external/subpack/lang/python/python3/patches/024-musl-find_library.patch

https://bugs.python.org/issue21622

Based on the patch from Alpine Linux
https://git.alpinelinux.org/aports/tree/main/python2/musl-find_library.patch

--- a/Lib/ctypes/util.py
+++ b/Lib/ctypes/util.py
@@ -92,6 +92,8 @@ elif sys.platform.startswith("aix"):
 elif os.name == "posix":
     # Andreas Degert's find functions, using gcc, /sbin/ldconfig, objdump
     import re, tempfile
+    from glob import glob
+    musl_ldso = glob('/lib/ld-musl-*.so.1')
 
     def _is_elf(filename):
         "Return True if the given file is an ELF file"
@@ -265,6 +267,57 @@ elif os.name == "posix":
         def find_library(name, is64 = False):
             return _get_soname(_findLib_crle(name, is64) or _findLib_gcc(name))
 
+    elif musl_ldso and os.path.isfile(musl_ldso[0]):
+
+        def _is_elf(filepath):
+            try:
+                with open(filepath, 'rb') as fh:
+                    return fh.read(4) == b'\x7fELF'
+            except:
+                return False
+
+        def find_library(name):
+            # absolute name?
+            if os.path.isabs(name):
+                if _is_elf(name):
+                    return name
+                else:
+                    return None
+
+            # special case for unified standard libs
+            stdlibs = ['libcrypt.so', 'libdl.so', 'libm.so', 'libpthread.so', 'libresolv.so', 'librt.so', 'libutil.so', 'libxnet.so']
+            if name in stdlibs:
+                name = 'libc.so'
+            elif ('lib' + name + '.so') in stdlibs:
+                name = 'c'
+
+            paths = []
+            # read path list from /etc/ld-musl-$(ARCH).path
+            path_list = musl_ldso[0].replace('/lib/', '/etc/').replace('.so.1', '.path')
+            try:
+                with open(path_list, 'r') as fh:
+                    paths = [path for line in fh for path in line.rstrip('\n').split(':') if path]
+            except:
+                paths = []
+            # default path list if /etc/ld-musl-$(ARCH).path is empty or does not exist
+            if not paths:
+                paths = ['/lib', '/usr/local/lib', '/usr/lib']
+
+            # prepend paths from LD_LIBRARY_PATH
+            if 'LD_LIBRARY_PATH' in os.environ:
+                paths = os.environ['LD_LIBRARY_PATH'].split(':') + paths
+
+            for d in paths:
+                f = os.path.join(d, name)
+                if _is_elf(f):
+                    return os.path.basename(f)
+
+                prefix = os.path.join(d, 'lib'+name)
+                for suffix in ['.so', '.so.*']:
+                    for f in glob('{0}{1}'.format(prefix, suffix)):
+                        if _is_elf(f):
+                            return os.path.basename(f)
+
     else:
 
         def _findSoname_ldconfig(name):