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gh-149474: use Py_fopen in Binary{Reader,Writer} for audit hook and path-like support #149524

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Merged
pablogsal merged 4 commits into from
May 9, 2026
Merged

gh-149474: use Py_fopen in Binary{Reader,Writer} for audit hook and path-like support #149524

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maurycy May 8, 2026
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maurycy May 8, 2026
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maurycy May 8, 2026
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Merge branch 'main' into remote-debugger-fopen
maurycy May 8, 2026
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14 changes: 14 additions & 0 deletions Lib/test/audit-tests.py
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Original file line number Diff line number Diff line change
Expand Up @@ -208,6 +208,16 @@ def rl(name):
else:
return None

try:
import _remote_debugging
except ImportError:
_remote_debugging = None

def rd(name):
if _remote_debugging:
return getattr(_remote_debugging, name, None)
return None

# Try a range of "open" functions.
# All of them should fail
with TestHook(raise_on_events={"open"}) as hook:
Expand All @@ -225,6 +235,8 @@ def rl(name):
(rl("append_history_file"), 0, None),
(rl("read_init_file"), testfn),
(rl("read_init_file"), None),
(rd("BinaryWriter"), testfn, 1000, 0),
(rd("BinaryReader"), testfn),
]:
if not fn:
continue
Expand Down Expand Up @@ -258,6 +270,8 @@ def rl(name):
("~/.history", "a") if rl("append_history_file") else None,
(testfn, "r") if readline else None,
("<readline_init_file>", "r") if readline else None,
(testfn, "wb") if rd("BinaryWriter") else None,
(testfn, "rb") if rd("BinaryReader") else None,
]
if i is not None
],
Expand Down
30 changes: 30 additions & 0 deletions Lib/test/test_profiling/test_sampling_profiler/test_binary_format.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

import json
import os
import pathlib
import random
import struct
import tempfile
Expand Down Expand Up @@ -814,6 +815,35 @@ def test_invalid_file_path(self):
with BinaryReader("/nonexistent/path/file.bin") as reader:
reader.replay_samples(RawCollector())

def test_path_arguments_round_trip(self):
"""Reader and writer accept str, bytes or os.PathLike."""
with tempfile.NamedTemporaryFile(suffix=".bin", delete=False) as f:
filename = f.name
self.temp_files.append(filename)

for path_arg in (filename, os.fsencode(filename), pathlib.Path(filename)):
with self.subTest(path_type=type(path_arg).__name__):
writer = _remote_debugging.BinaryWriter(path_arg, 1000, 0)
writer.finalize()
reader = _remote_debugging.BinaryReader(path_arg)
info = reader.get_info()
reader.close()
self.assertEqual(info["sample_count"], 0)

def test_rejects_non_pathlike(self):
"""Reader and writer raise TypeError on non-path-like filenames."""
with self.assertRaises(TypeError):
_remote_debugging.BinaryWriter(123, 1000, 0)
with self.assertRaises(TypeError):
_remote_debugging.BinaryReader(123)

def test_invalid_path_error_preserves_pathlib(self):
"""Missing path: OSError carries the original path object, not a string."""
missing = pathlib.Path("/i/do/not/exist")
with self.assertRaises(FileNotFoundError) as cm:
_remote_debugging.BinaryReader(missing)
self.assertEqual(os.fspath(cm.exception.filename), os.fspath(missing))

def test_writer_handles_empty_stack_first_sample(self):
"""BinaryWriter.write_sample tolerates an empty stack on a fresh thread.

Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Security/2026-05-08-02-18-54.gh-issue-149474.ujQ-mu.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
Fix the binary writer in :mod:`profiling.sampling` not firing the audit
(:pep:`578`) when creating the output file. The writer and the reader now
accept any path-like object. Patch by Maurycy Pawłowski-Wieroński.
12 changes: 4 additions & 8 deletions Modules/_remote_debugging/binary_io.h
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Original file line number Diff line number Diff line change
Expand Up @@ -253,7 +253,6 @@ typedef struct {
/* Main binary writer structure */
typedef struct {
FILE *fp;
char *filename;

/* Write buffer for batched I/O */
uint8_t *write_buffer;
Expand Down Expand Up @@ -311,10 +310,7 @@ typedef struct {

/* Main binary reader structure */
typedef struct {
char *filename;

