diff --git a/.github/workflows/scripts/db.sh b/.github/workflows/scripts/db.sh
index 1b69807..82ad251 100755
--- a/.github/workflows/scripts/db.sh
+++ b/.github/workflows/scripts/db.sh
@@ -73,7 +73,7 @@
 		# Looking for the failing directories and packing them
 		# example of line from which the failing fuzzer directory gets extracted:
 		#   - Makefile:87: recipe for target '000-db-init/000-init-db/run.xc7a100tfgg676-1.ok' failed --> fuzzers/000-db-init
-		grep -Po "recipe for target '\K(.*)(?=\/run\..*\.ok')" $tmp | sed -e 's/^/fuzzers\//' | xargs tar -zcf fuzzers/fails.tgz
+		grep -Po "recipe for target '\K(.*)(?=\/run.*\.ok')" $tmp | sed -e 's/^/fuzzers\//' | xargs tar -zcf fuzzers/fails.tgz
 		echo "----------------------------------------"
 		echo "A failure occurred during Database build."
 		echo "----------------------------------------"
diff --git a/prjxray/bitfilter.py b/prjxray/bitfilter.py
index 66a1c98..f7184bd 100644
--- a/prjxray/bitfilter.py
+++ b/prjxray/bitfilter.py
@@ -8,6 +8,9 @@
 # https://opensource.org/licenses/ISC
 #
 # SPDX-License-Identifier: ISC
+
+from prjxray.util import OpenSafeFile
+
 class Bitfilter(object):
     def __init__(
             self, frames_to_include=None, frames_to_exclude=[],
diff --git a/prjxray/bitstream.py b/prjxray/bitstream.py
index 83b264d..b120b5e 100644
--- a/prjxray/bitstream.py
+++ b/prjxray/bitstream.py
@@ -10,7 +10,7 @@
 # SPDX-License-Identifier: ISC
 import json
 import os
-from prjxray import util
+from prjxray.util import block_type_s2i
 
 # Break frames into WORD_SIZE bit words.
 WORD_SIZE_BITS = 32
@@ -119,7 +119,7 @@
     """Convert a deconstructed address to a 32 bit word"""
     # https://www.xilinx.com/support/documentation/user_guides/ug470_7Series_Config.pdf
     ret = 0
-    ret |= util.block_type_s2i[block_type] << 23
+    ret |= block_type_s2i[block_type] << 23
     ret |= {"top": 0, "bottom": 1}[top_bottom] << 22
     ret |= cfg_row << 17
     ret |= cfg_col << 7
diff --git a/prjxray/lib.py b/prjxray/lib.py
index 27dd236..20f1aa7 100644
--- a/prjxray/lib.py
+++ b/prjxray/lib.py
@@ -14,6 +14,8 @@
 import re
 from collections import namedtuple
 
+from prjxray.util import OpenSafeFile
+
 
 def read_root_csv(root_dir):
     """ Reads root.csv from raw db directory.
@@ -24,7 +26,7 @@
     tiles = {}
     nodes = []
 
-    with open(os.path.join(root_dir, 'root.csv')) as f:
+    with OpenSafeFile(os.path.join(root_dir, 'root.csv')) as f:
         for d in csv.DictReader(f):
             if d['filetype'] == 'tile':
                 if d['subtype'] not in tiles:
@@ -123,17 +125,17 @@
         import pyjson5 as json5
         import progressbar
         for node in progressbar.progressbar(nodes):
-            with open(node) as f:
+            with OpenSafeFile(node) as f:
                 node_wires = json5.load(f)
                 assert node_wires['node'] not in self.nodes
                 self.nodes[node_wires['node']] = node_wires['wires']
 
     def load_from_file(self, fname):
-        with open(fname, 'rb') as f:
+        with OpenSafeFile(fname, 'rb') as f:
             self.nodes = pickle.load(f)
 
     def save_to_file(self, fname):
-        with open(fname, 'wb') as f:
+        with OpenSafeFile(fname, 'wb') as f:
             pickle.dump(self.nodes, f)
 
     def site_pin_node_to_wires(self, tile, node):
diff --git a/prjxray/lms_solver.py b/prjxray/lms_solver.py
index d0fbb62..e68f566 100755
--- a/prjxray/lms_solver.py
+++ b/prjxray/lms_solver.py
@@ -54,6 +54,8 @@
 import numpy as np
 import numpy.linalg as linalg
 
+from prjxray.util import OpenSafeFile
+
 # =============================================================================
 
 
@@ -83,7 +85,7 @@
     segdata = None
     all_segdata = []
 
-    with open(file_name, "r") as fp:
+    with OpenSafeFile(file_name, "r") as fp:
         for line in fp.readlines():
             line = line.strip()
 
@@ -174,7 +176,7 @@
 
         lines.append(all_tags[r] + " " + " ".join(bits) + "\n")
 
-    with open(file_name, "w") as fp:
+    with OpenSafeFile(file_name, "w") as fp:
         for line in lines:
             fp.write(line)
 
@@ -702,7 +704,7 @@
     address_map = {}
 
     # Load tilegrid
-    with open(tilegrid_file, "r") as fp:
+    with OpenSafeFile(tilegrid_file, "r") as fp:
         tilegrid = json.load(fp)
 
     # Loop over tiles
@@ -982,7 +984,7 @@
 
     # Dump to CSV
     if args.x is not None:
-        with open(args.x, "w") as fp:
+        with OpenSafeFile(args.x, "w") as fp:
             dump_solution_to_csv(fp, tags_to_solve, bits_to_solve, X)
 
     # Dump results
diff --git a/prjxray/node_lookup.py b/prjxray/node_lookup.py
index 8b684f1..a6278ef 100644
--- a/prjxray/node_lookup.py
+++ b/prjxray/node_lookup.py
@@ -13,6 +13,7 @@
 import pyjson5 as json5
 import os.path
 
