1 /*
   2  * Copyright (c) 1995, 2013, 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 <ctype.h>
  43 #include <sys/wait.h>
  44 #include <signal.h>
  45 #include <string.h>
  46 
  47 #if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX)
  48 #include <spawn.h>
  49 #endif
  50 
  51 #include "childproc.h"
  52 
  53 /*
  54  * There are 4 possible strategies we might use to "fork":
  55  *
  56  * - fork(2).  Very portable and reliable but subject to
  57  *   failure due to overcommit (see the documentation on
  58  *   /proc/sys/vm/overcommit_memory in Linux proc(5)).
  59  *   This is the ancient problem of spurious failure whenever a large
  60  *   process starts a small subprocess.
  61  *
  62  * - vfork().  Using this is scary because all relevant man pages
  63  *   contain dire warnings, e.g. Linux vfork(2).  But at least it's
  64  *   documented in the glibc docs and is standardized by XPG4.
  65  *   http://www.opengroup.org/onlinepubs/000095399/functions/vfork.html
  66  *   On Linux, one might think that vfork() would be implemented using
  67  *   the clone system call with flag CLONE_VFORK, but in fact vfork is
  68  *   a separate system call (which is a good sign, suggesting that
  69  *   vfork will continue to be supported at least on Linux).
  70  *   Another good sign is that glibc implements posix_spawn using
  71  *   vfork whenever possible.  Note that we cannot use posix_spawn
  72  *   ourselves because there's no reliable way to close all inherited
  73  *   file descriptors.
  74  *
  75  * - clone() with flags CLONE_VM but not CLONE_THREAD.  clone() is
  76  *   Linux-specific, but this ought to work - at least the glibc
  77  *   sources contain code to handle different combinations of CLONE_VM
  78  *   and CLONE_THREAD.  However, when this was implemented, it
  79  *   appeared to fail on 32-bit i386 (but not 64-bit x86_64) Linux with
  80  *   the simple program
  81  *     Runtime.getRuntime().exec("/bin/true").waitFor();
  82  *   with:
  83  *     #  Internal Error (os_linux_x86.cpp:683), pid=19940, tid=2934639536
  84  *     #  Error: pthread_getattr_np failed with errno = 3 (ESRCH)
  85  *   We believe this is a glibc bug, reported here:
  86  *     http://sources.redhat.com/bugzilla/show_bug.cgi?id=10311
  87  *   but the glibc maintainers closed it as WONTFIX.
  88  *
  89  * - posix_spawn(). While posix_spawn() is a fairly elaborate and
  90  *   complicated system call, it can't quite do everything that the old
  91  *   fork()/exec() combination can do, so the only feasible way to do
  92  *   this, is to use posix_spawn to launch a new helper executable
  93  *   "jprochelper", which in turn execs the target (after cleaning
  94  *   up file-descriptors etc.) The end result is the same as before,
  95  *   a child process linked to the parent in the same way, but it
  96  *   avoids the problem of duplicating the parent (VM) process
  97  *   address space temporarily, before launching the target command.
  98  *
  99  * Based on the above analysis, we are currently using vfork() on
 100  * Linux and spawn() on other Unix systems, but the code to use clone()
 101  * and fork() remains.
 102  */
 103 
 104 
 105 static void
 106 setSIGCHLDHandler(JNIEnv *env)
 107 {
 108     /* There is a subtle difference between having the signal handler
 109      * for SIGCHLD be SIG_DFL and SIG_IGN.  We cannot obtain process
 110      * termination information for child processes if the signal
 111      * handler is SIG_IGN.  It must be SIG_DFL.
 112      *
 113      * We used to set the SIGCHLD handler only on Linux, but it's
 114      * safest to set it unconditionally.
 115      *
 116      * Consider what happens if java's parent process sets the SIGCHLD
 117      * handler to SIG_IGN.  Normally signal handlers are inherited by
 118      * children, but SIGCHLD is a controversial case.  Solaris appears
 119      * to always reset it to SIG_DFL, but this behavior may be
 120      * non-standard-compliant, and we shouldn't rely on it.