#if USE_MMAP
int fd;
uint8_t *mapped_data;
size_t mapped_size;
#else
Expand Down Expand Up @@ -522,7 +518,7 @@ grow_array_inplace(void **ptr_addr, size_t count, size_t *capacity, size_t elem_
* Create a new binary writer.
*
* Arguments:
* filename: Path to output file
* path: Path to output file
* sample_interval_us: Sampling interval in microseconds
* compression_type: COMPRESSION_NONE or COMPRESSION_ZSTD
* start_time_us: Start timestamp in microseconds (from time.monotonic() * 1e6)
Expand All @@ -531,7 +527,7 @@ grow_array_inplace(void **ptr_addr, size_t count, size_t *capacity, size_t elem_
* New BinaryWriter* on success, NULL on failure (PyErr set)
*/
BinaryWriter *binary_writer_create(
const char *filename,
PyObject *path,
uint64_t sample_interval_us,
int compression_type,
uint64_t start_time_us
Expand Down Expand Up @@ -583,12 +579,12 @@ void binary_writer_destroy(BinaryWriter *writer);
* Open a binary file for reading.
*
* Arguments:
* filename: Path to input file
* path: Path to input file
*
* Returns:
* New BinaryReader* on success, NULL on failure (PyErr set)
*/
BinaryReader *binary_reader_open(const char *filename);
BinaryReader *binary_reader_open(PyObject *path);

/*
* Replay samples from binary file through a collector.
Expand Down
45 changes: 15 additions & 30 deletions Modules/_remote_debugging/binary_io_reader.c
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Original file line number Diff line number Diff line change
Expand Up @@ -358,37 +358,26 @@ reader_parse_frame_table(BinaryReader *reader, const uint8_t *data, size_t file_
}

BinaryReader *
binary_reader_open(const char *filename)
binary_reader_open(PyObject *path)
{
BinaryReader *reader = PyMem_Calloc(1, sizeof(BinaryReader));
if (!reader) {
PyErr_NoMemory();
return NULL;
}

#if USE_MMAP
reader->fd = -1; /* Explicit initialization for cleanup safety */
#endif

reader->filename = PyMem_Malloc(strlen(filename) + 1);
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if (!reader->filename) {
PyMem_Free(reader);
PyErr_NoMemory();
return NULL;
}
strcpy(reader->filename, filename);

#if USE_MMAP
/* Open with mmap on Unix */
reader->fd = open(filename, O_RDONLY);
if (reader->fd < 0) {
PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
FILE *fp = Py_fopen(path, "rb");
if (!fp) {
goto error;
}
int fd = fileno(fp);

struct stat st;
if (fstat(reader->fd, &st) < 0) {
if (fstat(fd, &st) < 0) {
PyErr_SetFromErrno(PyExc_IOError);
Py_fclose(fp);
goto error;
}
reader->mapped_size = st.st_size;
Expand All @@ -400,14 +389,15 @@ binary_reader_open(const char *filename)
*/
#ifdef __linux__
reader->mapped_data = mmap(NULL, reader->mapped_size, PROT_READ,
MAP_PRIVATE | MAP_POPULATE, reader->fd, 0);
MAP_PRIVATE | MAP_POPULATE, fd, 0);
#else
reader->mapped_data = mmap(NULL, reader->mapped_size, PROT_READ,
MAP_PRIVATE, reader->fd, 0);
MAP_PRIVATE, fd, 0);
#endif
if (reader->mapped_data == MAP_FAILED) {
reader->mapped_data = NULL;
PyErr_SetFromErrno(PyExc_IOError);
Py_fclose(fp);
goto error;
}

Expand All @@ -428,19 +418,20 @@ binary_reader_open(const char *filename)

/* Add file descriptor-level hints for better kernel I/O scheduling */
#if defined(__linux__) && defined(POSIX_FADV_SEQUENTIAL)
(void)posix_fadvise(reader->fd, 0, 0, POSIX_FADV_SEQUENTIAL);
(void)posix_fadvise(fd, 0, 0, POSIX_FADV_SEQUENTIAL);
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@sobolevn sobolevn May 8, 2026

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Question: os_posix_fadvise_impl has two implementation details that this place does not: Py_BEGIN_ALLOW_THREADS is set and async_err = PyErr_CheckSignals() is checked.

Do we need to do this here?