+from prjxray.util import OpenSafeFile
 
 def create_tables(conn):
     c = conn.cursor()
@@ -63,7 +64,7 @@
 
         nodes_processed = set()
         for node in progressbar.progressbar(nodes):
-            with open(node) as f:
+            with OpenSafeFile(node) as f:
                 node_wires = json5.load(f)
                 assert node_wires['node'] not in nodes_processed
                 nodes_processed.add(node_wires['node'])
diff --git a/prjxray/segmaker.py b/prjxray/segmaker.py
index 4d6795f..542fcc8 100644
--- a/prjxray/segmaker.py
+++ b/prjxray/segmaker.py
@@ -24,7 +24,7 @@
 '''
 
 import os, json, re
-from prjxray import util
+from prjxray.util import OpenSafeFile, get_db_root, get_fabric
 
 BLOCK_TYPES = set(('CLB_IO_CLK', 'BLOCK_RAM', 'CFG_CLB'))
 
@@ -85,12 +85,12 @@
     def __init__(self, bitsfile, verbose=None, db_root=None, fabric=None):
         self.db_root = db_root
         if self.db_root is None:
-            self.db_root = util.get_db_root()
+            self.db_root = get_db_root()
             assert self.db_root, "No db root specified."
 
         self.fabric = fabric
         if self.fabric is None:
-            self.fabric = util.get_fabric()
+            self.fabric = get_fabric()
             assert self.fabric, "No fabric specified."
 
         self.verbose = verbose if verbose is not None else os.getenv(
@@ -129,7 +129,7 @@
 
     def load_grid(self):
         '''Load self.grid holding tile addresses'''
-        with open(os.path.join(self.db_root, self.fabric, "tilegrid.json"),
+        with OpenSafeFile(os.path.join(self.db_root, self.fabric, "tilegrid.json"),
                   "r") as f:
             self.grid = json.load(f)
         assert "segments" not in self.grid, "Old format tilegrid.json"
@@ -152,7 +152,7 @@
         '''
         self.bits = dict()
         print("Loading bits from %s." % bitsfile)
-        with open(bitsfile, "r") as f:
+        with OpenSafeFile(bitsfile, "r") as f:
             for line in f:
                 # ex: bit_00020500_000_17
                 line = line.split("_")
@@ -446,7 +446,7 @@
             segments = self.segments_by_type[segtype]
             if segments:
                 print("Writing %s." % filename)
-                with open(filename, "w") as f:
+                with OpenSafeFile(filename, "w") as f:
                     for segname, segdata in sorted(segments.items()):
                         # seg 00020300_010
                         print("seg %s" % segname, file=f)
diff --git a/prjxray/tile.py b/prjxray/tile.py
index cb008a4..68da011 100644
--- a/prjxray/tile.py
+++ b/prjxray/tile.py
@@ -13,6 +13,7 @@
 import json
 from prjxray import lib
 from prjxray.timing import fast_slow_tuple_to_corners, RcElement
+from prjxray.util import OpenSafeFile
 
 TileDbs = namedtuple(
     'TileDbs', 'segbits block_ram_segbits ppips mask tile_type')
@@ -313,7 +314,7 @@
                     backward_timing=get_pip_timing(pip.get('dst_to_src')),
                 )
 
-        with open(self.tile_dbs.tile_type) as f:
+        with OpenSafeFile(self.tile_dbs.tile_type) as f:
             tile_type = json.load(f)
             assert self.tilename_upper == tile_type['tile_type']
             self.wires = get_wires(tile_type['wires'])
diff --git a/prjxray/tile_segbits.py b/prjxray/tile_segbits.py
index 8fd6b15..5564a4b 100644
--- a/prjxray/tile_segbits.py
+++ b/prjxray/tile_segbits.py
@@ -10,8 +10,8 @@
 # SPDX-License-Identifier: ISC
 from collections import namedtuple
 from prjxray import bitstream
-from prjxray import util
 from prjxray.grid_types import BlockType
+from prjxray.util import OpenSafeFile
 import enum
 
 
@@ -84,22 +84,16 @@
         self.feature_addresses = {}
 
         if tile_db.ppips is not None:
-            with open(tile_db.ppips) as f:
-                util.lock_file(f, 10)
+            with OpenSafeFile(tile_db.ppips) as f:
                 self.ppips = read_ppips(f)
-                util.unlock_file(f)
 
         if tile_db.segbits is not None:
-            with open(tile_db.segbits) as f:
-                util.lock_file(f, 10)
+            with OpenSafeFile(tile_db.segbits) as f:
                 self.segbits[BlockType.CLB_IO_CLK] = read_segbits(f)
-                util.unlock_file(f)
 
         if tile_db.block_ram_segbits is not None:
-            with open(tile_db.block_ram_segbits) as f:
-                util.lock_file(f, 10)
+            with OpenSafeFile(tile_db.block_ram_segbits) as f:
                 self.segbits[BlockType.BLOCK_RAM] = read_segbits(f)
-                util.unlock_file(f)
 
         for block_type in self.segbits:
             for feature in self.segbits[block_type]:
diff --git a/prjxray/tile_segbits_alias.py b/prjxray/tile_segbits_alias.py
index 1e8a379..2eb536e 100644
--- a/prjxray/tile_segbits_alias.py
+++ b/prjxray/tile_segbits_alias.py
@@ -21,6 +21,7 @@
 from prjxray import bitstream
 from prjxray.grid_types import Bits
 from prjxray.tile_segbits import read_ppips
+from prjxray.util import OpenSafeFile
 
 
 class TileSegbitsAlias(object):
@@ -67,7 +68,7 @@
         self.ppips = {}
 
         if tile_db.ppips is not None:
-            with open(tile_db.ppips) as f:
+            with OpenSafeFile(tile_db.ppips) as f:
                 self.ppips = read_ppips(f)
         self.tile_segbits = db.get_tile_segbits(self.alias_tile_type)
 
diff --git a/prjxray/util.py b/prjxray/util.py
index 5ce4550..bb2efb0 100644
--- a/prjxray/util.py
+++ b/prjxray/util.py
@@ -18,6 +18,49 @@
 from .roi import Roi
 
 
+def timeout_handler(signum, frame):
+    raise Exception("ERROR TIMEOUT: could not lock file")
+
+
+class OpenSafeFile:
+    """
+    Opens a file in a thread-safe mode, allowing for safe read and writes
+    to a file that can potentially be modified by multiple processes at
+    the same time.
+    """
+
+    def __init__(self, name, mode="r", timeout=10):
+        self.name = name
+        self.mode = mode
+        self.timeout = timeout
+
+        self.fd = None
+
+    def __enter__(self):
+        self.fd = open(self.name, self.mode)
+        self.lock_file()
+        return self.fd
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        self.unlock_file()
+        self.fd.close()
+
+    def lock_file(self):
+        assert self.fd is not None
+        try:
+            signal.signal(signal.SIGALRM, timeout_handler)
+            signal.alarm(self.timeout)
+            fcntl.flock(self.fd.fileno(), fcntl.LOCK_EX)
+            signal.alarm(0)
+        except Exception as e:
+            print(f"{e}: {self.name}")
+            exit(1)
+
+    def unlock_file(self):
+        assert self.fd is not None
+        fcntl.flock(self.fd.fileno(), fcntl.LOCK_UN)
+
+
 def get_db_root():
     # Used during tilegrid db bootstrap
     ret = os.getenv("XRAY_DATABASE_ROOT", None)
@@ -44,7 +87,7 @@
     filename = os.path.join(db_root, "mapping", "parts.yaml")
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
-    with open(filename, 'r') as stream:
+    with OpenSafeFile(filename, 'r') as stream:
         part_mapping = yaml.load(stream, Loader=yaml.FullLoader)
     part = part_mapping.get(part, None)
     assert part, "Part {} not found in {}".format(part, part_mapping)
@@ -53,7 +96,7 @@
 
 def set_part_information(db_root, information):
     filename = os.path.join(db_root, "mapping", "parts.yaml")
-    with open(filename, 'w+') as stream:
+    with OpenSafeFile(filename, 'w+') as stream:
         yaml.dump(information, stream)
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
@@ -63,7 +106,7 @@
     filename = os.path.join(file_path, "resources.yaml")
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
-    with open(filename, 'r') as stream:
+    with OpenSafeFile(filename, 'r') as stream:
         res_mapping = yaml.load(stream, Loader=yaml.FullLoader)
     res = res_mapping.get(part, None)
     assert res, "Part {} not found in {}".format(part, part_mapping)
@@ -72,7 +115,7 @@
 
 def set_part_resources(file_path, information):
     filename = os.path.join(file_path, "resources.yaml")
-    with open(filename, 'w+') as stream:
+    with OpenSafeFile(filename, 'w+') as stream:
         yaml.dump(information, stream)
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
@@ -83,7 +126,7 @@
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
     part = get_part_information(db_root, part)
-    with open(filename, 'r') as stream:
+    with OpenSafeFile(filename, 'r') as stream:
         device_mapping = yaml.load(stream, Loader=yaml.FullLoader)
     device = device_mapping.get(part['device'], None)
     assert device, "Device {} not found in {}".format(
@@ -95,7 +138,7 @@
     filename = os.path.join(db_root, "mapping", "devices.yaml")
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
-    with open(filename, 'r') as stream:
+    with OpenSafeFile(filename, 'r') as stream:
         device_mapping = yaml.load(stream, Loader=yaml.FullLoader)
     return device_mapping
 
@@ -104,7 +147,7 @@
     filename = os.path.join(db_root, "mapping", "parts.yaml")
     assert os.path.isfile(filename), \
         "Mapping file {} does not exists".format(filename)
-    with open(filename, 'r') as stream:
+    with OpenSafeFile(filename, 'r') as stream:
         part_mapping = yaml.load(stream, Loader=yaml.FullLoader)
     return part_mapping
 
@@ -255,11 +298,9 @@
 
 
 def parse_db_lines(fn):
-    with open(fn, "r") as f:
-        lock_file(f, 10)
+    with OpenSafeFile(fn, "r") as f:
         for line in f:
             yield line, parse_db_line(line)
-        unlock_file(f)
 
 
 def write_db_lines(fn, entries, track_origin=False):
@@ -272,11 +313,9 @@
             new_line = " ".join([tag] + sorted(bits))
         new_lines.append(new_line)
 
-    with open(fn, "w") as f:
-        lock_file(f, 10)
+    with OpenSafeFile(fn, "w") as f:
         for line in sorted(new_lines):
             print(line, file=f)
-        unlock_file(f)
 
 
 def parse_tagbit(x):
@@ -409,21 +448,3 @@
     parser.add_argument(
         '--no-' + dashed, dest=dest, action='store_false', **kwargs)
 
-
-def timeout_handler(signum, frame):
-    raise Exception("ERROR: could not lock file!")
-
-
-def lock_file(fd, timeout):
-    try:
-        signal.signal(signal.SIGALRM, timeout_handler)
-        signal.alarm(timeout)
-        fcntl.flock(fd.fileno(), fcntl.LOCK_EX)
-        signal.alarm(0)
-    except Exception as e:
-        print(e)
-        exit(1)
-
-
-def unlock_file(fd):
-    fcntl.flock(fd.fileno(), fcntl.LOCK_UN)
diff --git a/utils/bit2fasm.py b/utils/bit2fasm.py
index d36a0ba..103b377 100755
--- a/utils/bit2fasm.py
+++ b/utils/bit2fasm.py
@@ -16,9 +16,10 @@
 import os
 import fasm
 import fasm.output
-from prjxray.db import Database
 from prjxray import fasm_disassembler
 from prjxray import bitstream
+from prjxray.db import Database
+from prjxray.util import OpenSafeFile
 import subprocess
 import tempfile
 
