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gh-158893: Add internal _Py_strerror() function #158982

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Merged
vstinner merged 1 commit into from
Oct 7, 2026
+147 −100
Merged

gh-158893: Add internal _Py_strerror() function #158982

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3 changes: 3 additions & 0 deletions Include/internal/pycore_fileutils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -321,6 +321,9 @@ extern int _Py_GetTicksPerSecond(long *ticks_per_second);
// Export for '_testcapi' shared extension
PyAPI_FUNC(int) _Py_IsValidFD(int fd);

// Export for '_remote_debugging' shared extension
PyAPI_FUNC(PyObject*) _Py_strerror(int code);

#ifdef __cplusplus
}
#endif
Expand Down
21 changes: 15 additions & 6 deletions Modules/_remote_debugging/subprocess.c
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Expand Up @@ -6,6 +6,7 @@
******************************************************************************/

#include "_remote_debugging.h"
#include "pycore_fileutils.h" // _Py_strerror()

#ifndef MS_WINDOWS
#include <unistd.h>
Expand Down Expand Up @@ -229,9 +230,13 @@ get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)
if (entry == NULL) {
if (errno != 0) {
int err = errno;
_set_debug_oserror_from_errno_with_filename(err, "/proc",
"Failed to read process directory '/proc': %s",
strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno_with_filename(err, "/proc",
"Failed to read process directory '/proc': %S",
message);
Py_DECREF(message);
}
goto done;
}
break;
Expand Down Expand Up @@ -259,9 +264,13 @@ get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)
if (closedir(proc_dir) != 0) {
int err = errno;
proc_dir = NULL;
_set_debug_oserror_from_errno_with_filename(err, "/proc",
"Failed to close process directory '/proc': %s",
strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno_with_filename(err, "/proc",
"Failed to close process directory '/proc': %S",
message);
Py_DECREF(message);
}
goto done;
}
proc_dir = NULL;
Expand Down
45 changes: 33 additions & 12 deletions Modules/_remote_debugging/threads.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
******************************************************************************/

#include "_remote_debugging.h"
#include "pycore_fileutils.h" // _Py_strerror()

#ifndef MS_WINDOWS
#include <unistd.h>
Expand Down Expand Up @@ -716,9 +717,13 @@ read_thread_ids(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_ThreadsState *st
int err = errno;
closedir(dir);
_Py_RemoteDebug_InitThreadsState(unwinder, st);
_set_debug_oserror_from_errno_with_filename(err, task_path,
"Failed to read process task directory '%s': %s",
task_path, strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno_with_filename(err, task_path,
"Failed to read process task directory '%s': %S",
task_path, message);
Py_DECREF(message);
}
return -1;
}
break;
Expand Down Expand Up @@ -749,9 +754,13 @@ read_thread_ids(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_ThreadsState *st
if (closedir(dir) != 0) {
int err = errno;
_Py_RemoteDebug_InitThreadsState(unwinder, st);
_set_debug_oserror_from_errno_with_filename(err, task_path,
"Failed to close process task directory '%s': %s",
task_path, strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno_with_filename(err, task_path,
"Failed to close process task directory '%s': %S",
task_path, message);
Py_DECREF(message);
}
return -1;
}
st->tids = unwinder->thread_tids;
Expand Down Expand Up @@ -816,8 +825,12 @@ _Py_RemoteDebug_StopAllThreads(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_T
}
if (ret < 0) {
detach_threads(st, seized);
_set_debug_oserror_from_errno(err,
"Failed to seize thread %d: %s", tid, strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno(err,
"Failed to seize thread %d: %S", tid, message);
Py_DECREF(message);
}
_Py_RemoteDebug_InitThreadsState(unwinder, st);
return -1;
}
Expand All @@ -827,8 +840,12 @@ _Py_RemoteDebug_StopAllThreads(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_T
err = errno;
if (err != ESRCH) {
detach_threads(st, seized);
_set_debug_oserror_from_errno(err,
"Failed to interrupt thread %d: %s", tid, strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno(err,
"Failed to interrupt thread %d: %S", tid, message);
Py_DECREF(message);
}
_Py_RemoteDebug_InitThreadsState(unwinder, st);
return -1;
}
Expand All @@ -839,8 +856,12 @@ _Py_RemoteDebug_StopAllThreads(RemoteUnwinderObject *unwinder, _Py_RemoteDebug_T
err = errno;
if (err != ECHILD && err != ESRCH) {
detach_threads(st, seized);
_set_debug_oserror_from_errno(err,
"waitpid failed for thread %d: %s", tid, strerror(err));
PyObject *message = _Py_strerror(err);
if (message != NULL) {
_set_debug_oserror_from_errno(err,
"waitpid failed for thread %d: %S", tid, message);
Py_DECREF(message);
}
_Py_RemoteDebug_InitThreadsState(unwinder, st);
return -1;
}
Expand Down
81 changes: 1 addition & 80 deletions Modules/posixmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -13923,86 +13923,7 @@ static PyObject *
os_strerror_impl(PyObject *module, int code)
/*[clinic end generated code: output=baebf09fa02a78f2 input=75a8673d97915a91]*/
{
#ifdef _Py_HAVE_STRERROR_R
// Check which strerror_r() API is used
# if defined(__GLIBC__) && !((_POSIX_C_SOURCE >= 200112L) && !defined(_GNU_SOURCE))
# define Py_STRERROR_R_GNU
# elif defined(__ANDROID__) && defined(_GNU_SOURCE)
# define Py_STRERROR_R_GNU
# endif
#endif

