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GeezerVison is showing github.com — graalpython/graalpython/python-libposix/src/fork_exec.c at master · soucod/graalpython Expand file tree/ Copy pathfork_exec.cMore file actions 665 lines (597 loc) · 20.7 KB / Copy pathfork_exec.cFile metadata and controls665 lines (597 loc) · 20.7 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 /* Copyright (c) 2021, 2026, Oracle and/or its affiliates. * Copyright (C) 1996-2020 Python Software Foundation * * Licensed under the PYTHON SOFTWARE FOUNDATION LICENSE VERSION 2 */ #ifdef _WIN32 #include <errno.h> #include <stdint.h> __declspec(dllexport) int32_t fork_exec( char *data, int64_t *offsets, int32_t offsetsLen, int32_t argsPos, int32_t envPos, int32_t cwdPos, int32_t stdinRdFd, int32_t stdinWrFd, int32_t stdoutRdFd, int32_t stdoutWrFd, int32_t stderrRdFd, int32_t stderrWrFd, int32_t errPipeRdFd, int32_t errPipeWrFd, int32_t closeFds, int32_t restoreSignals, int32_t callSetsid, int32_t pgidToSet, int32_t allowVFork, int32_t *fdsToKeep, int64_t fdsToKeepLen ) { errno = ENOSYS; return -1; } #else #if defined(__gnu_linux__) && !defined(_GNU_SOURCE) #define _GNU_SOURCE 1 #endif #include <unistd.h> #include <fcntl.h> #include <sys/types.h> #include <sys/stat.h> #if defined(__linux__) #include <sys/syscall.h> #endif #include <dirent.h> #include <errno.h> #include <assert.h> #include <string.h> #include <limits.h> #include <signal.h> #include "errno_capture.h" // These definitions emulate CPython's equivalents so that the copy&pasted code below works without too many changes #define HAVE_DIRFD 1 #define HAVE_SETSID 1 #if defined(__GNUC__) || defined(__clang__) #define Py_NO_INLINE __attribute__((noinline)) #elif defined(_MSC_VER) #define Py_NO_INLINE __declspec(noinline) #else #define Py_NO_INLINE #endif #if defined(__linux__) /* If this is ever expanded to non-Linux platforms, verify what calls are * allowed after vfork(). Ex: setsid() may be disallowed on macOS? */ #define VFORK_USABLE 1 #endif int32_t set_inheritable(int32_t fd, int32_t inheritable); // TODO JDK also handles EINTR for dup2 calls // TODO neither CPython nor JDK handle EINTR returned from close(), see NOTES on man page for close(2) static const char *Py_hexdigits = "0123456789abcdef"; static int _Py_set_inheritable_async_safe(int fd, int inheritable, int *atomic_flag_works) { assert(atomic_flag_works == NULL); return set_inheritable(fd, inheritable); } static void _Py_write_noraise(int fd, const void *buf, size_t count) { while (write(fd, buf, count) < 0 && errno == EINTR) ; } static void _Py_RestoreSignals() { } // The following code is taken directly from CPython's _posixsubprocess.c with some minor changes: // - py_fds_to_keep is not a PyObject, but an int array // - there's no preexec_fn #if defined(__FreeBSD__) || (defined(__APPLE__) && defined(__MACH__)) # define FD_DIR "/dev/fd" #else # define FD_DIR "/proc/self/fd" #endif #define POSIX_CALL(call) do { if ((call) == -1) goto error; } while (0) /* Convert ASCII to a positive int, no libc call. no overflow. -1 on error. */ static int _pos_int_from_ascii(const char *name) { int num = 0; while (*name >= '0' && *name <= '9') { num = num * 10 + (*name - '0'); ++name; } if (*name) return -1; /* Non digit found, not a number. */ return num; } /* Is fd found in the sorted Python Sequence? */ static int _is_fd_in_sorted_fd_sequence(int fd, int *fd_sequence, ssize_t fd_sequence_len) { /* Binary search. */ ssize_t search_min = 0; ssize_t search_max = fd_sequence_len - 1; if (search_max < 0) return 0; do { long middle = (search_min + search_max) / 2; int middle_fd = fd_sequence[middle]; if (fd == middle_fd) return 1; if (fd > middle_fd) search_min = middle + 1; else search_max = middle - 1; } while (search_min <= search_max); return 0; } static int make_inheritable(int *fds_to_keep, ssize_t len, int errpipe_write) { ssize_t i; for (i = 0; i < len; ++i) { int fd = fds_to_keep[i]; assert(0 <= fd && fd <= INT_MAX); if (fd == errpipe_write) { /* errpipe_write is part of py_fds_to_keep. It must be closed at exec(), but kept open in the child process until exec() is called. */ continue; } if (_Py_set_inheritable_async_safe(fd, 1, NULL) < 0) return -1; } return 0; } /* Get the maximum file descriptor that could be opened by this process. * This function is async signal safe for use between fork() and exec(). */ static long safe_get_max_fd(void) { long local_max_fd; #if defined(__NetBSD__) local_max_fd = fcntl(0, F_MAXFD); if (local_max_fd >= 0) return local_max_fd; #endif #if defined(HAVE_SYS_RESOURCE_H) && defined(__OpenBSD__) struct rlimit rl; /* Not on the POSIX async signal safe functions list but likely * safe. TODO - Someone should audit OpenBSD to make sure. */ if (getrlimit(RLIMIT_NOFILE, &rl) >= 0) return (long) rl.rlim_max; #endif #ifdef _SC_OPEN_MAX local_max_fd = sysconf(_SC_OPEN_MAX); if (local_max_fd == -1) #endif local_max_fd = 256; /* Matches legacy Lib/subprocess.py behavior. */ return local_max_fd; } /* Close all file descriptors in the range from start_fd and higher * except for those in py_fds_to_keep. If the range defined by * [start_fd, safe_get_max_fd()) is large this will take a long * time as it calls close() on EVERY possible fd. * * It isn't possible to know for sure what the max fd to go up to * is for processes with the capability of raising their maximum. */ static void _close_fds_by_brute_force(long start_fd, int *fds_to_keep, ssize_t num_fds_to_keep) { long end_fd = safe_get_max_fd(); ssize_t keep_seq_idx; int fd_num; /* As py_fds_to_keep is sorted we can loop through the list closing * fds in between any in the keep list falling within our range. */ for (keep_seq_idx = 0; keep_seq_idx < num_fds_to_keep; ++keep_seq_idx) { int keep_fd = fds_to_keep[keep_seq_idx]; if (keep_fd < start_fd) continue; for (fd_num = start_fd; fd_num < keep_fd; ++fd_num) { close(fd_num); } start_fd = keep_fd + 1; } if (start_fd <= end_fd) { for (fd_num = start_fd; fd_num < end_fd; ++fd_num) { close(fd_num); } } } #if defined(__linux__) && defined(SYS_getdents64) struct linux_dirent64 { unsigned long long d_ino; long long d_off; unsigned short d_reclen; unsigned char d_type; char d_name[256]; }; static void _close_open_fds_safe(long start_fd, int *fds_to_keep, ssize_t fds_to_keep_len) { int fd_dir_fd = open(FD_DIR, O_RDONLY); if (fd_dir_fd == -1) { _close_fds_by_brute_force(start_fd, fds_to_keep, fds_to_keep_len); return; } char buffer[sizeof(struct linux_dirent64)]; int bytes; while ((bytes = syscall(SYS_getdents64, fd_dir_fd, (struct linux_dirent64 *)buffer, sizeof(buffer))) > 0) { struct linux_dirent64 *entry; int offset; for (offset = 0; offset < bytes; offset += entry->d_reclen) { int fd; entry = (struct linux_dirent64 *)(buffer + offset); if ((fd = _pos_int_from_ascii(entry->d_name)) < 0) continue; if (fd != fd_dir_fd && fd >= start_fd && !