/* * Copyright 1995-2008 Sun Microsystems, Inc. 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. Sun designates this * particular file as subject to the "Classpath" exception as provided * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.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 #include #include #include #include #include /* * (Hopefully temporarily) disable the clone-exec feature pending * further investigation and bug-fixing. * 32-bit (but not 64-bit) Linux fails on the 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) * Linux kernel/pthread gurus are invited to figure this out. */ #define USE_CLONE 0 #ifndef USE_CLONE #ifdef __linux__ #define USE_CLONE 1 #else #define USE_CLONE 0 #endif #endif #if USE_CLONE #include #endif #ifndef STDIN_FILENO #define STDIN_FILENO 0 #endif #ifndef STDOUT_FILENO #define STDOUT_FILENO 1 #endif #ifndef STDERR_FILENO #define STDERR_FILENO 2 #endif #ifndef SA_NOCLDSTOP #define SA_NOCLDSTOP 0 #endif #ifndef SA_RESTART #define SA_RESTART 0 #endif #define FAIL_FILENO (STDERR_FILENO + 1) 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 * splitPath(JNIEnv *env, const char *path) { const char *p, *q; char **pathv; int i; int count = countOccurrences(path, ':') + 1; pathv = NEW(char*, count+1); pathv[count] = NULL; for (p = path, i = 0; i < count; i++, p = q + 1) { for (q = p; (*q != ':') && (*q != '\0'); q++) ; if (q == p) /* empty PATH component => "." */ pathv[i] = "./"; else { int addSlash = ((*(q - 1)) != '/'); pathv[i] = NEW(char, q - p + addSlash + 1); memcpy(pathv[i], p, q - p); if (addSlash) pathv[i][q - p] = '/'; pathv[i][q - p + addSlash] = '\0'; } } return (const char * const *) pathv; } /** * Cached value of JVM's effective PATH. * (We don't support putenv("PATH=...") in native code) */ static const char *parentPath; /** * Split, canonicalized version of parentPath */ static const char * const *parentPathv; static jfieldID field_exitcode; JNIEXPORT void JNICALL Java_java_lang_UNIXProcess_initIDs(JNIEnv *env, jclass clazz) { field_exitcode = (*env)->GetFieldID(env, clazz, "exitcode", "I"); parentPath = effectivePath(); parentPathv = splitPath(env, parentPath); 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_UNIXProcess_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 int isAsciiDigit(char c) { return c >= '0' && c <= '9'; } static int closeDescriptors(void) { DIR *dp; struct dirent64 *dirp; int from_fd = FAIL_FILENO + 1; /* We're trying to close all file descriptors, but opendir() might * itself be implemented using a file descriptor, and we certainly * don't want to close that while it's in use. We assume that if * opendir() is implemented using a file descriptor, then it uses * the lowest numbered file descriptor, just like open(). So we * close a couple explicitly. */ close(from_fd); /* for possible use by opendir() */ close(from_fd + 1); /* another one for good luck */ if ((dp = opendir("/proc/self/fd")) == NULL) return 0; /* We use readdir64 instead of readdir to work around Solaris bug * 6395699: /proc/self/fd fails to report file descriptors >= 1024 on Solaris 9 */ while ((dirp = readdir64(dp)) != NULL) { int fd; if (isAsciiDigit(dirp->d_name[0]) && (fd = strtol(dirp->d_name, NULL, 10)) >= from_fd + 2) close(fd); } closedir(dp); return 1; } static void moveDescriptor(int fd_from, int fd_to) { if (fd_from != fd_to) { dup2(fd_from, fd_to); close(fd_from); } } 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 initVectorFromBlock(const char**vector, const char* block, int count) { int i; const char *p; for (i = 0, p = block; i < count; i++) { /* Invariant: p always points to the start of a C string. */ vector[i] = p; while (*(p++)); } vector[count] = NULL; } 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)); 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 */ /** * Exec FILE as a traditional Bourne shell script (i.e. one without #!). * If we could do it over again, we would probably not support such an ancient * misfeature, but compatibility wins over sanity. The original support for * this was imported accidentally from execvp(). */ static void execve_as_traditional_shell_script(const char *file, const char *argv[], const char *const envp[]) { /* Use the extra word of space provided for us in argv by caller. */ const char *argv0 = argv[0]; const char *const *end = argv; while (*end != NULL) ++end; memmove(argv+2, argv+1, (end-argv) * sizeof (*end)); argv[0] = "/bin/sh"; argv[1] = file; execve(argv[0], (char **) argv, (char **) envp); /* Can't even exec /bin/sh? Big trouble, but let's soldier on... */ memmove(argv+1, argv+2, (end-argv) * sizeof (*end)); argv[0] = argv0; } /** * Like execve(2), except that in case of ENOEXEC, FILE is assumed to * be a shell script and the system default shell is invoked to run it. */ static void execve_with_shell_fallback(const char *file, const char *argv[], const char *const envp[]) { #if USE_CLONE execve(file, (char **) argv, (char **) envp); if (errno == ENOEXEC) execve_as_traditional_shell_script(file, argv, envp); #else /* Our address space is unshared, so can mutate environ. */ extern char **environ; environ = (char **) envp; execvp(file, (char **) argv); #endif } /** * execvpe should have been included in the Unix standards. * execvpe is identical to execvp, except that the child environment is * specified via the 3rd argument instead of being inherited from environ. */ static void execvpe(const char *file, const char *argv[], const char *const envp[]) { /* This is one of the rare times it's more portable to declare an * external symbol explicitly, rather than via a system header. * The declaration is standardized as part of UNIX98, but there is * no standard (not even de-facto) header file where the * declaration is to be found. See: * http://www.opengroup.org/onlinepubs/009695399/functions/environ.html * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_02.html * * "All identifiers in this volume of IEEE Std 1003.1-2001, except * environ, are defined in at least one of the headers" (!) */ extern char **environ; if (envp == NULL || (char **) envp == environ) { execvp(file, (char **) argv); return; } if (*file == '\0') { errno = ENOENT; return; } if (strchr(file, '/') != NULL) { execve_with_shell_fallback(file, argv, envp); } else { /* We must search PATH (parent's, not child's) */ char expanded_file[PATH_MAX]; int filelen = strlen(file); int sticky_errno = 0; const char * const * dirs; for (dirs = parentPathv; *dirs; dirs++) { const char * dir = *dirs; int dirlen = strlen(dir); if (filelen + dirlen + 1 >= PATH_MAX) { errno = ENAMETOOLONG; continue; } memcpy(expanded_file, dir, dirlen); memcpy(expanded_file + dirlen, file, filelen); expanded_file[dirlen + filelen] = '\0'; execve_with_shell_fallback(expanded_file, argv, envp); /* There are 3 responses to various classes of errno: * return immediately, continue (especially for ENOENT), * or continue with "sticky" errno. * * From exec(3): * * If permission is denied for a file (the attempted * execve returned EACCES), these functions will continue * searching the rest of the search path. If no other * file is found, however, they will return with the * global variable errno set to EACCES. */ switch (errno) { case EACCES: sticky_errno = errno; /* FALLTHRU */ case ENOENT: case ENOTDIR: #ifdef ELOOP case ELOOP: #endif #ifdef ESTALE case ESTALE: #endif #ifdef ENODEV case ENODEV: #endif #ifdef ETIMEDOUT case ETIMEDOUT: #endif break; /* Try other directories in PATH */ default: return; } } if (sticky_errno != 0) errno = sticky_errno; } } static void closeSafely(int fd) { if (fd != -1) close(fd); } /* * Reads nbyte bytes from file descriptor fd into buf, * The read operation is retried in case of EINTR or partial reads. * * Returns number of bytes read (normally nbyte, but may be less in * case of EOF). In case of read errors, returns -1 and sets errno. */ static ssize_t readFully(int fd, void *buf, size_t nbyte) { ssize_t remaining = nbyte; for (;;) { ssize_t n = read(fd, buf, remaining); if (n == 0) { return nbyte - remaining; } else if (n > 0) { remaining -= n; if (remaining <= 0) return nbyte; /* We were interrupted in the middle of reading the bytes. * Unlikely, but possible. */ buf = (void *) (((char *)buf) + n); } else if (errno == EINTR) { /* Strange signals like SIGJVM1 are possible at any time. * See http://www.dreamsongs.com/WorseIsBetter.html */ } else { return -1; } } } typedef struct _ChildStuff { int in[2]; int out[2]; int err[2]; int fail[2]; int fds[3]; const char **argv; const char **envv; const char *pdir; jboolean redirectErrorStream; } ChildStuff; static void copyPipe(int from[2], int to[2]) { to[0] = from[0]; to[1] = from[1]; } /** * Child process