/*
 * module: pip/jni/gdbm -- A Java interface to the GDBM library
 * file:   gdbmjava.c -- Native parts of the au.com.pharos.gdbm.GdbmFile
 *             Java class
 *
 * Copyright (C) 1997 Pharos IP Pty Ltd
 *
 * $Id$ 
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/* NOTE ON MEMORY MANAGEMENT: GDBM always mallocs memory and expects
 * the caller to free it.  Java requires native functions to interact
 * with it to lock and unlock buffers. */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifdef __MINGW32__
#define MSDOS
#endif

#if defined (_MSC_VER)
#include <gdbmdefs.h>
#include <gdbmerrno.h>
#define GDBM_FILE gdbm_file_info *
extern char* gdbm_version;
extern char *gdbm_strerror(gdbm_error);
#else
#include <gdbm.h>
#endif

#include <jni.h>

#ifdef __MINGW32__

/* (Cross) compiling for Windows Want the type definitions in *win32*
   version of jni_md.h but with the mingw c compiler this then leads
   to C-mangled style functions (param/num args encoded in function
   name) which we *don't* want.  The following achieves this */

#undef JNIEXPORT
#undef JNIIMPORT
#undef JNICALL

#define JNIEXPORT
#define JNIIMPORT
#define JNICALL
#endif

#include <au_com_pharos_gdbm_GdbmFile.h>

#ifdef DEBUG
#define ASSERT(x) if (!(x)) { \
  fprintf(stderr, "%s:%d: assertion failed\n", __FILE__, __LINE__); \
  abort(); }
#else /* !DEBUG */
#define ASSERT(x) 
#endif /* !DEBUG */

/* The Java class within which the native methods are declared */
#define JAVA_CLASS "au.com.pharos.gdbm.GdbmFile"

#define NULL_PTR_EXCEPTION(env) nullPtrException(env, __FILE__, __LINE__)
#define GDBM_EXCEPTION(env) gdbmException(env, __FILE__, __LINE__)

#define CHECK_NOT_NULL(ptr, env) if (!ptr) { NULL_PTR_EXCEPTION(env); return 0; }
#define CHECK_NOT_NULL_VOID(ptr, env) if (!ptr) { NULL_PTR_EXCEPTION(env); return; }

void gdbmException(JNIEnv *env, const char *file, int line);
void nullPtrException(JNIEnv *env, const char *file, int line);

void releaseArray(JNIEnv *env, jbyteArray array, datum *fromDatum);
void releaseArrayAbort(JNIEnv *env, jbyteArray array, datum *fromDatum);
int arrayToDatum(JNIEnv *env, jbyteArray fromArray, datum *toDatum);
jbyteArray datumToArray(JNIEnv *env, datum *fromDatum);

/* 
   The macros defined below for DBF_TO_JLONG(x) and JLONG_TO_DBF(x)
   expect SIZEOF_VOID_P and SIZEOF_LONG to be defined.

   It's possible for autoconf to determine these, but:
   (a) This currently doesn't appear to be bound into JAVAGDBM
       compilation sequence (config.h would need to be #included)
   (b) Even if this was done for Unix system, there would still
       need to be a way to do this for Windows: both 32-bit and
       64-bit as the values would be differnt

   In the event SIZEOF_VOID_P and SIZEON_LONG are not already set,
   the solution taken here is to test for various #ifdef values 
   known to be set by Unix/Windows *compilers* that indicate
   the type sizes they use for int, long, pointer, and
   from that information explicitly set the values used in
   the macro definition tests below.

   For more details on what these sizes are, two useful references are:

     https://en.cppreference.com/w/cpp/language/types
     https://unix.org/version2/whatsnew/lp64_wp.html
*/

#ifndef SIZEOF_VOID_P
#  if defined ( _MSC_VER ) /* i.e., Microsoft Visual Studio, not a Mingw based GCC */
#    if defined( _WIN64 )
#      define SIZEOF_VOID_P 8

#    elif defined( _WIN32 )
#      define SIZEOF_VOID_P 4

#    else
#error "VisualStudio C compile neither 32-bit nor 64-bit.  SIZEOF_VOID_P not specified"
#    endif

#  elif defined ( __GNUC__ ) /* Presumably Unix or Unix-like platform */

#    if defined( __i386__ ) /* i.e., ILP32: int, long and pointer are all 32-bits */
#      define SIZEOF_VOID_P 4

#    elif defined( __x86_64__ )    /* i.e., LP64:  long, and pointer are both 64-bits */
#      define SIZEOF_VOID_P 8

#    else
#error "GCC 'sizeof' model not matched as either ILP32 (32-bit) or LP64 (64-bit).  SIZEOF_VOID_P not specified"
#    endif

