Bug #388615 - optimize FEATURES=prelink-checksums

Only spawn prelink if the file has an ELF header.

diff --git a/pym/portage/checksum.py b/pym/portage/checksum.py
index e0bff2ada1ea8e0a882a5292466d54c391984299..8e5abfff219a9aa57d46c93cdc18d7ca26b43ea3 100644 (file)
--- a/pym/portage/checksum.py
+++ b/pym/portage/checksum.py
@@ -16,6 +16,21 @@ import tempfile
 hashfunc_map = {}
 hashorigin_map = {}
 
+def _open_file(filename):
+       try:
+               return open(_unicode_encode(filename,
+                       encoding=_encodings['fs'], errors='strict'), 'rb')
+       except IOError as e:
+               func_call = "open('%s')" % filename
+               if e.errno == errno.EPERM:
+                       raise portage.exception.OperationNotPermitted(func_call)
+               elif e.errno == errno.EACCES:
+                       raise portage.exception.PermissionDenied(func_call)
+               elif e.errno == errno.ENOENT:
+                       raise portage.exception.FileNotFound(filename)
+               else:
+                       raise
+
 class _generate_hash_function(object):
 
        __slots__ = ("_hashobject",)
@@ -33,19 +48,7 @@ class _generate_hash_function(object):
                @type filename: String
                @return: The hash and size of the data
                """
-               try:
-                       f = open(_unicode_encode(filename,
-                               encoding=_encodings['fs'], errors='strict'), 'rb')
-               except IOError as e:
-                       func_call = "open('%s')" % filename
-                       if e.errno == errno.EPERM:
-                               raise portage.exception.OperationNotPermitted(func_call)
-                       elif e.errno == errno.EACCES:
-                               raise portage.exception.PermissionDenied(func_call)
-                       elif e.errno == errno.ENOENT:
-                               raise portage.exception.FileNotFound(filename)
-                       else:
-                               raise
+               f = _open_file(filename)
                blocksize = HASHING_BLOCKSIZE
                data = f.read(blocksize)
                size = 0
@@ -156,6 +159,15 @@ if os.path.exists(PRELINK_BINARY):
                prelink_capable=1
        del results
 
+def is_prelinkable_elf(filename):
+       f = _open_file(filename)
+       try:
+               magic = f.read(17)
+       finally:
+               f.close()
+       return (len(magic) == 17 and magic.startswith(b'\x7fELF') and
+               magic[16] in (b'\x02', b'\x03')) # 2=ET_EXEC, 3=ET_DYN
+
 def perform_md5(x, calc_prelink=0):
        return perform_checksum(x, "MD5", calc_prelink)[0]
 
@@ -263,7 +275,8 @@ def perform_checksum(filename, hashname="MD5", calc_prelink=0):
        myfilename = filename
        prelink_tmpfile = None
        try:
-               if calc_prelink and prelink_capable:
+               if (calc_prelink and prelink_capable and
+                   is_prelinkable_elf(filename)):
                        # Create non-prelinked temporary file to checksum.
                        # Files rejected by prelink are summed in place.
                        try: