cpython/Modules/_remote_debugging/subprocess.c at 3.15 · python/cpython · GitHub

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/******************************************************************************

* Remote Debugging Module - Subprocess Enumeration

* This file contains platform-specific functions for enumerating child

* processes of a given PID.

******************************************************************************/

#include "_remote_debugging.h"

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

#ifndef MS_WINDOWS

#include <unistd.h>

#include <dirent.h>

#endif

#ifdef MS_WINDOWS

#include <tlhelp32.h>

#endif

/* ============================================================================

* INTERNAL DATA STRUCTURES

* ============================================================================ */

/* Simple dynamic array for collecting PIDs */

typedef struct {

pid_t *pids;

size_t count;

size_t capacity;

} pid_array_t;

static int

pid_array_init(pid_array_t *arr)

{

arr->capacity = 64;

arr->count = 0;

arr->pids = (pid_t *)PyMem_Malloc(arr->capacity * sizeof(pid_t));

if (arr->pids == NULL) {

PyErr_NoMemory();

return -1;

}

return 0;

}

static void

pid_array_cleanup(pid_array_t *arr)

{

if (arr->pids != NULL) {

PyMem_Free(arr->pids);

arr->pids = NULL;

}

arr->count = 0;

arr->capacity = 0;

}

static int

pid_array_append(pid_array_t *arr, pid_t pid)

{

if (arr->count >= arr->capacity) {

/* Check for overflow before multiplication */

if (arr->capacity > SIZE_MAX / 2) {

PyErr_SetString(PyExc_OverflowError, "PID array capacity overflow");

return -1;

}

size_t new_capacity = arr->capacity * 2;

/* Check allocation size won't overflow */

if (new_capacity > SIZE_MAX / sizeof(pid_t)) {

PyErr_SetString(PyExc_OverflowError, "PID array size overflow");

return -1;

}

pid_t *new_pids = (pid_t *)PyMem_Realloc(arr->pids, new_capacity * sizeof(pid_t));

if (new_pids == NULL) {

PyErr_NoMemory();

return -1;

}

arr->pids = new_pids;

arr->capacity = new_capacity;

}

arr->pids[arr->count++] = pid;

return 0;

}

static int

pid_array_contains(pid_array_t *arr, pid_t pid)

{

for (size_t i = 0; i < arr->count; i++) {

if (arr->pids[i] == pid) {

return 1;

}

return 0;

}

/* ============================================================================

* SHARED BFS HELPER

* ============================================================================ */

/* Find child PIDs using BFS traversal of the pid->ppid mapping.

* all_pids and ppids must have the same count (parallel arrays).

* Returns 0 on success, -1 on error. */

static int

find_children_bfs(pid_t target_pid, int recursive,

pid_t *all_pids, pid_t *ppids, size_t pid_count,

pid_array_t *result)

{

int retval = -1;

pid_array_t to_process = {0};

if (pid_array_init(&to_process) < 0) {

goto done;

}

if (pid_array_append(&to_process, target_pid) < 0) {

goto done;

}

size_t process_idx = 0;

while (process_idx < to_process.count) {

pid_t current_pid = to_process.pids[process_idx++];

for (size_t i = 0; i < pid_count; i++) {

if (ppids[i] != current_pid) {

continue;

}

pid_t child_pid = all_pids[i];

if (pid_array_contains(result, child_pid)) {

continue;

}

if (pid_array_append(result, child_pid) < 0) {

goto done;

}

if (recursive && pid_array_append(&to_process, child_pid) < 0) {

goto done;

}

if (!recursive) {

break;

}

retval = 0;

done:

pid_array_cleanup(&to_process);

return retval;

}

/* ============================================================================

* LINUX IMPLEMENTATION

* ============================================================================ */

#if defined(__linux__)

/* Parse /proc/{pid}/stat to get parent PID */

static pid_t

get_ppid_linux(pid_t pid)

{

char stat_path[64];

char buffer[2048];

snprintf(stat_path, sizeof(stat_path), "/proc/%d/stat", (int)pid);

int fd = open(stat_path, O_RDONLY);

if (fd == -1) {

return -1;