@@ -41,7 +42,7 @@
     grid = db.grid()
     disassembler = fasm_disassembler.FasmDisassembler(db)
 
-    with open(bits_file) as f:
+    with OpenSafeFile(bits_file) as f:
         bitdata = bitstream.load_bitdata(f)
 
     model = fasm.output.merge_and_sort(
diff --git a/utils/create_timing_worksheet_db.py b/utils/create_timing_worksheet_db.py
index e6dd4cf..54ca7c7 100644
--- a/utils/create_timing_worksheet_db.py
+++ b/utils/create_timing_worksheet_db.py
@@ -21,6 +21,7 @@
         PassTransistor, IntristicDelay, RcElement, PvtCorner
 from prjxray.math_models import ExcelMathModel
 from prjxray.db import Database
+from prjxray.util import OpenSafeFile
 from prjxray import util
 
 FAST = PvtCorner.FAST
@@ -481,7 +482,7 @@
 def build_wire_filter(wire_filter):
     wires_to_include = set()
 
-    with open(wire_filter) as f:
+    with OpenSafeFile(wire_filter) as f:
         for l in f:
             wire = l.strip()
             if not wire:
@@ -514,7 +515,7 @@
 
     args = parser.parse_args()
 
-    with open(args.timing_json) as f:
+    with OpenSafeFile(args.timing_json) as f:
         timing = json.load(f)
 
     db = Database(args.db_root, args.part)
diff --git a/utils/dbfixup.py b/utils/dbfixup.py
index 0e3310d..8005e51 100755
--- a/utils/dbfixup.py
+++ b/utils/dbfixup.py
@@ -218,7 +218,7 @@
     lines = []
     llast = None
 
-    with open(fn_in, "r") as f:
+    with util.OpenSafeFile(fn_in, "r") as f:
         for line in f:
             # Hack: skip duplicate lines
             # This happens while merging a new multibit entry
@@ -327,7 +327,7 @@
     mask_db_file = "%s/mask_%s.db" % (db_root, mask_db)
 
     if os.path.exists(mask_db_file):
-        with open(mask_db_file, "r") as f:
+        with util.OpenSafeFile(mask_db_file, "r") as f:
             for line in f:
                 line = line.split()
                 assert len(line) == 2
@@ -340,7 +340,7 @@
         if not os.path.exists(seg_db_file):
             continue
 
-        with open(seg_db_file, "r") as f:
+        with util.OpenSafeFile(seg_db_file, "r") as f:
             for line in f:
                 line = line.split()
                 for bit in line[1:]:
@@ -353,7 +353,7 @@
                     bits.add(bit)
 
     if len(bits) > 0:
-        with open(mask_db_file, "w") as f:
+        with util.OpenSafeFile(mask_db_file, "w") as f:
             for bit in sorted(bits):
                 print("bit %s" % bit, file=f)
 
@@ -361,14 +361,15 @@
 def load_zero_db(fn):
     # Remove comments and convert to list of lines
     ret = []
-    for l in open(fn, "r"):
-        pos = l.find("#")
-        if pos >= 0:
-            l = l[0:pos]
-        l = l.strip()
-        if not l:
-            continue
-        ret.append(l)
+    with util.OpenSafeFile(fn, "r") as f:
+        for l in f:
+            pos = l.find("#")
+            if pos >= 0:
+                l = l[0:pos]
+            l = l.strip()
+            if not l:
+                continue
+            ret.append(l)
     return ret
 
 
@@ -535,11 +536,9 @@
         )
         changes += new_changes
 
-        with open(fn_out, "w") as f:
-            util.lock_file(f, 10)
+        with util.OpenSafeFile(fn_out, "w") as f:
             for line in sorted(lines):
                 print(line, file=f)
-            util.unlock_file(f)
 
         if changes is not None:
             seg_files += 1
@@ -654,7 +653,7 @@
     tag_groups = []
 
     # Load tag group specifications
-    with open(file_name, "r") as fp:
+    with util.OpenSafeFile(file_name, "r") as fp:
         for line in fp:
             line = line.strip()
 
diff --git a/utils/fasm2frames.py b/utils/fasm2frames.py
index fe384db..82ddc35 100755
--- a/utils/fasm2frames.py
+++ b/utils/fasm2frames.py
@@ -23,6 +23,7 @@
 from prjxray import fasm_assembler, util
 from prjxray.db import Database
 from prjxray.roi import Roi
+from prjxray.util import OpenSafeFile
 
 import sys
 
@@ -133,11 +134,11 @@
     bank_to_tile = defaultdict(lambda: set())
 
     if part is not None:
-        with open(os.path.join(db_root, part, "package_pins.csv"), "r") as fp:
+        with OpenSafeFile(os.path.join(db_root, part, "package_pins.csv"), "r") as fp:
             reader = csv.DictReader(fp)
             package_pins = [l for l in reader]
 
-        with open(os.path.join(db_root, part, "part.json"), "r") as fp:
+        with OpenSafeFile(os.path.join(db_root, part, "part.json"), "r") as fp:
             part_data = json.load(fp)
 
         for bank, loc in part_data["iobanks"].items():
@@ -167,7 +168,7 @@
 
     extra_features = []
     if roi:
-        with open(roi) as f:
+        with OpenSafeFile(roi) as f:
             roi_j = json.load(f)
         x1 = roi_j['info']['GRID_X_MIN']
         x2 = roi_j['info']['GRID_X_MAX']
diff --git a/utils/find_missing_segbits.py b/utils/find_missing_segbits.py
index 7f06227..a8085a3 100755
--- a/utils/find_missing_segbits.py
+++ b/utils/find_missing_segbits.py
@@ -24,6 +24,8 @@
 import os
 import re
 
+from prjxray.util import OpenSafeFile
+
 # =============================================================================
 
 
@@ -33,7 +35,7 @@
     PIP name strings. Names are formatted as <dst_wire>.<src_wire>
     """
 
-    with open(tile_file, "r") as fp:
+    with OpenSafeFile(tile_file, "r") as fp:
         root = json.load(fp)
         pips = root["pips"]
 
@@ -53,7 +55,7 @@
     """
     ppips = {}
 
-    with open(ppips_file, "r") as fp:
+    with OpenSafeFile(ppips_file, "r") as fp:
         for line in fp.readlines():
             line = line.split()
             if len(line) == 2:
@@ -70,7 +72,7 @@
     """
     segbits = []
 
-    with open(segbits_file, "r") as fp:
+    with OpenSafeFile(segbits_file, "r") as fp:
         for line in fp.readlines():
             line = line.split()
             if len(line) > 1:
diff --git a/utils/group.py b/utils/group.py
index 34fa198..b8f59b5 100755
--- a/utils/group.py
+++ b/utils/group.py
@@ -21,6 +21,8 @@
 import re
 import itertools
 
+from prjxray.util import OpenSafeFile
+
 # =============================================================================
 
 
@@ -34,7 +36,7 @@
     tag_groups = []
 
     # Load tag group specifications
-    with open(file_name, "r") as fp:
+    with OpenSafeFile(file_name, "r") as fp:
         for line in fp:
             line = line.strip()
 
@@ -89,7 +91,7 @@
 
     segbits = {}
 
-    with open(file_name, "r") as fp:
+    with OpenSafeFile(file_name, "r") as fp:
         for line in fp:
             line = line.strip()
             fields = line.split()
@@ -114,7 +116,7 @@
     Save segbits to a .db or .rdb file
     """
 
-    with open(file_name, "w") as fp:
+    with OpenSafeFile(file_name, "w") as fp:
         for tag, bits in segbits.items():
 
             if isinstance(bits, str):
diff --git a/utils/groupmask.py b/utils/groupmask.py
index 87da46c..504c86d 100644
--- a/utils/groupmask.py
+++ b/utils/groupmask.py
@@ -10,7 +10,7 @@
 # SPDX-License-Identifier: ISC
 
 import sys, os, re
-from prjxray import util
+from prjxray.util import OpenSafeFile, parse_db_lines, write_db_lines
 
 
 def index_masks(fn_in, groups_in):
@@ -21,7 +21,7 @@
         groups[group] = set()
 
     # Index bits
-    for line, (tag, bits, mode) in util.parse_db_lines(fn_in):
+    for line, (tag, bits, mode) in parse_db_lines(fn_in):
         assert not mode, "Unresolved tag: %s" % (line, )
         prefix = tag[0:tag.rfind(".")]
         group = groups.get(prefix, None)
@@ -42,7 +42,7 @@
 def apply_masks(fn_in, groups):
     """Add 0 entries ("!") to .db entries based on groups definition"""
     new_db = {}
-    for line, (tag, bits, mode) in util.parse_db_lines(fn_in):
+    for line, (tag, bits, mode) in parse_db_lines(fn_in):
         assert not mode, "Unresolved tag: %s" % (line, )
         prefix = tag[0:tag.rfind(".")]
         group = groups.get(prefix, None)
@@ -58,8 +58,9 @@
 
 def load_groups(fn):
     ret = []
-    for l in open(fn, "r"):
-        ret.append(l.strip())
+    with OpenSafeFile(fn, "r") as f:
+        for l in f:
+            ret.append(l.strip())
     return ret
 
 
@@ -67,7 +68,7 @@
     groups_in = load_groups(groups_fn)
     groups = index_masks(fn_in, groups_in)
     new_db = apply_masks(fn_in, groups)
-    util.write_db_lines(fn_out, new_db)
+    write_db_lines(fn_out, new_db)
 
 
 def main():
diff --git a/utils/info_md.py b/utils/info_md.py
index 00638e8..d5e6411 100755
--- a/utils/info_md.py
+++ b/utils/info_md.py
@@ -15,6 +15,7 @@
 import parse as format_parser
 import subprocess
 import sys
+
 """Module for generating the Info.md file found in the database directory."""
 
 info_md_header = """
diff --git a/utils/make_ports.py b/utils/make_ports.py
index 27eecda..ffe7637 100644
--- a/utils/make_ports.py
+++ b/utils/make_ports.py
@@ -23,6 +23,8 @@
 
 from collections import defaultdict
 
+from prjxray.util import OpenSafeFile
+
 
 def main():
 
@@ -49,7 +51,7 @@
     args = parser.parse_args()
 
     # Load pin dump
-    with open(args.csv, "r") as fp:
+    with OpenSafeFile(args.csv, "r") as fp:
         pin_dump = list(csv.DictReader(fp))
 
     # Group pins into ports
@@ -103,7 +105,7 @@
         port["width"] += 1
 
     # Write pin ports to a JSON file
-    with open(args.json, "w") as fp:
+    with OpenSafeFile(args.json, "w") as fp:
         json.dump(ports, fp, indent=1, sort_keys=True)
 
 
diff --git a/utils/makesdf.py b/utils/makesdf.py
index 6ba2180..bfb2e14 100644
--- a/utils/makesdf.py
+++ b/utils/makesdf.py
@@ -12,6 +12,7 @@
 import json
 import argparse
 
+from prjxray.util import OpenSafeFile
 
 def get_elems_count(timings, slice, site, bel_type):
     combinational = 0
@@ -113,7 +114,7 @@
 """
 )"""
 
-        with open(outdir + '/' + slice + '.sdf', "w") as fp:
+        with OpenSafeFile(outdir + '/' + slice + '.sdf', "w") as fp:
             fp.write(sdf)
 
 
@@ -125,7 +126,7 @@
 
     args = parser.parse_args()
 
-    with open(args.json, 'r') as fp:
+    with OpenSafeFile(args.json, 'r') as fp:
         timings = json.load(fp)
 
     produce_sdf(timings, args.sdf)
diff --git a/utils/maskview.py b/utils/maskview.py
index 16cf5b3..663377a 100755
--- a/utils/maskview.py
+++ b/utils/maskview.py
@@ -24,6 +24,8 @@
 import argparse
 import re
 