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@pablogsal pablogsal May 9, 2026 •
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I don’t think we need it here. These calls are best-effort performance hints and intentionally ignore all posix_fadvise() failures, unlike os.posix_fadvise where the result is user-visible and must handle EINTR/signals correctly. PyErr_CheckSignals() would make an advisory hint observable by turning some interruptions into failures, which does not match the surrounding madvise()/posix_fadvise() handling.

y_BEGIN_ALLOW_THREADS also is not needed for correctness here; if we wanted to tune this path, we would probably need to look at the whole block, since mmap(... MAP_POPULATE) and madvise(... MADV_WILLNEED) are also currently called with the GIL held.

if (reader->mapped_size > (64 * 1024 * 1024)) {
(void)posix_fadvise(reader->fd, 0, 0, POSIX_FADV_WILLNEED);
(void)posix_fadvise(fd, 0, 0, POSIX_FADV_WILLNEED);
}
#endif

(void)Py_fclose(fp);

uint8_t *data = reader->mapped_data;
size_t file_size = reader->mapped_size;
#else
/* Use stdio on Windows */
reader->fp = fopen(filename, "rb");
reader->fp = Py_fopen(path, "rb");
if (!reader->fp) {
PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
goto error;
}

Expand Down Expand Up @@ -1263,8 +1254,6 @@ binary_reader_close(BinaryReader *reader)
return;
}

PyMem_Free(reader->filename);

#if USE_MMAP
if (reader->mapped_data) {
munmap(reader->mapped_data, reader->mapped_size);
Expand All @@ -1274,13 +1263,9 @@ binary_reader_close(BinaryReader *reader)
/* Clear sample_data which may point into the now-unmapped region */
reader->sample_data = NULL;
reader->sample_data_size = 0;
if (reader->fd >= 0) {
close(reader->fd);
reader->fd = -1; /* Mark as closed */
}
#else
if (reader->fp) {
fclose(reader->fp);
Py_fclose(reader->fp);
reader->fp = NULL;
}
if (reader->file_data) {
Expand Down
18 changes: 4 additions & 14 deletions Modules/_remote_debugging/binary_io_writer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -717,7 +717,7 @@ write_sample_with_encoding(BinaryWriter *writer, ThreadEntry *entry,
}

BinaryWriter *
binary_writer_create(const char *filename, uint64_t sample_interval_us, int compression_type,
binary_writer_create(PyObject *path, uint64_t sample_interval_us, int compression_type,
uint64_t start_time_us)
{
BinaryWriter *writer = PyMem_Calloc(1, sizeof(BinaryWriter));
Expand All @@ -726,14 +726,6 @@ binary_writer_create(const char *filename, uint64_t sample_interval_us, int comp
return NULL;
}

writer->filename = PyMem_Malloc(strlen(filename) + 1);
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if (!writer->filename) {
PyMem_Free(writer);
PyErr_NoMemory();
return NULL;
}
strcpy(writer->filename, filename);

writer->start_time_us = start_time_us;
writer->sample_interval_us = sample_interval_us;
writer->compression_type = compression_type;
Expand Down Expand Up @@ -799,9 +791,8 @@ binary_writer_create(const char *filename, uint64_t sample_interval_us, int comp
}
}

writer->fp = fopen(filename, "wb");
writer->fp = Py_fopen(path, "wb");
if (!writer->fp) {
PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
goto error;
}

Expand Down Expand Up @@ -1193,7 +1184,7 @@ binary_writer_finalize(BinaryWriter *writer)
return -1;
}

if (fclose(writer->fp) != 0) {
if (Py_fclose(writer->fp) != 0) {
writer->fp = NULL;
PyErr_SetFromErrno(PyExc_IOError);
return -1;
Expand All @@ -1211,10 +1202,9 @@ binary_writer_destroy(BinaryWriter *writer)
}

if (writer->fp) {
fclose(writer->fp);
Py_fclose(writer->fp);
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@sobolevn sobolevn May 8, 2026 •
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question: why don't we check the return code here? Because the returned type is void?

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@pablogsal pablogsal May 8, 2026

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There is nothing we can do if close fails, we could log perhaps...

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@picnixz picnixz May 9, 2026

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In this case I woudl suggest that we explicitly suppress the returned value and add a comment. We can also raise an unraisable exception (which I do in curses)

}

PyMem_Free(writer->filename);
PyMem_Free(writer->write_buffer);

#ifdef HAVE_ZSTD
Expand Down
38 changes: 7 additions & 31 deletions Modules/_remote_debugging/clinic/module.c.h
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