}

ssize_t n = read(fd, buffer, sizeof(buffer) - 1);

close(fd);

if (n <= 0) {

return -1;

}

buffer[n] = '\0';

/* Find closing paren of comm field - stat format: pid (comm) state ppid ... */

char *p = strrchr(buffer, ')');

if (!p) {

return -1;

}

/* Skip ") " with bounds checking */

char *end = buffer + n;

p += 2;

if (p >= end) {

return -1;

}

if (*p == ' ') {

p++;

if (p >= end) {

return -1;

}

/* Parse: state ppid */

char state;

int ppid;

if (sscanf(p, "%c %d", &state, &ppid) != 2) {

return -1;

}

return (pid_t)ppid;

}

static int

get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)

{

int retval = -1;

pid_array_t all_pids = {0};

pid_array_t ppids = {0};

DIR *proc_dir = NULL;

if (pid_array_init(&all_pids) < 0) {

goto done;

}

if (pid_array_init(&ppids) < 0) {

goto done;

}

proc_dir = opendir("/proc");

if (!proc_dir) {

PyErr_SetFromErrnoWithFilename(PyExc_OSError, "/proc");

goto done;

}

/* Single pass: collect PIDs and their PPIDs together */

for (;;) {

errno = 0;

struct dirent *entry = readdir(proc_dir);

if (entry == NULL) {

if (errno != 0) {

int err = errno;

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;

}

/* Skip non-numeric entries (also skips . and ..) */

if (entry->d_name[0] < '1' || entry->d_name[0] > '9') {

continue;

}

char *endptr;

long pid_long = strtol(entry->d_name, &endptr, 10);

if (*endptr != '\0' || pid_long <= 0) {

continue;

}

pid_t pid = (pid_t)pid_long;

pid_t ppid = get_ppid_linux(pid);

if (ppid < 0) {

continue;

}

if (pid_array_append(&all_pids, pid) < 0 ||

pid_array_append(&ppids, ppid) < 0) {

goto done;

}

if (closedir(proc_dir) != 0) {

int err = errno;

proc_dir = NULL;

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;

if (find_children_bfs(target_pid, recursive,

all_pids.pids, ppids.pids, all_pids.count,

result) < 0) {

goto done;

}

retval = 0;

done:

if (proc_dir) {

closedir(proc_dir);

}

pid_array_cleanup(&all_pids);

pid_array_cleanup(&ppids);

return retval;

}

#endif /* __linux__ */

/* ============================================================================

* MACOS IMPLEMENTATION

* ============================================================================ */

#if defined(__APPLE__) && TARGET_OS_OSX

#include <libproc.h>

#include <sys/proc_info.h>

static int

get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)

{

int retval = -1;

pid_t *pid_list = NULL;

pid_t *ppids = NULL;

/* Get count of all PIDs */

int n_pids = proc_listpids(PROC_ALL_PIDS, 0, NULL, 0);

if (n_pids <= 0) {

PyErr_SetString(PyExc_OSError, "Failed to get process count");

goto done;

}

n_pids /= sizeof(pid_t);

/* Allocate buffer for PIDs (add some slack for new processes) */

int buffer_size = n_pids + 64;

pid_list = (pid_t *)PyMem_Malloc(buffer_size * sizeof(pid_t));

if (!pid_list) {

PyErr_NoMemory();

goto done;

}

/* Get actual PIDs */

int actual = proc_listpids(PROC_ALL_PIDS, 0, pid_list, buffer_size * sizeof(pid_t));

if (actual <= 0) {

PyErr_SetString(PyExc_OSError, "Failed to list PIDs");

goto done;

}

actual /= sizeof(pid_t);

/* Build pid -> ppid mapping */

ppids = (pid_t *)PyMem_Malloc(actual * sizeof(pid_t));

if (!ppids) {

PyErr_NoMemory();

goto done;