#  else
#error "Unrecognized compiler: SIZEOF_LONG not specified"

#  endif
#endif



#ifndef SIZEOF_LONG
#  if defined ( _MSC_VER ) /* i.e., Microsoft Visual Studio, not a Mingw based GCC */
#    if defined( _WIN64 )
#      define SIZEOF_LONG 4 /* but note that SIZEOF_VOID_P above is 8 ! */

#    elif defined( _WIN32 )
#      define SIZEOF_LONG 4

#    else
#error "VisualStudio C compiler neither 32-bit nor 64-bit.  SIZEOF_LONG not specified"
#    endif

#  elif __GNUC__  /* Presumably Unix or Unix-like platform */
#    if defined( __i386__ )
#      define SIZEOF_LONG 4

#    elif defined( __x86_64__ )
#      define SIZEOF_LONG 8

#    else
#error "GCC 'sizeof' model not matched as either ILP32 (32-bit) or LP64 (64-bit_.  SIZEOF_LONG not specified"
#    endif

#  else
#error "Unrecognized compiler: SIZEOF_LONG not specified"
#  endif
#endif



/* Convert between a jlong and a void ptr using a well-defined cast.
 * (Casting between a pointer and an integer of different sizes spooks
 * both gcc and mbp. */

#if (SIZEOF_VOID_P == SIZEOF_LONG)
#  define DBF_TO_JLONG(x) ((jlong)((long) x))
#  define JLONG_TO_DBF(x) ((GDBM_FILE)((long) x))
#elif (SIZEOF_VOID_P == SIZEOF_INT)
#  define DBF_TO_JLONG(x) ((jlong)((int) (x)))
#  define JLONG_TO_DBF(x) ((GDBM_FILE)((int) (x)))
#else
#  define DBF_TO_JLONG(x) ((jlong)(x))
#  define JLONG_TO_DBF(x) ((GDBM_FILE)(x))
#endif


JNIEXPORT jlong JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1open
    (JNIEnv *env, jobject obj, jstring fileName, jint flags)
{
    GDBM_FILE dbf;
    const char *utfFileName;
   
    utfFileName = (*env)->GetStringUTFChars(env, fileName, 0);
    if (!utfFileName) 
	return 0;
    
    setbuf(stderr, 0);
   
    /* XXX: Should we let the caller specify the file mode?  I think
     * not -- Java is above the level of octal file modes. [mbp] */
    /* Couldn't get it to work properly on Windows without the 0 here - 
       wouldn't allow mulitple READs on a single file [kjdon] */
#if defined (__WIN32__) 
    dbf = gdbm_open((char *) utfFileName, 0, flags, 0660, NULL, 0);
#else
    dbf = gdbm_open((char *) utfFileName, 0, flags, 0660, NULL);
#endif
    if (utfFileName)
	(*env)->ReleaseStringUTFChars(env, fileName, utfFileName);

    if (!dbf) {
	GDBM_EXCEPTION(env);
	return 0;
    }	
   
    return DBF_TO_JLONG(dbf);
}





JNIEXPORT jbyteArray JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1firstkey
(JNIEnv *env, jobject obj, jlong dbf)
{
    datum	keyDatum;
    jbyteArray 	keyArray;

    CHECK_NOT_NULL(dbf, env);

    keyDatum = gdbm_firstkey(JLONG_TO_DBF(dbf));
    if ( gdbm_errno != GDBM_NO_ERROR ) {
	GDBM_EXCEPTION(env);
	return 0;
    }
    if ( !keyDatum.dptr )
	return 0;

    keyArray = datumToArray(env, &keyDatum);
    free(keyDatum.dptr); 

    return keyArray;
}





JNIEXPORT jbyteArray JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1nextkey
(JNIEnv *env, jobject this, jlong dbf, jbyteArray keyArray)
{
    datum	keyDatum;
    datum	nextDatum;
    jbyteArray	nextArray;

