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

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

R=ahe@google.com, brianwilkerson@google.com, rnystrom@google.com
BUG=9409
Committed: https://code.google.com/p/dart/source/detail?r=30287

[nweiz, 2013-11-11 23:47:29]

I've tested this on Linux and OS X, running the executables directly, through a
symlink to dart-sdk, and through a symlink to the executable scripts themselves.

I feel like there are probably other folks who should be on this CL, but I'm not
sure who exactly.

[Bob Nystrom, 2013-11-12 00:03:46]

+Peter and Brian

I think it looks fine, but honestly bash is mostly line noise to me. :)

[ahe, 2013-11-12 10:14:42]

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js
File sdk/bin/dart2js (left):

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#oldcode9
sdk/bin/dart2js:9: 1="$(readlink "$1")"
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"
}

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#oldcode18
sdk/bin/dart2js:18: BIN_DIR="$(follow_links "$(cd "${PROG_NAME%/*}" ; pwd -P)")"
I guess follow_links is unnecessary here.

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js
File sdk/bin/dart2js (right):

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#newcode9
sdk/bin/dart2js:9: SCRIPT=`readlink "$0" || echo "$0"`
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 10:15:57]

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js
File sdk/bin/dart2js (right):

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#newcode9
sdk/bin/dart2js:9: SCRIPT=`readlink "$0" || echo "$0"`
On 2013/11/12 10:14:43, ahe wrote:
> 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.

... is a symlink to a symlink itself.

[Brian Wilkerson, 2013-11-12 20:14:47]

LGTM, but like Bob, bash is a foreign language to me

[nweiz, 2013-11-12 20:26:39]

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js
File sdk/bin/dart2js (left):

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#oldcode9
sdk/bin/dart2js:9: 1="$(readlink "$1")"
On 2013/11/12 10:14:43, ahe wrote:
> 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"
> }

Done.

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#oldcode18
sdk/bin/dart2js:18: BIN_DIR="$(follow_links "$(cd "${PROG_NAME%/*}" ; pwd -P)")"
On 2013/11/12 10:14:43, ahe wrote:
> I guess follow_links is unnecessary here.

Done.

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js
File sdk/bin/dart2js (right):

https://codereview.chromium.org/68503004/diff/1/sdk/bin/dart2js#newcode9
sdk/bin/dart2js:9: SCRIPT=`readlink "$0" || echo "$0"`
On 2013/11/12 10:14:43, ahe wrote:
> 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.

Done.

[ahe, 2013-11-14 15:36:04]

Thank you, Nathan. This is awesome, LGTM!

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dart
File sdk/bin/dart (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dart#newcode15
sdk/bin/dart:15: # Unlike $0, $BASH_SOURCE points to the absolute path of this
file.
Lines 15-19 have some weird stuff at the end of the line. It show up as red
chevrons in rietveld.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dart2js
File sdk/bin/dart2js (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dart2js#newcode15
sdk/bin/dart2js:15: # Unlike $0, $BASH_SOURCE points to the absolute path of
this file.
Weird line endings here as well.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartanalyzer
File sdk/bin/dartanalyzer (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartanalyzer#new...
sdk/bin/dartanalyzer:17: # Unlike $0, $BASH_SOURCE points to the absolute path
of this file.
Weird line endings here as well.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartanalyzer_dev...
File sdk/bin/dartanalyzer_developer (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartanalyzer_dev...
sdk/bin/dartanalyzer_developer:32: # Unlike $0, $BASH_SOURCE points to the
absolute path of this file.
Weird line endings.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartdoc
File sdk/bin/dartdoc (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/dartdoc#newcode15
sdk/bin/dartdoc:15: # Unlike $0, $BASH_SOURCE points to the absolute path of
this file.
Weird line endings.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/pub
File sdk/bin/pub (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/pub#newcode18
sdk/bin/pub:18: # Unlike $0, $BASH_SOURCE points to the absolute path of this
file.
Weird line endings.

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/pub_developer
File sdk/bin/pub_developer (right):

https://codereview.chromium.org/68503004/diff/100001/sdk/bin/pub_developer#ne...
sdk/bin/pub_developer:18: # Unlike $0, $BASH_SOURCE points to the absolute path
of this file.
Weird line endings.

[nweiz, 2013-11-14 19:28:20]

Removed trailing whitespace.

[nweiz, 2013-11-14 19:28:27]

Committed patchset #3 manually as r30287 (presubmit successful).