 121      *
 122      * References:
 123      * http://www.opengroup.org/onlinepubs/7908799/xsh/exec.html
 124      * http://www.pasc.org/interps/unofficial/db/p1003.1/pasc-1003.1-132.html
 125      */
 126     struct sigaction sa;
 127     sa.sa_handler = SIG_DFL;
 128     sigemptyset(&sa.sa_mask);
 129     sa.sa_flags = SA_NOCLDSTOP | SA_RESTART;
 130     if (sigaction(SIGCHLD, &sa, NULL) < 0)
 131         JNU_ThrowInternalError(env, "Can't set SIGCHLD handler");
 132 }
 133 
 134 static void*
 135 xmalloc(JNIEnv *env, size_t size)
 136 {
 137     void *p = malloc(size);
 138     if (p == NULL)
 139         JNU_ThrowOutOfMemoryError(env, NULL);
 140     return p;
 141 }
 142 
 143 #define NEW(type, n) ((type *) xmalloc(env, (n) * sizeof(type)))
 144 
 145 /**
 146  * If PATH is not defined, the OS provides some default value.
 147  * Unfortunately, there's no portable way to get this value.
 148  * Fortunately, it's only needed if the child has PATH while we do not.
 149  */
 150 static const char*
 151 defaultPath(void)
 152 {
 153 #ifdef __solaris__
 154     /* These really are the Solaris defaults! */
 155     return (geteuid() == 0 || getuid() == 0) ?
 156         "/usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin:/usr/sbin" :
 157         "/usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin:";
 158 #else
 159     return ":/bin:/usr/bin";    /* glibc */
 160 #endif
 161 }
 162 
 163 static const char*
 164 effectivePath(void)
 165 {
 166     const char *s = getenv("PATH");
 167     return (s != NULL) ? s : defaultPath();
 168 }
 169 
 170 static int
 171 countOccurrences(const char *s, char c)
 172 {
 173     int count;
 174     for (count = 0; *s != '\0'; s++)
 175         count += (*s == c);
 176     return count;
 177 }
 178 
 179 static const char * const *
 180 effectivePathv(JNIEnv *env)
 181 {
 182     char *p;
 183     int i;
 184     const char *path = effectivePath();
 185     int count = countOccurrences(path, ':') + 1;
 186     size_t pathvsize = sizeof(const char *) * (count+1);
 187     size_t pathsize = strlen(path) + 1;
 188     const char **pathv = (const char **) xmalloc(env, pathvsize + pathsize);
 189 
 190     if (pathv == NULL)
 191         return NULL;
 192     p = (char *) pathv + pathvsize;
 193     memcpy(p, path, pathsize);
 194     /* split PATH by replacing ':' with NULs; empty components => "." */
 195     for (i = 0; i < count; i++) {
 196         char *q = p + strcspn(p, ":");
 197         pathv[i] = (p == q) ? "." : p;
 198         *q = '\0';
 199         p = q + 1;
 200     }
 201     pathv[count] = NULL;
 202     return pathv;
 203 }
 204 
 205 JNIEXPORT void JNICALL
 206 Java_java_lang_UNIXProcess_init(JNIEnv *env, jclass clazz)
 207 {
 208     parentPathv = effectivePathv(env);
 209     setSIGCHLDHandler(env);
 210 }
 211 
 212 
 213 #ifndef WIFEXITED
 214 #define WIFEXITED(status) (((status)&0xFF) == 0)
 215 #endif
 216 
 217 #ifndef WEXITSTATUS
 218 #define WEXITSTATUS(status) (((status)>>8)&0xFF)
 219 #endif
 220 
 221 #ifndef WIFSIGNALED
 222 #define WIFSIGNALED(status) (((status)&0xFF) > 0 && ((status)&0xFF00) == 0)
 223 #endif
 224 
 225 #ifndef WTERMSIG
 226 #define WTERMSIG(status) ((status)&0x7F)
 227 #endif
 228 
 229 /* Block until a child process exits and return its exit code.
 230    Note, can only be called once for any given pid. */
 231 JNIEXPORT jint JNICALL
 232 Java_java_lang_UNIXProcess_waitForProcessExit(JNIEnv* env,
 233                                               jobject junk,
 234                                               jint pid)
 235 {
 236     /* We used to use waitid() on Solaris, waitpid() on Linux, but
 237      * waitpid() is more standard, so use it on all POSIX platforms. */
 238     int status;
 239     /* Wait for the child process to exit.  This returns immediately if
 240        the child has already exited. */
 241     while (waitpid(pid, &status, 0) < 0) {
 242         switch (errno) {
 243         case ECHILD: return 0;
 244         case EINTR: break;
 245         default: return -1;
 246         }
 247     }
 248 
 249     if (WIFEXITED(status)) {
 250         /*
 251          * The child exited normally; get its exit code.
 252          */
 253         return WEXITSTATUS(status);
 254     } else if (WIFSIGNALED(status)) {
 255         /* The child exited because of a signal.
