Only sanitize invalid pattern regexes

CHANGELOG.md

@@ -1,3 +1,7 @@
+## v0.16.0 (Unreleased)
+
+`Santize` now only removes property `pattern` regexes not supported by Go.
+
 ## v0.15.0 (January 26, 2022)
 
 Expand properties in arrays of objects.

sanitize.go

@@ -1,20 +1,57 @@
 package cfschema
 
 import (
+	"bufio"
+	"encoding/json"
 	"regexp"
+	"strings"
 )
 
 var (
-	sanitizePattern           = regexp.MustCompile(`(?m)^(\s+"pattern"\s*:\s*)".*"`)
+	sanitizePattern           = regexp.MustCompile(`^(\s*"pattern"\s*:\s*)"(.*)"(\s*,?\s*)$`)
 	sanitizePatternProperties = regexp.MustCompile(`(?m)^(\s+"patternProperties"\s*:\s*{\s*)".*?"`)
 )
 
 // Sanitize returns a sanitized copy of the specified JSON Schema document.
-// The santized copy rewrites all pattern and patternProperty regexes to the empty string,
-// working around any problems with JSON Schema regex validation.
-func Sanitize(document string) string {
-	document = sanitizePattern.ReplaceAllString(document, `$1""`)
+// The sanitized copy works around any problems with JSON Schema regex validation by
+//  - Rewriting all patternProperty regexes to the empty string (the regex is never used anyway)
+//  - Rewriting all unsupported (valid for ECMA-262 but not for Go) pattern regexes to the empty string
+func Sanitize(document string) (string, error) {
 	document = sanitizePatternProperties.ReplaceAllString(document, `$1""`)
 
-	return document
+	var sb strings.Builder
+	scanner := bufio.NewScanner(strings.NewReader(document))
+	for scanner.Scan() {
+		line := scanner.Text()
+
+		if v := sanitizePattern.FindStringSubmatch(line); len(v) == 4 {
+			if expr := v[2]; expr != "" && !isSupportedRegexp(expr) {
+				line = v[1] + "\"\"" + v[3]
+			}
+		}
+		if _, err := sb.WriteString(line); err != nil {
+			return "", err
+		}
+		if _, err := sb.WriteString("\n"); err != nil {
+			return "", err
+		}
+	}
+	if err := scanner.Err(); err != nil {
+		return "", err
+	}
+
+	return sb.String(), nil
+}
+
+func isSupportedRegexp(expr string) bool {
+	// github.com/xeipuuv/gojsonschema attempts to compile the regex after it has been unmarshaled from JSON.
+	var v string
+	b := []byte("\"" + expr + "\"")
+
+	if err := json.Unmarshal(b, &v); err != nil {
+		return false
+	}
+
+	_, err := regexp.Compile(v)
+	return err == nil
 }

sanitize_test.go

@@ -1,6 +1,7 @@
 package cfschema_test
 
 import (
+	"strings"
 	"testing"
 
 	cfschema "github.com/hashicorp/aws-cloudformation-resource-schema-sdk-go"
@@ -49,8 +50,33 @@ func TestSanitize(t *testing.T) {
   "KmsKeyId": {
     "description": "The Amazon Resource Name (ARN) of the CMK to use when encrypting log data.",
     "type": "string",
-    "pattern": "^arn:[a-z0-9-]+:kms:[a-z0-9-]+:\\d{12}:(key|alias)/.+\\Z",
+    "pattern":"^arn:[a-z0-9-]+:kms:[a-z0-9-]+:\\d{12}:(key|alias)/.+\\Z",
     "maxLength": 256
+  },
+  "Key" : {
+    "type" : "string",
+    "pattern" : "^(?!aws:)[a-zA-Z+-=._:/]+$",
+    "description" : "The key name of the tag. You can specify a value that is 1 to 128 Unicode characters in length and cannot be prefixed with aws:. You can use any of the following characters: the set of Unicode letters, digits, whitespace, _, ., /, =, +, and -.",
+    "minLength" : 1,
+    "maxLength" : 128
+  },
+  "VirtualMfaDeviceName": {
+    "minLength": 1,
+    "maxLength": 226,
+    "pattern": "[\\w+=,.@-]+",
+    "type": "string"
+  },
+  "Path": {
+    "minLength": 1,
+    "maxLength": 512,
+    "pattern": "(\\u002F)|(\\u002F[\\u0021-\\u007F]+\\u002F)",
+    "type": "string"
+  },
+  "SerialNumber": {
+    "minLength": 9,
+    "maxLength": 256,
+    "pattern": "[\\w+=/:,.@-]+",
+    "type": "string"
   }
 }
 			`,
@@ -66,8 +92,33 @@ func TestSanitize(t *testing.T) {
   "KmsKeyId": {
     "description": "The Amazon Resource Name (ARN) of the CMK to use when encrypting log data.",
     "type": "string",
-    "pattern": "",
+    "pattern":"",
     "maxLength": 256
+  },
+  "Key" : {
+    "type" : "string",
+    "pattern" : "",
+    "description" : "The key name of the tag. You can specify a value that is 1 to 128 Unicode characters in length and cannot be prefixed with aws:. You can use any of the following characters: the set of Unicode letters, digits, whitespace, _, ., /, =, +, and -.",
+    "minLength" : 1,
+    "maxLength" : 128
+  },
+  "VirtualMfaDeviceName": {
+    "minLength": 1,
+    "maxLength": 226,
+    "pattern": "[\\w+=,.@-]+",
+    "type": "string"
+  },
+  "Path": {
+    "minLength": 1,
+    "maxLength": 512,
+    "pattern": "",
+    "type": "string"
+  },
+  "SerialNumber": {
+    "minLength": 9,
+    "maxLength": 256,
+    "pattern": "[\\w+=/:,.@-]+",
+    "type": "string"
   }
 }
 			`,
@@ -125,10 +176,14 @@ func TestSanitize(t *testing.T) {
 		testCase := testCase
 
 		t.Run(testCase.TestDescription, func(t *testing.T) {
-			got := cfschema.Sanitize(testCase.InputDocument)
+			got, err := cfschema.Sanitize(testCase.InputDocument)
+
+			if err != nil {
+				t.Fatalf("%s", err)
+			}
 
-			if got != testCase.SanitizedDocument {
-				t.Errorf("expected: %s, got: %s", testCase.SanitizedDocument, got)
+			if strings.TrimSpace(got) != strings.TrimSpace(testCase.SanitizedDocument) {
+				t.Errorf("expected: %s\ngot: %s", testCase.SanitizedDocument, got)
 			}
 		})
 	}