/*

 * Copyright (c) 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.

 */

#include "jni.h"

#include "jni_util.h"

#include "java_lang_ProcessHandleImpl.h"

#include "java_lang_ProcessHandleImpl_Info.h"

#include "ProcessHandleImpl_unix.h"

#include <fcntl.h>

#include <limits.h>

#include <stdlib.h>

#include <unistd.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <string.h>

#include <ctype.h>

/*

 * Implementation of native ProcessHandleImpl functions for Linux.

 * See ProcessHandleImpl_unix.c for more details.

 */

/* Signatures for internal OS specific functions. */

static long long getBoottime(JNIEnv *env);

/* A static offset in milliseconds since boot. */

static long long bootTime_ms;

static long clock_ticks_per_second;

static int pageSize;

void os_initNative(JNIEnv *env, jclass clazz) {

    bootTime_ms = getBoottime(env);

    clock_ticks_per_second = sysconf(_SC_CLK_TCK);

    pageSize = sysconf(_SC_PAGESIZE);

}

jint os_getChildren(JNIEnv *env, jlong jpid, jlongArray jarray,

                    jlongArray jparentArray, jlongArray jstimesArray) {

    return unix_getChildren(env, jpid, jarray, jparentArray, jstimesArray);

}

/**

 * Read /proc/<pid>/stat and return the ppid, total cputime and start time.

 * -1 is fail;  >=  0 is parent pid

 * 'total' will contain the running time of 'pid' in nanoseconds.

 * 'start' will contain the start time of 'pid' in milliseconds since epoch.

 */

pid_t os_getParentPidAndTimings(JNIEnv *env, pid_t pid,

                                jlong *totalTime, jlong* startTime) {

    FILE* fp;

    char buffer[2048];

    int statlen;

    char fn[32];

    char* s;

    int parentPid;

    long unsigned int utime = 0;      // clock tics

    long unsigned int stime = 0;      // clock tics

    long long unsigned int start = 0; // microseconds

    /*

     * Try to stat and then open /proc/%d/stat

     */

    snprintf(fn, sizeof fn, "/proc/%d/stat", pid);

    fp = fopen(fn, "r");

    if (fp == NULL) {

        return -1;              // fail, no such /proc/pid/stat

    }

    /*

     * The format is: pid (command) state ppid ...

     * As the command could be anything we must find the right most

     * ")" and then skip the white spaces that follow it.

     */

    statlen = fread(buffer, 1, (sizeof buffer - 1), fp);

    fclose(fp);

    if (statlen < 0) {

        return -1;               // parent pid is not available

    }

    buffer[statlen] = '\0';

    s = strchr(buffer, '(');

    if (s == NULL) {

        return -1;               // parent pid is not available

    }

    // Found start of command, skip to end

    s++;

    s = strrchr(s, ')');

    if (s == NULL) {

        return -1;               // parent pid is not available

    }

    s++;

    // Scan the needed fields from status, retaining only ppid(4),

    // utime (14), stime(15), starttime(22)

    if (4 != sscanf(s, " %*c %d %*d %*d %*d %*d %*d %*u %*u %*u %*u %lu %lu %*d %*d %*d %*d %*d %*d %llu",

            &parentPid, &utime, &stime, &start)) {

        return 0;              // not all values parsed; return error

    }

    *totalTime = (utime + stime) * (jlong)(1000000000 / clock_ticks_per_second);

    *startTime = bootTime_ms + ((start * 1000) / clock_ticks_per_second);

    return parentPid;

}

void os_getCmdlineAndUserInfo(JNIEnv *env, jobject jinfo, pid_t pid) {

    int fd;

    int cmdlen = 0;

    char *cmdline = NULL, *cmdEnd = NULL; // used for command line args and exe

    char *args = NULL;

    jstring cmdexe = NULL;

    char fn[32];

    struct stat stat_buf;

    /*

     * Stat /proc/<pid> to get the user id

     */

    snprintf(fn, sizeof fn, "/proc/%d", pid);

    if (stat(fn, &stat_buf) == 0) {

        unix_getUserInfo(env, jinfo, stat_buf.st_uid);

    }

    /*

     * Try to open /proc/<pid>/cmdline

     */

    strncat(fn, "/cmdline", sizeof fn - strnlen(fn, sizeof fn) - 1);

    if ((fd = open(fn, O_RDONLY)) < 0) {

        return;

    }

    do {                // Block to break out of on errors

        int i, truncated = 0;

        int count;

        char *s;

        /*

         * The path name read by readlink() is limited to PATH_MAX characters.

