highwind / clog

Simple blogging engine for my personal use, written in C. Yes, C.

clog / db.c
100644 159 lines (128 sloc) 2.945 kb
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#include <stdlib.h>
#include <string.h>
#include <time.h>
 
#include "db.h"
 
// clog_allocate_query() allocates memory for a 
// string that is enough to hold whatever is contained
// in the *transaction object. -qlen- upon a successful
// return will contain the exact size of the string.
// to avoid, malloc'ing all the time, buffer is reused.
static char *
clog_allocate_query(
	struct clog_transaction *transaction,
	int *qlen);
 
 
 
// compute nearest power of two that is
// greater than or equal to n
inline int pow2(int n)
{
	int i;
	for (i=1;i<n;i*=2); 
	return i;
}
 
sqlite3 *
clog_db_open(const char *name)
{
	sqlite3 *db;
	sqlite3_open(name, &db);
	return db;
}
 
void
clog_db_close(sqlite3 *db)
{
	if (!db)
		return;
 
	sqlite3_close(db);
}
 
char *
clog_allocate_query(
	struct clog_transaction *transaction,
	int *qlen)
{
	static int querylen = 0;
	static char *query = NULL;
  
	int total_length;
 
	if (!transaction ||
		!transaction->title ||
		!transaction->content) {
		return NULL;
	}
 
	total_length += strlen(transaction->title) + SYMBOL_PAD;
	total_length += strlen(transaction->content) + SYMBOL_PAD;
	total_length += RFCDATE_PAD + QUERY_PAD;
	total_length = pow2(total_length);
 
	if (!query) {
		query = (char *) malloc(total_length);
		querylen = total_length;
	} else if (total_length > querylen) {
		query = (char *) realloc(query, total_length);
		querylen = total_length;
	}
 
	(*qlen) = querylen;
	return query;
}
 
int 
clog_modify_db(
	sqlite3 *db,
	struct clog_transaction *transaction) 
{
	mod_type mtype;
	char *querystr, *zErrMsg;
	int len, qlen, rc;
 
	if (!transaction ||
		!transaction->title ||
		!transaction->content ||
		transaction->time <= 0) {
		return -1;
	}
 
	mtype = transaction->type;
	if (mtype != CLOG_DB_INSERT &&
		transaction->id < 0) {
		return -1;
	}
 
	querystr = clog_allocate_query(transaction, &qlen);
 
	// TODO: take care of single-quote(') and backslash (\)
 
	switch (mtype) {
 
	case CLOG_DB_INSERT:
		len = snprintf(querystr, qlen,
				"INSERT INTO entries "
				"(title, content, c_time) "
				"VALUES ('%s','%s',%d)",
				transaction->title,
				transaction->content,
				(int)transaction->time);
		break;
 
	case CLOG_DB_UPDATE:
		len = snprintf(querystr, qlen,
				"UPDATE entries SET "
				"title = '%s',"
				"content = '%s',"
				"u_time = %d "
				"WHERE id = %d "
				"LIMIT 1",
				transaction->title,
				transaction->content,
				(int)transaction->time,
				transaction->id);
		break;
 
	case CLOG_DB_DELETE:
		len = snprintf(querystr, qlen,
				"DELETE FROM entries "
				"WHERE id = %d "
				"LIMIT 1", 
				transaction->id);
		break;
 
	default:
		return -1;
 
	}
 
	if (len >= qlen) {
		// a return value of qlen or more means that the output was truncated. 
		// don't want truncated a query, bail out.
		return -1;
	}
 
    rc = sqlite3_exec(db, querystr, NULL, 0, &zErrMsg);
    if (rc != SQLITE_OK) {
        sqlite3_free(zErrMsg);
        return -1;
    }
 
	return 0;
}