Merge branch 'public/build/multiarchsimple' of git://trac.sagemath.or…

…g/sage into public/refactoring/pytest-numerical-backends

src/sage/env.py

@@ -28,14 +28,15 @@
 #                  https://www.gnu.org/licenses/
 # ****************************************************************************
 
+from typing import List, Optional
 
 import sage
-import glob
 import os
 import socket
 import sys
 import sysconfig
 from . import version
+from pathlib import Path
 
 
 # All variables set by var() appear in this SAGE_ENV dict and also
@@ -208,7 +209,7 @@ def var(key, *fallbacks, **kwds):
 var('SAGE_IMPORTALL', 'yes')
 
 
-def _get_shared_lib_filename(libname, *additional_libnames):
+def _get_shared_lib_path(*libnames: str) -> Optional[str]:
     """
     Return the full path to a shared library file installed in
     ``$SAGE_LOCAL/lib`` or the directories associated with the
@@ -226,78 +227,75 @@ def _get_shared_lib_filename(libname, *additional_libnames):
     For distributions like Debian that use a multiarch layout, we also try the
     multiarch lib paths (i.e. ``/usr/lib/<arch>/``).
 
-    This returns ``None`` if the file does not exist.
+    This returns ``None`` if no matching library file could be found.
 
     EXAMPLES::
 
         sage: import sys
         sage: from fnmatch import fnmatch
-        sage: from sage.env import _get_shared_lib_filename
-        sage: lib_filename = _get_shared_lib_filename("Singular",
-        ....:                                         "singular-Singular")
+        sage: from sage.env import _get_shared_lib_path
+        sage: lib_filename = _get_shared_lib_path("Singular", "singular-Singular")
         sage: if sys.platform == 'cygwin':
         ....:     pattern = "*/cygSingular-*.dll"
         ....: elif sys.platform == 'darwin':
-        ....:     pattern = "*/libSingular.dylib"
+        ....:     pattern = "*/libSingular-*.dylib"
         ....: else:
-        ....:     pattern = "*/lib*Singular.so"
-        sage: fnmatch(lib_filename, pattern)
+        ....:     pattern = "*/lib*Singular-*.so"
+        sage: fnmatch(str(lib_filename), pattern)
         True
-        sage: _get_shared_lib_filename("an_absurd_lib") is None
+        sage: _get_shared_lib_path("an_absurd_lib") is None
         True
     """
 
-    for libname in (libname,) + additional_libnames:
+    for libname in libnames:
+        search_directories: List[Path] = []
+        patterns: List[str] = []
         if sys.platform == 'cygwin':
-            # Later down we take the last matching DLL found, so search
-            # SAGE_LOCAL second so that it takes precedence
-            bindirs = [
-                sysconfig.get_config_var('BINDIR'),
-                os.path.join(SAGE_LOCAL, 'bin')
+            # Later down we take the first matching DLL found, so search
+            # SAGE_LOCAL first so that it takes precedence
+            search_directories = [
+                Path(SAGE_LOCAL) / 'bin',
+                Path(sysconfig.get_config_var('BINDIR')),
             ]
-            pats = ['cyg{}.dll'.format(libname), 'cyg{}-*.dll'.format(libname)]
-            filenames = []
-            for bindir in bindirs:
-                for pat in pats:
-                    filenames += glob.glob(os.path.join(bindir, pat))
-
-            # Note: This is not very robust, since if there are multi DLL
+            # Note: The following is not very robust, since if there are multible
             # versions for the same library this just selects one more or less
-            # at arbitrary.  However, practically speaking, on Cygwin, there
+            # at arbitrary. However, practically speaking, on Cygwin, there
             # will only ever be one version
-            if filenames:
-                return filenames[-1]
+            patterns = [f'cyg{libname}.dll', f'cyg{libname}-*.dll']
         else:
             if sys.platform == 'darwin':
                 ext = 'dylib'
             else:
                 ext = 'so'
 
-            libdirs = [
-                os.path.join(SAGE_LOCAL, 'lib'),
-                sysconfig.get_config_var('LIBDIR')
-            ]
-            multilib = sysconfig.get_config_var('MULTILIB')
-            if multilib:
-                libdirs.insert(1, os.path.join(libdirs[0], multilib))
+            search_directories = [Path(SAGE_LOCAL) / 'lib']
+            libdir = sysconfig.get_config_var('LIBDIR')
+            if libdir is not None:
+                libdir = Path(libdir)
+                search_directories.append(libdir)
+
+                multiarchlib = sysconfig.get_config_var('MULTIARCH')
+                if multiarchlib is not None: 
+                    search_directories.append(libdir / multiarchlib),
 
-            for libdir in libdirs:
-                basename = 'lib{}.{}'.format(libname, ext)
-                filename = os.path.join(libdir, basename)
-                if os.path.exists(filename):
-                    return filename
+            patterns = [f'lib{libname}.{ext}']
+
+        for directory in search_directories:
+            for pattern in patterns:
+                path = next(directory.glob(pattern), None)
+                if path is not None:
+                    return str(path.resolve())
 
     # Just return None if no files were found
     return None
 
-
 # locate singular shared object
 # On Debian it's libsingular-Singular so try that as well
-SINGULAR_SO = _get_shared_lib_filename('Singular', 'singular-Singular')
+SINGULAR_SO = _get_shared_lib_path('Singular', 'singular-Singular')
 var('SINGULAR_SO', SINGULAR_SO)
 
 # locate libgap shared object
-GAP_SO= _get_shared_lib_filename('gap','')
+GAP_SO = _get_shared_lib_path('gap')
 var('GAP_SO', GAP_SO)
 
 # post process

src/sage/libs/gap/util.pyx

@@ -227,6 +227,7 @@ cdef initialize():
     # global symbol table
     # Note: we could use RTLD_NOLOAD and avoid the subsequent dlclose() but
     # this isn't portable
+
     cdef void* handle
     libgapname = str_to_bytes(sage.env.GAP_SO)
     handle = dlopen(libgapname, RTLD_NOW | RTLD_GLOBAL)

src/sage/libs/singular/singular.pyx

@@ -771,20 +771,15 @@ cdef init_libsingular():
     from sage.env import SINGULAR_SO
     if not SINGULAR_SO or not os.path.exists(SINGULAR_SO):
         raise RuntimeError(
-            "libSingular not found--a working Singular install in $SAGE_LOCAL "
+            "libSingular not found--a working Singular install "
             "is required for Sage to work")
 
-    lib = SINGULAR_SO
-
-    if not os.path.exists(lib):
-        raise ImportError("cannot locate Singular library ({})".format(lib))
-
-    lib = str_to_bytes(lib, FS_ENCODING, "surrogateescape")
+    lib = str_to_bytes(SINGULAR_SO, FS_ENCODING, "surrogateescape")
 
     handle = dlopen(lib, RTLD_GLOBAL|RTLD_LAZY)
     if not handle:
         err = dlerror()
-        raise ImportError("cannot load Singular library ({})".format(err))
+        raise ImportError(f"cannot load Singular library from {SINGULAR_SO} ({err})")
 
     # load SINGULAR
     siInit(lib)