 256          * The best value to return is 0x80 + signal number,
 257          * because that is what all Unix shells do, and because
 258          * it allows callers to distinguish between process exit and
 259          * process death by signal.
 260          * Unfortunately, the historical behavior on Solaris is to return
 261          * the signal number, and we preserve this for compatibility. */
 262 #ifdef __solaris__
 263         return WTERMSIG(status);
 264 #else
 265         return 0x80 + WTERMSIG(status);
 266 #endif
 267     } else {
 268         /*
 269          * Unknown exit code; pass it through.
 270          */
 271         return status;
 272     }
 273 }
 274 
 275 static const char *
 276 getBytes(JNIEnv *env, jbyteArray arr)
 277 {
 278     return arr == NULL ? NULL :
 279         (const char*) (*env)->GetByteArrayElements(env, arr, NULL);
 280 }
 281 
 282 static void
 283 releaseBytes(JNIEnv *env, jbyteArray arr, const char* parr)
 284 {
 285     if (parr != NULL)
 286         (*env)->ReleaseByteArrayElements(env, arr, (jbyte*) parr, JNI_ABORT);
 287 }
 288 
 289 static void
 290 throwIOException(JNIEnv *env, int errnum, const char *defaultDetail)
 291 {
 292     static const char * const format = "error=%d, %s";
 293     const char *detail = defaultDetail;
 294     char *errmsg;
 295     jstring s;
 296 
 297     if (errnum != 0) {
 298         const char *s = strerror(errnum);
 299         if (strcmp(s, "Unknown error") != 0)
 300             detail = s;
 301     }
 302     /* ASCII Decimal representation uses 2.4 times as many bits as binary. */
 303     errmsg = NEW(char, strlen(format) + strlen(detail) + 3 * sizeof(errnum));
 304     if (errmsg == NULL)
 305         return;
 306 
 307     sprintf(errmsg, format, errnum, detail);
 308     s = JNU_NewStringPlatform(env, errmsg);
 309     if (s != NULL) {
 310         jobject x = JNU_NewObjectByName(env, "java/io/IOException",
 311                                         "(Ljava/lang/String;)V", s);
 312         if (x != NULL)
 313             (*env)->Throw(env, x);
 314     }
 315     free(errmsg);
 316 }
 317 
 318 #ifdef DEBUG_PROCESS
 319 /* Debugging process code is difficult; where to write debug output? */
 320 static void
 321 debugPrint(char *format, ...)
 322 {
 323     FILE *tty = fopen("/dev/tty", "w");
 324     va_list ap;
 325     va_start(ap, format);
 326     vfprintf(tty, format, ap);
 327     va_end(ap);
 328     fclose(tty);
 329 }
 330 #endif /* DEBUG_PROCESS */
 331 
 332 static void
 333 copyPipe(int from[2], int to[2])
 334 {
 335     to[0] = from[0];
 336     to[1] = from[1];
 337 }
 338 
 339 /* arg is an array of pointers to 0 terminated strings. array is terminated
 340  * by a null element.
 341  *
 342  * *nelems and *nbytes receive the number of elements of array (incl 0)
 343  * and total number of bytes (incl. 0)
 344  * Note. An empty array will have one null element
 345  * But if arg is null, then *nelems set to 0, and *nbytes to 0
 346  */
 347 static void arraysize(const char * const *arg, int *nelems, int *nbytes)
 348 {
 349     int i, bytes, count;
 350     const char * const *a = arg;
 351     char *p;
 352     int *q;
 353     if (arg == 0) {
 354         *nelems = 0;
 355         *nbytes = 0;
 356         return;
 357     }
 358     /* count the array elements and number of bytes */
 359     for (count=0, bytes=0; *a != 0; count++, a++) {
 360         bytes += strlen(*a)+1;
 361     }
 362     *nbytes = bytes;
 363     *nelems = count+1;
 364 }
 365 
 366 /* copy the strings from arg[] into buf, starting at given offset
 367  * return new offset to next free byte
 368  */
 369 static int copystrings(char *buf, int offset, const char * const *arg) {
 370     char *p;
 371     const char * const *a;
 372     int count=0;
 373 
 374     if (arg == 0) {
 375         return offset;
 376     }
 377     for (p=buf+offset, a=arg; *a != 0; a++) {
 378         int len = strlen(*a) +1;
 379         memcpy(p, *a, len);
 380         p += len;
 381         count += len;
 382     }
 383     return offset+count;
 384 }
 385 
 386 /**
 387  * We are unusually paranoid; use of clone/vfork is
 388  * especially likely to tickle gcc/glibc bugs.
