1 /*
2 * Copyright (c) 1995, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 #undef _LARGEFILE64_SOURCE
27 #define _LARGEFILE64_SOURCE 1
28
29 #include "jni.h"
30 #include "jvm.h"
31 #include "jvm_md.h"
32 #include "jni_util.h"
33 #include "io_util.h"
34
35 /*
36 * Platform-specific support for java.lang.Process
37 */
38 #include <assert.h>
39 #include <stddef.h>
40 #include <stdlib.h>
41 #include <sys/types.h>
42 #include <sys/stat.h>
43 #include <ctype.h>
44 #include <sys/wait.h>
45 #include <signal.h>
46 #include <string.h>
47
48 #include <spawn.h>
49
50 #include "childproc.h"
51
52 /*
53 *
54 * When starting a child on Unix, we need to do three things:
55 * - fork off
56 * - in the child process, do some pre-exec work: duping/closing file
57 * descriptors to set up stdio-redirection, setting environment variables,
58 * changing paths...
59 * - then exec(2) the target binary
60 *
61 * There are three ways to fork off:
62 *
63 * A) fork(2). Portable and safe (no side effects) but may fail with ENOMEM on
64 * all Unices when invoked from a VM with a high memory footprint. On Unices
65 * with strict no-overcommit policy this problem is most visible.
66 *
67 * This is because forking the VM will first create a child process with
68 * theoretically the same memory footprint as the parent - even if you plan
69 * to follow up with exec'ing a tiny binary. In reality techniques like
70 * copy-on-write etc mitigate the problem somewhat but we still run the risk
71 * of hitting system limits.
72 *
73 * For a Linux centric description of this problem, see the documentation on
74 * /proc/sys/vm/overcommit_memory in Linux proc(5).
75 *
76 * B) vfork(2): Portable and fast but very unsafe. It bypasses the memory
77 * problems related to fork(2) by starting the child in the memory image of
78 * the parent. Things that can go wrong include:
79 * - Programming errors in the child process before the exec(2) call may
80 * trash memory in the parent process, most commonly the stack of the
81 * thread invoking vfork.
82 * - Signals received by the child before the exec(2) call may be at best
83 * misdirected to the parent, at worst immediately kill child and parent.
84 *
85 * This is mitigated by very strict rules about what one is allowed to do in
86 * the child process between vfork(2) and exec(2), which is basically nothing.
87 * However, we always broke this rule by doing the pre-exec work between
88 * vfork(2) and exec(2).
89 *
90 * Also note that vfork(2) has been deprecated by the OpenGroup, presumably
91 * because of its many dangers.
92 *
93 * C) clone(2): This is a Linux specific call which gives the caller fine
94 * grained control about how exactly the process fork is executed. It is
95 * powerful, but Linux-specific.
96 *
97 * Aside from these three possibilities there is a forth option: posix_spawn(3).
98 * Where fork/vfork/clone all fork off the process and leave pre-exec work and
99 * calling exec(2) to the user, posix_spawn(3) offers the user fork+exec-like
100 * functionality in one package, similar to CreateProcess() on Windows.
101 *
102 * It is not a system call in itself, but usually a wrapper implemented within
103 * the libc in terms of one of (fork|vfork|clone)+exec - so whether or not it
104 * has advantages over calling the naked (fork|vfork|clone) functions depends
105 * on how posix_spawn(3) is implemented.
106 *
107 * Note that when using posix_spawn(3), we exec twice: first a tiny binary called
108 * the jspawnhelper, then in the jspawnhelper we do the pre-exec work and exec a
109 * second time, this time the target binary (similar to the "exec-twice-technique"
110 * described in http://mail.openjdk.java.net/pipermail/core-libs-dev/2018-September/055333.html).
111 *
112 * This is a JDK-specific implementation detail which just happens to be
113 * implemented for jdk.lang.Process.launchMechanism=POSIX_SPAWN.
114 *
115 * --- Linux-specific ---
116 *
117 * How does glibc implement posix_spawn?
