From 3f2c55f7d5b5c7717dd12eef4572c52a4e8ff550 Mon Sep 17 00:00:00 2001
From: Alex Crichton <alex@alexcrichton.com>
Date: Tue, 8 Apr 2014 10:15:46 -0700
Subject: [PATCH] rustc: Use realpath() for sysroot/rpath

When calculating the sysroot, it's more accurate to use realpath() rather than
just one readlink() to account for any intermediate symlinks that the rustc
binary resolves itself to.

For rpath, realpath() is necessary because the rpath must dictate a relative
rpath from the destination back to the originally linked library, which works
more robustly if there are no symlinks involved.

Concretely, any binary generated on OSX into $TMPDIR requires an absolute rpath
because the temporary directory is behind a symlink with one layer of
indirection. This symlink causes all relative rpaths to fail to resolve.

cc #11734
cc #11857
---
 src/librustc/back/rpath.rs          |  7 ++++---
 src/librustc/metadata/filesearch.rs | 17 ++++++-----------
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/src/librustc/back/rpath.rs b/src/librustc/back/rpath.rs
index 4b54b1f60088..e455c4ad23ce 100644
--- a/src/librustc/back/rpath.rs
+++ b/src/librustc/back/rpath.rs
@@ -12,9 +12,10 @@
 use driver::session::Session;
 use metadata::cstore;
 use metadata::filesearch;
+use util::fs;
 
 use collections::HashSet;
-use std::{os, slice};
+use std::os;
 use syntax::abi;
 
 fn not_win32(os: abi::Os) -> bool {
@@ -121,9 +122,9 @@ pub fn get_rpath_relative_to_output(os: abi::Os,
         abi::OsWin32 => unreachable!()
     };
 
-    let mut lib = os::make_absolute(lib);
+    let mut lib = fs::realpath(&os::make_absolute(lib)).unwrap();
     lib.pop();
-    let mut output = os::make_absolute(output);
+    let mut output = fs::realpath(&os::make_absolute(output)).unwrap();
     output.pop();
     let relative = lib.path_relative_from(&output);
     let relative = relative.expect("could not create rpath relative to output");
diff --git a/src/librustc/metadata/filesearch.rs b/src/librustc/metadata/filesearch.rs
index 7a531c5c128b..f4ea386a2eca 100644
--- a/src/librustc/metadata/filesearch.rs
+++ b/src/librustc/metadata/filesearch.rs
@@ -15,6 +15,8 @@ use std::os;
 use std::io::fs;
 use collections::HashSet;
 
+use myfs = util::fs;
+
 pub enum FileMatch { FileMatches, FileDoesntMatch }
 
 // A module for searching for libraries
@@ -156,17 +158,10 @@ fn make_rustpkg_target_lib_path(sysroot: &Path,
 pub fn get_or_default_sysroot() -> Path {
     // Follow symlinks.  If the resolved path is relative, make it absolute.
     fn canonicalize(path: Option<Path>) -> Option<Path> {
-        path.and_then(|mut path|
-            match fs::readlink(&path) {
-                Ok(canon) => {
-                    if canon.is_absolute() {
-                        Some(canon)
-                    } else {
-                        path.pop();
-                        Some(path.join(canon))
-                    }
-                },
-                Err(..) => Some(path),
+        path.and_then(|path|
+            match myfs::realpath(&path) {
+                Ok(canon) => Some(canon),
+                Err(e) => fail!("failed to get realpath: {}", e),
             })
     }