search for libblosc2 with pkg-config if not in the python blosc2 inst…

…allation

setup.py

@@ -97,11 +97,12 @@ def get_blosc2_version(headername):
 
 
 def get_blosc2_directories():
-    """Get Blosc2 directories for the C library by using wheel metadata"""
+    """Get Blosc2 directories for the C library"""
     try:
         import blosc2
     except ModuleNotFoundError:
         raise EnvironmentError("Cannot import the blosc2 requirement")
+    # The published wheels package the c-blosc2 library directly
     version = blosc2.__version__
     basepath = Path(os.path.dirname(blosc2.__file__))
     recinfo = basepath.parent / f'blosc2-{version}.dist-info' / 'RECORD'
@@ -111,10 +112,18 @@ def get_blosc2_directories():
             library_path = Path(os.path.abspath(basepath.parent /
                                                 Path(line[:line.find('libblosc2')])))
             break
-    if not library_path:
-        raise NotADirectoryError("Library directory not found for blosc2!")
+    if library_path:
+        include_path = library_path.parent / 'include'
+    else:
+        # Linux distributions like to package the library separately, search by pkg-config
+        try:
+            cmd = [PKG_CONFIG, '--variable=libdir', 'blosc2']
+            library_path = Path(subprocess.check_output(cmd, text=True).strip())
+            cmd = [PKG_CONFIG, '--variable=includedir', 'blosc2']
+            include_path = Path(subprocess.check_output(cmd, text=True).strip())
+        except CalledProcessError as e:
+            raise NotADirectoryError("Library directory not found for blosc2!") from e
 
-    include_path = library_path.parent / 'include'
     if not os.path.isfile(include_path / 'blosc2.h'):
         install_path = os.path.abspath(library_path.parent)
         raise NotADirectoryError(
@@ -841,7 +850,7 @@ def find_runtime_path(self, locations=default_runtime_dirs):
                         shared_libs = glob.glob(str(libdir) + '/libblosc2*.dylib')
                         for lib in shared_libs:
                             shutil.copy(lib, dll_dir)
-                        
+
                 else:
                     copy_libs += ['libblosc2.dll']
                     dll_dir = 'C:\\Miniconda\\envs\\build\\Library\\bin'