118 * (see: sysdeps/posix/spawni.c for glibc < 2.24,
119 * sysdeps/unix/sysv/linux/spawni.c for glibc >= 2.24):
120 *
121 * 1) Before glibc 2.4 (released 2006), posix_spawn(3) used just fork(2)/exec(2).
122 * This would be bad for the JDK since we would risk the known memory issues with
123 * fork(2). But since this only affects glibc variants which have long been
124 * phased out by modern distributions, this is irrelevant.
125 *
126 * 2) Between glibc 2.4 and glibc 2.23, posix_spawn uses either fork(2) or
127 * vfork(2) depending on how exactly the user called posix_spawn(3):
128 *
129 * <quote>
130 * The child process is created using vfork(2) instead of fork(2) when
131 * either of the following is true:
132 *
133 * * the spawn-flags element of the attributes object pointed to by
134 * attrp contains the GNU-specific flag POSIX_SPAWN_USEVFORK; or
135 *
136 * * file_actions is NULL and the spawn-flags element of the attributes
137 * object pointed to by attrp does not contain
138 * POSIX_SPAWN_SETSIGMASK, POSIX_SPAWN_SETSIGDEF,
139 * POSIX_SPAWN_SETSCHEDPARAM, POSIX_SPAWN_SETSCHEDULER,
140 * POSIX_SPAWN_SETPGROUP, or POSIX_SPAWN_RESETIDS.
141 * </quote>
142 *
143 * Due to the way the JDK calls posix_spawn(3), it would therefore call vfork(2).
144 * So we would avoid the fork(2) memory problems. However, there still remains the
145 * risk associated with vfork(2). But it is smaller than were we to call vfork(2)
146 * directly since we use the jspawnhelper, moving all pre-exec work off to after
147 * the first exec, thereby reducing the vulnerable time window.
148 *
149 * 3) Since glibc >= 2.24, glibc uses clone+exec:
150 *
151 * new_pid = CLONE (__spawni_child, STACK (stack, stack_size), stack_size,
152 * CLONE_VM | CLONE_VFORK | SIGCHLD, &args);
153 *
154 * This is even better than (2):
155 *
156 * CLONE_VM means we run in the parent's memory image, as with (2)
157 * CLONE_VFORK means parent waits until we exec, as with (2)
158 *
159 * However, error possibilities are further reduced since:
160 * - posix_spawn(3) passes a separate stack for the child to run on, eliminating
161 * the danger of trashing the forking thread's stack in the parent process.
162 * - posix_spawn(3) takes care to temporarily block all incoming signals to the
163 * child process until the first exec(2) has been called,
164 *
165 * TL;DR
166 * Calling posix_spawn(3) for glibc
167 * (2) < 2.24 is not perfect but still better than using plain vfork(2), since
168 * the chance of an error happening is greatly reduced
169 * (3) >= 2.24 is the best option - portable, fast and as safe as possible.
170 *
171 * ---
172 *
173 * How does muslc implement posix_spawn?
174 *
175 * They always did use the clone (.. CLONE_VM | CLONE_VFORK ...)
176 * technique. So we are safe to use posix_spawn() here regardless of muslc
177 * version.
178 *
179 * </Linux-specific>
180 *
181 *
182 * Based on the above analysis, we are currently defaulting to posix_spawn()
183 * on all Unices including Linux.
184 */
185
186 static void
187 setSIGCHLDHandler(JNIEnv *env)
188 {
189 /* There is a subtle difference between having the signal handler
190 * for SIGCHLD be SIG_DFL and SIG_IGN. We cannot obtain process
191 * termination information for child processes if the signal
192 * handler is SIG_IGN. It must be SIG_DFL.
193 *
194 * We used to set the SIGCHLD handler only on Linux, but it's
195 * safest to set it unconditionally.
196 *
197 * Consider what happens if java's parent process sets the SIGCHLD
198 * handler to SIG_IGN. Normally signal handlers are inherited by
199 * children, but SIGCHLD is a controversial case. Solaris appears
200 * to always reset it to SIG_DFL, but this behavior may be
201 * non-standard-compliant, and we shouldn't rely on it.