    CHECK_NOT_NULL(dbf, env);

    if (!arrayToDatum(env, keyArray, &keyDatum)) {
	NULL_PTR_EXCEPTION(env);
	return 0;
    }
    
    nextDatum = gdbm_nextkey(JLONG_TO_DBF(dbf), keyDatum);
    releaseArrayAbort(env, keyArray, &keyDatum);

    if ( gdbm_errno != GDBM_NO_ERROR ) {
	GDBM_EXCEPTION(env);
	return 0;
    }
    if ( !nextDatum.dptr )
	return 0;

    nextArray = datumToArray(env, &nextDatum);
    free(nextDatum.dptr);
    
    return nextArray;
}






JNIEXPORT jbyteArray JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1fetch
  (JNIEnv *env, jobject this, jlong dbf, jbyteArray keyArray)
{
    datum 	keyDatum;
    datum 	valueDatum;
    jbyteArray	valueArray;

    CHECK_NOT_NULL(dbf, env);

    if (!arrayToDatum(env, keyArray, &keyDatum)) {
	NULL_PTR_EXCEPTION(env);
	return 0;
    }

    valueDatum = gdbm_fetch(JLONG_TO_DBF(dbf), keyDatum);
    releaseArrayAbort(env, keyArray, &keyDatum);

    if ( !valueDatum.dptr )
	return 0;
    if ( gdbm_errno != GDBM_NO_ERROR ) {
	GDBM_EXCEPTION(env);
	return 0;
    }

    valueArray = datumToArray(env, &valueDatum);
    free(valueDatum.dptr);

    return valueArray;
}



JNIEXPORT jboolean JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1exists
  (JNIEnv *env, jobject obj, jlong dbf, jbyteArray keyArray)
{
    datum 	keyDatum;
    int		result;

    CHECK_NOT_NULL(dbf, env);
    if (!arrayToDatum(env, keyArray, &keyDatum)) {
	NULL_PTR_EXCEPTION(env);
	return JNI_FALSE;
    }
    result = gdbm_exists(JLONG_TO_DBF(dbf), keyDatum);
    if ( gdbm_errno != GDBM_NO_ERROR ) {
	GDBM_EXCEPTION(env);
	return 0;
    }
    releaseArrayAbort(env, keyArray, &keyDatum);
    return result ? JNI_TRUE : JNI_FALSE;
}





JNIEXPORT void JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1store
  (JNIEnv *env, jobject obj, jlong dbf, 
   jbyteArray keyArray, jbyteArray valueArray, jboolean replace)
{
    datum	keyDatum;
    datum	valueDatum;
    
    CHECK_NOT_NULL_VOID(dbf, env);
    
    if ( !arrayToDatum(env, keyArray, &keyDatum)
	 || !arrayToDatum(env, valueArray, &valueDatum) ) {
	NULL_PTR_EXCEPTION(env);
	return;
    }

    gdbm_store(JLONG_TO_DBF(dbf), keyDatum, valueDatum, 
	       replace ? GDBM_REPLACE : 0);

    releaseArrayAbort(env, keyArray, &keyDatum);
    releaseArrayAbort(env, valueArray, &valueDatum);

    if ( gdbm_errno != GDBM_NO_ERROR )
	GDBM_EXCEPTION(env);
}



JNIEXPORT void JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1delete
   (JNIEnv *env, jobject obj, jlong dbf, jbyteArray keyArray)
{
    datum 	keyDatum;

    CHECK_NOT_NULL_VOID(dbf, env);

    if (!arrayToDatum(env, keyArray, &keyDatum)) {
	NULL_PTR_EXCEPTION(env);
	return;
    }

    gdbm_delete(JLONG_TO_DBF(dbf), keyDatum);

    releaseArrayAbort(env, keyArray, &keyDatum);
    
    if ( gdbm_errno != GDBM_NO_ERROR )
	GDBM_EXCEPTION(env);
}



JNIEXPORT jstring JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1getversion
  (JNIEnv *env, jclass cls)
{
    return (*env)->NewStringUTF(env, gdbm_version);
}


JNIEXPORT jstring JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1wrapperVersion
  (JNIEnv *env, jclass cls)
{
    return (*env)->NewStringUTF(env, "JavaGDBM release 0005 built " __DATE__);
}
				



JNIEXPORT void JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1reorganize
  (JNIEnv *env, jobject obj, jlong dbf)
{
    CHECK_NOT_NULL_VOID(dbf, env);

    gdbm_reorganize(JLONG_TO_DBF(dbf));

    if ( gdbm_errno != GDBM_NO_ERROR )
	GDBM_EXCEPTION(env);
}



JNIEXPORT void JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1close
  (JNIEnv *env, jobject obj, jlong dbf)
{
    CHECK_NOT_NULL_VOID(dbf, env);

    gdbm_close(JLONG_TO_DBF(dbf));

    if ( gdbm_errno != GDBM_NO_ERROR )
	GDBM_EXCEPTION(env);
}



JNIEXPORT void JNICALL 
Java_au_com_pharos_gdbm_GdbmFile_gdbm_1sync
  (JNIEnv *env, jobject obj, jlong dbf)
{
    CHECK_NOT_NULL_VOID(dbf, env);

    gdbm_sync(JLONG_TO_DBF(dbf));

    if ( gdbm_errno != GDBM_NO_ERROR )
	GDBM_EXCEPTION(env);
}




/**********************************************************************
 *
 * Following are support functions which aid in interfacing C to 
 * Java. */