after a successful fork() or clone(). * This function must not return, and must be prepared for either all * of its address space to be shared with its parent, or to be a copy. * It must not modify global variables such as "environ". */ static int childProcess(void *arg) { const ChildStuff* p = (const ChildStuff*) arg; /* Close the parent sides of the pipes. Closing pipe fds here is redundant, since closeDescriptors() would do it anyways, but a little paranoia is a good thing. */ closeSafely(p->in[1]); closeSafely(p->out[0]); closeSafely(p->err[0]); closeSafely(p->fail[0]); /* Give the child sides of the pipes the right fileno's. */ /* Note: it is possible for in[0] == 0 */ moveDescriptor(p->in[0] != -1 ? p->in[0] : p->fds[0], STDIN_FILENO); moveDescriptor(p->out[1]!= -1 ? p->out[1] : p->fds[1], STDOUT_FILENO); if (p->redirectErrorStream) { closeSafely(p->err[1]); dup2(STDOUT_FILENO, STDERR_FILENO); } else { moveDescriptor(p->err[1] != -1 ? p->err[1] : p->fds[2], STDERR_FILENO); } moveDescriptor(p->fail[1], FAIL_FILENO); /* close everything */ if (closeDescriptors() == 0) { /* failed, close the old way */ int max_fd = (int)sysconf(_SC_OPEN_MAX); int i; for (i = FAIL_FILENO + 1; i < max_fd; i++) close(i); } /* change to the new working directory */ if (p->pdir != NULL && chdir(p->pdir) < 0) goto WhyCantJohnnyExec; if (fcntl(FAIL_FILENO, F_SETFD, FD_CLOEXEC) == -1) goto WhyCantJohnnyExec; execvpe(p->argv[0], p->argv, p->envv); WhyCantJohnnyExec: /* We used to go to an awful lot of trouble to predict whether the * child would fail, but there is no reliable way to predict the * success of an operation without *trying* it, and there's no way * to try a chdir or exec in the parent. Instead, all we need is a * way to communicate any failure back to the parent. Easy; we just * send the errno back to the parent over a pipe in case of failure. * The tricky thing is, how do we communicate the *success* of exec? * We use FD_CLOEXEC together with the fact that a read() on a pipe * yields EOF when the write ends (we have two of them!) are closed. */ { int errnum = errno; write(FAIL_FILENO, &errnum, sizeof(errnum)); } close(FAIL_FILENO); _exit(-1); return 0; /* Suppress warning "no return value from function" */ } JNIEXPORT jint JNICALL Java_java_lang_UNIXProcess_forkAndExec(JNIEnv *env, jobject process, jbyteArray prog, jbyteArray argBlock, jint argc, jbyteArray envBlock, jint envc, jbyteArray dir, jintArray std_fds, jboolean redirectErrorStream) { int errnum; int resultPid = -1; #if USE_CLONE void *clone_stack = NULL; #endif int in[2], out[2], err[2], fail[2]; jint *fds = 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; if ((c = NEW(ChildStuff, 1)) == NULL) return -1; c->argv = NULL; c->envv = NULL; c->pdir = NULL; /* Convert prog + argBlock into a char ** argv. * Add one word room for expansion of argv for use by * execve_as_traditional_shell_script. */ assert(prog != NULL && argBlock != NULL); 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; 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(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); c->redirectErrorStream = redirectErrorStream; { #if USE_CLONE /* See clone(2). * Instead of worrying about which direction the stack grows, just * allocate twice as much and start the stack in the middle. */ const int stack_size = 64 * 1024; if ((clone_stack = NEW(char, 2 * stack_size)) == NULL) goto Catch; resultPid = clone(childProcess, clone_stack + stack_size, /* CLONE_VFORK | // works, but unnecessary */ CLONE_VM | SIGCHLD, c); #else /* From 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(0); /* childProcess must not return */ } #endif } if (resultPid < 0) { throwIOException(env, errno, "Fork failed"); goto Catch; } /* parent process */ close(fail[1]); fail[1] = -1; /* See: WhyCantJohnnyExec */ 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: #if USE_CLONE free(clone_stack); #endif /* Always clean up the child's side of the pipes */ closeSafely(in [0]); closeSafely(out[1]); closeSafely(err[1]); /* Always clean up fail descriptors */ closeSafely(fail[0]); closeSafely(fail[1]); 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]); closeSafely(out[0]); closeSafely(err[0]); goto Finally; } JNIEXPORT void JNICALL Java_java_lang_UNIXProcess_destroyProcess(JNIEnv *env, jobject junk, jint pid) { kill(pid, SIGTERM); }