[checksum.py] adds support for checksum checks against file paths in a valid checksum files

tools/scripts/checksum/checksum.py

@@ -1,18 +1,30 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
 
-#----------------------------------------------------------------
+#------------------------------------------------------------------------------------------------------
 # checksum.py
 #  A SHA1 hash checksum list generator for fonts and fontTools
-#  XML dumps of font OpenType table data
+#  XML dumps of font OpenType table data + checksum testing
+#  script
 #
 # Copyright 2018 Christopher Simpkins
 # MIT License
 #
+# Dependencies: Python fontTools library
+#
 # Usage: checksum.py (options) [file path 1]...[file path n]
 #
-# Dependencies: Python fontTools library
-#----------------------------------------------------------------
+# Options:
+#   -h, --help          Help
+#   -t, --ttx           Calculate SHA1 hash values from ttx dump of XML (default = font binary)
+#   -s, --stdout        Stream to standard output stream (default = write to disk as 'checksum.txt')
+#   -c, --check         Test SHA1 checksum values against a valid checksum file
+#
+# Options, --ttx only:
+#   -e, --exclude       Excluded OpenType table (may be used more than once, mutually exclusive with -i)
+#   -i, --include       Included OpenType table (may be used more than once, mutually exclusive with -e)
+#   -n, --noclean       Do not discard .ttx files that are used to calculate SHA1 hashes
+#-------------------------------------------------------------------------------------------------------
 
 import argparse
 import hashlib
@@ -24,7 +36,7 @@ from os.path import basename
 from fontTools.ttLib import TTFont
 
 
-def main(filepaths, stdout_write=False, use_ttx=False, include_tables=None, exclude_tables=None, do_not_cleanup=False):
+def write_checksum(filepaths, stdout_write=False, use_ttx=False, include_tables=None, exclude_tables=None, do_not_cleanup=False):
     checksum_dict = {}
     for path in filepaths:
         if not os.path.exists(path):
@@ -42,6 +54,8 @@ def main(filepaths, stdout_write=False, use_ttx=False, include_tables=None, excl
             temp_ttx_path = path + ".ttx"
 
             tt = TTFont(path)
+            # important to keep the newlinestr value defined here as hash values will change across platforms
+            # if platform specific newline values are assumed
             tt.saveXML(temp_ttx_path, newlinestr="\n", skipTables=exclude_tables, tables=include_tables)
             checksum_path = temp_ttx_path
         else:
@@ -55,7 +69,7 @@ def main(filepaths, stdout_write=False, use_ttx=False, include_tables=None, excl
                 sys.exit(1)
             checksum_path = path
 
-        file_contents = read_binary(checksum_path)
+        file_contents = _read_binary(checksum_path)
 
         # store SHA1 hash data and associated file path basename in the checksum_dict dictionary
         checksum_dict[basename(checksum_path)] = hashlib.sha1(file_contents).hexdigest()
@@ -78,7 +92,48 @@ def main(filepaths, stdout_write=False, use_ttx=False, include_tables=None, excl
             file.write(checksum_out_data)
 
 
-def read_binary(filepath):
+def check_checksum(filepaths):
+    check_failed = False
+    for path in filepaths:
+        if not os.path.exists(path):
+            sys.stderr.write("[checksum.py] ERROR: " + filepath + " is not a valid filepath" + os.linesep)
+            sys.exit(1)
+
+        with open(path, mode='r') as file:
+            for line in file.readlines():
+                cleaned_line = line.rstrip()
+                line_list = cleaned_line.split(" ")
+                # eliminate empty strings parsed from > 1 space characters
+                line_list = list(filter(None, line_list))
+                if len(line_list) == 2:
+                    expected_sha1 = line_list[0]
+                    test_path = line_list[1]
+                else:
+                    sys.stderr.write("[checksum.py] ERROR: failed to parse checksum file values" + os.linesep)
+                    sys.exit(1)
+
+                if not os.path.exists(test_path):
+                    print(test_path + ": Filepath is not valid, ignored")
+                else:
+                    file_contents = _read_binary(test_path)
+                    observed_sha1 = hashlib.sha1(file_contents).hexdigest()
+                    if observed_sha1 == expected_sha1:
+                        print(test_path + ": OK")
+                    else:
+                        print("-" * 80)
+                        print(test_path + ": === FAIL ===")
+                        print("Expected vs. Observed:")
+                        print(expected_sha1)
+                        print(observed_sha1)
+                        print("-" * 80)
+                        check_failed = True
+
+    # exit with status code 1 if any fails detected across all tests in the check
+    if check_failed is True:
+        sys.exit(1)
+
+
+def _read_binary(filepath):
     with open(filepath, mode='rb') as file:
         return file.read()
 
@@ -88,6 +143,7 @@ if __name__ == '__main__':
     parser.add_argument("-t", "--ttx", help="Calculate from ttx file", action="store_true")
     parser.add_argument("-s", "--stdout", help="Write output to stdout stream", action="store_true")
     parser.add_argument("-n", "--noclean", help="Do not discard *.ttx files used to calculate SHA1 hashes", action="store_true")
+    parser.add_argument("-c", "--check", help="Verify checksum values vs. files", action="store_true")
     parser.add_argument("filepaths", nargs="+", help="One or more file paths to font binary files")
 
     parser.add_argument("-i", "--include", action="append", help="Included OpenType tables for ttx data dump")
@@ -95,4 +151,7 @@ if __name__ == '__main__':
 
     args = parser.parse_args(sys.argv[1:])
 
-    main(args.filepaths, stdout_write=args.stdout, use_ttx=args.ttx, do_not_cleanup=args.noclean, include_tables=args.include, exclude_tables=args.exclude)
+    if args.check is True:
+        check_checksum(args.filepaths)
+    else:
+        write_checksum(args.filepaths, stdout_write=args.stdout, use_ttx=args.ttx, do_not_cleanup=args.noclean, include_tables=args.include, exclude_tables=args.exclude)