 389  */
 390 #ifdef __attribute_noinline__  /* See: sys/cdefs.h */
 391 __attribute_noinline__
 392 #endif
 393 
 394 #define START_CHILD_USE_CLONE 0  /* clone() currently disabled; see above. */
 395 
 396 #ifdef START_CHILD_USE_CLONE
 397 static pid_t
 398 cloneChild(ChildStuff *c) {
 399 #ifdef __linux__
 400 #define START_CHILD_CLONE_STACK_SIZE (64 * 1024)
 401     /*
 402      * See clone(2).
 403      * Instead of worrying about which direction the stack grows, just
 404      * allocate twice as much and start the stack in the middle.
 405      */
 406     if ((c->clone_stack = malloc(2 * START_CHILD_CLONE_STACK_SIZE)) == NULL)
 407         /* errno will be set to ENOMEM */
 408         return -1;
 409     return clone(childProcess,
 410                  c->clone_stack + START_CHILD_CLONE_STACK_SIZE,
 411                  CLONE_VFORK | CLONE_VM | SIGCHLD, c);
 412 #else
 413 /* not available on Solaris / Mac */
 414     assert(0);
 415     return -1;
 416 #endif
 417 }
 418 #endif
 419 
 420 static pid_t
 421 vforkChild(ChildStuff *c) {
 422     volatile pid_t resultPid;
 423 
 424     /*
 425      * We separate the call to vfork into a separate function to make
 426      * very sure to keep stack of child from corrupting stack of parent,
 427      * as suggested by the scary gcc warning:
 428      *  warning: variable 'foo' might be clobbered by 'longjmp' or 'vfork'
 429      */
 430     resultPid = vfork();
 431 
 432     if (resultPid == 0) {
 433         childProcess(c);
 434     }
 435     assert(resultPid != 0);  /* childProcess never returns */
 436     return resultPid;
 437 }
 438 
 439 static pid_t
 440 forkChild(ChildStuff *c) {
 441     pid_t resultPid;
 442 
 443     /*
 444      * From Solaris fork(2): In Solaris 10, a call to fork() is
 445      * identical to a call to fork1(); only the calling thread is
 446      * replicated in the child process. This is the POSIX-specified
 447      * behavior for fork().
 448      */
 449     resultPid = fork();
 450 
 451     if (resultPid == 0) {
 452         childProcess(c);
 453     }
 454     assert(resultPid != 0);  /* childProcess never returns */
 455     return resultPid;
 456 }
 457 
 458 #if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX)
 459 static pid_t
 460 spawnChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) {
 461     pid_t resultPid;
 462     jboolean isCopy;
 463     int i, offset, rval, bufsize, magic;
 464     char *buf, buf1[16];
 465     char *hlpargs[2];
 466     SpawnInfo sp;
 467 
 468     /* need to tell helper which fd is for receiving the childstuff
 469      * and which fd to send response back on
 470      */
 471     snprintf(buf1, sizeof(buf1), "%d:%d", c->childenv[0], c->fail[1]);
 472     /* put the fd string as argument to the helper cmd */
 473     hlpargs[0] = buf1;
 474     hlpargs[1] = 0;
 475 
 476     /* Following items are sent down the pipe to the helper
 477      * after it is spawned.
 478      * All strings are null terminated. All arrays of strings
 479      * have an empty string for termination.
 480      * - the ChildStuff struct
 481      * - the SpawnInfo struct
 482      * - the argv strings array
 483      * - the envv strings array
 484      * - the home directory string
 485      * - the parentPath string
 486      * - the parentPathv array
 487      */
 488     /* First calculate the sizes */
 489     arraysize(c->argv, &sp.nargv, &sp.argvBytes);
 490     bufsize = sp.argvBytes;
 491     arraysize(c->envv, &sp.nenvv, &sp.envvBytes);
 492     bufsize += sp.envvBytes;
 493     sp.dirlen = c->pdir == 0 ? 0 : strlen(c->pdir)+1;
 494     bufsize += sp.dirlen;
 495     arraysize(parentPathv, &sp.nparentPathv, &sp.parentPathvBytes);
 496     bufsize += sp.parentPathvBytes;
 497     /* We need to clear FD_CLOEXEC if set in the fds[].
 498      * Files are created FD_CLOEXEC in Java.