202 *
203 * References:
204 * http://www.opengroup.org/onlinepubs/7908799/xsh/exec.html
205 * http://www.pasc.org/interps/unofficial/db/p1003.1/pasc-1003.1-132.html
206 */
207 struct sigaction sa;
208 sa.sa_handler = SIG_DFL;
209 sigemptyset(&sa.sa_mask);
210 sa.sa_flags = SA_NOCLDSTOP | SA_RESTART;
211 if (sigaction(SIGCHLD, &sa, NULL) < 0)
212 JNU_ThrowInternalError(env, "Can't set SIGCHLD handler");
213 }
214
215 static void*
216 xmalloc(JNIEnv *env, size_t size)
217 {
218 void *p = malloc(size);
219 if (p == NULL)
220 JNU_ThrowOutOfMemoryError(env, NULL);
221 return p;
222 }
223
224 #define NEW(type, n) ((type *) xmalloc(env, (n) * sizeof(type)))
225
226 /**
227 * If PATH is not defined, the OS provides some default value.
228 * Unfortunately, there's no portable way to get this value.
229 * Fortunately, it's only needed if the child has PATH while we do not.
230 */
231 static const char*
232 defaultPath(void)
233 {
234 #ifdef __solaris__
235 /* These really are the Solaris defaults! */
236 return (geteuid() == 0 || getuid() == 0) ?
237 "/usr/xpg4/bin:/usr/bin:/opt/SUNWspro/bin:/usr/sbin" :
238 "/usr/xpg4/bin:/usr/bin:/opt/SUNWspro/bin:";
239 #else
240 return ":/bin:/usr/bin"; /* glibc */
241 #endif
242 }
243
244 static const char*
245 effectivePath(void)
246 {
247 const char *s = getenv("PATH");
248 return (s != NULL) ? s : defaultPath();
249 }
250
251 static int
252 countOccurrences(const char *s, char c)
253 {
254 int count;
255 for (count = 0; *s != '\0'; s++)
256 count += (*s == c);
257 return count;
258 }
259
260 static const char * const *
261 effectivePathv(JNIEnv *env)
262 {
263 char *p;
264 int i;
265 const char *path = effectivePath();
266 int count = countOccurrences(path, ':') + 1;
267 size_t pathvsize = sizeof(const char *) * (count+1);
268 size_t pathsize = strlen(path) + 1;
269 const char **pathv = (const char **) xmalloc(env, pathvsize + pathsize);
270
271 if (pathv == NULL)
272 return NULL;
273 p = (char *) pathv + pathvsize;
274 memcpy(p, path, pathsize);
275 /* split PATH by replacing ':' with NULs; empty components => "." */
276 for (i = 0; i < count; i++) {
277 char *q = p + strcspn(p, ":");
278 pathv[i] = (p == q) ? "." : p;
279 *q = '\0';
280 p = q + 1;
281 }
282 pathv[count] = NULL;
283 return pathv;
284 }
285
286 JNIEXPORT void JNICALL
287 Java_java_lang_ProcessImpl_init(JNIEnv *env, jclass clazz)
288 {
289 parentPathv = effectivePathv(env);
290 CHECK_NULL(parentPathv);
291 setSIGCHLDHandler(env);
292 }
293
294
295 #ifndef WIFEXITED
296 #define WIFEXITED(status) (((status)&0xFF) == 0)
297 #endif
298
299 #ifndef WEXITSTATUS
300 #define WEXITSTATUS(status) (((status)>>8)&0xFF)
301 #endif
302
303 #ifndef WIFSIGNALED
304 #define WIFSIGNALED(status) (((status)&0xFF) > 0 && ((status)&0xFF00) == 0)
305 #endif
306
307 #ifndef WTERMSIG
308 #define WTERMSIG(status) ((status)&0x7F)
309 #endif
310
311 static const char *
312 getBytes(JNIEnv *env, jbyteArray arr)
313 {
314 return arr == NULL ? NULL :