/** Create a new Java byte array from a GDBM datum, and return a
 * pointer thereto.  */

jbyteArray datumToArray(JNIEnv *env, datum *fromDatum) 
{
    jbyteArray toArray;

    if (!fromDatum || !fromDatum->dptr)
	return 0;

    toArray = (*env)->NewByteArray(env, fromDatum->dsize);
    ASSERT(toArray);
    (*env)->SetByteArrayRegion(env, toArray, 
			       0, fromDatum->dsize, fromDatum->dptr);
    
    return toArray;
}

/** Convert a Java byte array to a GDBM datum.
 *
 * The Java array is pinned or copied for use in the datum, and must
 * be released after use by releaseBytes. 
 *
 * Returns true if the array is non-null and could be pinned.  Otherwise,
 * returns false. 
 */
int arrayToDatum(JNIEnv *env, jbyteArray fromArray, datum *toDatum)
{
    if (fromArray) {
	toDatum->dptr = (*env)->GetByteArrayElements(env, fromArray, 0);
	toDatum->dsize = (*env)->GetArrayLength(env, fromArray);
	return (int) toDatum->dptr;
    }
    else 
	return 0;
}

/** Release a byte array pinned or copied for use in a datum. */
void releaseArray(JNIEnv *env, jbyteArray array, datum *fromDatum) 
{
    ASSERT(fromDatum->dptr);
    (*env)->ReleaseByteArrayElements(env, array, fromDatum->dptr, 0);
    fromDatum->dptr = 0;	/* no longer valid */
}

/** Release a byte array pinned or copied for use in a datum, aborting 
 * any changes.  This potentially saves the runtime from having to 
 * copy back an unchanged array. */
void releaseArrayAbort(JNIEnv *env, jbyteArray array, datum *fromDatum) 
{
    ASSERT(fromDatum->dptr);
    (*env)->ReleaseByteArrayElements(env, array, fromDatum->dptr, 
				     JNI_ABORT);
    fromDatum->dptr = 0;	/* no longer valid */
}


/** Throw a null pointer exception. */
void nullPtrException(JNIEnv *env, const char *file, int line) 
{
    jclass exClass;
    char reason[1024];
    sprintf(reason, "Null pointer exception in GDBM wrapper (%s:%d)",
	    file, line);
    
    exClass = (*env)->FindClass(env, "java/lang/NullPointerException");
    ASSERT(exClass);

    (*env)->ThrowNew(env, exClass, reason);
}

/** Translate the GDBM error into throw a Java exception, and throw
 * same. 
 *
 * TODO: Throw different classes of exceptions depending on what the 
 * underlying error is. 
 */
void gdbmException(JNIEnv *env, const char *file, int line) {
    jclass exClass;
    static char reason[1500];
    static char srcLocation[500];

    exClass = (*env)->FindClass(env, "au/com/pharos/gdbm/GdbmException");
    ASSERT(exClass);

    strncpy(reason, gdbm_strerror(gdbm_errno), 500);
    sprintf(srcLocation, " (%s:%d)", file, line);

    /* If the error code suggests that an OS or stdio error may have occurred,
     * include supplementary information from errno. */
    switch (gdbm_errno) {
    case GDBM_FILE_OPEN_ERROR:
    case GDBM_FILE_WRITE_ERROR:
    case GDBM_FILE_SEEK_ERROR:
    case GDBM_FILE_READ_ERROR:
    case GDBM_MALLOC_ERROR:
    case GDBM_REORGANIZE_FAILED:
	strcat(reason, ": ");
	strncat(reason, strerror(errno), 490);
	strcat(reason, "?");
    default:
	/* errno is probably not useful */
	;
    }
    
    strncat(reason, srcLocation, 495);
    gdbm_errno = GDBM_NO_ERROR;	/* this one has been handled */
    (*env)->ThrowNew(env, exClass, reason);    
}

/* 
 * Local variables:
 * c-basic-offset: 4
 * End:
 */