header_t readBlockHeader(const QByteArray& blockHeader) {
Q_ASSERT(blockHeader.size() >= 12);
header_t header;
header.fingerprint = readShortFromByteArray(blockHeader);
header.recordCount = readIntFromByteArray(blockHeader.mid(4, 4));
header.recordSize = readIntFromByteArray(blockHeader.right(4));
return header;
}
int Select(int argc, char **argv) {
if (g_DBOpenFlag != OK) {
return ErrorMsgs(DB_NOT_OPEN, g_PrintFlag);
}
int relNum, newRelNum, numAttrs, count, i, retVal, offset, attrFoundFlag = 0;
int attrSize, intVal;
float floatVal;
struct attrCatalog* head;
datatype type;
Rid startRid = { 1, 0 }, *foundRid;
char **createArgumentList, *recPtr;
if (argc < 6)
return ErrorMsgs(ARGC_INSUFFICIENT, g_PrintFlag);
if (OpenRel(argv[2]) == NOTOK)
return ErrorMsgs(RELNOEXIST, g_PrintFlag);
/* Finding the relNum of Source Relation */
relNum = FindRelNum(argv[2]);
head = g_CatCache[relNum].attrList;
numAttrs = g_CatCache[relNum].numAttrs;
/* Preparing Argument list which should be passed to Create() */
createArgumentList = malloc(sizeof(char*) * (numAttrs + 1) * 2);
createArgumentList[0] = malloc(sizeof(char) * RELNAME);
createArgumentList[1] = malloc(sizeof(char) * RELNAME);
for (count = 2; count < (numAttrs + 1) * 2; count++) {
createArgumentList[count] = malloc(sizeof(char) * RELNAME);
createArgumentList[count + 1] = malloc(sizeof(char) * 4);
}
strcpy(createArgumentList[0], "create");
strcpy(createArgumentList[1], argv[1]);
count = 2;
while (head != NULL) {
strcpy(createArgumentList[count], head->attrName);
switch (head->type) {
case INTEGER:
strcpy(createArgumentList[count + 1], "i");
break;
case STRING:
sprintf(createArgumentList[count + 1], "s%d", head->length);
break;
case FLOAT:
strcpy(createArgumentList[count + 1], "f");
break;
}
/* This is to catch the desired attribute's specifications from Source relation.
Expected to happen only once in this loop */
if (strcmp(head->attrName, argv[3]) == 0) {
attrFoundFlag = 1;
offset = head->offset;
type = head->type;
attrSize = head->length;
}
head = head->next;
count = count + 2;
}
/* Given attribute name never appeared in attr linkedlist */
if (attrFoundFlag == 0)
return ErrorMsgs(ATTRNOEXIST, g_PrintFlag);
retVal = Create((numAttrs + 1) * 2, createArgumentList);
for (i = 0; i < (numAttrs + 1) * 2; i++)
free(createArgumentList[i]);
free(createArgumentList);
if (retVal == NOTOK)
return NOTOK;
OpenRel(argv[1]);
newRelNum = FindRelNum(argv[1]);
switch (type) {
case STRING:
break;
case INTEGER:
intVal = atoi(argv[5]);
convertIntToByteArray(intVal, argv[5]);
break;
case FLOAT:
floatVal = atof(argv[5]);
convertFloatToByteArray(floatVal, argv[5]);
break;
}
/* Finding record from Source, which satisfying given condition, and Adding to Result Relation*/
while (FindRec(relNum, &startRid, &foundRid, &recPtr, type, attrSize, offset, argv[5],
readIntFromByteArray(argv[4], 0)) == OK) {
InsertRec(newRelNum, recPtr);
startRid = (*foundRid);
free(foundRid);
}
return OK;
}