 499      * Otherwise, they will be closed when the target gets exec'd */
 500     for (i=0; i<3; i++) {
 501         if (c->fds[i] != -1) {
 502             int flags = fcntl(c->fds[i], F_GETFD);
 503             if (flags & FD_CLOEXEC) {
 504                 fcntl(c->fds[i], F_SETFD, flags & (~1));
 505             }
 506         }
 507     }
 508 
 509     rval = posix_spawn(&resultPid, helperpath, 0, 0, (char * const *) hlpargs, environ);
 510 
 511     if (rval != 0) {
 512         return -1;
 513     }
 514 
 515     /* now the lengths are known, copy the data */
 516     buf = NEW(char, bufsize);
 517     if (buf == 0) {
 518         return -1;
 519     }
 520     offset = copystrings(buf, 0, &c->argv[0]);
 521     offset = copystrings(buf, offset, &c->envv[0]);
 522     memcpy(buf+offset, c->pdir, sp.dirlen);
 523     offset += sp.dirlen;
 524     offset = copystrings(buf, offset, parentPathv);
 525     assert(offset == bufsize);
 526 
 527     magic = magicNumber();
 528 
 529     /* write the two structs and the data buffer */
 530     write(c->childenv[1], (char *)&magic, sizeof(magic)); // magic number first
 531     write(c->childenv[1], (char *)c, sizeof(*c));
 532     write(c->childenv[1], (char *)&sp, sizeof(sp));
 533     write(c->childenv[1], buf, bufsize);
 534     free(buf);
 535 
 536     /* In this mode an external main() in invoked which calls back into
 537      * childProcess() in this file, rather than directly
 538      * via the statement below */
 539     return resultPid;
 540 }
 541 #endif
 542 
 543 /*
 544  * Start a child process running function childProcess.
 545  * This function only returns in the parent.
 546  */
 547 static pid_t
 548 startChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) {
 549     switch (c->mode) {
 550       case MODE_VFORK:
 551         return vforkChild(c);
 552       case MODE_FORK:
 553         return forkChild(c);
 554 #if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX)
 555       case MODE_POSIX_SPAWN:
 556         return spawnChild(env, process, c, helperpath);
 557 #endif
 558       default:
 559         return -1;
 560     }
 561 }
 562 
 563 JNIEXPORT jint JNICALL
 564 Java_java_lang_UNIXProcess_forkAndExec(JNIEnv *env,
 565                                        jobject process,
 566                                        jint mode,
 567                                        jbyteArray helperpath,
 568                                        jbyteArray prog,
 569                                        jbyteArray argBlock, jint argc,
 570                                        jbyteArray envBlock, jint envc,
 571                                        jbyteArray dir,
 572                                        jintArray std_fds,
 573                                        jboolean redirectErrorStream)
 574 {
 575     int errnum;
 576     int resultPid = -1;
 577     int in[2], out[2], err[2], fail[2], childenv[2];
 578     jint *fds = NULL;
 579     const char *phelperpath = NULL;
 580     const char *pprog = NULL;
 581     const char *pargBlock = NULL;
 582     const char *penvBlock = NULL;
 583     ChildStuff *c;
 584 
 585     in[0] = in[1] = out[0] = out[1] = err[0] = err[1] = fail[0] = fail[1] = -1;
 586     childenv[0] = childenv[1] = -1;
 587 
 588     if ((c = NEW(ChildStuff, 1)) == NULL) return -1;
 589     c->argv = NULL;
 590     c->envv = NULL;
 591     c->pdir = NULL;
 592     c->clone_stack = NULL;
 593 
 594     /* Convert prog + argBlock into a char ** argv.
 595      * Add one word room for expansion of argv for use by
 596      * execve_as_traditional_shell_script.
