/* MDB Tools - A library for reading MS Access database files
 * Copyright (C) 2000 Brian Bruns
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#include "mdbtools.h"

#ifdef DMALLOC
#include "dmalloc.h"
#endif

MdbFormatConstants MdbJet4Constants = {
	4096, 0x0c, 16, 45, 47, 51, 55, 56, 63, 12, 15, 23, 5, 25, 59
};
MdbFormatConstants MdbJet3Constants = {
	2048, 0x08, 12, 25, 27, 31, 35, 36, 43, 8, 13, 16, 1, 18, 39
};

static size_t _mdb_read_pg(MdbHandle *mdb, unsigned char *pg_buf, unsigned long pg);
static int mdb_find_file(char *file_name, char *file_path, int bufsize)
{
struct stat status;
gchar *s, *mdbpath;
gchar *dir, *tmpfname;
int ret;

	/* try the provided file name first */
	if (!stat(file_name, &status)) {
		if (strlen(file_name)> bufsize) 
			return strlen(file_name);
		strcpy(file_path, file_name);
		return 0;
	}
	
	/* Now pull apart $MDBPATH and try those */
	s = (gchar *) getenv("MDBPATH");
	if (!s || !strlen(s)) return -1; /* no path, can't find file */

	mdbpath = g_strdup(s);
	dir = strtok(mdbpath,":"); 
	do {
		tmpfname = (gchar *) g_malloc(strlen(dir)+strlen(file_name)+2);
		strcpy(tmpfname, dir);
		if (dir[strlen(dir)-1]!='/') strcat(tmpfname, "/");
		strcat(tmpfname, file_name);
		if (!stat(tmpfname, &status)) {
			if (strlen(tmpfname)> bufsize) {
				ret = strlen(tmpfname);
				g_free(tmpfname);
				return ret;
			}
			strcpy(file_path, tmpfname);
			g_free(tmpfname);
			return 0;
		}
		g_free(tmpfname);
	} while ((dir = strtok(NULL, ":")));
	return -1;
}
MdbHandle *_mdb_open(char *filename, gboolean writable)
{
MdbHandle *mdb;
int bufsize;
MdbFile *f;

	mdb = mdb_alloc_handle();
	/* need something to bootstrap with, reassign after page 0 is read */
	mdb->fmt = &MdbJet3Constants;
	mdb->f = mdb_alloc_file();
	f = mdb->f;
	f->filename = (char *) malloc(strlen(filename)+1);
	bufsize = strlen(filename)+1;
	bufsize = mdb_find_file(filename, f->filename, bufsize);
	if (bufsize) {
		f->filename = (char *) realloc(f->filename, bufsize+1);
		bufsize = mdb_find_file(filename, f->filename, bufsize);
		if (bufsize) { 
			fprintf(stderr, "Can't alloc filename\n");
			mdb_free_handle(mdb);
			return NULL; 
		}
	}
	//strcpy(f->filename, filename);
	if (writable) {
		f->writable = TRUE;
		f->fd = open(f->filename,O_RDWR);
	} else {
		f->fd = open(f->filename,O_RDONLY);
	}

	if (f->fd==-1) {
		fprintf(stderr,"Couldn't open file %s\n",f->filename); 
		return NULL;
	}
	if (!mdb_read_pg(mdb, 0)) {
		fprintf(stderr,"Couldn't read first page.\n");
		return NULL;
	}
	if (mdb->pg_buf[0] != 0) {
		close(f->fd);
		return NULL; 
	}
	f->jet_version = mdb_pg_get_int32(mdb, 0x14);
	if (IS_JET4(mdb)) {
		mdb->fmt = &MdbJet4Constants;
	} else if (IS_JET3(mdb)) {
		mdb->fmt = &MdbJet3Constants;
	} else {
		fprintf(stderr,"Unknown Jet version.\n");
		return NULL; 
	}

	f->refs++;
	return mdb;
}
MdbHandle *mdb_open(char *filename)
{
	return _mdb_open(filename, FALSE);
}

void 
mdb_close(MdbHandle *mdb)
{
	if (mdb->f) {
		mdb->f->refs--;
		if (mdb->f->refs<=0) {
			mdb_free_file(mdb->f);
			mdb->f = NULL;
		}
	}
}
MdbHandle *mdb_clone_handle(MdbHandle *mdb)
{
	MdbHandle *newmdb;
	MdbCatalogEntry *entry;
	int i;

	newmdb = mdb_alloc_handle();
	memcpy(newmdb, mdb, sizeof(MdbHandle));
	newmdb->stats = NULL;
	newmdb->catalog = g_ptr_array_new();
	for (i=0;i<mdb->num_catalog;i++) {
		entry = g_ptr_array_index(mdb->catalog,i);
		g_ptr_array_add(newmdb->catalog, entry);
	}
	mdb->backend_name = NULL;
	if (mdb->f) {
		mdb->f->refs++;
	}
	return newmdb;
}

