gis: Now use ctypes.util.find_library to get the C library names. This is preferrable to manually specifying the different library naming schemes used by different platforms/distributions.

git-svn-id: http://code.djangoproject.com/svn/django/branches/gis@8012 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/contrib/gis/gdal/libgdal.py

@@ -6,28 +6,35 @@ from django.contrib.gis.gdal.error import OGRException
 # Custom library path set?
 try:
     from django.conf import settings
-    lib_name = settings.GDAL_LIBRARY_PATH
+    lib_path = settings.GDAL_LIBRARY_PATH
 except (AttributeError, EnvironmentError, ImportError):
-    lib_name = None
+    lib_path = None
 
-if lib_name:
-    pass
+if lib_path:
+    lib_names = None
 elif os.name == 'nt':
     # Windows NT shared library
-    lib_name = 'gdal15.dll'
+    lib_names = ['gdal15']
 elif os.name == 'posix':
-    platform = os.uname()[0]
-    if platform == 'Darwin':
-        # Mac OSX shared library
-        lib_name = 'libgdal.dylib'
-    else: 
-        # Attempting to use .so extension for all other platforms.
-        lib_name = 'libgdal.so'
+    # *NIX library names.
+    lib_names = ['gdal', 'gdal1.5.0']
 else:
     raise OGRException('Unsupported OS "%s"' % os.name)
 
+# Using the ctypes `find_library` utility  to find the 
+# path to the GDAL library from the list of library names.
+if lib_names:
+    for lib_name in lib_names:
+        lib_path = find_library(lib_name)
+        if not lib_path is None: break
+        
+if lib_path is None:
+    raise OGRException('Could not find the GDAL library (tried "%s"). '
+                       'Try setting GDAL_LIBRARY_PATH in your settings.' % 
+                       '", "'.join(lib_names))
+
 # This loads the GDAL/OGR C library
-lgdal = CDLL(lib_name)
+lgdal = CDLL(lib_path)
 
 # On Windows, the GDAL binaries have some OSR routines exported with 
 # STDCALL, while others are not.  Thus, the library will also need to 

django/contrib/gis/geos/libgeos.py

@@ -8,6 +8,7 @@
 """
 import atexit, os, re, sys
 from ctypes import c_char_p, Structure, CDLL, CFUNCTYPE, POINTER
+from ctypes.util import find_library
 from django.contrib.gis.geos.error import GEOSException
 
 # NumPy supported?
@@ -20,33 +21,41 @@ except ImportError:
 # Custom library path set?
 try:
     from django.conf import settings
-    lib_name = settings.GEOS_LIBRARY_PATH
+    lib_path = settings.GEOS_LIBRARY_PATH
 except (AttributeError, EnvironmentError, ImportError):
-    lib_name = None
+    lib_path = None
 
-# Setting the appropriate name for the GEOS-C library, depending on which
-# OS and POSIX platform we're running.
-if lib_name:
-    pass
+# Setting the appropriate names for the GEOS-C library.
+if lib_path:
+    lib_names = None
 elif os.name == 'nt':
-    # Windows NT library
-    lib_name = 'libgeos_c-1.dll'
+    # Windows NT libraries
+    lib_names = ['libgeos_c-1']
 elif os.name == 'posix':
-    platform = os.uname()[0] # Using os.uname()
-    if platform == 'Darwin':
-        # Mac OSX Shared Library (Thanks Matt!)
-        lib_name = 'libgeos_c.dylib'
-    else:
-        # Attempting to use the .so extension for all other platforms
-        lib_name = 'libgeos_c.so'
+    # *NIX libraries
+    lib_names = ['geos_c']
 else:
     raise GEOSException('Unsupported OS "%s"' % os.name)
 
+# Using the ctypes `find_library` utility to find the the path to the GEOS 
+# shared library.  This is better than manually specifiying each library name 
+# and extension (e.g., libgeos_c.[so|so.1|dylib].).
+if lib_names: 
+    for lib_name in lib_names:
+        lib_path = find_library(lib_name)
+        if not lib_path is None: break
+
+# No GEOS library could be found.
+if lib_path is None: 
+    raise GEOSException('Could not find the GEOS library (tried "%s"). '
+                        'Try setting GEOS_LIBRARY_PATH in your settings.' % 
+                        '", "'.join(lib_names))
+
 # Getting the GEOS C library.  The C interface (CDLL) is used for
 #  both *NIX and Windows.
 # See the GEOS C API source code for more details on the library function calls:
 #  http://geos.refractions.net/ro/doxygen_docs/html/geos__c_8h-source.html
-lgeos = CDLL(lib_name)
+lgeos = CDLL(lib_path)
 
 # The notice and error handler C function callback definitions.
 #  Supposed to mimic the GEOS message handler (C below):

django/contrib/gis/utils/geoip.py

@@ -40,6 +40,7 @@
 """
 import os, re
 from ctypes import c_char_p, c_float, c_int, Structure, CDLL, POINTER
+from ctypes.util import find_library
 from django.conf import settings
 if not settings._target: settings.configure()
 
@@ -47,26 +48,24 @@ if not settings._target: settings.configure()
 GEOIP_SETTINGS = dict((key, getattr(settings, key)) 
                       for key in ('GEOIP_PATH', 'GEOIP_LIBRARY_PATH', 'GEOIP_COUNTRY', 'GEOIP_CITY')
                       if hasattr(settings, key))
-lib_name = GEOIP_SETTINGS.get('GEOIP_LIBRARY_PATH', None)
+lib_path = GEOIP_SETTINGS.get('GEOIP_LIBRARY_PATH', None)
 
 # GeoIP Exception class.
 class GeoIPException(Exception): pass
 
 # The shared library for the GeoIP C API.  May be downloaded
 #  from http://www.maxmind.com/download/geoip/api/c/
-if lib_name:
-    pass
-elif os.name == 'nt':
-    lib_name = 'libGeoIP.dll'
-elif os.name == 'posix':
-    platform = os.uname()[0]
-    if platform == 'Darwin':
-        lib_name = 'libGeoIP.dylib'
+if lib_path:
+    lib_name = None
 else:
-        lib_name = 'libGeoIP.so'
-else:
-    raise GeoIPException('Unknown POSIX platform "%s"' % platform)
-lgeoip = CDLL(lib_name)
+    # TODO: Is this really the library name for Windows?
+    lib_name = 'GeoIP'
+
+# Getting the path to the GeoIP library.
+if lib_name: lib_path = find_library(lib_name)
+if lib_path is None: raise GeoIPException('Could not find the GeoIP library (tried "%s"). '
+                                          'Try setting GEOIP_LIBRARY_PATH in your settings.' % lib_name)
+lgeoip = CDLL(lib_path)
 
 # Regular expressions for recognizing IP addresses and the GeoIP
 # free database editions.