From 5c0c21322c611a39b98c99bd8207cccc246917a0 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Thu, 28 Jan 2016 20:07:56 -0800
Subject: [PATCH] Build UStar archives by default

The tar::Builder type by default will build GNU archives, but
unfortunately we force it here to use UStar archives instead. The
UStar format has more limitations on the length of path name that it
can encode, so it's not quite as nice to use.

Older cargos, however, had a bug where GNU archives were interpreted
as UStar archives. This bug means that if we publish a GNU archive
which has fully filled out metadata it'll be corrupt when unpacked by
older cargos.

Hopefully in the future after enough cargos have been running around
with the bugfixed tar-rs library we'll be able to switch this over to
GNU archives, but for now we'll just say that you can't encode paths
in archives that are *too* long.

Closes #2326
---
 src/cargo/ops/cargo_package.rs | 33 +++++++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/src/cargo/ops/cargo_package.rs b/src/cargo/ops/cargo_package.rs
index 7a2ad7ab561..8ccc11aac3e 100644
--- a/src/cargo/ops/cargo_package.rs
+++ b/src/cargo/ops/cargo_package.rs
@@ -2,7 +2,7 @@ use std::io::prelude::*;
 use std::fs::{self, File};
 use std::path::{self, Path, PathBuf};
 
-use tar::{Archive, Builder};
+use tar::{Archive, Builder, Header};
 use flate2::{GzBuilder, Compression};
 use flate2::read::GzDecoder;
 
@@ -135,7 +135,36 @@ fn tar(pkg: &Package,
         }));
         let path = format!("{}-{}{}{}", pkg.name(), pkg.version(),
                            path::MAIN_SEPARATOR, relative);
-        try!(ar.append_file(&path, &mut file).chain_error(|| {
+
+        // The tar::Builder type by default will build GNU archives, but
+        // unfortunately we force it here to use UStar archives instead. The
+        // UStar format has more limitations on the length of path name that it
+        // can encode, so it's not quite as nice to use.
+        //
+        // Older cargos, however, had a bug where GNU archives were interpreted
+        // as UStar archives. This bug means that if we publish a GNU archive
+        // which has fully filled out metadata it'll be corrupt when unpacked by
+        // older cargos.
+        //
+        // Hopefully in the future after enough cargos have been running around
+        // with the bugfixed tar-rs library we'll be able to switch this over to
+        // GNU archives, but for now we'll just say that you can't encode paths
+        // in archives that are *too* long.
+        //
+        // For an instance of this in the wild, use the tar-rs 0.3.3 library to
+        // unpack the selectors 0.4.0 crate on crates.io. Either that or take a
+        // look at rust-lang/cargo#2326
+        let mut header = Header::new_ustar();
+        let metadata = try!(file.metadata().chain_error(|| {
+            human(format!("could not learn metadata for: `{}`", relative))
+        }));
+        try!(header.set_path(&path).chain_error(|| {
+            human(format!("failed to add to archive: `{}`", relative))
+        }));
+        header.set_metadata(&metadata);
+        header.set_cksum();
+
+        try!(ar.append(&header, &mut file).chain_error(|| {
             internal(format!("could not archive source file `{}`", relative))
         }));
     }