/* 
** mdb_read a wrapper for read that bails if anything is wrong 
*/
size_t mdb_read_pg(MdbHandle *mdb, unsigned long pg)
{
size_t len;

	if (pg && mdb->cur_pg == pg) return mdb->fmt->pg_size;

	len = _mdb_read_pg(mdb, mdb->pg_buf, pg);
	//fprintf(stderr, "read page %d type %02x\n", pg, mdb->pg_buf[0]);
	mdb->cur_pg = pg;
	/* kan - reset the cur_pos on a new page read */
	mdb->cur_pos = 0; /* kan */
	return len;
}
size_t mdb_read_alt_pg(MdbHandle *mdb, unsigned long pg)
{
size_t len;

	len = _mdb_read_pg(mdb, mdb->alt_pg_buf, pg);
	return len;
}
static size_t _mdb_read_pg(MdbHandle *mdb, unsigned char *pg_buf, unsigned long pg)
{
size_t len;
struct stat status;
off_t offset = pg * mdb->fmt->pg_size;

        fstat(mdb->f->fd, &status);
        if (status.st_size < offset) { 
                fprintf(stderr,"offset %lu is beyond EOF\n",offset);
                return 0;
        }
	if (mdb->stats && mdb->stats->collect) 
		mdb->stats->pg_reads++;

	lseek(mdb->f->fd, offset, SEEK_SET);
	len = read(mdb->f->fd,pg_buf,mdb->fmt->pg_size);
	if (len==-1) {
		perror("read");
		return 0;
	}
	else if (len<mdb->fmt->pg_size) {
		/* fprintf(stderr,"EOF reached %d bytes returned.\n",len, mdb->fmt->pg_size); */
		return 0;
	} 
	return len;
}
void mdb_swap_pgbuf(MdbHandle *mdb)
{
char tmpbuf[MDB_PGSIZE];

	memcpy(tmpbuf,mdb->pg_buf, MDB_PGSIZE);
	memcpy(mdb->pg_buf,mdb->alt_pg_buf, MDB_PGSIZE);
	memcpy(mdb->alt_pg_buf,tmpbuf,MDB_PGSIZE);
}
/* really stupid, just here for consistancy */
unsigned char mdb_get_byte(unsigned char *buf, int offset)
{
	return buf[offset];
}
unsigned char mdb_pg_get_byte(MdbHandle *mdb, int offset)
{
unsigned char c;

	c = mdb->pg_buf[offset];
	mdb->cur_pos++;
	return c;
}
int 
mdb_get_int16(unsigned char *buf, int offset)
{
	return buf[offset+1]*256+buf[offset];
}
int 
mdb_pg_get_int16(MdbHandle *mdb, int offset)
{
int           i;

	if (offset < 0 || offset+2 > mdb->fmt->pg_size) return -1;

	i = mdb_get_int16(mdb->pg_buf, offset);

	mdb->cur_pos+=2;
	return i;
	
}
gint32 
mdb_pg_get_int24_msb(MdbHandle *mdb, int offset)
{
gint32 l;
unsigned char *c;

	if (offset <0 || offset+3 > mdb->fmt->pg_size) return -1;
	c = &mdb->pg_buf[offset];
	l =c[0]; l<<=8;
	l+=c[1]; l<<=8;
	l+=c[2];

	mdb->cur_pos+=3;
	return l;
}
gint32
mdb_get_int24(unsigned char *buf, int offset)
{
gint32 l = 0;
unsigned char *c;

	c = &buf[offset];

	l =c[2]; l<<=8;
	l+=c[1]; l<<=8;
	l+=c[0];

	return l;
}
gint32 mdb_pg_get_int24(MdbHandle *mdb, int offset)
{
	guint32 l;

	if (offset <0 || offset+4 > mdb->fmt->pg_size) return -1;

	l = mdb_get_int24(mdb->pg_buf, offset);
	mdb->cur_pos+=3;
	return l;
}
long mdb_get_int32(unsigned char *buf, int offset)
{
long l;
unsigned char *c;

	c = &buf[offset];
	l =c[3]; l<<=8;
	l+=c[2]; l<<=8;
	l+=c[1]; l<<=8;
	l+=c[0];

	return l;
}
long mdb_pg_get_int32(MdbHandle *mdb, int offset)
{
long l;

	if (offset <0 || offset+4 > mdb->fmt->pg_size) return -1;

	l = mdb_get_int32(mdb->pg_buf, offset);
	mdb->cur_pos+=4;
	return l;
}
float 
mdb_get_single(unsigned char *buf, int offset)
{
#ifdef WORDS_BIGENDIAN
	float f2;
	int i;
	unsigned char *c;
#endif
	float f;


       memcpy(&f, &buf[offset], 4);

#ifdef WORDS_BIGENDIAN
       f2 = f;
       for (i=0; i<sizeof(f); i++) {
               *(((unsigned char *)&f)+i) =
               *(((unsigned char *)&f2)+sizeof(f)-1-i);
       }
#endif
       return f;
}
float 
mdb_pg_get_single(MdbHandle *mdb, int offset)
{
       if (offset <0 || offset+4 > mdb->fmt->pg_size) return -1;

       mdb->cur_pos+=4;
       return mdb_get_single(mdb->pg_buf, offset);
}

double 
mdb_get_double(unsigned char *buf, int offset)
{
#ifdef WORDS_BIGENDIAN
	double d2;
	int i;
	unsigned char *c;
#endif
	double d;


	memcpy(&d, &buf[offset], 8);

#ifdef WORDS_BIGENDIAN
	d2 = d;
	for (i=0; i<sizeof(d); i++) {
		*(((unsigned char *)&d)+i) =
		*(((unsigned char *)&d2)+sizeof(d)-1-i);
	}
#endif
	return d;

}
double 
mdb_pg_get_double(MdbHandle *mdb, int offset)
{
	if (offset <0 || offset+8 > mdb->fmt->pg_size) return -1;
	mdb->cur_pos+=8;
	return mdb_get_double(mdb->pg_buf, offset);
}
int 
mdb_set_pos(MdbHandle *mdb, int pos)
{
	if (pos<0 || pos >= mdb->fmt->pg_size) return 0;

	mdb->cur_pos=pos;
	return pos;
}
int mdb_get_pos(MdbHandle *mdb)
{
	return mdb->cur_pos;
}