diff -r 2f79ecb05ada -r fe8344cf6496 jdk/src/java.base/unix/native/libjava/ProcessImpl_md.c --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/jdk/src/java.base/unix/native/libjava/ProcessImpl_md.c Mon Jan 26 10:55:27 2015 -0500 @@ -0,0 +1,724 @@ +/* + * Copyright (c) 1995, 2015, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. Oracle designates this + * particular file as subject to the "Classpath" exception as provided + * by Oracle in the LICENSE file that accompanied this code. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + */ + +#undef _LARGEFILE64_SOURCE +#define _LARGEFILE64_SOURCE 1 + +#include "jni.h" +#include "jvm.h" +#include "jvm_md.h" +#include "jni_util.h" +#include "io_util.h" + +/* + * Platform-specific support for java.lang.Process + */ +#include +#include +#include +#include +#include +#include +#include +#include + +#if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX) +#include +#endif + +#include "childproc.h" + +/* + * There are 4 possible strategies we might use to "fork": + * + * - fork(2). Very portable and reliable but subject to + * failure due to overcommit (see the documentation on + * /proc/sys/vm/overcommit_memory in Linux proc(5)). + * This is the ancient problem of spurious failure whenever a large + * process starts a small subprocess. + * + * - vfork(). Using this is scary because all relevant man pages + * contain dire warnings, e.g. Linux vfork(2). But at least it's + * documented in the glibc docs and is standardized by XPG4. + * http://www.opengroup.org/onlinepubs/000095399/functions/vfork.html + * On Linux, one might think that vfork() would be implemented using + * the clone system call with flag CLONE_VFORK, but in fact vfork is + * a separate system call (which is a good sign, suggesting that + * vfork will continue to be supported at least on Linux). + * Another good sign is that glibc implements posix_spawn using + * vfork whenever possible. Note that we cannot use posix_spawn + * ourselves because there's no reliable way to close all inherited + * file descriptors. + * + * - clone() with flags CLONE_VM but not CLONE_THREAD. clone() is + * Linux-specific, but this ought to work - at least the glibc + * sources contain code to handle different combinations of CLONE_VM + * and CLONE_THREAD. However, when this was implemented, it + * appeared to fail on 32-bit i386 (but not 64-bit x86_64) Linux with + * the simple program + * Runtime.getRuntime().exec("/bin/true").waitFor(); + * with: + * # Internal Error (os_linux_x86.cpp:683), pid=19940, tid=2934639536 + * # Error: pthread_getattr_np failed with errno = 3 (ESRCH) + * We believe this is a glibc bug, reported here: + * http://sources.redhat.com/bugzilla/show_bug.cgi?id=10311 + * but the glibc maintainers closed it as WONTFIX. + * + * - posix_spawn(). While posix_spawn() is a fairly elaborate and + * complicated system call, it can't quite do everything that the old + * fork()/exec() combination can do, so the only feasible way to do + * this, is to use posix_spawn to launch a new helper executable + * "jprochelper", which in turn execs the target (after cleaning + * up file-descriptors etc.) The end result is the same as before, + * a child process linked to the parent in the same way, but it + * avoids the problem of duplicating the parent (VM) process + * address space temporarily, before launching the target command. + * + * Based on the above analysis, we are currently using vfork() on + * Linux and spawn() on other Unix systems, but the code to use clone() + * and fork() remains. + */ + + +static void +setSIGCHLDHandler(JNIEnv *env) +{ + /* There is a subtle difference between having the signal handler + * for SIGCHLD be SIG_DFL and SIG_IGN. We cannot obtain process + * termination information for child processes if the signal + * handler is SIG_IGN. It must be SIG_DFL. + * + * We used to set the SIGCHLD handler only on Linux, but it's + * safest to set it unconditionally. + * + * Consider what happens if java's parent process sets the SIGCHLD + * handler to SIG_IGN. Normally signal handlers are inherited by + * children, but SIGCHLD is a controversial case. Solaris appears + * to always reset it to SIG_DFL, but this behavior may be + * non-standard-compliant, and we shouldn't rely on it. + * + * References: + * http://www.opengroup.org/onlinepubs/7908799/xsh/exec.html + * http://www.pasc.org/interps/unofficial/db/p1003.1/pasc-1003.1-132.html + */ + struct sigaction sa; + sa.sa_handler = SIG_DFL; + sigemptyset(&sa.sa_mask); + sa.sa_flags = SA_NOCLDSTOP | SA_RESTART; + if (sigaction(SIGCHLD, &sa, NULL) < 0) + JNU_ThrowInternalError(env, "Can't set SIGCHLD handler"); +} + +static void* +xmalloc(JNIEnv *env, size_t size) +{ + void *p = malloc(size); + if (p == NULL) + JNU_ThrowOutOfMemoryError(env, NULL); + return p; +} + +#define NEW(type, n) ((type *) xmalloc(env, (n) * sizeof(type))) + +/** + * If PATH is not defined, the OS provides some default value. + * Unfortunately, there's no portable way to get this value. + * Fortunately, it's only needed if the child has PATH while we do not. + */ +static const char* +defaultPath(void) +{ +#ifdef __solaris__ + /* These really are the Solaris defaults! */ + return (geteuid() == 0 || getuid() == 0) ? + "/usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin:/usr/sbin" : + "/usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin:"; +#else + return ":/bin:/usr/bin"; /* glibc */ +#endif +} + +static const char* +effectivePath(void) +{ + const char *s = getenv("PATH"); + return (s != NULL) ? s : defaultPath(); +} + +static int +countOccurrences(const char *s, char c) +{ + int count; + for (count = 0; *s != '\0'; s++) + count += (*s == c); + return count; +} + +static const char * const * +effectivePathv(JNIEnv *env) +{ + char *p; + int i; + const char *path = effectivePath(); + int count = countOccurrences(path, ':') + 1; + size_t pathvsize = sizeof(const char *) * (count+1); + size_t pathsize = strlen(path) + 1; + const char **pathv = (const char **) xmalloc(env, pathvsize + pathsize); + + if (pathv == NULL) + return NULL; + p = (char *) pathv + pathvsize; + memcpy(p, path, pathsize); + /* split PATH by replacing ':' with NULs; empty components => "." */ + for (i = 0; i < count; i++) { + char *q = p + strcspn(p, ":"); + pathv[i] = (p == q) ? "." : p; + *q = '\0'; + p = q + 1; + } + pathv[count] = NULL; + return pathv; +} + +JNIEXPORT void JNICALL +Java_java_lang_ProcessImpl_init(JNIEnv *env, jclass clazz) +{ + parentPathv = effectivePathv(env); + CHECK_NULL(parentPathv); + setSIGCHLDHandler(env); +} + + +#ifndef WIFEXITED +#define WIFEXITED(status) (((status)&0xFF) == 0) +#endif + +#ifndef WEXITSTATUS +#define WEXITSTATUS(status) (((status)>>8)&0xFF) +#endif + +#ifndef WIFSIGNALED +#define WIFSIGNALED(status) (((status)&0xFF) > 0 && ((status)&0xFF00) == 0) +#endif + +#ifndef WTERMSIG +#define WTERMSIG(status) ((status)&0x7F) +#endif + +/* Block until a child process exits and return its exit code. + Note, can only be called once for any given pid. */ +JNIEXPORT jint JNICALL +Java_java_lang_ProcessImpl_waitForProcessExit(JNIEnv* env, + jobject junk, + jint pid) +{ + /* We used to use waitid() on Solaris, waitpid() on Linux, but + * waitpid() is more standard, so use it on all POSIX platforms. */ + int status; + /* Wait for the child process to exit. This returns immediately if + the child has already exited. */ + while (waitpid(pid, &status, 0) < 0) { + switch (errno) { + case ECHILD: return 0; + case EINTR: break; + default: return -1; + } + } + + if (WIFEXITED(status)) { + /* + * The child exited normally; get its exit code. + */ + return WEXITSTATUS(status); + } else if (WIFSIGNALED(status)) { + /* The child exited because of a signal. + * The best value to return is 0x80 + signal number, + * because that is what all Unix shells do, and because + * it allows callers to distinguish between process exit and + * process death by signal. + * Unfortunately, the historical behavior on Solaris is to return + * the signal number, and we preserve this for compatibility. */ +#ifdef __solaris__ + return WTERMSIG(status); +#else + return 0x80 + WTERMSIG(status); +#endif + } else { + /* + * Unknown exit code; pass it through. + */ + return status; + } +} + +static const char * +getBytes(JNIEnv *env, jbyteArray arr) +{ + return arr == NULL ? NULL : + (const char*) (*env)->GetByteArrayElements(env, arr, NULL); +} + +static void +releaseBytes(JNIEnv *env, jbyteArray arr, const char* parr) +{ + if (parr != NULL) + (*env)->ReleaseByteArrayElements(env, arr, (jbyte*) parr, JNI_ABORT); +} + +static void +throwIOException(JNIEnv *env, int errnum, const char *defaultDetail) +{ + static const char * const format = "error=%d, %s"; + const char *detail = defaultDetail; + char *errmsg; + jstring s; + + if (errnum != 0) { + const char *s = strerror(errnum); + if (strcmp(s, "Unknown error") != 0) + detail = s; + } + /* ASCII Decimal representation uses 2.4 times as many bits as binary. */ + errmsg = NEW(char, strlen(format) + strlen(detail) + 3 * sizeof(errnum)); + if (errmsg == NULL) + return; + + sprintf(errmsg, format, errnum, detail); + s = JNU_NewStringPlatform(env, errmsg); + if (s != NULL) { + jobject x = JNU_NewObjectByName(env, "java/io/IOException", + "(Ljava/lang/String;)V", s); + if (x != NULL) + (*env)->Throw(env, x); + } + free(errmsg); +} + +#ifdef DEBUG_PROCESS +/* Debugging process code is difficult; where to write debug output? */ +static void +debugPrint(char *format, ...) +{ + FILE *tty = fopen("/dev/tty", "w"); + va_list ap; + va_start(ap, format); + vfprintf(tty, format, ap); + va_end(ap); + fclose(tty); +} +#endif /* DEBUG_PROCESS */ + +static void +copyPipe(int from[2], int to[2]) +{ + to[0] = from[0]; + to[1] = from[1]; +} + +/* arg is an array of pointers to 0 terminated strings. array is terminated + * by a null element. + * + * *nelems and *nbytes receive the number of elements of array (incl 0) + * and total number of bytes (incl. 0) + * Note. An empty array will have one null element + * But if arg is null, then *nelems set to 0, and *nbytes to 0 + */ +static void arraysize(const char * const *arg, int *nelems, int *nbytes) +{ + int i, bytes, count; + const char * const *a = arg; + char *p; + int *q; + if (arg == 0) { + *nelems = 0; + *nbytes = 0; + return; + } + /* count the array elements and number of bytes */ + for (count=0, bytes=0; *a != 0; count++, a++) { + bytes += strlen(*a)+1; + } + *nbytes = bytes; + *nelems = count+1; +} + +/* copy the strings from arg[] into buf, starting at given offset + * return new offset to next free byte + */ +static int copystrings(char *buf, int offset, const char * const *arg) { + char *p; + const char * const *a; + int count=0; + + if (arg == 0) { + return offset; + } + for (p=buf+offset, a=arg; *a != 0; a++) { + int len = strlen(*a) +1; + memcpy(p, *a, len); + p += len; + count += len; + } + return offset+count; +} + +/** + * We are unusually paranoid; use of clone/vfork is + * especially likely to tickle gcc/glibc bugs. + */ +#ifdef __attribute_noinline__ /* See: sys/cdefs.h */ +__attribute_noinline__ +#endif + +#define START_CHILD_USE_CLONE 0 /* clone() currently disabled; see above. */ + +#ifdef START_CHILD_USE_CLONE +static pid_t +cloneChild(ChildStuff *c) { +#ifdef __linux__ +#define START_CHILD_CLONE_STACK_SIZE (64 * 1024) + /* + * See clone(2). + * Instead of worrying about which direction the stack grows, just + * allocate twice as much and start the stack in the middle. + */ + if ((c->clone_stack = malloc(2 * START_CHILD_CLONE_STACK_SIZE)) == NULL) + /* errno will be set to ENOMEM */ + return -1; + return clone(childProcess, + c->clone_stack + START_CHILD_CLONE_STACK_SIZE, + CLONE_VFORK | CLONE_VM | SIGCHLD, c); +#else +/* not available on Solaris / Mac */ + assert(0); + return -1; +#endif +} +#endif + +static pid_t +vforkChild(ChildStuff *c) { + volatile pid_t resultPid; + + /* + * We separate the call to vfork into a separate function to make + * very sure to keep stack of child from corrupting stack of parent, + * as suggested by the scary gcc warning: + * warning: variable 