[lint] add newlines linter to lintrunner (#67894)

Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67894

As title. Confirmed that the code base passes by running:

```
lintrunner --paths-cmd='git grep -Il ""' --take NEWLINE
```

and seeing that it pases

Test Plan: Imported from OSS

Reviewed By: H-Huang

Differential Revision: D32250604

Pulled By: suo

fbshipit-source-id: de9bcba635d21f8832bb25147b19b7b2e8802247

.lintrunner.toml

@@ -158,3 +158,20 @@ init_args = [
     'ruamel.yaml==0.17.4',
 ]
 bypass_matched_file_filter = true
+
+[[linter]]
+name = 'NEWLINE'
+include_patterns=['**']
+exclude_patterns=[
+    '**/contrib/**',
+    'third_party/**',
+    '**/*.expect',
+    '**/*.ipynb',
+    'tools/clang_format_hash/**',
+]
+args = [
+    'python3',
+    'tools/linter/adapters/newlines_linter.py',
+    '--',
+    '@{{PATHSFILE}}',
+]

tools/linter/adapters/newlines_linter.py

@@ -0,0 +1,144 @@
+"""
+NEWLINE: Checks files to make sure there are no trailing newlines.
+"""
+import argparse
+import json
+import logging
+import os
+import sys
+
+from enum import Enum
+from typing import NamedTuple, Optional
+
+NEWLINE = 10  # ASCII "\n"
+LINTER_CODE = "NEWLINE"
+
+
+class LintSeverity(str, Enum):
+    ERROR = "error"
+    WARNING = "warning"
+    ADVICE = "advice"
+    DISABLED = "disabled"
+
+
+class LintMessage(NamedTuple):
+    path: Optional[str]
+    line: Optional[int]
+    char: Optional[int]
+    code: str
+    severity: LintSeverity
+    name: str
+    original: Optional[str]
+    replacement: Optional[str]
+    description: Optional[str]
+    bypassChangedLineFiltering: Optional[bool]
+
+
+def correct_trailing_newlines(filename: str) -> bool:
+    with open(filename, "rb") as f:
+        a = len(f.read(2))
+        if a == 0:
+            return True
+        elif a == 1:
+            # file is wrong whether or not the only byte is a newline
+            return False
+        else:
+            f.seek(-2, os.SEEK_END)
+            b, c = f.read(2)
+            # no ASCII byte is part of any non-ASCII character in UTF-8
+            return b != NEWLINE and c == NEWLINE
+
+
+def check_file(filename: str) -> Optional[LintMessage]:
+    logging.debug("Checking file %s", filename)
+
+    with open(filename, "rb") as f:
+        a = len(f.read(2))
+        if a == 0:
+            # File is empty, just leave it alone.
+            return None
+        elif a == 1:
+            # file is wrong whether or not the only byte is a newline
+            return LintMessage(
+                path=filename,
+                line=None,
+                char=None,
+                code=LINTER_CODE,
+                severity=LintSeverity.ERROR,
+                name="testestTrailing newline",
+                original=None,
+                replacement=None,
+                description="Trailing newline found. Run `lintunner --take NEWLINE -a` to apply changes.",
+                bypassChangedLineFiltering=None,
+            )
+
+        else:
+            # Read the last two bytes
+            f.seek(-2, os.SEEK_END)
+            b, c = f.read(2)
+            # no ASCII byte is part of any non-ASCII character in UTF-8
+            if b != NEWLINE and c == NEWLINE:
+                return None
+            else:
+                f.seek(0)
+                try:
+                    original = f.read().decode("utf-8")
+                except Exception as err:
+                    return LintMessage(
+                        path=filename,
+                        line=None,
+                        char=None,
+                        code=LINTER_CODE,
+                        severity=LintSeverity.ERROR,
+                        name="Decoding failure",
+                        original=None,
+                        replacement=None,
+                        description=f"utf-8 decoding failed due to {err.__class__.__name__}:\n{err}",
+                        bypassChangedLineFiltering=None,
+                    )
+
+                return LintMessage(
+                    path=filename,
+                    line=None,
+                    char=None,
+                    code=LINTER_CODE,
+                    severity=LintSeverity.ERROR,
+                    name="Trailing newline",
+                    original=original,
+                    replacement=original.rstrip("\n") + "\n",
+                    description="Trailing newline found. Run `lintunner --take NEWLINE -a` to apply changes.",
+                    bypassChangedLineFiltering=None,
+                )
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(
+        description="native functions linter", fromfile_prefix_chars="@",
+    )
+    parser.add_argument(
+        "--verbose", action="store_true", help="location of native_functions.yaml",
+    )
+    parser.add_argument(
+        "filenames", nargs="+", help="paths to lint",
+    )
+
+    args = parser.parse_args()
+
+    logging.basicConfig(
+        format="<%(threadName)s:%(levelname)s> %(message)s",
+        level=logging.NOTSET
+        if args.verbose
+        else logging.DEBUG
+        if len(args.filenames) < 1000
+        else logging.INFO,
+        stream=sys.stderr,
+    )
+
+    lint_messages = []
+    for filename in args.filenames:
+        lint_message = check_file(filename)
+        if lint_message is not None:
+            lint_messages.append(lint_message)
+
+    for lint_message in lint_messages:
+        print(json.dumps(lint_message._asdict()), flush=True)