gh-148225: Validate profiling.sampling replay input

Author: pablogsal

Lib/profiling/sampling/cli.py

@@ -86,6 +86,8 @@ def __call__(self, parser, namespace, values, option_string=None):
 _PROCESS_KILL_TIMEOUT_SEC = 2.0
 _READY_MESSAGE = b"ready"
 _RECV_BUFFER_SIZE = 1024
+_BINARY_PROFILE_HEADER_SIZE = 64
+_BINARY_PROFILE_MAGICS = (b"HCAT", b"TACH")
 
 # Format configuration
 FORMAT_EXTENSIONS = {
@@ -650,6 +652,89 @@ def _open_in_browser(path):
         print(f"Warning: Could not open browser: {e}", file=sys.stderr)
 
 
+def _validate_replay_input_file(filename):
+    """Validate that the replay input looks like a sampling binary profile."""
+    try:
+        with open(filename, "rb") as file:
+            header = file.read(_BINARY_PROFILE_HEADER_SIZE)
+    except OSError as exc:
+        sys.exit(f"Error: Could not read input file {filename}: {exc}")
+
+    if (
+        len(header) < _BINARY_PROFILE_HEADER_SIZE
+        or header[:4] not in _BINARY_PROFILE_MAGICS
+    ):
+        sys.exit(
+            "Error: Input file is not a binary sampling profile. "
+            "The replay command only accepts files created with --binary; "
+            "the default --pstats output written by -o cannot be replayed."
+        )
+
+
+def _replay_with_reader(args, reader):
+    """Replay samples from an open binary reader."""
+    info = reader.get_info()
+    interval = info['sample_interval_us']
+
+    print(f"Replaying {info['sample_count']} samples from {args.input_file}")
+    print(f"  Sample interval: {interval} us")
+    print(
+        "  Compression: "
+        f"{'zstd' if info.get('compression_type', 0) == 1 else 'none'}"
+    )
+
+    collector = _create_collector(
+        args.format, interval, skip_idle=False,
+        diff_baseline=args.diff_baseline
+    )
+
+    def progress_callback(current, total):
+        if total > 0:
+            pct = current / total
+            bar_width = 40
+            filled = int(bar_width * pct)
+            bar = '█' * filled + '░' * (bar_width - filled)
+            print(
+                f"\r  [{bar}] {pct*100:5.1f}% ({current:,}/{total:,})",
+                end="",
+                flush=True,
+            )
+
+    count = reader.replay_samples(collector, progress_callback)
+    print()
+
+    if args.format == "pstats":
+        if args.outfile:
+            collector.export(args.outfile)
+        else:
+            sort_choice = (
+                args.sort if args.sort is not None else "nsamples"
+            )
+            limit = args.limit if args.limit is not None else 15
+            sort_mode = _sort_to_mode(sort_choice)
+            collector.print_stats(
+                sort_mode, limit, not args.no_summary,
+                PROFILING_MODE_WALL
+            )
+    else:
+        filename = (
+            args.outfile
+            or _generate_output_filename(args.format, os.getpid())
+        )
+        collector.export(filename)
+
+        # Auto-open browser for HTML output if --browser flag is set
+        if (
+            args.format in (
+                'flamegraph', 'diff_flamegraph', 'heatmap'
+            )
+            and getattr(args, 'browser', False)
+        ):
+            _open_in_browser(filename)
+
+    print(f"Replayed {count} samples")
+
+
 def _handle_output(collector, args, pid, mode):
     """Handle output for the collector based on format and arguments.
 
@@ -1201,47 +1286,13 @@ def _handle_replay(args):
     if not os.path.exists(args.input_file):
         sys.exit(f"Error: Input file not found: {args.input_file}")
 
-    with BinaryReader(args.input_file) as reader:
-        info = reader.get_info()
-        interval = info['sample_interval_us']
+    _validate_replay_input_file(args.input_file)
 
-        print(f"Replaying {info['sample_count']} samples from {args.input_file}")
-        print(f"  Sample interval: {interval} us")
-        print(f"  Compression: {'zstd' if info.get('compression_type', 0) == 1 else 'none'}")
-
-        collector = _create_collector(
-            args.format, interval, skip_idle=False,
-            diff_baseline=args.diff_baseline
-        )
-
-        def progress_callback(current, total):
-            if total > 0:
-                pct = current / total
-                bar_width = 40
-                filled = int(bar_width * pct)
-                bar = '█' * filled + '░' * (bar_width - filled)
-                print(f"\r  [{bar}] {pct*100:5.1f}% ({current:,}/{total:,})", end="", flush=True)
-
-        count = reader.replay_samples(collector, progress_callback)
-        print()
-
-        if args.format == "pstats":
-            if args.outfile:
-                collector.export(args.outfile)
-            else:
-                sort_choice = args.sort if args.sort is not None else "nsamples"
-                limit = args.limit if args.limit is not None else 15
-                sort_mode = _sort_to_mode(sort_choice)
-                collector.print_stats(sort_mode, limit, not args.no_summary, PROFILING_MODE_WALL)
-        else:
-            filename = args.outfile or _generate_output_filename(args.format, os.getpid())
-            collector.export(filename)
-
-            # Auto-open browser for HTML output if --browser flag is set
-            if args.format in ('flamegraph', 'diff_flamegraph', 'heatmap') and getattr(args, 'browser', False):
-                _open_in_browser(filename)
-
-        print(f"Replayed {count} samples")
+    try:
+        with BinaryReader(args.input_file) as reader:
+            _replay_with_reader(args, reader)
+    except (OSError, ValueError) as exc:
+        sys.exit(f"Error: {exc}")
 
 
 if __name__ == "__main__":

Lib/test/test_profiling/test_sampling_profiler/test_cli.py

@@ -1,8 +1,10 @@
 """Tests for sampling profiler CLI argument parsing and functionality."""
 
 import io
+import os
 import subprocess
 import sys
+import tempfile
 import unittest
 from unittest import mock
 
@@ -722,3 +724,39 @@ def test_cli_attach_nonexistent_pid(self):
                 main()
 
             self.assertIn(fake_pid, str(cm.exception))
+
+    def test_cli_replay_rejects_non_binary_profile(self):
+        with tempfile.TemporaryDirectory() as tempdir:
+            profile = os.path.join(tempdir, "output.prof")
+            with open(profile, "wb") as file:
+                file.write(b"not a binary sampling profile")
+
+            with mock.patch("sys.argv", ["profiling.sampling.cli", "replay", profile]):
+                with self.assertRaises(SystemExit) as cm:
+                    main()
+
+        error = str(cm.exception)
+        self.assertIn("not a binary sampling profile", error)
+        self.assertIn("--binary", error)
+        self.assertIn("--pstats", error)
+
+    def test_cli_replay_reader_errors_exit_cleanly(self):
+        with tempfile.TemporaryDirectory() as tempdir:
+            profile = os.path.join(tempdir, "output.bin")
+            with open(profile, "wb") as file:
+                file.write(b"HCAT" + (b"\0" * 60))
+
+            with (
+                mock.patch("sys.argv", ["profiling.sampling.cli", "replay", profile]),
+                mock.patch(
+                    "profiling.sampling.cli.BinaryReader",
+                    side_effect=ValueError("Unsupported format version 2"),
+                ),
+            ):
+                with self.assertRaises(SystemExit) as cm:
+                    main()
+
+        self.assertEqual(
+            str(cm.exception),
+            "Error: Unsupported format version 2",
+        )

Misc/NEWS.d/next/Library/2026-04-08-11-44-12.gh-issue-148225.H34yJp.rst

@@ -0,0 +1,3 @@
+The :mod:`profiling.sampling` ``replay`` command now rejects non-binary
+profile files with a clear error explaining that replay only accepts files
+created with ``--binary``.