#ifdef Py_STRERROR_R_GNU
// Implementation for the GNU flavor of strerror_r()

// On Linux, the longest translated strerror() message is 86 bytes
// (including the NUL byte).
char buffer[100];
char *message = strerror_r(code, buffer, Py_ARRAY_LENGTH(buffer));
// The strerror_r() GNU flavor doesn't provide a way to check if the error
// message was truncated or not.
//
// When the buffer is used, a trailing NUL byte is always written.
assert(message != buffer || memchr(buffer, 0, Py_ARRAY_LENGTH(buffer)) != NULL);
return PyUnicode_DecodeLocale(message, "surrogateescape");

#elif defined(_Py_HAVE_STRERROR_R)
// Implementation for the XSI-compliant flavor of strerror_r()

// On Linux and FreeBSD, the longest translated strerror() message is 86
// bytes (including the NUL byte).
char small_buffer[100];
size_t buflen = Py_ARRAY_LENGTH(small_buffer);
char *buffer = NULL;
#ifndef NDEBUG
// Make sure that strerror_r() writes a trailing null byte
small_buffer[buflen - 1] = '#';
#endif
int len = strerror_r(code, small_buffer, buflen);
if (len == ERANGE) {
while (len == ERANGE) {
if (buflen > (size_t)PY_SSIZE_T_MAX / 2) {
PyMem_Free(buffer);
PyErr_NoMemory();
return NULL;
}
buflen = buflen * 2;

char *new_buffer = PyMem_Realloc(buffer, buflen);
if (new_buffer == NULL) {
PyMem_Free(buffer);
PyErr_NoMemory();
return NULL;
}
buffer = new_buffer;
#ifndef NDEBUG
buffer[buflen - 1] = '#';
#endif
len = strerror_r(code, buffer, buflen);
}
}
else {
buffer = small_buffer;
}

// strerror_r() always writes a trailing NUL byte
assert(memchr(buffer, 0, buflen) != NULL);
PyObject *result = PyUnicode_DecodeLocale(buffer, "surrogateescape");
if (buffer != small_buffer) {
PyMem_Free(buffer);
}
return result;

#else
// strerror() implementation
char *message = strerror(code);
if (message == NULL) {
PyErr_SetString(PyExc_ValueError,
"strerror() argument out of range");
return NULL;
}
return PyUnicode_DecodeLocale(message, "surrogateescape");
#endif
return _Py_strerror(code);
}