315 (const char*) (*env)->GetByteArrayElements(env, arr, NULL);
316 }
317
318 static void
319 releaseBytes(JNIEnv *env, jbyteArray arr, const char* parr)
320 {
321 if (parr != NULL)
322 (*env)->ReleaseByteArrayElements(env, arr, (jbyte*) parr, JNI_ABORT);
323 }
324
325 #define IOE_FORMAT "error=%d, %s"
326
327 static void
328 throwIOException(JNIEnv *env, int errnum, const char *defaultDetail)
329 {
330 const char *detail = defaultDetail;
331 char *errmsg;
332 size_t fmtsize;
333 char tmpbuf[1024];
334 jstring s;
335
336 if (errnum != 0) {
337 int ret = getErrorString(errnum, tmpbuf, sizeof(tmpbuf));
338 if (ret != EINVAL)
339 detail = tmpbuf;
340 }
341 /* ASCII Decimal representation uses 2.4 times as many bits as binary. */
342 fmtsize = sizeof(IOE_FORMAT) + strlen(detail) + 3 * sizeof(errnum);
343 errmsg = NEW(char, fmtsize);
344 if (errmsg == NULL)
345 return;
346
347 snprintf(errmsg, fmtsize, IOE_FORMAT, errnum, detail);
348 s = JNU_NewStringPlatform(env, errmsg);
349 if (s != NULL) {
350 jobject x = JNU_NewObjectByName(env, "java/io/IOException",
351 "(Ljava/lang/String;)V", s);
352 if (x != NULL)
353 (*env)->Throw(env, x);
354 }
355 free(errmsg);
356 }
357
358 #ifdef DEBUG_PROCESS
359 /* Debugging process code is difficult; where to write debug output? */
360 static void
361 debugPrint(char *format, ...)
362 {
363 FILE *tty = fopen("/dev/tty", "w");
364 va_list ap;
365 va_start(ap, format);
366 vfprintf(tty, format, ap);
367 va_end(ap);
368 fclose(tty);
369 }
370 #endif /* DEBUG_PROCESS */
371
372 static void
373 copyPipe(int from[2], int to[2])
374 {
375 to[0] = from[0];
376 to[1] = from[1];
377 }
378
379 /* arg is an array of pointers to 0 terminated strings. array is terminated
380 * by a null element.
381 *
382 * *nelems and *nbytes receive the number of elements of array (incl 0)
383 * and total number of bytes (incl. 0)
384 * Note. An empty array will have one null element
385 * But if arg is null, then *nelems set to 0, and *nbytes to 0
386 */
387 static void arraysize(const char * const *arg, int *nelems, int *nbytes)
388 {
389 int i, bytes, count;
390 const char * const *a = arg;
391 char *p;
392 int *q;
393 if (arg == 0) {
394 *nelems = 0;
395 *nbytes = 0;
396 return;
397 }
398 /* count the array elements and number of bytes */
399 for (count=0, bytes=0; *a != 0; count++, a++) {
400 bytes += strlen(*a)+1;
401 }
402 *nbytes = bytes;
403 *nelems = count+1;
404 }
405
406 /* copy the strings from arg[] into buf, starting at given offset
407 * return new offset to next free byte
408 */
409 static int copystrings(char *buf, int offset, const char * const *arg) {
410 char *p;
411 const char * const *a;
412 int count=0;
413
414 if (arg == 0) {
415 return offset;
416 }
417 for (p=buf+offset, a=arg; *a != 0; a++) {
418 int len = strlen(*a) +1;
419 memcpy(p, *a, len);
420 p += len;
421 count += len;
422 }
423 return offset+count;
424 }
425
426 /**
427 * We are unusually paranoid; use of vfork is
428 * especially likely to tickle gcc/glibc bugs.