'foo' might be clobbered by 'longjmp' or 'vfork' + */ + resultPid = vfork(); + + if (resultPid == 0) { + childProcess(c); + } + assert(resultPid != 0); /* childProcess never returns */ + return resultPid; +} + +static pid_t +forkChild(ChildStuff *c) { + pid_t resultPid; + + /* + * From Solaris fork(2): In Solaris 10, a call to fork() is + * identical to a call to fork1(); only the calling thread is + * replicated in the child process. This is the POSIX-specified + * behavior for fork(). + */ + resultPid = fork(); + + if (resultPid == 0) { + childProcess(c); + } + assert(resultPid != 0); /* childProcess never returns */ + return resultPid; +} + +#if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX) +static pid_t +spawnChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) { + pid_t resultPid; + jboolean isCopy; + int i, offset, rval, bufsize, magic; + char *buf, buf1[16]; + char *hlpargs[2]; + SpawnInfo sp; + + /* need to tell helper which fd is for receiving the childstuff + * and which fd to send response back on + */ + snprintf(buf1, sizeof(buf1), "%d:%d", c->childenv[0], c->fail[1]); + /* put the fd string as argument to the helper cmd */ + hlpargs[0] = buf1; + hlpargs[1] = 0; + + /* Following items are sent down the pipe to the helper + * after it is spawned. + * All strings are null terminated. All arrays of strings + * have an empty string for termination. + * - the ChildStuff struct + * - the SpawnInfo struct + * - the argv strings array + * - the envv strings array + * - the home directory string + * - the parentPath string + * - the parentPathv array + */ + /* First calculate the sizes */ + arraysize(c->argv, &sp.nargv, &sp.argvBytes); + bufsize = sp.argvBytes; + arraysize(c->envv, &sp.nenvv, &sp.envvBytes); + bufsize += sp.envvBytes; + sp.dirlen = c->pdir == 0 ? 0 : strlen(c->pdir)+1; + bufsize += sp.dirlen; + arraysize(parentPathv, &sp.nparentPathv, &sp.parentPathvBytes); + bufsize += sp.parentPathvBytes; + /* We need to clear FD_CLOEXEC if set in the fds[]. + * Files are created FD_CLOEXEC in Java. + * Otherwise, they will be closed when the target gets exec'd */ + for (i=0; i<3; i++) { + if (c->fds[i] != -1) { + int flags = fcntl(c->fds[i], F_GETFD); + if (flags & FD_CLOEXEC) { + fcntl(c->fds[i], F_SETFD, flags & (~1)); + } + } + } + + rval = posix_spawn(&resultPid, helperpath, 0, 0, (char * const *) hlpargs, environ); + + if (rval != 0) { + return -1; + } + + /* now the lengths are known, copy the data */ + buf = NEW(char, bufsize); + if (buf == 0) { + return -1; + } + offset = copystrings(buf, 0, &c->argv[0]); + offset = copystrings(buf, offset, &c->envv[0]); + memcpy(buf+offset, c->pdir, sp.dirlen); + offset += sp.dirlen; + offset = copystrings(buf, offset, parentPathv); + assert(offset == bufsize); + + magic = magicNumber(); + + /* write the two structs and the data buffer */ + write(c->childenv[1], (char *)&magic, sizeof(magic)); // magic number first + write(c->childenv[1], (char *)c, sizeof(*c)); + write(c->childenv[1], (char *)&sp, sizeof(sp)); + write(c->childenv[1], buf, bufsize); + free(buf); + + /* In this mode an external main() in invoked which calls back into + * childProcess() in this file, rather than directly + * via the statement below */ + return resultPid; +} +#endif + +/* + * Start a child process running function childProcess. + * This function only returns in the parent. + */ +static pid_t +startChild(JNIEnv *env, jobject process, ChildStuff *c, const char *helperpath) { + switch (c->mode) { + case MODE_VFORK: + return vforkChild(c); + case MODE_FORK: + return forkChild(c); +#if defined(__solaris__) || defined(_ALLBSD_SOURCE) || defined(_AIX) + case MODE_POSIX_SPAWN: + return spawnChild(env, process, c, helperpath); +#endif + default: + return -1; + } +} + +JNIEXPORT jint JNICALL +Java_java_lang_ProcessImpl_forkAndExec(JNIEnv *env, + jobject process, + jint mode, + jbyteArray helperpath, + jbyteArray prog, + jbyteArray argBlock, jint argc, + jbyteArray envBlock, jint envc, + jbyteArray dir, + jintArray std_fds, + jboolean