Expand Down
3 changes: 1 addition & 2 deletions Python/errors.c
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Original file line number Diff line number Diff line change
Expand Up @@ -842,8 +842,7 @@ PyErr_SetFromErrnoWithFilenameObjects(PyObject *exc, PyObject *filenameObject, P

#ifndef MS_WINDOWS
if (i != 0) {
const char *s = strerror(i);
message = PyUnicode_DecodeLocale(s, "surrogateescape");
message = _Py_strerror(i);
}
else {
/* Sometimes errno didn't get set */
Expand Down
94 changes: 94 additions & 0 deletions Python/fileutils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3302,3 +3302,97 @@ _Py_IsValidFD(int fd)
return (fstat(fd, &st) == 0);
#endif
}


// Call strerror_r(code) if available, or use strerror() otherwise. Decode the
// result from the locale encoding using surrogateescape error handler.
//
// On success, return a Unicode string. On error, set an exception and return
// NULL.
PyObject*
_Py_strerror(int code)
/*[clinic end generated code: output=baebf09fa02a78f2 input=75a8673d97915a91]*/
{
const char *errors = "surrogateescape";

#ifdef _Py_HAVE_STRERROR_R
// Check which strerror_r() API is used
# if defined(__GLIBC__) && !((_POSIX_C_SOURCE >= 200112L) && !defined(_GNU_SOURCE))
# define Py_STRERROR_R_GNU
# elif defined(__ANDROID__) && defined(_GNU_SOURCE)
# define Py_STRERROR_R_GNU
# endif
#endif

#ifdef Py_STRERROR_R_GNU
// Implementation for the GNU flavor of strerror_r()

// On Linux, the longest translated strerror() message is 86 bytes
// (including the NUL byte).
char buffer[100];
char *message = strerror_r(code, buffer, Py_ARRAY_LENGTH(buffer));
// The strerror_r() GNU flavor doesn't provide a way to check if the error
// message was truncated or not.
//
// When the buffer is used, a trailing NUL byte is always written.
assert(message != buffer || memchr(buffer, 0, Py_ARRAY_LENGTH(buffer)) != NULL);
return PyUnicode_DecodeLocale(message, errors);

#elif defined(_Py_HAVE_STRERROR_R)
// Implementation for the XSI-compliant flavor of strerror_r()

// On Linux and FreeBSD, the longest translated strerror() message is 86
// bytes (including the NUL byte).
char small_buffer[100];
size_t buflen = Py_ARRAY_LENGTH(small_buffer);
char *buffer = NULL;
#ifndef NDEBUG
// Make sure that strerror_r() writes a trailing null byte
small_buffer[buflen - 1] = '#';
#endif
int len = strerror_r(code, small_buffer, buflen);
if (len == ERANGE) {
while (len == ERANGE) {
if (buflen > (size_t)PY_SSIZE_T_MAX / 2) {
PyMem_Free(buffer);
PyErr_NoMemory();
return NULL;
}
buflen = buflen * 2;

char *new_buffer = PyMem_Realloc(buffer, buflen);
if (new_buffer == NULL) {
PyMem_Free(buffer);
PyErr_NoMemory();
return NULL;
}
buffer = new_buffer;
#ifndef NDEBUG
buffer[buflen - 1] = '#';
#endif
len = strerror_r(code, buffer, buflen);
}
}
else {
buffer = small_buffer;
}

// strerror_r() always writes a trailing NUL byte
assert(memchr(buffer, 0, buflen) != NULL);
PyObject *result = PyUnicode_DecodeLocale(buffer, errors);
if (buffer != small_buffer) {
PyMem_Free(buffer);
}
return result;

#else
// strerror() implementation (usually not thread-safe)
char *message = strerror(code);
if (message == NULL) {
PyErr_SetString(PyExc_ValueError,
"strerror() argument out of range");
return NULL;
}
return PyUnicode_DecodeLocale(message, errors);
#endif
}
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