/*

 * 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.

 *

 * 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 <door.h>

#include <errno.h>

#include <fcntl.h>

#include <limits.h>

#include <poll.h>

#include <signal.h>

#include <stdarg.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <thread.h>

#include <unistd.h>

#include "jvm_dtrace.h"

// NOTE: These constants are used in JVM code as well.

// KEEP JVM CODE IN SYNC if you are going to change these...

#define DTRACE_ALLOC_PROBES   0x1

#define DTRACE_METHOD_PROBES  0x2

#define DTRACE_MONITOR_PROBES 0x4

#define DTRACE_ALL_PROBES     -1

// generic error messages

#define JVM_ERR_OUT_OF_MEMORY            "out of memory (native heap)"

#define JVM_ERR_INVALID_PARAM            "invalid input parameter(s)"

#define JVM_ERR_NULL_PARAM               "input paramater is NULL"

// error messages for attach

#define JVM_ERR_CANT_OPEN_DOOR           "cannot open door file"

#define JVM_ERR_CANT_CREATE_ATTACH_FILE  "cannot create attach file"

#define JVM_ERR_DOOR_FILE_PERMISSION     "door file is not secure"

#define JVM_ERR_CANT_SIGNAL              "cannot send SIGQUIT to target"

// error messages for enable probe

#define JVM_ERR_DOOR_CMD_SEND            "door command send failed"

#define JVM_ERR_DOOR_CANT_READ_STATUS    "cannot read door command status"

#define JVM_ERR_DOOR_CMD_STATUS          "door command error status"

// error message for detach

#define JVM_ERR_CANT_CLOSE_DOOR          "cannot close door file"

#define RESTARTABLE(_cmd, _result) do { \

    do { \

        _result = _cmd; \

    } while((_result == -1) && (errno == EINTR)); \

} while(0)

struct _jvm_t {

    pid_t pid;

    int door_fd;

};

static int libjvm_dtrace_debug;

static void print_debug(const char* fmt,...) {

    if (libjvm_dtrace_debug) {

        va_list alist;

        va_start(alist, fmt);

        fputs("libjvm_dtrace DEBUG: ", stderr);

        vfprintf(stderr, fmt, alist);

        va_end(alist);

    }

}

/* Key for thread local error message */

static thread_key_t jvm_error_key;

/* init function for this library */

static void init_jvm_dtrace() {

    /* check for env. var for debug mode */

    libjvm_dtrace_debug = getenv("LIBJVM_DTRACE_DEBUG") != NULL;

    /* create key for thread local error message */

    if (thr_keycreate(&jvm_error_key, NULL) != 0) {

        print_debug("can't create thread_key_t for jvm error key\n");

        // exit(1); ?

    }

}

#pragma init(init_jvm_dtrace)

/* set thread local error message */

static void set_jvm_error(const char* msg) {

    thr_setspecific(jvm_error_key, (void*)msg);

}

/* clear thread local error message */

static void clear_jvm_error() {

    thr_setspecific(jvm_error_key, NULL);

}

/* file handling functions that can handle interrupt */

static int file_open(const char* path, int flag) {

    int ret;

    RESTARTABLE(open(path, flag), ret);

    return ret;

}

static int file_close(int fd) {

    int ret;

    RESTARTABLE(close(fd), ret);

    return ret;

}

static int file_read(int fd, char* buf, int len) {

    int ret;

    RESTARTABLE(read(fd, buf, len), ret);

    return ret;

}

/* send SIGQUIT signal to given process */

static int send_sigquit(pid_t pid) {

    int ret;

    RESTARTABLE(kill(pid, SIGQUIT), ret);

    return ret;

}

/* called to check permissions on attach file */

static int check_permission(const char* path) {

    struct stat64 sb;

    uid_t uid, gid;

    int res;

    /*

     * Check that the path is owned by the effective uid/gid of this

     * process. Also check that group/other access is not allowed.