429 */
430 #ifdef __attribute_noinline__ /* See: sys/cdefs.h */
431 __attribute_noinline__
432 #endif
433
434 /* vfork(2) is deprecated on Solaris */
435 #ifndef __solaris__
436 static pid_t
437 vforkChild(ChildStuff *c) {
438 volatile pid_t resultPid;
439
440 /*
441 * We separate the call to vfork into a separate function to make
442 * very sure to keep stack of child from corrupting stack of parent,
443 * as suggested by the scary gcc warning:
444 * warning: variable 'foo' might be clobbered by 'longjmp' or 'vfork'
445 */
446 resultPid = vfork();
447
448 if (resultPid == 0) {
449 childProcess(c);
450 }
451 assert(resultPid != 0); /* childProcess never returns */
452 return resultPid;
453 }
454 #endif
455
456 static pid_t
457 forkChild(ChildStuff *c) {
458 pid_t resultPid;
459
460 /*
461 * From Solaris fork(2): In Solaris 10, a call to fork() is
462 * identical to a call to fork1(); only the calling thread is
463 * replicated in the child process. This is the POSIX-specified
464 * behavior for fork().
465 */
466 resultPid = fork();
467
468 if (resultPid == 0) {
469 childProcess(c);
470 }
471 assert(resultPid != 0); /* childProcess never returns */
472 return resultPid;
473 }
474
475 /* Returns 1 if spawnhelper executable bits are set as expected. */
476 static int check_helper(const char* helperpath) {
477 struct stat s;
478 int rc = stat(helperpath, &s);
479 if (rc == 0) {
480 /* Require all bits set since this is how jspawnhelper
481 * is set up in a canonical installation */
482 if (s.st_mode & S_IXUSR &&
483 s.st_mode & S_IXGRP &&
484 s.st_mode & S_IXOTH) {
485 return 1;
486 } else {
487 return 0;
488 }
489 } else {
490 return 0;
491 }
492 }
493
494 static pid_t
495 spawnChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) {
496 pid_t resultPid;
497 jboolean isCopy;
498 int i, offset, rval, bufsize, magic;
499 char *buf, buf1[16];
500 char *hlpargs[2];
501 SpawnInfo sp;
502
503 /* Some posix_spawn() implementations do not report exec() errors back to the caller;
504 * POSIX leaves that up to the implementor, it only requires the child process to fail with
505 * error code 127.
506 * Since we cannot use that information (the payload binary may also use exit code 127 for
507 * its own purposes), lets do at least a basic guess if exec(jspawnhelper) will succeed.
508 * There are many reasons why it could fail, most of which one cannot be tested without
509 * exec'ing, but we can at least check permissions. Since jspawnhelper is part of the JDK
510 * it should have the execute permissions set correctly. */
511 if (check_helper(helperpath) == 0) {
512 throwIOException(env, 0, "jspawnhelper is not accessible.");
513 return -1;
514 }
515
516 /* need to tell helper which fd is for receiving the childstuff
517 * and which fd to send response back on
518 */
519 snprintf(buf1, sizeof(buf1), "%d:%d", c->childenv[0], c->fail[1]);
520 /* put the fd string as argument to the helper cmd */
521 hlpargs[0] = buf1;
522 hlpargs[1] = 0;
523
524 /* Following items are sent down the pipe to the helper
525 * after it is spawned.
526 * All strings are null terminated. All arrays of strings
527 * have an empty string for termination.
528 * - the ChildStuff struct
529 * - the SpawnInfo struct
530 * - the argv strings array
531 * - the envv strings array
532 * - the home directory string
533 * - the parentPath string
534 * - the parentPathv array
535 */
536 /* First calculate the sizes */
537 arraysize(c->argv, &sp.nargv, &sp.argvBytes);
538 bufsize = sp.argvBytes;
539 arraysize(c->envv, &sp.nenvv, &sp.envvBytes);
540 bufsize += sp.envvBytes;
541 sp.dirlen = c->pdir == 0 ? 0 : strlen(c->pdir)+1;
542 bufsize += sp.dirlen;
543 arraysize(parentPathv, &sp.nparentPathv, &sp.parentPathvBytes);
544 bufsize += sp.parentPathvBytes;
545 /* We need to clear FD_CLOEXEC if set in the fds[].
546 * Files are created FD_CLOEXEC in Java.
