From 79e840fc4061b8483c1e580b98e18ab31869b063 Mon Sep 17 00:00:00 2001
From: Tristan Gingold <tgingold@free.fr>
Date: Thu, 20 Jun 2019 19:01:30 +0200
Subject: libghdl/__init__.py: rework prefix search.

---
 python/libghdl/__init__.py | 78 ++++++++++++++++++++++++++++++++--------------
 1 file changed, 55 insertions(+), 23 deletions(-)

diff --git a/python/libghdl/__init__.py b/python/libghdl/__init__.py
index 97b7acc82..6f55d666f 100644
--- a/python/libghdl/__init__.py
+++ b/python/libghdl/__init__.py
@@ -1,6 +1,6 @@
 import ctypes
 from os import environ
-from os.path import dirname, join
+from os.path import dirname, join, exists
 from shutil import which
 from libghdl.config import __libghdl__
 
@@ -9,29 +9,60 @@ def _to_char_p(arg):
     return ctypes.c_char_p(arg), len(arg)
 
 
-def get_ghdl_path():
-    _dir = None
-    for envvar in [environ.get(item) for item in ['GHDL_BIN_PATH', 'VUNIT_GHDL_PATH']]:
-        if envvar:
-            _dir = envvar
-            break
-    if not _dir:
-        _dir = which(environ.get('GHDL', 'ghdl'))
-    if _dir:
-        _dir = join(dirname(_dir), '..', 'lib')
-    return _dir
-
-
-_basedir = get_ghdl_path() or dirname(__file__)
-
-libghdl = ctypes.CDLL(join(_basedir, __libghdl__))
+def check_libghdl_libdir(libdir):
+    """Return libghdl path in :param libdir" if found or None"""
+    if libdir is None:
+        return None
+    # print('libghdl: check in {}'.format(libdir))
+    res = join(libdir, __libghdl__)
+    if exists(res):
+        return res
+    return None
+
+def check_libghdl_bindir(bindir):
+    """Return libghdl path in :param bindir" if found or None"""
+    if bindir is None:
+        return None
+    return check_libghdl_libdir(join(bindir, '..', 'lib'))
+
+def get_libghdl_path():
+    """Locate the directory where the shared library is"""
+    # Try VUNIT_GHDL_PATH (path of the ghdl binary when using VUnit).
+    r = check_libghdl_bindir (environ.get('VUNIT_GHDL_PATH'))
+    if r is not None:
+        return r
+    # Try GHDL (name/path of the ghdl binary)
+    r = environ.get('GHDL', 'ghdl')
+    r = which(r)
+    if r is not None:
+        r = check_libghdl_bindir(dirname(r))
+        if r is not None:
+            return r
+    # Try within libghdl/ python installation
+    r = __file__
+    r = check_libghdl_bindir(dirname(r))
+    if r is not None:
+        return r
+    # Try when running from the build directory
+    r = join(dirname(__file__), '..', '..', 'lib')
+    r = check_libghdl_libdir(r)
+    if r is not None:
+        return r
+    # Failed.
+    return None
+
+libghdl_path = get_libghdl_path()
+
+if libghdl_path is None:
+    raise Exception('Cannot find libghdl')
+
+libghdl = ctypes.CDLL(libghdl_path)
 
 libghdl.libghdl_init()
 
 
 def set_option(opt):
-    arg = _to_char_p(opt)
-    return libghdl.libghdl__set_option(arg[0], arg[1])
+    return libghdl.libghdl__set_option(*_to_char_p(opt))
 
 
 def analyze_init():
@@ -39,9 +70,10 @@ def analyze_init():
 
 
 def analyze_file(fname):
-    arg = _to_char_p(fname)
-    return libghdl.libghdl__analyze_file(arg[0], arg[1])
+    return libghdl.libghdl__analyze_file(*_to_char_p(fname))
 
 
-_prefix = environ.get("LIBGHDL_PREFIX") or '--PREFIX=%s' % join(_basedir, 'ghdl')
-set_option(_prefix.encode('utf-8'))
+if False:
+    _prefix = environ.get("LIBGHDL_PREFIX") or '--PREFIX=%s' % join(dirname(libghdl_path), 'ghdl')
+    print('ghdl prefix: {}'.format(_prefix))
+    set_option(_prefix.encode('utf-8'))
-- 
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