+from prjxray.util import OpenSafeFile
+
 # =============================================================================
 
 
@@ -32,7 +34,7 @@
     Read bits from a .db or .rdb file. Ignores tags and bit values.
     """
 
-    with open(file_name, "r") as fp:
+    with OpenSafeFile(file_name, "r") as fp:
         lines = fp.readlines()
 
     bits = set()
diff --git a/utils/parsedb.py b/utils/parsedb.py
index 157e416..72b8601 100755
--- a/utils/parsedb.py
+++ b/utils/parsedb.py
@@ -10,11 +10,12 @@
 # SPDX-License-Identifier: ISC
 
 import sys, re
-from prjxray import util
+from prjxray.util import OpenSafeFile, db_root_arg, parse_db_line
 
 
 def run(fnin, fnout=None, strict=False, verbose=False):
-    lines = open(fnin, 'r').read().split('\n')
+    with OpenSafeFile(fnin) as f:
+        lines = f.read().split('\n')
     tags = dict()
     bitss = dict()
     for line in lines:
@@ -24,7 +25,7 @@
         # TODO: figure out what to do with masks
         if line.startswith("bit "):
             continue
-        tag, bits, mode, _ = util.parse_db_line(line)
+        tag, bits, mode, _ = parse_db_line(line)
         if strict:
             if mode != "always":
                 assert not mode, "strict: got ill defined line: %s" % (line, )
@@ -39,7 +40,7 @@
             bitss[bits] = tag
 
     if fnout:
-        with open(fnout, "w") as fout:
+        with OpenSafeFile(fnout, "w") as fout:
             for line in sorted(lines):
                 line = line.strip()
                 if line == '':
@@ -53,7 +54,7 @@
     parser = argparse.ArgumentParser(
         description="Parse a db file, checking for consistency")
 
-    util.db_root_arg(parser)
+    db_root_arg(parser)
     parser.add_argument('--verbose', action='store_true', help='')
     parser.add_argument(
         '--strict',
diff --git a/utils/sdfmerge.py b/utils/sdfmerge.py
index 75ea7b5..c38365d 100644
--- a/utils/sdfmerge.py
+++ b/utils/sdfmerge.py
@@ -11,7 +11,9 @@
 
 import argparse
 import json
+
 from sdf_timing import sdfparse
+from prjxray.util import OpenSafeFile
 
 
 def merge(timings_list, site):
@@ -59,15 +61,16 @@
     timings_list = list()
 
     for sdf in args.sdfs:
-        with open(sdf, 'r') as fp:
+        with OpenSafeFile(sdf, 'r') as fp:
             timing = sdfparse.parse(fp.read())
             timings_list.append(timing)
 
     merged_sdf = merge(timings_list, args.site)
-    open(args.out, 'w').write(sdfparse.emit(merged_sdf, timescale='1ns'))
+    with OpenSafeFile(args.out, 'w') as fp:
+        fp.write(sdfparse.emit(merged_sdf, timescale='1ns'))
 
     if args.json is not None:
-        with open(args.json, 'w') as fp:
+        with OpenSafeFile(args.json, 'w') as fp:
             json.dump(merged_sdf, fp, indent=4, sort_keys=True)
 
 
diff --git a/utils/segprint.py b/utils/segprint.py
index 87e8ce7..35fba63 100755
--- a/utils/segprint.py
+++ b/utils/segprint.py
@@ -19,7 +19,7 @@
 import copy
 from prjxray import bitstream
 from prjxray import db as prjxraydb
-from prjxray import util
+from prjxray.util import OpenSafeFile, parse_tagbit, db_root_arg, part_arg
 
 
 class NoDB(Exception):
@@ -39,7 +39,7 @@
     verbose and print("process_db(%s): %s" % (tile_type, fns))
     for fn in fns:
         if fn:
-            with open(fn, "r") as f:
+            with OpenSafeFile(fn, "r") as f:
                 for line in f:
                     process(line)
 
@@ -61,7 +61,7 @@
                 return
             tagbits = []
         else:
-            tagbits = [util.parse_tagbit(x) for x in parts[1:]]
+            tagbits = [parse_tagbit(x) for x in parts[1:]]
 
         tags.append(list([name] + tagbits))
 
@@ -430,7 +430,7 @@
 
 def load_tiles(db_root, part):
     # TODO: Migrate to new tilegrid format via library.
-    with open("%s/%s/tilegrid.json" % (db_root, part), "r") as f:
+    with OpenSafeFile("%s/%s/tilegrid.json" % (db_root, part), "r") as f:
         tiles = json.load(f)
     return tiles
 
@@ -449,7 +449,8 @@
     db = prjxraydb.Database(db_root, part)
     tiles = load_tiles(db_root, part)
     segments = mk_segments(tiles)
-    bitdata = bitstream.load_bitdata2(open(bits_file, "r"))
+    with OpenSafeFile(bits_file) as f:
+        bitdata = bitstream.load_bitdata2(f)
 
     if flag_unknown_bits:
         print_unknown_bits(tiles, bitdata)
@@ -486,8 +487,8 @@
     parser = argparse.ArgumentParser(
         description="Decode bits within a tile's address space")
 
-    util.db_root_arg(parser)
-    util.part_arg(parser)
+    db_root_arg(parser)
+    part_arg(parser)
     parser.add_argument('--verbose', action='store_true', help='')
     parser.add_argument(
         '-z',
diff --git a/utils/segview.py b/utils/segview.py
index 47ef88d..8031fdc 100755
--- a/utils/segview.py
+++ b/utils/segview.py
@@ -21,6 +21,8 @@
 
 import itertools
 
+from prjxray.util import OpenSafeFile
+
 # =============================================================================
 
 
@@ -69,7 +71,7 @@
 
     # Load segbits
     segbits = {}
-    with open(file_name, "r") as fp:
+    with OpenSafeFile(file_name, "r") as fp:
         lines = fp.readlines()
 
         # Parse lines
diff --git a/utils/simpleroute.py b/utils/simpleroute.py
index 0ba969b..dfd10d1 100755
--- a/utils/simpleroute.py
+++ b/utils/simpleroute.py
@@ -12,6 +12,7 @@
 import sys, os, json
 import pickle
 
+from prjxray.util import OpenSafeFile
 
 class MergeFind:
     def __init__(self):
@@ -34,11 +35,11 @@
 def db_gen():
     print("Reading database..")
 