}

/* Get parent PIDs for each process */

int valid_count = 0;

for (int i = 0; i < actual; i++) {

struct proc_bsdinfo proc_info;

int ret = proc_pidinfo(pid_list[i], PROC_PIDTBSDINFO, 0,

&proc_info, sizeof(proc_info));

if (ret != sizeof(proc_info)) {

continue;

}

pid_list[valid_count] = pid_list[i];

ppids[valid_count] = proc_info.pbi_ppid;

valid_count++;

}

if (find_children_bfs(target_pid, recursive,

pid_list, ppids, valid_count,

result) < 0) {

goto done;

}

retval = 0;

done:

PyMem_Free(pid_list);

PyMem_Free(ppids);

return retval;

}

#endif /* __APPLE__ && TARGET_OS_OSX */

/* ============================================================================

* WINDOWS IMPLEMENTATION

* ============================================================================ */

#ifdef MS_WINDOWS

static int

get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)

{

int retval = -1;

pid_array_t all_pids = {0};

pid_array_t ppids = {0};

HANDLE snapshot = INVALID_HANDLE_VALUE;

snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);

if (snapshot == INVALID_HANDLE_VALUE) {

DWORD error = GetLastError();

PyErr_SetFromWindowsErr(error);

goto done;

}

if (pid_array_init(&all_pids) < 0) {

goto done;

}

if (pid_array_init(&ppids) < 0) {

goto done;

}

/* Single pass: collect PIDs and PPIDs together */

PROCESSENTRY32 pe;

pe.dwSize = sizeof(PROCESSENTRY32);

if (!Process32First(snapshot, &pe)) {

DWORD error = GetLastError();

PyErr_SetFromWindowsErr(error);

goto done;

}

do {

if (pid_array_append(&all_pids, (pid_t)pe.th32ProcessID) < 0 ||

pid_array_append(&ppids, (pid_t)pe.th32ParentProcessID) < 0) {

goto done;

}

} while (Process32Next(snapshot, &pe));

DWORD error = GetLastError();

if (error != ERROR_NO_MORE_FILES) {

PyErr_SetFromWindowsErr(error);

goto done;

}

CloseHandle(snapshot);

snapshot = INVALID_HANDLE_VALUE;

if (find_children_bfs(target_pid, recursive,

all_pids.pids, ppids.pids, all_pids.count,

result) < 0) {

goto done;

}

retval = 0;

done:

if (snapshot != INVALID_HANDLE_VALUE) {

CloseHandle(snapshot);

}

pid_array_cleanup(&all_pids);

pid_array_cleanup(&ppids);

return retval;

}

#endif /* MS_WINDOWS */

/* ============================================================================

* UNSUPPORTED PLATFORM STUB

* ============================================================================ */

#if !defined(__linux__) && !(defined(__APPLE__) && TARGET_OS_OSX) && !defined(MS_WINDOWS)

static int

get_child_pids_platform(pid_t target_pid, int recursive, pid_array_t *result)

{

PyErr_SetString(PyExc_NotImplementedError,

"Subprocess enumeration not supported on this platform");

return -1;

}

#endif

/* ============================================================================

* PUBLIC API

* ============================================================================ */

PyObject *

enumerate_child_pids(pid_t target_pid, int recursive)

{

pid_array_t result;

if (pid_array_init(&result) < 0) {

return NULL;

}

if (get_child_pids_platform(target_pid, recursive, &result) < 0) {

pid_array_cleanup(&result);

return NULL;

}

/* Convert to Python list */

PyObject *list = PyList_New(result.count);

if (list == NULL) {

pid_array_cleanup(&result);

return NULL;

}

for (size_t i = 0; i < result.count; i++) {

PyObject *pid_obj = PyLong_FromLong((long)result.pids[i]);

if (pid_obj == NULL) {

Py_DECREF(list);

pid_array_cleanup(&result);

return NULL;

}

PyList_SET_ITEM(list, i, pid_obj);

}

pid_array_cleanup(&result);

return list;

}

cpython/Modules/_remote_debugging/subprocess.c at 3.15 · python/cpython · GitHub

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