     */

    uid = geteuid();

    gid = getegid();

    res = stat64(path, &sb);

    if (res != 0) {

        print_debug("stat failed for %s\n", path);

        return -1;

    }

    if ((sb.st_uid != uid) || (sb.st_gid != gid) ||

        ((sb.st_mode & (S_IRGRP|S_IWGRP|S_IROTH|S_IWOTH)) != 0)) {

        print_debug("well-known file %s is not secure\n", path);

        return -1;

    }

    return 0;

}

#define ATTACH_FILE_PATTERN "/tmp/.attach_pid%d"

/* fill-in the name of attach file name in given buffer */

static void fill_attach_file_name(char* path, int len, pid_t pid) {

    memset(path, 0, len);

    sprintf(path, ATTACH_FILE_PATTERN, pid);

}

#define DOOR_FILE_PATTERN "/tmp/.java_pid%d"

/* open door file for the given JVM */

static int open_door(pid_t pid) {

    char path[PATH_MAX + 1];

    int fd;

    sprintf(path, DOOR_FILE_PATTERN, pid);

    fd = file_open(path, O_RDONLY);

    if (fd < 0) {

        set_jvm_error(JVM_ERR_CANT_OPEN_DOOR);

        print_debug("cannot open door file %s\n", path);

        return -1;

    }

    print_debug("opened door file %s\n", path);

    if (check_permission(path) != 0) {

        set_jvm_error(JVM_ERR_DOOR_FILE_PERMISSION);

        print_debug("check permission failed for %s\n", path);

        file_close(fd);

        fd = -1;

    }

    return fd;

}

/* create attach file for given process */

static int create_attach_file(pid_t pid) {

    char path[PATH_MAX + 1];

    int fd;

    fill_attach_file_name(path, sizeof(path), pid);

    fd = file_open(path, O_CREAT | O_RDWR);

    if (fd < 0) {

        set_jvm_error(JVM_ERR_CANT_CREATE_ATTACH_FILE);

        print_debug("cannot create file %s\n", path);

    } else {

        print_debug("created attach file %s\n", path);

    }

    return fd;

}

/* delete attach file for given process */

static void delete_attach_file(pid_t pid) {

    char path[PATH_MAX + 1];

    fill_attach_file_name(path, sizeof(path), pid);

    int res = unlink(path);

    if (res) {

        print_debug("cannot delete attach file %s\n", path);

    } else {

        print_debug("deleted attach file %s\n", path);

    }

}

/* attach to given JVM */

jvm_t* jvm_attach(pid_t pid) {

    jvm_t* jvm;

    int door_fd, attach_fd, i;

    jvm = (jvm_t*) calloc(1, sizeof(jvm_t));

    if (jvm == NULL) {

        set_jvm_error(JVM_ERR_OUT_OF_MEMORY);

        print_debug("calloc failed in %s at %d\n", __FILE__, __LINE__);

        return NULL;

    }

    jvm->pid = pid;

    attach_fd = -1;

    door_fd = open_door(pid);

    if (door_fd < 0) {

        print_debug("trying to create attach file\n");

        if ((attach_fd = create_attach_file(pid)) < 0) {

            goto quit;

        }

        /* send QUIT signal to the target so that it will

         * check for the attach file.

         */

        if (send_sigquit(pid) != 0) {

            set_jvm_error(JVM_ERR_CANT_SIGNAL);

            print_debug("sending SIGQUIT failed\n");

            goto quit;

        }

        /* give the target VM time to start the attach mechanism */

        do {

            int res;

            RESTARTABLE(poll(0, 0, 200), res);

            door_fd = open_door(pid);

            i++;

        } while (i <= 50 && door_fd == -1);

        if (door_fd < 0) {

            print_debug("Unable to open door to process %d\n", pid);

            goto quit;

        }

    }

quit:

    if (attach_fd >= 0) {

        file_close(attach_fd);

        delete_attach_file(jvm->pid);

    }

    if (door_fd >= 0) {

        jvm->door_fd = door_fd;

        clear_jvm_error();

