Issue 5020 - Part 2: Fix usage of paths in compile script

compile

Index: compile
===================================================================
--- a/compile
+++ b/compile
@@ -1,26 +1,27 @@
 #!/usr/bin/env python
 
 import os
 import re
 import subprocess
 
-EMSCRIPTEN_PATH = '../emscripten'
-SOURCE_DIR = './compiled'
+BASE_DIR = os.path.dirname(__file__) or os.getcwd()

[Vasily Kuznetsov, 2017/03/21 18:01:42]

BASE_DIR (which I suppose is the path to the directory where this file lives)
will be absolute if we run it from that same directory (in this case the left
operand of "or" will be an empty string) or relative if we run it from any other
directory. Perhaps it would be more consistent to always generate an absolute
path: os.path.abspath(os.path.dirname(__file__)) or always use a relative path
by omitting "or os.getcwd()".

Or am I misunderstanding the intention here?

[Wladimir Palant, 2017/03/22 08:44:20]

It's fine to have relative paths for almost all purposes (shell file being an
exception which is why we generate an absolute path there). The point is rather
that this script *can* be run from a different directory, so
../adblockpluscore/compile will still do the right thing (e.g. find the files to
be compiled in ../adblockpluscore/compiled).

[Vasily Kuznetsov, 2017/03/22 09:52:58]

I guess I'm missing some part of the picture here. What do you mean by "shell
file" and why would that case be an exception and require an absolute path?

[Wladimir Palant, 2017/03/22 14:59:29]

See SHELL_FILE key in GENERATION_PARAMS below. It is an Emscripten parameter and
for some reason Emscripten insists that it has to be an absolute path.

[Vasily Kuznetsov, 2017/03/22 19:16:01]

Ah, ok, now I get it. But then we don't really need "or os.getcwd()" in this
line since empty BASE_DIR would be a correct relative path in case this script
is run from the directory where it's located. And Emscripten will be happy
anyway because there's another os.path.abspath there.

[Wladimir Palant, 2017/03/23 11:55:28]

Fair enough, I verified that os.path.join('', 'foo') will do the right thing - I
wasn't aware of that. Removed the fallback.

+EMSCRIPTEN_PATH = os.path.join(BASE_DIR, '..', 'emscripten')
+SOURCE_DIR = os.path.join(BASE_DIR, 'compiled')
 SOURCE_FILES = [
     os.path.join(path, f)
     for (path, dirs, files) in os.walk(SOURCE_DIR)
     for f in files
     if f.endswith('.cpp')
 ]
 BINDINGS_FILE = os.path.join(SOURCE_DIR, 'bindings.cpp')
 BINDINGS_GENERATOR = os.path.join(SOURCE_DIR, 'bindings.cpp.js')
 BINDINGS_OUTPUT = os.path.join(SOURCE_DIR, 'bindings.js')
-COMPILER_OUTPUT = './lib/compiled.js'
+COMPILER_OUTPUT = os.path.join(BASE_DIR, 'lib', 'compiled.js')
 GENERATION_PARAMS = {
     'SHELL_FILE': "'%s'" % os.path.abspath(os.path.join(SOURCE_DIR,
                                                         'shell.js')),
     'ASM_JS': 2,  # "almost asm"
     'TOTAL_MEMORY': 16*1024*1024,
     'TOTAL_STACK': 1*1024*1024,
     'ALLOW_MEMORY_GROWTH': 1,
     'NO_EXIT_RUNTIME': 1,