_is_fd_in_sorted_fd_sequence(fd, fds_to_keep, fds_to_keep_len)) { close(fd); } } } close(fd_dir_fd); } #define _close_open_fds _close_open_fds_safe #else /* Close all open file descriptors from start_fd and higher. * Do not close any in the sorted py_fds_to_keep tuple. * * This function violates the strict use of async signal safe functions. :( * It calls opendir(), readdir() and closedir(). Of these, the one most * likely to ever cause a problem is opendir() as it performs an internal * malloc(). Practically this should not be a problem. The Java VM makes the * same calls between fork and exec in its own UNIXProcess_md.c implementation. * * readdir_r() is not used because it provides no benefit. It is typically * implemented as readdir() followed by memcpy(). See also: * http://womble.decadent.org.uk/readdir_r-advisory.html */ static void _close_open_fds_maybe_unsafe(long start_fd, int* fds_to_keep, ssize_t fds_to_keep_len) { DIR *proc_fd_dir; #ifndef HAVE_DIRFD while (_is_fd_in_sorted_fd_sequence(start_fd, fds_to_keep, fds_to_keep_len)) { ++start_fd; } /* Close our lowest fd before we call opendir so that it is likely to * reuse that fd otherwise we might close opendir's file descriptor in * our loop. This trick assumes that fd's are allocated on a lowest * available basis. */ close(start_fd); ++start_fd; #endif #if defined(__FreeBSD__) if (!_is_fdescfs_mounted_on_dev_fd()) proc_fd_dir = NULL; else #endif proc_fd_dir = opendir(FD_DIR); if (!proc_fd_dir) { /* No way to get a list of open fds. */ _close_fds_by_brute_force(start_fd, fds_to_keep, fds_to_keep_len); } else { struct dirent *dir_entry; #ifdef HAVE_DIRFD int fd_used_by_opendir = dirfd(proc_fd_dir); #else int fd_used_by_opendir = start_fd - 1; #endif errno = 0; while ((dir_entry = readdir(proc_fd_dir))) { int fd; if ((fd = _pos_int_from_ascii(dir_entry->d_name)) < 0) continue; /* Not a number. */ if (fd != fd_used_by_opendir && fd >= start_fd && !_is_fd_in_sorted_fd_sequence(fd, fds_to_keep, fds_to_keep_len)) { close(fd); } errno = 0; } if (errno) { /* readdir error, revert behavior. Highly Unlikely. */ _close_fds_by_brute_force(start_fd, fds_to_keep, fds_to_keep_len); } closedir(proc_fd_dir); } } #define _close_open_fds _close_open_fds_maybe_unsafe #endif #ifdef VFORK_USABLE static void reset_signal_handlers(const sigset_t *child_sigmask) { struct sigaction sa_dfl = {.sa_handler = SIG_DFL}; for (int sig = 1; sig < _NSIG; sig++) { if (sig == SIGKILL || sig == SIGSTOP) { continue; } if (sigismember(child_sigmask, sig) == 1) { continue; } struct sigaction sa; if (sigaction(sig, NULL, &sa) == -1) { continue; } void *h = (sa.sa_flags & SA_SIGINFO ? (void *)sa.sa_sigaction : (void *)sa.sa_handler); if (h == SIG_IGN || h == SIG_DFL) { continue; } (void) sigaction(sig, &sa_dfl, NULL); } } #endif /* * This function is code executed in the child process immediately after fork * to set things up and call exec(). * * All of the code in this function must only use async-signal-safe functions, * listed at `man 7 signal` or * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html. * * This restriction is documented at * http://www.opengroup.org/onlinepubs/009695399/functions/fork.html. * * If this function is called after vfork(), even more care must be taken. * The child shares the parent's address space until execve() or _exit(). */ Py_NO_INLINE static void child_exec(char *const exec_array[], char *const argv[], char *const envp[], const char *cwd, int p2cread, int p2cwrite, int c2pread, int c2pwrite, int errread, int errwrite, int errpipe_read, int errpipe_write, int close_fds, int restore_signals, int call_setsid, int pgid_to_set, const void *child_sigmask, int *fds_to_keep, ssize_t fds_to_keep_len) { int i, saved_errno; /* Buffer large enough to hold a hex integer. We can't malloc. */ char hex_errno[sizeof(saved_errno)*2+1]; const char *err_msg = "noexec"; if (make_inheritable(fds_to_keep, fds_to_keep_len, errpipe_write) < 0) goto error; /* Close parent's pipe ends. */ if (p2cwrite != -1) POSIX_CALL(close(p2cwrite)); if (c2pread != -1) POSIX_CALL(close(c2pread)); if (errread != -1) POSIX_CALL(close(errread)); POSIX_CALL(close(errpipe_read)); /* When duping