glibc: add package (#39695)

lib/spack/spack/util/elf.py

@@ -432,6 +432,47 @@ def get_rpaths(path):
     return rpath.split(":")
 
 
+def delete_rpath(path):
+    """Modifies a binary to remove the rpath. It zeros out the rpath string
+    and also drops the DT_R(UN)PATH entry from the dynamic section, so it doesn't
+    show up in 'readelf -d file', nor in 'strings file'."""
+    with open(path, "rb+") as f:
+        elf = parse_elf(f, interpreter=False, dynamic_section=True)
+
+        if not elf.has_rpath:
+            return
+
+        # Zero out the rpath *string* in the binary
+        new_rpath_string = b"\x00" * len(elf.dt_rpath_str)
+        rpath_offset = elf.pt_dynamic_strtab_offset + elf.rpath_strtab_offset
+        f.seek(rpath_offset)
+        f.write(new_rpath_string)
+
+        # Next update the dynamic array
+        f.seek(elf.pt_dynamic_p_offset)
+        dynamic_array_fmt = elf.byte_order + ("qQ" if elf.is_64_bit else "lL")
+        dynamic_array_size = calcsize(dynamic_array_fmt)
+        new_offset = elf.pt_dynamic_p_offset  # points to the new dynamic array
+        old_offset = elf.pt_dynamic_p_offset  # points to the current dynamic array
+        for _ in range(elf.pt_dynamic_p_filesz // dynamic_array_size):
+            data = read_exactly(f, dynamic_array_size, "Malformed dynamic array entry")
+            tag, _ = unpack(dynamic_array_fmt, data)
+
+            # Overwrite any entry that is not DT_RPATH or DT_RUNPATH, including DT_NULL
+            if tag != ELF_CONSTANTS.DT_RPATH and tag != ELF_CONSTANTS.DT_RUNPATH:
+                if new_offset != old_offset:
+                    f.seek(new_offset)
+                    f.write(data)
+                    f.seek(old_offset + dynamic_array_size)
+                new_offset += dynamic_array_size
+
+            # End of the dynamic array
+            if tag == ELF_CONSTANTS.DT_NULL:
+                break
+
+            old_offset += dynamic_array_size
+
+
 def replace_rpath_in_place_or_raise(path, substitutions):
     regex = re.compile(b"|".join(re.escape(p) for p in substitutions.keys()))