Add optional owner to node creation from data

Cargo.lock

@@ -548,6 +548,7 @@ name = "tar"
 version = "0.1.0"
 dependencies = [
  "deku",
+ "libc",
  "thiserror",
 ]
 

tar/Cargo.toml

@@ -6,4 +6,5 @@ license = "GPL-3.0-only"
 
 [dependencies]
 deku = "0.16"
+libc = "0.2"
 thiserror = "1.0.40"

tar/src/error.rs

@@ -1,7 +1,4 @@
-use std::io;
-use std::num::ParseIntError;
-use std::str::Utf8Error;
-
+use std::{fmt, io, num::ParseIntError, str::Utf8Error};
 use thiserror::Error;
 
 #[derive(Error, Debug)]
@@ -20,4 +17,6 @@ pub enum Error {
     InvalidMagic,
     #[error("Invalid Checksum")]
     InvalidChecksum,
+    #[error("Parse int failed")]
+    Parse(#[from] fmt::Error),
 }

tar/src/header.rs

@@ -2,6 +2,7 @@ use crate::Error;
 use deku::prelude::*;
 use std::{
     env,
+    ffi::CStr,
     fmt::{self, Write},
     fs::{self, Metadata},
     ops::Deref,
@@ -48,6 +49,24 @@ where
     }
 }
 
+pub struct Owner {
+    pub uid: u32,
+    pub gid: u32,
+    pub username: String,
+    pub groupname: String,
+}
+
+impl Default for Owner {
+    fn default() -> Self {
+        Self {
+            uid: 0,
+            gid: 0,
+            username: "root".into(),
+            groupname: "root".into(),
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug, PartialEq, DekuRead, DekuWrite)]
 #[deku(endian = "little")]
 pub struct Header {
@@ -107,6 +126,82 @@ impl Header {
         Ok(s)
     }
 
+    pub fn mode(&self) -> Result<u32, Error> {
+        let mut s = String::new();
+        for c in self.mode {
+            if c != b'\0' {
+                write!(s, "{c}")?;
+            } else {
+                break;
+            }
+        }
+        let mode = u32::from_str_radix(&s, 8)?;
+        Ok(mode)
+    }
+
+    fn uid(&self) -> Result<u32, Error> {
+        let mut s = String::new();
+        for c in self.mode {
+            if c != b'\0' {
+                write!(s, "{c}")?;
+            } else {
+                break;
+            }
+        }
+        let uid = u32::from_str_radix(&s, 8)?;
+        Ok(uid)
+    }
+
+    fn gid(&self) -> Result<u32, Error> {
+        let mut s = String::new();
+        for c in self.mode {
+            if c != b'\0' {
+                write!(s, "{c}")?;
+            } else {
+                break;
+            }
+        }
+        let gid = u32::from_str_radix(&s, 8)?;
+        Ok(gid)
+    }
+
+    fn username(&self) -> Result<String, fmt::Error> {
+        let mut s = String::new();
+        for c in self.username {
+            if c != b'\0' {
+                write!(s, "{c}")?;
+            } else {
+                break;
+            }
+        }
+        Ok(s)
+    }
+
+    fn groupname(&self) -> Result<String, fmt::Error> {
+        let mut s = String::new();
+        for c in self.groupname {
+            if c != b'\0' {
+                write!(s, "{c}")?;
+            } else {
+                break;
+            }
+        }
+        Ok(s)
+    }
+
+    pub fn owner(&self) -> Result<Owner, Error> {
+        let uid = self.uid()?;
+        let gid = self.gid()?;
+        let username = self.username()?;
+        let groupname = self.groupname()?;
+        Ok(Owner {
+            uid,
+            gid,
+            username,
+            groupname,
+        })
+    }
+
     pub fn new(filename: &str) -> Result<Self, Error> {
         let mut header = Header::default();
         let meta = fs::symlink_metadata(filename)?;
@@ -149,14 +244,23 @@ impl Header {
         Ok(header)
     }
 
-    pub fn new_from_meta(filename: &str, meta: &Metadata) -> Result<Self, Error> {
+    pub fn new_from_meta(filename: &str, meta: &Metadata, owner: Option<Owner>) -> Result<Self, Error> {
         let mut header = Header::default();
         header.fname[..filename.len()].copy_from_slice(filename.as_bytes());
         let mode = format!("{:07o}", meta.st_mode());
         header.mode[..mode.len()].copy_from_slice(mode.as_bytes());
-        let uid = format!("{:07o}", 0);
+        let owner = match owner {
+            Some(o) => o,
+            None => Owner {
+                uid: meta.st_uid(),
+                gid: meta.st_gid(),
+                username: get_username_for_uid(meta.st_uid())?.into(),
+                groupname: get_groupname_for_gid(meta.st_gid())?.into(),
+            }
+        };
+        let uid = format!("{:07o}", owner.uid);
         header.uid[..uid.len()].copy_from_slice(uid.as_bytes());
-        let gid = format!("{:07o}", 0);
+        let gid = format!("{:07o}", owner.gid);
         header.gid[..gid.len()].copy_from_slice(gid.as_bytes());
         let size = format!("{:011o}", meta.len());
         header.size[..size.len()].copy_from_slice(size.as_bytes());
@@ -172,10 +276,9 @@ impl Header {
             let minor = format!("{:07o}", meta.st_rdev());
             header.device_minor[..minor.len()].copy_from_slice(minor.as_bytes());
         }
-        let user = "root";
-        header.username[..user.len()].copy_from_slice(user.as_bytes());
+        header.username[..owner.username.len()].copy_from_slice(owner.username.as_bytes());
         let group = "root";
-        header.groupname[..group.len()].copy_from_slice(group.as_bytes());
+        header.groupname[..group.len()].copy_from_slice(owner.groupname.as_bytes());
         header.update_checksum()?;
         Ok(header)
     }
@@ -244,3 +347,22 @@ impl Header {
         Ok(checksum)
     }
 }
+
+fn get_username_for_uid<'a>(uid: u32) -> Result<&'a str, std::str::Utf8Error> {
+    let user = unsafe {
+        let pw = libc::getpwuid(uid);
+        let name = (*pw).pw_name;
+        CStr::from_ptr(name)
+    };
+    user.to_str()
+}
+
+pub fn get_groupname_for_gid<'a>(gid: u32) -> Result<&'a str, std::str::Utf8Error> {
+    let group = unsafe {
+        let gr = libc::getgrgid(gid);
+        let name = (*gr).gr_name;
+        CStr::from_ptr(name)
+    };
+    group.to_str()
+}
+

tar/src/lib.rs

@@ -1,4 +1,7 @@
-use std::{fs::File, io::{self, BufReader}};
+use std::{
+    fs::File,
+    io::{self, BufReader},
+};
 
 mod error;
 mod header;

tar/src/node.rs

@@ -1,8 +1,8 @@
-use crate::{Error, FileType, Header};
+use crate::{Error, FileType, Header, header::Owner};
 use deku::prelude::*;
 use std::{
     fs::{File, Metadata},
-    io::BufReader,
+    io::{self, BufReader},
     str,
 };
 
@@ -14,7 +14,7 @@ pub struct Node {
 
 impl Node {
     /// Write out a single file within the tar to a file or something with a ``std::io::Write`` trait.
-    pub fn write<T: std::io::Write>(self, mut input: T) -> Result<usize, Error> {
+    pub fn write<T: io::Write>(self, mut input: T) -> Result<usize, Error> {
         input.write_all(&self.header.to_bytes()?)?;
         let mut written = 512;
         for d in self.data {
@@ -26,7 +26,7 @@ impl Node {
     }
 
     /// Read a TarNode in from a file or something with a ``std::io::Read`` trait.
-    pub fn read<T: std::io::Read>(mut input: T) -> Result<Node, Error> {
+    pub fn read<T: io::Read>(mut input: T) -> Result<Node, Error> {
         let mut h = vec![0u8; 512];
         input.read_exact(&mut h)?;
 
@@ -67,8 +67,8 @@ impl Node {
     }
 
     /// Create a Node from in memory data, given the filename and metadata
-    pub fn read_data_to_tar(data: &[u8], filename: &str, meta: &Metadata) -> Result<Node, Error> {
-        let header = Header::new_from_meta(filename, meta)?;
+    pub fn read_data_to_tar(data: &[u8], filename: &str, meta: &Metadata, owner: Option<Owner>) -> Result<Node, Error> {
+        let header = Header::new_from_meta(filename, meta, owner)?;
         if header.link_indicator[0] != FileType::Normal as u8 {
             return Ok(Node {
                 header,