 597      * This word is also used when using spawn mode
 598      */
 599     assert(prog != NULL && argBlock != NULL);
 600     if ((phelperpath = getBytes(env, helperpath))   == NULL) goto Catch;
 601     if ((pprog       = getBytes(env, prog))         == NULL) goto Catch;
 602     if ((pargBlock   = getBytes(env, argBlock))     == NULL) goto Catch;
 603     if ((c->argv     = NEW(const char *, argc + 3)) == NULL) goto Catch;
 604     c->argv[0] = pprog;
 605     c->argc = argc + 2;
 606     initVectorFromBlock(c->argv+1, pargBlock, argc);
 607 
 608     if (envBlock != NULL) {
 609         /* Convert envBlock into a char ** envv */
 610         if ((penvBlock = getBytes(env, envBlock))   == NULL) goto Catch;
 611         if ((c->envv = NEW(const char *, envc + 1)) == NULL) goto Catch;
 612         initVectorFromBlock(c->envv, penvBlock, envc);
 613     }
 614 
 615     if (dir != NULL) {
 616         if ((c->pdir = getBytes(env, dir)) == NULL) goto Catch;
 617     }
 618 
 619     assert(std_fds != NULL);
 620     fds = (*env)->GetIntArrayElements(env, std_fds, NULL);
 621     if (fds == NULL) goto Catch;
 622 
 623     if ((fds[0] == -1 && pipe(in)  < 0) ||
 624         (fds[1] == -1 && pipe(out) < 0) ||
 625         (fds[2] == -1 && pipe(err) < 0) ||
 626         (pipe(childenv) < 0) ||
 627         (pipe(fail) < 0)) {
 628         throwIOException(env, errno, "Bad file descriptor");
 629         goto Catch;
 630     }
 631     c->fds[0] = fds[0];
 632     c->fds[1] = fds[1];
 633     c->fds[2] = fds[2];
 634 
 635     copyPipe(in,   c->in);
 636     copyPipe(out,  c->out);
 637     copyPipe(err,  c->err);
 638     copyPipe(fail, c->fail);
 639     copyPipe(childenv, c->childenv);
 640 
 641     c->redirectErrorStream = redirectErrorStream;
 642     c->mode = mode;
 643 
 644     resultPid = startChild(env, process, c, phelperpath);
 645     assert(resultPid != 0);
 646 
 647     if (resultPid < 0) {
 648         switch (c->mode) {
 649           case MODE_VFORK:
 650             throwIOException(env, errno, "vfork failed");
 651             break;
 652           case MODE_FORK:
 653             throwIOException(env, errno, "fork failed");
 654             break;
 655           case MODE_POSIX_SPAWN:
 656             throwIOException(env, errno, "spawn failed");
 657             break;
 658         }
 659         goto Catch;
 660     }
 661     close(fail[1]); fail[1] = -1; /* See: WhyCantJohnnyExec  (childproc.c)  */
 662 
 663     switch (readFully(fail[0], &errnum, sizeof(errnum))) {
 664     case 0: break; /* Exec succeeded */
 665     case sizeof(errnum):
 666         waitpid(resultPid, NULL, 0);
 667         throwIOException(env, errnum, "Exec failed");
 668         goto Catch;
 669     default:
 670         throwIOException(env, errno, "Read failed");
 671         goto Catch;
 672     }
 673 
 674     fds[0] = (in [1] != -1) ? in [1] : -1;
 675     fds[1] = (out[0] != -1) ? out[0] : -1;
 676     fds[2] = (err[0] != -1) ? err[0] : -1;
 677 
 678  Finally:
 679     free(c->clone_stack);
 680 
 681     /* Always clean up the child's side of the pipes */
 682     closeSafely(in [0]);
 683     closeSafely(out[1]);
 684     closeSafely(err[1]);
 685 
 686     /* Always clean up fail and childEnv descriptors */
 687     closeSafely(fail[0]);
 688     closeSafely(fail[1]);
 689     closeSafely(childenv[0]);
 690     closeSafely(childenv[1]);
 691 
 692     releaseBytes(env, helperpath, phelperpath);
 693     releaseBytes(env, prog,       pprog);
 694     releaseBytes(env, argBlock,   pargBlock);
 695     releaseBytes(env, envBlock,   penvBlock);
 696     releaseBytes(env, dir,        c->pdir);
 697 
 698     free(c->argv);
 699     free(c->envv);
 700     free(c);
 701 
 702     if (fds != NULL)
 703         (*env)->ReleaseIntArrayElements(env, std_fds, fds, 0);
 704 
 705     return resultPid;
 706 
 707  Catch:
 708     /* Clean up the parent's side of the pipes in case of failure only */
 709     closeSafely(in [1]); in[1] = -1;
 710     closeSafely(out[0]); out[0] = -1;
 711     closeSafely(err[0]); err[0] = -1;
 712     goto Finally;
 713 }
 714 
 715 JNIEXPORT void JNICALL
 716 Java_java_lang_UNIXProcess_destroyProcess(JNIEnv *env,
 717                                           jobject junk,
 718                                           jint pid,
 719                                           jboolean force)
 720 {
 721     int sig = (force == JNI_TRUE) ? SIGKILL : SIGTERM;
 722     kill(pid, sig);
 723 }