fds, if there arises a situation where one of the fds is either 0, 1 or 2, it is possible that it is overwritten (#12607). */ if (c2pwrite == 0) { POSIX_CALL(c2pwrite = dup(c2pwrite)); /* issue32270 */ if (_Py_set_inheritable_async_safe(c2pwrite, 0, NULL) < 0) { goto error; } } while (errwrite == 0 || errwrite == 1) { POSIX_CALL(errwrite = dup(errwrite)); /* issue32270 */ if (_Py_set_inheritable_async_safe(errwrite, 0, NULL) < 0) { goto error; } } /* Dup fds for child. dup2() removes the CLOEXEC flag but we must do it ourselves if dup2() would be a no-op (issue #10806). */ if (p2cread == 0) { if (_Py_set_inheritable_async_safe(p2cread, 1, NULL) < 0) goto error; } else if (p2cread != -1) POSIX_CALL(dup2(p2cread, 0)); /* stdin */ if (c2pwrite == 1) { if (_Py_set_inheritable_async_safe(c2pwrite, 1, NULL) < 0) goto error; } else if (c2pwrite != -1) POSIX_CALL(dup2(c2pwrite, 1)); /* stdout */ if (errwrite == 2) { if (_Py_set_inheritable_async_safe(errwrite, 1, NULL) < 0) goto error; } else if (errwrite != -1) POSIX_CALL(dup2(errwrite, 2)); /* stderr */ /* We no longer manually close p2cread, c2pwrite, and errwrite here as * _close_open_fds takes care when it is not already non-inheritable. */ if (cwd) { if (chdir(cwd) == -1) { err_msg = "noexec:chdir"; goto error; } } if (restore_signals) _Py_RestoreSignals(); #ifdef VFORK_USABLE if (child_sigmask) { reset_signal_handlers((const sigset_t *)child_sigmask); if ((errno = pthread_sigmask(SIG_SETMASK, child_sigmask, NULL))) { goto error; } } #endif #ifdef HAVE_SETSID if (call_setsid) POSIX_CALL(setsid()); #endif if (pgid_to_set >= 0) POSIX_CALL(setpgid(0, pgid_to_set)); err_msg = ""; /* close FDs after executing preexec_fn, which might open FDs */ if (close_fds) { /* TODO HP-UX could use pstat_getproc() if anyone cares about it. */ _close_open_fds(3, fds_to_keep, fds_to_keep_len); } /* This loop matches the Lib/os.py _execvpe()'s PATH search when */ /* given the executable_list generated by Lib/subprocess.py. */ saved_errno = 0; for (i = 0; exec_array[i] != NULL; ++i) { const char *executable = exec_array[i]; if (envp) { execve(executable, argv, envp); } else { execv(executable, argv); } if (errno != ENOENT && errno != ENOTDIR && saved_errno == 0) { saved_errno = errno; } } /* Report the first exec error, not the last. */ if (saved_errno) errno = saved_errno; error: saved_errno = errno; /* Report the posix error to our parent process. */ /* We ignore all write() return values as the total size of our writes is less than PIPEBUF and we cannot do anything about an error anyways. Use _Py_write_noraise() to retry write() if it is interrupted by a signal (fails with EINTR). */ if (saved_errno) { char *cur; _Py_write_noraise(errpipe_write, "OSError:", 8); cur = hex_errno + sizeof(hex_errno); while (saved_errno != 0 && cur != hex_errno) { *--cur = Py_hexdigits[saved_errno % 16]; saved_errno /= 16; } _Py_write_noraise(errpipe_write, cur, hex_errno + sizeof(hex_errno) - cur); _Py_write_noraise(errpipe_write, ":", 1); /* We can't call strerror(saved_errno). It is not async signal safe. * The parent process will look the error message up. */ } else { _Py_write_noraise(errpipe_write, "SubprocessError:0:", 18); } _Py_write_noraise(errpipe_write, err_msg, strlen(err_msg)); } Py_NO_INLINE static pid_t do_fork_exec(char *const exec_list[], char *const argv[], char *const envp[], const char *cwd, int stdinRdFd, int stdinWrFd, int stdoutRdFd, int stdoutWrFd, int stderrRdFd, int stderrWrFd, int errPipeRdFd, int errPipeWrFd, int closeFds, int restoreSignals, int callSetsid, int pgidToSet, const void *childSigmask, int *fdsToKeep, int64_t fdsToKeepLen) { pid_t pid; #ifdef VFORK_USABLE if (childSigmask) { pid = vfork(); } else #endif { pid = fork(); } if (pid != 0) { return pid; } child_exec( exec_list, argv, envp, cwd, stdinRdFd, stdinWrFd, stdoutRdFd, stdoutWrFd, stderrRdFd, stderrWrFd, errPipeRdFd, errPipeWrFd, closeFds, restoreSignals, callSetsid, pgidToSet, childSigmask, fdsToKeep, fdsToKeepLen ); _exit(255); } /* * data, offsets, offsetsLen, argsPos, envPos, cwdPos - see comment in NativePosixSupport.forkExec() * stdinRdFd - read end of the pipe for the child's stdin - closed by parent, dupped to fd 0 by child * stdinWrFd - write end of the pipe for the child's stdin - closed by child, written to by parent * stdoutRdFd - read end of the pipe for the child's stdout - closed by child, read from by parent * stdoutWrFd - write end of the pipe for the child's stdout - closed by parent, dupped to fd 1 by child * stderrRdFd - read end of the pipe for the child's stderr - closed by child, read from by parent * stderrWrFd - write end of the pipe for the child's stderr - closed by parent, dupped to fd 2 by child * errPipeRdFd - read end of the pipe for reporting exec errors to parent - closed by child, read from by parent * errPipeWrFd - write end of the pipe for reporting exec errors to parent - closed by parent, written to by child if an error occurs - the child process closes this fd in any case: - on success, no data is written and the fd is closed by exec() because its O_CLOEXEC is set - on error, the error code is written and the fd is closed because the child process exits * closeFds - nonzero if all fds except 0, 1, 2 and those in fdsToKeep should be explicitly closed by the child * (if nonzero, then errPipeWrFd must be in fdsToKeep) * restoreSignals - currently not used * callSetsid - if nonzero, the child calls setsid before exec() * pgidToSet - if non-negative, the child calls setpgid(0, pgidToSet) before exec() * allowVFork - if nonzero, use vfork() instead of fork() where it is safe and supported * fdsToKeep, fdsToKeepLen - a sorted list of fds to keep open (the child clears their O_CLOEXEC) */ int32_t fork_exec( char *data, int64_t *offsets, int32_t offsetsLen, int32_t argsPos, int32_t envPos, int32_t cwdPos, int32_t stdinRdFd, int32_t stdinWrFd, int32_t stdoutRdFd, int32_t stdoutWrFd, int32_t stderrRdFd, int32_t stderrWrFd, int32_t errPipeRdFd, int32_t errPipeWrFd, int32_t closeFds, int32_t restoreSignals, int32_t callSetsid, int32_t pgidToSet, int32_t allowVFork, int32_t *fdsToKeep, int64_t fdsToKeepLen ) { // We reuse the memory allocated for offsets to avoid the need to allocate and reliably free another array char **strings = (char **) offsets; for (int32_t i = 0; i < offsetsLen; ++i) { strings[i] = offsets[i] == -1 ? NULL : data + offsets[i]; } char **exec_list = strings; char **argv = strings + argsPos; char **envp = envPos == -1 ? NULL : strings + envPos; char *cwd = cwdPos == -1 ? NULL : strings[cwdPos]; #ifdef VFORK_USABLE const void *oldSigmask = NULL; sigset_t oldSigs; /* Keep process-group setup on the normal fork path. */ if (allowVFork && pgidToSet < 0) { sigset_t allSigs; sigfillset(&allSigs); int err = pthread_sigmask(SIG_BLOCK, &allSigs, &oldSigs); if (err) { errno = err; capture_errno(); return -1; } oldSigmask = &oldSigs; } #else const void *oldSigmask = NULL; #endif pid_t pid = do_fork_exec( exec_list, argv, envp, cwd, stdinRdFd, stdinWrFd, stdoutRdFd, stdoutWrFd, stderrRdFd, stderrWrFd, errPipeRdFd, errPipeWrFd, closeFds, restoreSignals, callSetsid, pgidToSet, oldSigmask, fdsToKeep, fdsToKeepLen ); #ifdef VFORK_USABLE if (oldSigmask) { (void) pthread_sigmask(SIG_SETMASK, oldSigmask, NULL); } #endif capture_errno(); return pid; } #endif |
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