-    with open("%s/%s/tilegrid.json" % (os.getenv("XRAY_DATABASE_DIR"),
+    with OpenSafeFile("%s/%s/tilegrid.json" % (os.getenv("XRAY_DATABASE_DIR"),
                                        os.getenv("XRAY_DATABASE")), "r") as f:
         tilegrid = json.load(f)
 
-    with open("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
+    with OpenSafeFile("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
                                        os.getenv("XRAY_DATABASE")), "r") as f:
         tileconn = json.load(f)
 
@@ -81,7 +82,7 @@
     reverse_node_node = dict()
 
     for tile_type in ["int_l", "int_r"]:
-        with open("%s/%s/segbits_%s.db" %
+        with OpenSafeFile("%s/%s/segbits_%s.db" %
                   (os.getenv("XRAY_DATABASE_DIR"), os.getenv("XRAY_DATABASE"),
                    tile_type), "r") as f:
             for line in f:
diff --git a/utils/sort_db.py b/utils/sort_db.py
index 2d09a86..b94110b 100755
--- a/utils/sort_db.py
+++ b/utils/sort_db.py
@@ -65,8 +65,8 @@
 import json
 import utils.xjson as xjson
 import utils.cmp as cmp
-from prjxray.util import lock_file, unlock_file
 
+from prjxray.util import OpenSafeFile
 
 def split_all(s, chars):
     """Split on multiple character values.
@@ -323,7 +323,8 @@
     else:
         return False
 
-    lines = open(pathname).readlines()
+    with OpenSafeFile(pathname) as f:
+        lines = f.readlines()
 
     tosort = []
     for l in lines:
@@ -334,22 +335,10 @@
 
     tosort.sort(key=cmp.cmp_key)
 
-    # Make sure the sort is stable
-    #for i in range(0, 4):
-    #    copy = tosort.copy()
-    #    random.shuffle(copy)
-    #    copy.sort(key=cmp.cmp_key)
-    #    assert len(copy) == len(tosort)
-    #    for i in range(0, len(copy)):
-    #        assert copy[i] == tosort[i], "\n%r\n != \n%r\n" % (
-    #            copy[i], tosort[i])
-
     with open(pathname, 'w') as f:
-        lock_file(f, 10)
         for _, l in tosort:
             f.write(l)
             f.write('\n')
-        unlock_file(f)
 
     return True
 
@@ -387,13 +376,15 @@
 
 def sort_json(filename):
     """Sort a XXX.json file."""
+
     try:
-        d = json.load(open(filename))
+        with OpenSafeFile(filename) as f:
+            d = json.load(f)
     except json.JSONDecodeError as e:
         print(e)
         return False
 
-    with open(filename, 'w') as f:
+    with OpenSafeFile(filename, 'w') as f:
         xjson.pprint(f, d)
 
     return True
@@ -401,17 +392,15 @@
 
 def sort_db_text(n):
     rows = []
-    with open(n) as f:
+    with OpenSafeFile(n) as f:
         for l in f:
             rows.append(([extract_num(s) for s in l.split()], l))
 
     rows.sort(key=lambda i: i[0])
 
-    with open(n, 'w') as f:
-        lock_file(f, 10)
+    with OpenSafeFile(n, 'w') as f:
         for l in rows:
             f.write(l[-1])
-        unlock_file(f)
 
     return True
 
diff --git a/utils/sp6_bitstream_analyzer.py b/utils/sp6_bitstream_analyzer.py
index f70b65d..40296f0 100755
--- a/utils/sp6_bitstream_analyzer.py
+++ b/utils/sp6_bitstream_analyzer.py
@@ -25,6 +25,8 @@
 import argparse
 from io import StringIO
 
+from prjxray.util import OpenSafeFile
+
 conf_regs = {
     0: "CRC",
     1: "FAR_MAJ",
@@ -124,7 +126,7 @@
         self.curr_fdri_write_len = 0
         self.curr_crc_check = 0
         self.fdri_in_progress = False
-        with open(file_name, "rb") as f:
+        with OpenSafeFile(file_name, "rb") as f:
             self.bytes = f.read()
         pos, self.header = self.get_header()
         self.body = [
@@ -395,7 +397,7 @@
             else:
                 frame_stream.write(
                     "#{:3}:{:6},".format(i % 65, hex(self.frame_data[i])))
-        with open(file_name, "w") as f:
+        with OpenSafeFile(file_name, "w") as f:
             print(frame_stream.getvalue(), file=f)
 
     def write_frames(self, file_name):
@@ -409,7 +411,7 @@
                 frame_stream.write("\n")
             elif i < len(self.frame_data) - 1:
                 frame_stream.write(",")
-        with open(file_name, "w") as f:
+        with OpenSafeFile(file_name, "w") as f:
             print(frame_stream.getvalue(), file=f)
 
 
diff --git a/utils/test_fasm2frames.py b/utils/test_fasm2frames.py
index 133c171..ef957b3 100755
--- a/utils/test_fasm2frames.py
+++ b/utils/test_fasm2frames.py
@@ -19,6 +19,7 @@
 
 import prjxray
 import utils.fasm2frames as fasm2frames
+from prjxray.util import OpenSafeFile
 
 from textx.exceptions import TextXSyntaxError
 
@@ -69,7 +70,7 @@
         return os.path.join(os.path.dirname(__file__), 'test_data', fname)
 
