/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "com_google_ase_Exec.h"

#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <termios.h>
#include <unistd.h>

#include "android/log.h"

#define LOG_TAG "Exec"
#define LOG(...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)

void JNU_ThrowByName(JNIEnv * env, const char *name, const char *msg) {
    jclass clazz = env->FindClass(name);
    if (clazz != NULL) {
        env->ThrowNew(clazz, msg);
    }
    env->DeleteLocalRef(clazz);
}

char *JNU_GetStringNativeChars(JNIEnv * env, jstring jstr) {
    if (jstr == NULL) {
        return NULL;
    }
    jbyteArray bytes = 0;
    jthrowable exc;
    char *result = 0;
    if (env->EnsureLocalCapacity(2) < 0) {
        return 0;                                          /* out of memory error */
    }
    jclass Class_java_lang_String = env->FindClass("java/lang/String");
    jmethodID MID_String_getBytes = env->GetMethodID(Class_java_lang_String, "getBytes", "()[B");
    bytes = (jbyteArray) env->CallObjectMethod(jstr, MID_String_getBytes);
    exc = env->ExceptionOccurred();
    if (!exc) {
        jint len = env->GetArrayLength(bytes);
        result = (char *) malloc(len + 1);
        if (result == 0) {
            JNU_ThrowByName(env, "java/lang/OutOfMemoryError", 0);
            env->DeleteLocalRef(bytes);
            return 0;
        }
        env->GetByteArrayRegion(bytes, 0, len, (jbyte *) result);
        result[len] = 0;                                   /* NULL-terminate */
    } else {
        env->DeleteLocalRef(exc);
    }
    env->DeleteLocalRef(bytes);
    return result;
}

int jniGetFDFromFileDescriptor(JNIEnv * env, jobject fileDescriptor) {
    jclass Class_java_io_FileDescriptor = env->FindClass("java/io/FileDescriptor");
    jfieldID descriptor = env->GetFieldID(Class_java_io_FileDescriptor,
                                          "descriptor", "I");
    return env->GetIntField(fileDescriptor, descriptor);
}

static int create_subprocess(const char *cmd, const char *arg0, const char *arg1, int *pProcessId) {
    char *devname;
    int ptm;
    pid_t pid;

    ptm = open("/dev/ptmx", O_RDWR);                       // | O_NOCTTY);
    if (ptm < 0) {
        LOG("[ cannot open /dev/ptmx - %s ]\n", strerror(errno));
        return -1;
    }
    fcntl(ptm, F_SETFD, FD_CLOEXEC);

    if (grantpt(ptm) || unlockpt(ptm) || ((devname = (char *) ptsname(ptm)) == 0)) {
        LOG("[ trouble with /dev/ptmx - %s ]\n", strerror(errno));
        return -1;
    }

    pid = fork();
    if (pid < 0) {
        LOG("- fork failed: %s -\n", strerror(errno));
        return -1;
    }

    if (pid == 0) {
        int pts;

        setsid();

        pts = open(devname, O_RDWR);
        if (pts < 0)
            exit(-1);

        dup2(pts, 0);
        dup2(pts, 1);
        dup2(pts, 2);

        close(ptm);

        execl(cmd, cmd, arg0, arg1, NULL);
        exit(-1);
    } else {
        *pProcessId = (int) pid;
        return ptm;
    }
}

JNIEXPORT jobject JNICALL Java_com_google_ase_Exec_createSubprocess(JNIEnv * env, jclass clazz,
                                                                    jstring cmd, jstring arg0,
                                                                    jstring arg1,
                                                                    jintArray processIdArray) {
    char *cmd_8 = JNU_GetStringNativeChars(env, cmd);
    char *arg0_8 = JNU_GetStringNativeChars(env, arg0);
    char *arg1_8 = JNU_GetStringNativeChars(env, arg1);

    int procId;
    int ptm = create_subprocess(cmd_8, arg0_8, arg1_8, &procId);

    if (processIdArray) {
        int procIdLen = env->GetArrayLength(processIdArray);
        if (procIdLen > 0) {
            jboolean isCopy;
            int *pProcId = (int *) env->GetPrimitiveArrayCritical(processIdArray, &isCopy);
            if (pProcId) {
                *pProcId = procId;
                env->ReleasePrimitiveArrayCritical(processIdArray, pProcId, 0);
            }
        }
    }

    jclass Class_java_io_FileDescriptor = env->FindClass("java/io/FileDescriptor");
    jmethodID init = env->GetMethodID(Class_java_io_FileDescriptor,
                                      "<init>", "()V");
    jobject result = env->NewObject(Class_java_io_FileDescriptor, init);

    if (!result) {
        LOG("Couldn't create a FileDescriptor.");
    } else {
        jfieldID descriptor = env->GetFieldID(Class_java_io_FileDescriptor,
                                              "descriptor", "I");
        env->SetIntField(result, descriptor, ptm);
    }

    return result;
}

JNIEXPORT void Java_com_google_ase_Exec_setPtyWindowSize(JNIEnv * env, jclass clazz,
                                                         jobject fileDescriptor, jint row, jint col,
                                                         jint xpixel, jint ypixel) {
    int fd;
    struct winsize sz;

    fd = jniGetFDFromFileDescriptor(env, fileDescriptor);

    if (env->ExceptionOccurred() != NULL) {
        return;
    }

    sz.ws_row = row;
    sz.ws_col = col;
    sz.ws_xpixel = xpixel;
    sz.ws_ypixel = ypixel;

    ioctl(fd, TIOCSWINSZ, &sz);
}

JNIEXPORT jint Java_com_google_ase_Exec_waitFor(JNIEnv * env, jclass clazz, jint procId) {
    int status;
    waitpid(procId, &status, 0);
    int result = 0;
    if (WIFEXITED(status)) {
        result = WEXITSTATUS(status);
    }
    return result;
}