Ensure proper path traversals for linked commands;

sdk/bin/dart2js

Index: sdk/bin/dart2js
diff --git a/sdk/bin/dart2js b/sdk/bin/dart2js
index 96354cae4a715da8d334d30567aa05b23249fbb2..c57436b5a35c470df11ffda58ccb64a2d84bd859 100755
--- a/sdk/bin/dart2js
+++ b/sdk/bin/dart2js
@@ -2,22 +2,19 @@
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # 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
+function link_dir() {
+  a="$1"
+  while [ -h "$a" ]; do
     # On Mac OS, readlink -f doesn't work.
-    1="$(readlink "$1")"
+    a="$(readlink "$a")"
   done
-  echo "$1"
+  # if dir linked, not file, need to follow dir path:

[ahe, 2013/05/30 10:00:19]

This comment does not make sense to me.

[yarkot1, 2013/05/31 22:22:17]

if $a (filename) is a file, readlink handles following to the linked target;
If, however, $(dirname a) was the link, we readlink will miss it;  then we
need the $(cd ...; pwd -P) to follow to the linked target.

i.e. if the dirname (not the filename) was what was linked, we need this next
line.

[ahe, 2013/06/03 10:29:01]

Could you change the comment to:

# If the parent directory of $a is a symlink, we need to follow it.  pwd -P does
that:

+  echo "$(cd $(dirname "$a"); pwd -P)"

[ahe, 2013/05/30 10:00:19]

This invokes the external command dirname.  That adds overhead that I have tried
to avoid by using "${a%/*}".

[yarkot1, 2013/05/31 22:22:17]

yes - you are correct.  Timing this confirms.

 }
 
-# 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.

[ahe, 2013/05/30 10:00:19]

You're still not handling this case.

[nweiz, 2013/05/31 19:35:21]

This case is handled by the "pwd -P" call in link_dir.

[ahe, 2013/06/03 10:29:01]

Thank you.  I just studied the man page, and you're absolutely right.

-BIN_DIR="$(follow_links "$(cd "${PROG_NAME%/*}" ; pwd -P)")"
-
-SDK_DIR="$(cd "${BIN_DIR}/.." ; pwd -P)"
+BIN_DIR="$(link_dir "$0")"

[ahe, 2013/05/30 10:00:19]

$0 is not the right thing to use.  See the difference:

$ mkdir subdir
$ cat > subdir/script.bash
#!/bin/bash

echo "$0"
echo "$BASH_SOURCE"
$ cat > super.bash
#!/bin/bash

. subdir/script.bash
$ bash super.bash 
super.bash
subdir/script.bash
$

[yarkot1, 2013/05/31 22:22:17]

yes - this is true in the case of sourced scripts;  will change.

+SDK_DIR="${BIN_DIR%/*}"
 
 DART2JS="$SDK_DIR/lib/_internal/compiler/implementation/dart2js.dart"