     def get_test_data(self, fname):
-        with open(self.filename_test_data(fname)) as f:
+        with OpenSafeFile(self.filename_test_data(fname)) as f:
             return f.read()
 
     def fasm2frames(self, fin_data, **kw):
diff --git a/utils/tileconnloops.py b/utils/tileconnloops.py
index ab55b4a..4fffac9 100755
--- a/utils/tileconnloops.py
+++ b/utils/tileconnloops.py
@@ -14,13 +14,14 @@
 
 import os, sys, json
 
+from prjxray.util import OpenSafeFile
 
 def main():
-    with open("%s/%s/tilegrid.json" % (os.getenv("XRAY_DATABASE_DIR"),
+    with OpenSafeFile("%s/%s/tilegrid.json" % (os.getenv("XRAY_DATABASE_DIR"),
                                        os.getenv("XRAY_DATABASE")), "r") as f:
         tilegrid = json.load(f)
 
-    with open("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
+    with OpenSafeFile("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
                                        os.getenv("XRAY_DATABASE")), "r") as f:
         tileconn = json.load(f)
 
diff --git a/utils/tileconnwire.py b/utils/tileconnwire.py
index 368d2df..21ef9f5 100755
--- a/utils/tileconnwire.py
+++ b/utils/tileconnwire.py
@@ -11,13 +11,14 @@
 
 import os, sys, json
 
+from prjxray.util import OpenSafeFile
 
 def main(argv):
     if len(argv) != 3:
         print("Usage example: python3 %s HCLK_R HCLK_SW6E3" % sys.argv[0])
         sys.exit(1)
 
-    with open("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
+    with OpenSafeFile("%s/%s/tileconn.json" % (os.getenv("XRAY_DATABASE_DIR"),
                                        os.getenv("XRAY_DATABASE")), "r") as f:
         tileconn = json.load(f)
 
diff --git a/utils/update_resources.py b/utils/update_resources.py
index d5d3b26..bc5c8f5 100755
--- a/utils/update_resources.py
+++ b/utils/update_resources.py
@@ -15,7 +15,7 @@
 import re
 import tempfile
 import json
-from prjxray import util
+from prjxray.util import OpenSafeFile, db_root_arg, get_parts, set_part_resources
 
 
 def main():
@@ -31,7 +31,7 @@
         'family',
         help="Name of the device family.",
         choices=['artix7', 'kintex7', 'zynq7', 'spartan7'])
-    util.db_root_arg(parser)
+    db_root_arg(parser)
 
     args = parser.parse_args()
     env = os.environ.copy()
@@ -40,7 +40,7 @@
         os.getenv('XRAY_DIR'), 'settings', args.family)
     information = {}
 
-    parts = util.get_parts(args.db_root)
+    parts = get_parts(args.db_root)
     processed_parts = dict()
     for part in parts.keys():
         # Skip parts which differ only in the speedgrade, as they have the same pins
@@ -64,7 +64,7 @@
             cwd=cwd,
             stdout=subprocess.PIPE)
 
-        with open(tmp_file, "r") as fp:
+        with OpenSafeFile(tmp_file, "r") as fp:
             pins_json = json.load(fp)
 
         os.remove(tmp_file)
@@ -81,7 +81,7 @@
         processed_parts[common_part] = {'pins': pins}
 
     # Overwrites the <family>/resources.yaml file completly with new data
-    util.set_part_resources(resource_path, information)
+    set_part_resources(resource_path, information)
 
 
 if __name__ == '__main__':
diff --git a/utils/verify_tile_connections.py b/utils/verify_tile_connections.py
index b9b7238..213bdcf 100755
--- a/utils/verify_tile_connections.py
+++ b/utils/verify_tile_connections.py
@@ -18,7 +18,7 @@
 import pyjson5 as json5
 import json
 import sys
-from prjxray import util
+from prjxray.util import OpenSafeFile, db_root_arg, part_arg
 
 
 def full_wire_name(wire_in_grid):
@@ -64,7 +64,7 @@
 
 
 def read_json5(fname):
-    with open(fname, 'r') as f:
+    with OpenSafeFile(fname, 'r') as f:
         return json5.load(f)
 
 
@@ -72,8 +72,8 @@
     parser = argparse.ArgumentParser(
         description="Tests database against raw node list.")
 
-    util.db_root_arg(parser)
-    util.part_arg(parser)
+    db_root_arg(parser)
+    part_arg(parser)
     parser.add_argument('--raw_node_root', required=True)
     parser.add_argument('--error_nodes', default="error_nodes.json")
     parser.add_argument('--ignored_wires')
@@ -109,7 +109,7 @@
 
     if len(error_nodes) > 0:
         if args.ignored_wires:
-            with open(args.ignored_wires, 'r') as f:
+            with OpenSafeFile(args.ignored_wires, 'r') as f:
                 ignored_wires = [l.strip() for l in f.readlines()]
 
         print(
@@ -119,7 +119,7 @@
                 args.error_nodes,
             ))
 
-        with open(args.error_nodes, 'w') as f:
+        with OpenSafeFile(args.error_nodes, 'w') as f:
             json.dump(error_nodes, f, indent=2)
 
         if not args.ignored_wires:
diff --git a/utils/xjson.py b/utils/xjson.py
index d45cfa0..995824a 100755
--- a/utils/xjson.py
+++ b/utils/xjson.py
@@ -11,6 +11,7 @@
 import sys
 import json
 from prjxray.xjson import pprint
+from prjxray.util import OpenSafeFile
 
 if __name__ == "__main__":
     if len(sys.argv) == 1:
@@ -18,5 +19,6 @@
         doctest.testmod()
     else:
         assert len(sys.argv) == 2
-        d = json.load(open(sys.argv[1]))
+        with OpenSafeFile(sys.argv[1]) as f:
+            d = json.load(f)
         pprint(sys.stdout, d)