    } else {

        free(jvm);

        jvm = NULL;

    }

    return jvm;

}

/* return the last thread local error message */

const char* jvm_get_last_error() {

    const char* res = NULL;

    thr_getspecific(jvm_error_key, (void**)&res);

    return res;

}

/* detach the givenb JVM */

int jvm_detach(jvm_t* jvm) {

    if (jvm) {

        int res;

        if (jvm->door_fd != -1) {

            if (file_close(jvm->door_fd) != 0) {

                set_jvm_error(JVM_ERR_CANT_CLOSE_DOOR);

                res = -1;

            } else {

                clear_jvm_error();

                res = 0;

            }

        }

        free(jvm);

        return res;

    } else {

        set_jvm_error(JVM_ERR_NULL_PARAM);

        print_debug("jvm_t* is NULL\n");

        return -1;

    }

}

/*

 * A simple table to translate some known errors into reasonable

 * error messages

 */

static struct {

    int err;

    const char* msg;

} const error_messages[] = {

    { 100,      "Bad request" },

    { 101,      "Protocol mismatch" },

    { 102,      "Resource failure" },

    { 103,      "Internal error" },

    { 104,      "Permission denied" },

};

/*

 * Lookup the given error code and return the appropriate

 * message. If not found return NULL.

 */

static const char* translate_error(int err) {

    int table_size = sizeof(error_messages) / sizeof(error_messages[0]);

    int i;

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

        if (err == error_messages[i].err) {

            return error_messages[i].msg;

        }

    }

    return NULL;

}

/*

 * Current protocol version

 */

static const char* PROTOCOL_VERSION = "1";

#define RES_BUF_SIZE 128

/*

 * Enqueue attach-on-demand command to the given JVM

 */

static

int enqueue_command(jvm_t* jvm, const char* cstr, int arg_count, const char** args) {

    size_t size;

    door_arg_t door_args;

    char res_buffer[RES_BUF_SIZE];

    int rc, i;

    char* buf = NULL;

    int result = -1;

    /*

     * First we get the command string and create the start of the

     * argument string to send to the target VM:

     * <ver>\0<cmd>\0

     */

    if (cstr == NULL) {

        print_debug("command name is NULL\n");

        goto quit;

    }

    size = strlen(PROTOCOL_VERSION) + strlen(cstr) + 2;

    buf = (char*)malloc(size);

    if (buf != NULL) {

        char* pos = buf;

        strcpy(buf, PROTOCOL_VERSION);

        pos += strlen(PROTOCOL_VERSION)+1;

        strcpy(pos, cstr);

    } else {

        set_jvm_error(JVM_ERR_OUT_OF_MEMORY);

        print_debug("malloc failed at %d in %s\n", __LINE__, __FILE__);

        goto quit;

    }

    /*

     * Next we iterate over the arguments and extend the buffer

     * to include them.

     */

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

        cstr = args[i];

        if (cstr != NULL) {

            size_t len = strlen(cstr);

            char* newbuf = (char*)realloc(buf, size+len+1);

            if (newbuf == NULL) {

                set_jvm_error(JVM_ERR_OUT_OF_MEMORY);

                print_debug("realloc failed in %s at %d\n", __FILE__, __LINE__);

                goto quit;

            }

            buf = newbuf;

            strcpy(buf+size, cstr);

            size += len+1;

        }

    }

    /*

     * The arguments to the door function are in 'buf' so we now

     * do the door call

     */

    door_args.data_ptr = buf;

    door_args.data_size = size;

    door_args.desc_ptr = NULL;

    door_args.desc_num = 0;

    door_args.rbuf = (char*)&res_buffer;

    door_args.rsize = sizeof(res_buffer);

    RESTARTABLE(door_call(jvm->door_fd, &door_args), rc);

    /*

     * door_call failed

     */

    if (rc == -1) {

        print_debug("door_call failed\n");

    } else {

        /*

         * door_call succeeded but the call didn't return the the expected jint.