redirectErrorStream) +{ + int errnum; + int resultPid = -1; + int in[2], out[2], err[2], fail[2], childenv[2]; + jint *fds = NULL; + const char *phelperpath = NULL; + const char *pprog = NULL; + const char *pargBlock = NULL; + const char *penvBlock = NULL; + ChildStuff *c; + + in[0] = in[1] = out[0] = out[1] = err[0] = err[1] = fail[0] = fail[1] = -1; + childenv[0] = childenv[1] = -1; + + if ((c = NEW(ChildStuff, 1)) == NULL) return -1; + c->argv = NULL; + c->envv = NULL; + c->pdir = NULL; + c->clone_stack = NULL; + + /* Convert prog + argBlock into a char ** argv. + * Add one word room for expansion of argv for use by + * execve_as_traditional_shell_script. + * This word is also used when using spawn mode + */ + assert(prog != NULL && argBlock != NULL); + if ((phelperpath = getBytes(env, helperpath)) == NULL) goto Catch; + if ((pprog = getBytes(env, prog)) == NULL) goto Catch; + if ((pargBlock = getBytes(env, argBlock)) == NULL) goto Catch; + if ((c->argv = NEW(const char *, argc + 3)) == NULL) goto Catch; + c->argv[0] = pprog; + c->argc = argc + 2; + initVectorFromBlock(c->argv+1, pargBlock, argc); + + if (envBlock != NULL) { + /* Convert envBlock into a char ** envv */ + if ((penvBlock = getBytes(env, envBlock)) == NULL) goto Catch; + if ((c->envv = NEW(const char *, envc + 1)) == NULL) goto Catch; + initVectorFromBlock(c->envv, penvBlock, envc); + } + + if (dir != NULL) { + if ((c->pdir = getBytes(env, dir)) == NULL) goto Catch; + } + + assert(std_fds != NULL); + fds = (*env)->GetIntArrayElements(env, std_fds, NULL); + if (fds == NULL) goto Catch; + + if ((fds[0] == -1 && pipe(in) < 0) || + (fds[1] == -1 && pipe(out) < 0) || + (fds[2] == -1 && pipe(err) < 0) || + (pipe(childenv) < 0) || + (pipe(fail) < 0)) { + throwIOException(env, errno, "Bad file descriptor"); + goto Catch; + } + c->fds[0] = fds[0]; + c->fds[1] = fds[1]; + c->fds[2] = fds[2]; + + copyPipe(in, c->in); + copyPipe(out, c->out); + copyPipe(err, c->err); + copyPipe(fail, c->fail); + copyPipe(childenv, c->childenv); + + c->redirectErrorStream = redirectErrorStream; + c->mode = mode; + + resultPid = startChild(env, process, c, phelperpath); + assert(resultPid != 0); + + if (resultPid < 0) { + switch (c->mode) { + case MODE_VFORK: + throwIOException(env, errno, "vfork failed"); + break; + case MODE_FORK: + throwIOException(env, errno, "fork failed"); + break; + case MODE_POSIX_SPAWN: + throwIOException(env, errno, "spawn failed"); + break; + } + goto Catch; + } + close(fail[1]); fail[1] = -1; /* See: WhyCantJohnnyExec (childproc.c) */ + + switch (readFully(fail[0], &errnum, sizeof(errnum))) { + case 0: break; /* Exec succeeded */ + case sizeof(errnum): + waitpid(resultPid, NULL, 0); + throwIOException(env, errnum, "Exec failed"); + goto Catch; + default: + throwIOException(env, errno, "Read failed"); + goto Catch; + } + + fds[0] = (in [1] != -1) ? in [1] : -1; + fds[1] = (out[0] != -1) ? out[0] : -1; + fds[2] = (err[0] != -1) ? err[0] : -1; + + Finally: + free(c->clone_stack); + + /* Always clean up the child's side of the pipes */ + closeSafely(in [0]); + closeSafely(out[1]); + closeSafely(err[1]); + + /* Always clean up fail and childEnv descriptors */ + closeSafely(fail[0]); + closeSafely(fail[1]); + closeSafely(childenv[0]); + closeSafely(childenv[1]); + + releaseBytes(env, helperpath, phelperpath); + releaseBytes(env, prog, pprog); + releaseBytes(env, argBlock, pargBlock); + releaseBytes(env, envBlock, penvBlock); + releaseBytes(env, dir, c->pdir); + + free(c->argv); + free(c->envv); + free(c); + + if (fds != NULL) + (*env)->ReleaseIntArrayElements(env, std_fds, fds, 0); + + return resultPid; + + Catch: + /* Clean up the parent's side of the pipes in case of failure only */ + closeSafely(in [1]); in[1] = -1; + closeSafely(out[0]); out[0] = -1; + closeSafely(err[0]); err[0] = -1; + goto Finally; +} + +JNIEXPORT void JNICALL +Java_java_lang_ProcessImpl_destroyProcess(JNIEnv *env, + jobject junk, + jint pid, + jboolean force) +{ + int sig = (force == JNI_TRUE) ? SIGKILL : SIGTERM; + kill(pid, sig); +}