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tc_dbf.arc
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D_OPEN.C
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1987-07-12
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/*
** file: d_open.c
** purpose: routine to open a dbaseiii file for access by the other routines
** in dbf.lib.
** usage: d = (struct DBF *)malloc(sizeof(struct DBF));
** strcpy(d->filename,"filename.dbf");
** d_open(d);
** ... access file with other routines ...
** d_close(d);
** free(d);
** notes: compile with "tcc -c d_open". include this file in dbf.lib
** see dbf.h for structure of DBF. copy filename into structure
** before calling d_open.
** returns: 0 if successful with structure filled in
** NO_FILE if unable to find file
** OUT_OF_MEM if not enough memory
** BAD_FORMAT if not dBASE file
** author: Mark Sadler
** revised: 6/18/87
*/
#include <stdio.h>
#include <alloc.h>
#include "dbf.h"
int d_open(struct DBF *d)
{
int i;
int n;
d->status = not_open; /* in case can not open */
if((d->file_ptr = fopen(d->filename,"r+b")) == NULL)
return(NO_FILE);
rewind(d->file_ptr);
fread((void *)&d->dbf_version,(unsigned)1,(unsigned)12,d->file_ptr); /* read prolog */
if (d->dbf_version != DB3FILE /* check for dbiii file marker */
&& d->dbf_version != DB3WITHMEMO
|| d->update_mo == 0)
{
fclose(d->file_ptr);
return(BAD_FORMAT);
}
d->current_record = 0L;
d->num_fields = ((d->header_length - (FIELD_REC_LEN+1)) / HEADER_PROLOG);
if((d->fields_ptr = (struct FIELD_RECORD *)malloc((unsigned)(d->num_fields * FIELD_REC_LEN)))==NULL)
return(OUT_OF_MEM);
/* position at field descriptions */
fseek(d->file_ptr,(long)HEADER_PROLOG,0);
/* read into field description array */
fread((void *)d->fields_ptr,sizeof *d->fields_ptr,(unsigned)d->num_fields,d->file_ptr);
if((d->record_ptr = (char *)malloc(d->record_length))==NULL)
return(OUT_OF_MEM);
/* initialize pointers to fields in record. */
for(i=0,n=1;i<d->num_fields;i++) /* n is offset from start of rec */
{ /* @ n=0 is the deleted record flag */
d->fields_ptr[i].field_data_address = d->record_ptr + n;
n += d->fields_ptr[i].len;
}
d->status = not_updated; /* open successfull */
return(0);
}
#ifdef DEBUG_MAIN /* test program */
main(int argc,char **argv)
{
struct DBF d;
int errornum;
int i;
if (argc != 2)
{
printf("Usage d_open filename");
exit(1);
}
strcpy(d.filename,argv[1]);
if(!strchr(d.filename,'.')) /* default to .dbf file */
strcat(d.filename,".DBF");
if((errornum = d_open(&d))!=0) /* open file */
{
printf("Error opening file: ");
switch (errornum)
{
case OUT_OF_MEM:
printf("Not enough memory.\n");
break;
case NO_FILE:
printf("Can not open file %s.\n",d.filename);
break;
case BAD_FORMAT:
printf("File %s is not a dBASE III file.\n",d.filename);
break;
}
exit(1);
}
printf("\nFile Name: %s",d.filename);
printf("\nCurrent Record: %ld",d.current_record);
printf("\nDBF signature: %d",d.dbf_version);
if (d.status==not_updated)
printf("\nStatus Not Updated");
else
printf("\nStatus Not Open");
printf("\nNumber of Fields: %d",d.num_fields);
printf("\nUpdate Year: %d",d.update_yr);
printf("\nUpdate Month: %d",d.update_mo);
printf("\nUpdate Day: %d",d.update_day);
printf("\nNumber of Records: %ld",d.records);
printf("\nRecord Length: %d",d.record_length);
for (i=0;i<d.num_fields;i++)
printf("\nField #%d: %s",i,d.fields_ptr[i].name);
}
#endif