Support symlinking to dart-sdk executables on Linux and Mac.

sdk/bin/dart2js

Index: sdk/bin/dart2js
diff --git a/sdk/bin/dart2js b/sdk/bin/dart2js
index 084df7ea3a261461fea026298b689aed482a9ce0..60e0b00a9024dfad7513196bd36909f5519e87c7 100755
--- a/sdk/bin/dart2js
+++ b/sdk/bin/dart2js
@@ -3,20 +3,11 @@
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
-function follow_links() {
-  while [ -h "$1" ]; do
-    # On Mac OS, readlink -f doesn't work.
-    1="$(readlink "$1")"

[ahe, 2013/11/12 10:14:43]

This is a bug: it should be something like:

function follow_links() {
  file="$1"
  while [ -h "$file" ]; do
    # On Mac OS, readlink -f doesn't work.
    file="$(readlink "$file")"
  done
  echo "$file"
}

[nweiz, 2013/11/12 20:26:40]

Done.

-  done
-  echo "$1"
-}
-
-# Unlike $0, $BASH_SOURCE points to the absolute path of this file.
-PROG_NAME="$(follow_links "$BASH_SOURCE")"
-
-# Handle the case where dart-sdk/bin has been symlinked to.
-BIN_DIR="$(follow_links "$(cd "${PROG_NAME%/*}" ; pwd -P)")"

[ahe, 2013/11/12 10:14:43]

I guess follow_links is unnecessary here.

[nweiz, 2013/11/12 20:26:40]

Done.

-
+# Setting BIN_DIR this way is ugly, but is needed to handle the case where
+# dart-sdk/bin or the script itself has been symlinked to. On MacOS, readlink -f
+# doesn't work with this case.
+SCRIPT=`readlink "$0" || echo "$0"`

[ahe, 2013/11/12 10:14:43]

Unlike $0, $BASH_SOURCE points to this file. This is important if you use "." to
include this file, as we do for dart2js_developer.

In addition, I think it is important to restore follow_links, because:

1. it is faster than calling readlink (an external process)
2. readlink without -f doesn't support the general situation where $0 (or
$BASH_SOURCE) is a symlink itself.

[ahe, 2013/11/12 10:16:01]

... is a symlink to a symlink itself.

[nweiz, 2013/11/12 20:26:40]

Done.

+BIN_DIR="$(cd "${SCRIPT%/*}" ; pwd -P)"
 SDK_DIR="$(cd "${BIN_DIR}/.." ; pwd -P)"
 
 DART2JS="$SDK_DIR/lib/_internal/compiler/implementation/dart2js.dart"