         * The content of /proc/<pid>/cmdline is limited to PAGE_SIZE characters.

         */

        cmdline = (char*)malloc((PATH_MAX > pageSize ? PATH_MAX : pageSize) + 1);

        if (cmdline == NULL) {

            break;

        }

        /*

         * On Linux, the full path to the executable command is the link in

         * /proc/<pid>/exe. But it is only readable for processes we own.

         */

        snprintf(fn, sizeof fn, "/proc/%d/exe", pid);

        if ((cmdlen = readlink(fn, cmdline, PATH_MAX)) > 0) {

            // null terminate and create String to store for command

            cmdline[cmdlen] = '\0';

            cmdexe = JNU_NewStringPlatform(env, cmdline);

            (*env)->ExceptionClear(env);        // unconditionally clear any exception

        }

        /*

         * The command-line arguments appear as a set of strings separated by

         * null bytes ('\0'), with a further null byte after the last

         * string. The last string is only null terminated if the whole command

         * line is not exceeding (PAGE_SIZE - 1) characters.

         */

        cmdlen = 0;

        s = cmdline;

        while ((count = read(fd, s, pageSize - cmdlen)) > 0) {

            cmdlen += count;

            s += count;

        }

        if (count < 0) {

            break;

        }

        // We have to null-terminate because the process may have changed argv[]

        // or because the content in /proc/<pid>/cmdline is truncated.

        cmdline[cmdlen] = '\0';

        if (cmdlen == pageSize && cmdline[pageSize - 1] != '\0') {

            truncated = 1;

        } else if (cmdlen == 0) {

            // /proc/<pid>/cmdline was empty. This usually happens for kernel processes

            // like '[kthreadd]'. We could try to read /proc/<pid>/comm in the future.

        }

        if (cmdlen > 0 && (cmdexe == NULL || truncated)) {

            // We have no exact command or the arguments are truncated.

            // In this case we save the command line from /proc/<pid>/cmdline.

            args = (char*)malloc(pageSize + 1);

            if (args != NULL) {

                memcpy(args, cmdline, cmdlen + 1);

                for (i = 0; i < cmdlen; i++) {

                    if (args[i] == '\0') {

                        args[i] = ' ';

                    }

                }

            }

        }

        i = 0;

        if (!truncated) {

            // Count the arguments

            cmdEnd = &cmdline[cmdlen];

            for (s = cmdline; *s != '\0' && (s < cmdEnd); i++) {

                s += strnlen(s, (cmdEnd - s)) + 1;

            }

        }

        unix_fillArgArray(env, jinfo, i, cmdline, cmdEnd, cmdexe, args);

    } while (0);

    if (cmdline != NULL) {

        free(cmdline);

    }

    if (args != NULL) {

        free(args);

    }

    if (fd >= 0) {

        close(fd);

    }

}

/**

 * Read the boottime from /proc/stat.

 */

static long long getBoottime(JNIEnv *env) {

    FILE *fp;

    char *line = NULL;

    size_t len = 0;

    long long bootTime = 0;

    fp = fopen("/proc/stat", "r");

    if (fp == NULL) {

        return -1;

    }

    while (getline(&line, &len, fp) != -1) {

        if (sscanf(line, "btime %llu", &bootTime) == 1) {

            break;

        }

    }

    free(line);

    if (fp != 0) {

        fclose(fp);

    }

    return bootTime * 1000;

}