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File.c
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File.c
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#include <string.h>
#include "File.h"
#define LEADER_LEN 24
#define DIRECTORY_ENTRY_LEN 12
static void File_Init(File*);
File File_in( char *file )
{
File This;
File_Init(&This);
This.filename = file;
This.cnt = 0;
This.fh = fopen(file, "r+");
if ( This.fh == NULL ) {
printf("can't open file: %s\n", file);
exit(EXIT_FAILURE);
}
return This;
}
static void File_Init(File *This) {
This->Next = File_Next;
}
Record *File_Next(File *This) {
char * record;
Record *r;
if ( ( record = get_next_record(This) ) != NULL ) {
r = decode(record);
} else {
r = NULL;
}
return r;
}
char * get_next_record(File *This) {
char * recBuffer, record[10000];
int caractere;
int i = 0;
while ( (caractere = fgetc(This->fh)) ) {
if ( caractere == 29 || caractere == EOF ) { break; }
record[i] = caractere;
i++;
}
recBuffer = malloc(strlen(record) + 1);
if (recBuffer != NULL && caractere != -1) {
strcpy(recBuffer, record);
} else {
recBuffer = NULL;
}
return recBuffer;
}
Record *decode(char *record) {
Record *myNewRecord = new_Record();
char * r = record;
// Extract LDR ( characters 0 to 23 )
char * ldr = substr(r, 0, LEADER_LEN);
myNewRecord->set_leader(myNewRecord, ldr);
//Extract Data start
int start_data = atoi(substr(r, 12, 5));
// The directory comes immediatly after the leader
char * dir = substr(r, LEADER_LEN, start_data - LEADER_LEN -1);
int nfields;
if ( strlen(dir) % DIRECTORY_ENTRY_LEN == 0 ) {
nfields = strlen(dir) / DIRECTORY_ENTRY_LEN;
int i = 0;
while ( i < nfields ) {
char * field = substr(dir, i*DIRECTORY_ENTRY_LEN, DIRECTORY_ENTRY_LEN);
char * tag = substr(field, 0, 3);
int taglen = atoi(substr(field, 3, 4));
int offset = atoi(substr(field, 7, 5));
char * tagdata = substr(r, start_data + offset, taglen);
char * value = substr(tagdata, 0, strlen(tagdata) -1);
char * tmp_controlchar = substr(value, 2, 1);
int controlchar = tmp_controlchar[0];
int is_control_field = ( controlchar == 31 ) ? 0 : 1;
Field *myNewField = new_Field(tag, is_control_field);
// if control field
if ( controlchar != 31 ) {
myNewField->add_subfield(myNewField, ' ', value);
}
// if no control field
else {
char * subfield;
const char base[] = "";
char delimiter [1];
char ascii = 31;
sprintf(delimiter, "%s%c", base, ascii);
int number_of_subfields = 0;
subfield = strtok(value, delimiter );
myNewField->add_indicators(myNewField, subfield[0], subfield[1]);
while ( subfield != NULL ) {
if ( number_of_subfields > 0 ) {
char * tmpsubtag = substr(subfield, 0, 1);
char subtag = tmpsubtag[0];
char * value_of_subfiled = substr(subfield, 1, strlen(subfield)-1);
myNewField->add_subfield(myNewField, subtag, value_of_subfiled);
}
subfield = strtok(NULL, delimiter );
number_of_subfields++;
}
}
i++;
myNewRecord->add_field(myNewRecord, myNewField);
}
}
else {
printf("That's wrong\n");
}
return myNewRecord;
//return record;
}
char * substr(char *src, int pos, int len) {
char *dest=NULL;
if (len>0) {
dest = (char *) malloc(len+1);
strncat(dest,src+pos,len);
}
return dest;
}