547 * Otherwise, they will be closed when the target gets exec'd */
548 for (i=0; i<3; i++) {
549 if (c->fds[i] != -1) {
550 int flags = fcntl(c->fds[i], F_GETFD);
551 if (flags & FD_CLOEXEC) {
552 fcntl(c->fds[i], F_SETFD, flags & (~1));
553 }
554 }
555 }
556
557 rval = posix_spawn(&resultPid, helperpath, 0, 0, (char * const *) hlpargs, environ);
558
559 if (rval != 0) {
560 return -1;
561 }
562
563 /* now the lengths are known, copy the data */
564 buf = NEW(char, bufsize);
565 if (buf == 0) {
566 return -1;
567 }
568 offset = copystrings(buf, 0, &c->argv[0]);
569 offset = copystrings(buf, offset, &c->envv[0]);
570 memcpy(buf+offset, c->pdir, sp.dirlen);
571 offset += sp.dirlen;
572 offset = copystrings(buf, offset, parentPathv);
573 assert(offset == bufsize);
574
575 magic = magicNumber();
576
577 /* write the two structs and the data buffer */
578 write(c->childenv[1], (char *)&magic, sizeof(magic)); // magic number first
579 write(c->childenv[1], (char *)c, sizeof(*c));
580 write(c->childenv[1], (char *)&sp, sizeof(sp));
581 write(c->childenv[1], buf, bufsize);
582 free(buf);
583
584 /* In this mode an external main() in invoked which calls back into
585 * childProcess() in this file, rather than directly
586 * via the statement below */
587 return resultPid;
588 }
589
590 /*
591 * Start a child process running function childProcess.
592 * This function only returns in the parent.
593 */
594 static pid_t
595 startChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) {
596 switch (c->mode) {
597 /* vfork(2) is deprecated on Solaris */
598 #ifndef __solaris__
599 case MODE_VFORK:
600 return vforkChild(c);
601 #endif
602 case MODE_FORK:
603 return forkChild(c);
604 case MODE_POSIX_SPAWN:
605 return spawnChild(env, process, c, helperpath);
606 default:
607 return -1;
608 }
609 }
610
611 JNIEXPORT jint JNICALL
612 Java_java_lang_ProcessImpl_forkAndExec(JNIEnv *env,
613 jobject process,
614 jint mode,
615 jbyteArray helperpath,
616 jbyteArray prog,
617 jbyteArray argBlock, jint argc,
618 jbyteArray envBlock, jint envc,
619 jbyteArray dir,
620 jintArray std_fds,
621 jboolean redirectErrorStream)
622 {
623 int errnum;
624 int resultPid = -1;
625 int in[2], out[2], err[2], fail[2], childenv[2];
626 jint *fds = NULL;
627 const char *phelperpath = NULL;
628 const char *pprog = NULL;
629 const char *pargBlock = NULL;
630 const char *penvBlock = NULL;
631 ChildStuff *c;
632
633 in[0] = in[1] = out[0] = out[1] = err[0] = err[1] = fail[0] = fail[1] = -1;
634 childenv[0] = childenv[1] = -1;
635
636 if ((c = NEW(ChildStuff, 1)) == NULL) return -1;
637 c->argv = NULL;
638 c->envv = NULL;
639 c->pdir = NULL;
640
641 /* Convert prog + argBlock into a char ** argv.
642 * Add one word room for expansion of argv for use by
643 * execve_as_traditional_shell_script.
