buf_reader = std::io::BufReader::new(fd);
+
+    let stat = file.metadata().context("stat on file")?;
+
+    let header = format!("blob {}\0", stat.size());
+
+    let mut hasher = Sha1::new();
+    hasher.update(header.as_bytes());
+    copy(&mut buf_reader, &mut hasher)?;
+    let hash_bytes = hasher.finalize();
+
+    Ok(hex::encode(hash_bytes))
+}
+
+pub fn write_object(repo_path: &Path, file: &Path) -> Result<String> {
+    if !file.exists() || !is_path_in_repo(repo_path, file)? {
+        return Err(anyhow!("path does not exist"));
+    }
+
+    let hash = hash_file(file)?;
+    let bytes_num = file.metadata()?.len();
+    let mut buf_reader = std::io::BufReader::new(File::open(file)?);
+
+    let target_dir = repo_path.join(".git").join("objects").join(&hash[..2]);
+
+    if !target_dir.exists() {
+        create_dir(&target_dir).context("could not create directory in .git/objects")?;
+    }
+
+    let target_file = target_dir.join(&hash[2..]);
+    let file_out_fd = File::create(target_file).context("could not open target file")?;
+
+    let mut zlib_out = ZlibEncoder::new(file_out_fd, Compression::default());
+    write!(zlib_out, "blob {}\0", bytes_num).context("could not write header")?;
+
+    std::io::copy(&mut buf_reader, &mut zlib_out).context("could not compress or write file")?;
+
+    Ok(hash)
+}
+
 impl<R: BufRead> Object<R> {
     pub fn string(&mut self) -> Result<String> {
         let mut buf: Vec<u8> = Vec::new();