New Sast Regex transformer (#788)

* create sast regex transformer

* optimize

Author: clavedeluna

src/codemodder/codemods/regex_transformer.py

@@ -23,26 +23,17 @@ def __init__(
         self.replacement = replacement
         self.change_description = change_description
 
-    def apply(
-        self,
-        context: CodemodExecutionContext,
-        file_context: FileContext,
-        results: list[Result] | None,
-    ) -> ChangeSet | None:
+    def _apply_regex(self, line):
+        return re.sub(self.pattern, self.replacement, line)
+
+    def _apply(self, original_lines, file_context, results):
         del results
 
         changes = []
         updated_lines = []
 
-        original_lines = (
-            file_context.file_path.read_bytes()
-            .decode("utf-8")
-            .splitlines(keepends=True)
-        )
-
         for lineno, line in enumerate(original_lines):
-            # TODO: use results to filter out which lines to change
-            changed_line = re.sub(self.pattern, self.replacement, line)
+            changed_line = self._apply_regex(line)
             updated_lines.append(changed_line)
             if line != changed_line:
                 changes.append(
@@ -52,6 +43,22 @@ def apply(
                         findings=file_context.get_findings_for_location(lineno),
                     )
                 )
+        return changes, updated_lines
+
+    def apply(
+        self,
+        context: CodemodExecutionContext,
+        file_context: FileContext,
+        results: list[Result] | None,
+    ) -> ChangeSet | None:
+
+        original_lines = (
+            file_context.file_path.read_bytes()
+            .decode("utf-8")
+            .splitlines(keepends=True)
+        )
+
+        changes, updated_lines = self._apply(original_lines, file_context, results)
 
         if not changes:
             logger.debug("No changes produced for %s", file_context.file_path)
@@ -67,3 +74,46 @@ def apply(
             diff=diff,
             changes=changes,
         )
+
+
+class SastRegexTransformerPipeline(RegexTransformerPipeline):
+    def line_matches_result(self, lineno: int, result_linenums: list[int]) -> bool:
+        return lineno in result_linenums
+
+    def report_unfixed(self, file_context: FileContext, line_number: int, reason: str):
+        findings = file_context.get_findings_for_location(line_number)
+        file_context.add_unfixed_findings(findings, reason, line_number)
+
+    def _apply(self, original_lines, file_context, results):
+        changes = []
+        updated_lines = []
+        if results is not None and not results:
+            return changes, updated_lines
+
+        result_linenums = [
+            location.start.line for result in results for location in result.locations
+        ]
+        for lineno, line in enumerate(original_lines):
+            if self.line_matches_result(one_idx_lineno := lineno + 1, result_linenums):
+                changed_line = self._apply_regex(line)
+                updated_lines.append(changed_line)
+                if line == changed_line:
+                    logger.warn("Unable to update html line: %s", line)
+                    self.report_unfixed(
+                        file_context,
+                        one_idx_lineno,
+                        reason="Unable to update html line",
+                    )
+                    continue
+
+                changes.append(
+                    Change(
+                        lineNumber=lineno + 1,
+                        description=self.change_description,
+                        findings=file_context.get_findings_for_location(lineno),
+                    )
+                )
+
+            else:
+                updated_lines.append(line)
+        return changes, updated_lines

tests/test_regex_transformer.py

@@ -1,8 +1,12 @@
 import logging
 
-from codemodder.codemods.regex_transformer import RegexTransformerPipeline
+from codemodder.codemods.regex_transformer import (
+    RegexTransformerPipeline,
+    SastRegexTransformerPipeline,
+)
 from codemodder.context import CodemodExecutionContext
 from codemodder.file_context import FileContext
+from codemodder.semgrep import SemgrepResult
 
 
 def test_transformer_no_change(mocker, caplog, tmp_path_factory):
@@ -106,3 +110,71 @@ def test_transformer_windows_carriage(mocker, tmp_path_factory):
     assert changeset is not None
     assert code.read_bytes() == text.replace(b"world", b"Earth")
     assert changeset.changes[0].lineNumber == 1
+
+
+def test_sast_transformer(mocker, tmp_path_factory):
+    base_dir = tmp_path_factory.mktemp("foo")
+    code = base_dir / "code.py"
+    text = "# Something that will match pattern hello"
+    code.write_text(text)
+
+    file_context = FileContext(
+        base_dir,
+        code,
+    )
+    execution_context = CodemodExecutionContext(
+        directory=base_dir,
+        dry_run=False,
+        verbose=False,
+        registry=mocker.MagicMock(),
+        providers=mocker.MagicMock(),
+        repo_manager=mocker.MagicMock(),
+        path_include=[],
+        path_exclude=[],
+    )
+    pipeline = SastRegexTransformerPipeline(
+        pattern=r"hello", replacement="bye", change_description="testing"
+    )
+
+    data = {
+        "runs": [
+            {
+                "results": [
+                    {
+                        "fingerprints": {"matchBasedId/v1": "123"},
+                        "locations": [
+                            {
+                                "ruleId": "rule",
+                                "physicalLocation": {
+                                    "artifactLocation": {
+                                        "uri": "code.py",
+                                        "uriBaseId": "%SRCROOT%",
+                                    },
+                                    "region": {
+                                        "snippet": {"text": "snip"},
+                                        "endColumn": 1,
+                                        "endLine": 1,
+                                        "startColumn": 1,
+                                        "startLine": 1,
+                                    },
+                                },
+                            }
+                        ],
+                        "ruleId": "rule",
+                    }
+                ]
+            }
+        ]
+    }
+    sarif_run = data["runs"]
+    sarif_results = sarif_run[0]["results"]
+    results = [SemgrepResult.from_sarif(sarif_results[0], sarif_run)]
+
+    changeset = pipeline.apply(
+        context=execution_context,
+        file_context=file_context,
+        results=results,
+    )
+    assert changeset is not None
+    assert code.read_text() == text.replace("hello", "bye")
+    assert changeset.changes[0].lineNumber == 1