644 * This word is also used when using posix_spawn mode
645 */
646 assert(prog != NULL && argBlock != NULL);
647 if ((phelperpath = getBytes(env, helperpath)) == NULL) goto Catch;
648 if ((pprog = getBytes(env, prog)) == NULL) goto Catch;
649 if ((pargBlock = getBytes(env, argBlock)) == NULL) goto Catch;
650 if ((c->argv = NEW(const char *, argc + 3)) == NULL) goto Catch;
651 c->argv[0] = pprog;
652 c->argc = argc + 2;
653 initVectorFromBlock(c->argv+1, pargBlock, argc);
654
655 if (envBlock != NULL) {
656 /* Convert envBlock into a char ** envv */
657 if ((penvBlock = getBytes(env, envBlock)) == NULL) goto Catch;
658 if ((c->envv = NEW(const char *, envc + 1)) == NULL) goto Catch;
659 initVectorFromBlock(c->envv, penvBlock, envc);
660 }
661
662 if (dir != NULL) {
663 if ((c->pdir = getBytes(env, dir)) == NULL) goto Catch;
664 }
665
666 assert(std_fds != NULL);
667 fds = (*env)->GetIntArrayElements(env, std_fds, NULL);
668 if (fds == NULL) goto Catch;
669
670 if ((fds[0] == -1 && pipe(in) < 0) ||
671 (fds[1] == -1 && pipe(out) < 0) ||
672 (fds[2] == -1 && pipe(err) < 0) ||
673 (pipe(childenv) < 0) ||
674 (pipe(fail) < 0)) {
675 throwIOException(env, errno, "Bad file descriptor");
676 goto Catch;
677 }
678 c->fds[0] = fds[0];
679 c->fds[1] = fds[1];
680 c->fds[2] = fds[2];
681
682 copyPipe(in, c->in);
683 copyPipe(out, c->out);
684 copyPipe(err, c->err);
685 copyPipe(fail, c->fail);
686 copyPipe(childenv, c->childenv);
687
688 c->redirectErrorStream = redirectErrorStream;
689 c->mode = mode;
690
691 resultPid = startChild(env, process, c, phelperpath);
692 assert(resultPid != 0);
693
694 if (resultPid < 0) {
695 /* Throw an IOException with a generic text unless an exception was already raised. */
696 if (!(*env)->ExceptionCheck(env)) {
697 switch (c->mode) {
698 case MODE_VFORK:
699 throwIOException(env, errno, "vfork failed");
700 break;
701 case MODE_FORK:
702 throwIOException(env, errno, "fork failed");
703 break;
704 case MODE_POSIX_SPAWN:
705 throwIOException(env, errno, "posix_spawn failed");
706 break;
707 }
708 }
709 goto Catch;
710 }
711 close(fail[1]); fail[1] = -1; /* See: WhyCantJohnnyExec (childproc.c) */
712
713 switch (readFully(fail[0], &errnum, sizeof(errnum))) {
714 case 0: break; /* Exec succeeded */
715 case sizeof(errnum):
716 waitpid(resultPid, NULL, 0);
717 throwIOException(env, errnum, "Exec failed");
718 goto Catch;
719 default:
720 throwIOException(env, errno, "Read failed");
721 goto Catch;
722 }
723
724 fds[0] = (in [1] != -1) ? in [1] : -1;
725 fds[1] = (out[0] != -1) ? out[0] : -1;
726 fds[2] = (err[0] != -1) ? err[0] : -1;
727
728 Finally:
729 /* Always clean up the child's side of the pipes */
730 closeSafely(in [0]);
731 closeSafely(out[1]);
732 closeSafely(err[1]);
733
734 /* Always clean up fail and childEnv descriptors */
735 closeSafely(fail[0]);
736 closeSafely(fail[1]);
737 closeSafely(childenv[0]);
738 closeSafely(childenv[1]);
739
740 releaseBytes(env, helperpath, phelperpath);
741 releaseBytes(env, prog, pprog);
742 releaseBytes(env, argBlock, pargBlock);
743 releaseBytes(env, envBlock, penvBlock);
744 releaseBytes(env, dir, c->pdir);
745
746 free(c->argv);
747 free(c->envv);
748 free(c);
749
750 if (fds != NULL)
751 (*env)->ReleaseIntArrayElements(env, std_fds, fds, 0);
752
753 return resultPid;
754
755 Catch:
756 /* Clean up the parent's side of the pipes in case of failure only */
757 closeSafely(in [1]); in[1] = -1;
758 closeSafely(out[0]); out[0] = -1;
759 closeSafely(err[0]); err[0] = -1;
760 goto Finally;
761 }
762