         */

        if (door_args.data_size < sizeof(int)) {

            print_debug("Enqueue error - reason unknown as result is truncated!");

        } else {

            int* res = (int*)(door_args.data_ptr);

            if (*res != 0) {

                const char* msg = translate_error(*res);

                if (msg == NULL) {

                    print_debug("Unable to enqueue command to target VM: %d\n", *res);

                } else {

                    print_debug("Unable to enqueue command to target VM: %s\n", msg);

                }

            } else {

                /*

                 * The door call should return a file descriptor to one end of

                 * a socket pair

                 */

                if ((door_args.desc_ptr != NULL) &&

                    (door_args.desc_num == 1) &&

                    (door_args.desc_ptr->d_attributes & DOOR_DESCRIPTOR)) {

                    result = door_args.desc_ptr->d_data.d_desc.d_descriptor;

                } else {

                    print_debug("Reply from enqueue missing descriptor!\n");

                }

            }

        }

    }

quit:

    if (buf) free(buf);

    return result;

}

/* read status code for a door command */

static int read_status(int fd) {

    char ch, buf[16];

    int index = 0;

    while (1) {

        if (file_read(fd, &ch, sizeof(ch)) != sizeof(ch)) {

            set_jvm_error(JVM_ERR_DOOR_CANT_READ_STATUS);

            print_debug("door cmd status: read status failed\n");

            return -1;

        }

        buf[index++] = ch;

        if (ch == '\n') {

            buf[index - 1] = '\0';

            return atoi(buf);

        }

        if (index == sizeof(buf)) {

            set_jvm_error(JVM_ERR_DOOR_CANT_READ_STATUS);

            print_debug("door cmd status: read status overflow\n");

            return -1;

        }

    }

}

static const char* ENABLE_DPROBES_CMD = "enabledprobes";

/* enable one or more DTrace probes for a given JVM */

int jvm_enable_dtprobes(jvm_t* jvm, int num_probe_types, const char** probe_types) {

    int fd, status = 0;

    char ch;

    const char* args[1];

    char buf[16];

    int probe_type = 0, index;

    int count = 0;

    if (jvm == NULL) {

        set_jvm_error(JVM_ERR_NULL_PARAM);

        print_debug("jvm_t* is NULL\n");

        return -1;

    }

    if (num_probe_types == 0 || probe_types == NULL ||

        probe_types[0] == NULL) {

        set_jvm_error(JVM_ERR_INVALID_PARAM);

        print_debug("invalid probe type argument(s)\n");

        return -1;

    }

    for (index = 0; index < num_probe_types; index++) {

        const char* p = probe_types[index];

        if (strcmp(p, JVM_DTPROBE_OBJECT_ALLOC) == 0) {

            probe_type |= DTRACE_ALLOC_PROBES;

            count++;

        } else if (strcmp(p, JVM_DTPROBE_METHOD_ENTRY) == 0 ||

                   strcmp(p, JVM_DTPROBE_METHOD_RETURN) == 0) {

            probe_type |= DTRACE_METHOD_PROBES;

            count++;

        } else if (strcmp(p, JVM_DTPROBE_MONITOR_ENTER) == 0   ||

                   strcmp(p, JVM_DTPROBE_MONITOR_ENTERED) == 0 ||

                   strcmp(p, JVM_DTPROBE_MONITOR_EXIT) == 0    ||

                   strcmp(p, JVM_DTPROBE_MONITOR_WAIT) == 0    ||

                   strcmp(p, JVM_DTPROBE_MONITOR_WAITED) == 0  ||

                   strcmp(p, JVM_DTPROBE_MONITOR_NOTIFY) == 0  ||

                   strcmp(p, JVM_DTPROBE_MONITOR_NOTIFYALL) == 0) {

            probe_type |= DTRACE_MONITOR_PROBES;

            count++;

        } else if (strcmp(p, JVM_DTPROBE_ALL) == 0) {