/* Opening or Creating a database */
DB *db_open(const char *pathname, int oflag, int mode)
{
DB *db;
int i, len;
char asciiptr[PTR_SZ + 1], hash[(NHASH_DEF + 1) * PTR_SZ +2]; /* +2 for newline and NULL */
struct stat statbuff;
/* Allocating a Database structure and the buffer it requires. */
len = strlen(pathname);
if((db = _db_alloc(len)) == NULL)
err_dump("error");
db->oflag = oflag; /* saving a copy of the open flags */
/* Opening index file */
strcpy(db->name, pathname);
strcat(db->name, ".idx");
if((db->idxfd = open(db->name, oflag, mode)) < 0)
{
_db_free(db);
return(NULL);
}
/* Opening data file */
strcpy(db->name + len, ".dat");
if((db->datfd = open(db->name, oflag, mode)) < 0)
{
_db_free(db);
return(NULL);
}
/* If the database was created, then initialize it */
if((oflag & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
{
/* write lock the entire file and so that, we can stat the file, check it's size & initialize it */
if(writew_lock(db->idxfd, 0, SEEK_SET, 0) < 0)
err_dump("error");
if(fstat(db->idxfd, &statbuff) < 0)
err_sys("error");
if(statbuff.st_size==0)
{
/*
We gotta build a list of (NHASH_DEF + 1) chain ptr with a value of 0.
The +1 is for free list pointer that precedes the hash table.
*/
sprintf(asciiptr, "%*d", PTR_SZ, 0);
hash[0] = 0;
for(i=0;i<(NHASH_DEF + 1);i++)
strcat(hash, asciiptr);
strcat(hash, "\n");
i = strlen(hash);
if(write(db->idxfd, hash, i) != i)
err_dump("error");
}
if(un_lock(db->idxfd, 0, SEEK_SET, 0) < 0)
err_dump("error");
}
db->nhash = NHASH_DEF; /* hash table size */
db->hashoff = HASH_OFF; /* offset in index file of hash table */
/* free list ptr always at FREE_OFF */
db_rewind(db);
return(db);
}
void
db_close(DB *db)
{
_db_free(db); /* closes fds, free buffers & struct */
}
void db_close(DB *db)
{
_db_free(db); /* closes file descriptors, free the buffers & struct */
}