made db connection not constant

fileHost.py

@@ -3,9 +3,10 @@
 Simple file host using Flask.
 """
 import os
-import sqlite3
-import secrets
 import string
+import secrets
+import sqlite3
+import threading
 
 from passlib.hash import argon2
 from flask import Flask, session, request, abort, redirect, url_for, g, \
@@ -52,6 +53,21 @@ app.wsgi_app = ReverseProxied(app.wsgi_app)
 app.config['MAX_CONTENT_LENGTH'] = 128 * 1024 * 1024
 app.config["UPLOAD_DIR"] = "/usr/local/www/html/up"
 app.config["DB_NAME"] = "fileHost.db"
+app.config["DB_LOCK"] = threading.Lock()
+
+
+def db_execute(*args, **kwargs):
+	"""
+	Opens a connection to the app's database and executes the SQL statements
+	passed to this function.
+	"""
+	with sqlite3.connect(app.config.get("DB_NAME")) as con:
+		app.config.get("DB_LOCK").acquire()
+		cur = con.cursor()
+		res = cur.execute(*args, **kwargs)
+		app.config.get("DB_LOCK").release()
+		return res
+
 
 
 def init():
@@ -69,38 +85,33 @@ def init():
 			file.write(secret_key)
 	app.secret_key = secret_key
 
-	con = sqlite3.connect(app.config.get("DB_NAME"))
-	db = con.cursor()
 	try:
-		db.execute("SELECT * FROM users").fetchone()
-		db.execute("SELECT * FROM uploads").fetchone()
+		db_execute("SELECT * FROM users").fetchone()
+		db_execute("SELECT * FROM uploads").fetchone()
 	except sqlite3.OperationalError:
-		db.execute("CREATE TABLE users("
+		db_execute("CREATE TABLE users("
 			"id INTEGER PRIMARY KEY,"
 			"username TEXT,"
 			"pw_hash TEXT,"
 			"admin BOOL DEFAULT FALSE)")
 
-		db.execute("CREATE TABLE uploads("
+		db_execute("CREATE TABLE uploads("
 			"filename TEXT, uploaded_by TEXT,"
 			"uploaded_date INT DEFAULT (STRFTIME('%s', 'now')))")
 
-	return con, db
-
 
 def add_user(username, password, admin="FALSE"):
 	"""
 	Adds a user to the database.
 	"""
-	u = db.execute("SELECT username FROM users WHERE username = ?",
+	u = db_execute("SELECT username FROM users WHERE username = ?",
 		(username,)).fetchone()
 	if u:
 		return False
 
 	pw_hash = argon2.hash(password)
-	db.execute("INSERT INTO users (username, pw_hash, admin) VALUES (?,?,?)",
+	db_execute("INSERT INTO users (username, pw_hash, admin) VALUES (?,?,?)",
 		(username, pw_hash, admin))
-	con.commit()
 	return True
 
 
@@ -126,7 +137,7 @@ def verify_username(username):
 	"""
 	Checks to see if the given username is in the database.
 	"""
-	user = db.execute("SELECT * FROM users WHERE username = ?",
+	user = db_execute("SELECT * FROM users WHERE username = ?",
 		(username,)).fetchone()
 	if user:
 		return user
@@ -212,7 +223,7 @@ def change_password():
 		return "The new passwords do not match!"
 
 	pw_hash = argon2.hash(new_password)
-	db.execute("UPDATE users SET pw_hash = ? WHERE username = ?",
+	db_execute("UPDATE users SET pw_hash = ? WHERE username = ?",
 		(pw_hash, username))
 	session.pop("username")
 	return redirect(url_for("login"))
@@ -267,9 +278,8 @@ def index():
 		fname = pre + "_" + fname
 	file.save(os.path.join(fdir, fname))
 
-	db.execute("INSERT INTO uploads (filename, uploaded_by) VALUES (?,?)",
+	db_execute("INSERT INTO uploads (filename, uploaded_by) VALUES (?,?)",
 		(fname, username))
-	con.commit()
 
 	#TODO: make this not hardcoded
 	# url = request.url_root + "up/" + fname
@@ -289,8 +299,8 @@ def get_rand_chars(n):
 	return "".join(chars)
 
 
-con, db = init()
-# TODO: make these not global variables
+init()
+# TODO: make these not global variables?
 if __name__ == "__main__":
 	import sys
 	add_user(sys.argv[1], sys.argv[2], "TRUE")