Escape database underscore wildcard

if the $MYSQL_DATABASE environment variable contains underscores ("_")
they are now escaped, so that the GRANT matches exactly the given
database name.

Author: Istador

.template.Debian/docker-entrypoint.sh

@@ -284,7 +284,7 @@ docker_setup_db() {
 
 		if [ -n "$MYSQL_DATABASE" ]; then
 			mysql_note "Giving user ${MYSQL_USER} access to schema ${MYSQL_DATABASE}"
-			docker_process_sql --database=mysql <<<"GRANT ALL ON \`$MYSQL_DATABASE\`.* TO '$MYSQL_USER'@'%' ;"
+			docker_process_sql --database=mysql <<<"GRANT ALL ON \`${MYSQL_DATABASE//_/\\_}\`.* TO '$MYSQL_USER'@'%' ;"
 		fi
 
 		docker_process_sql --database=mysql <<<"FLUSH PRIVILEGES ;"

5.6/docker-entrypoint.sh

@@ -284,7 +284,7 @@ docker_setup_db() {
 
 		if [ -n "$MYSQL_DATABASE" ]; then
 			mysql_note "Giving user ${MYSQL_USER} access to schema ${MYSQL_DATABASE}"
-			docker_process_sql --database=mysql <<<"GRANT ALL ON \`$MYSQL_DATABASE\`.* TO '$MYSQL_USER'@'%' ;"
+			docker_process_sql --database=mysql <<<"GRANT ALL ON \`${MYSQL_DATABASE//_/\\_}\`.* TO '$MYSQL_USER'@'%' ;"
 		fi
 
 		docker_process_sql --database=mysql <<<"FLUSH PRIVILEGES ;"

5.7/docker-entrypoint.sh

@@ -284,7 +284,7 @@ docker_setup_db() {
 
 		if [ -n "$MYSQL_DATABASE" ]; then
 			mysql_note "Giving user ${MYSQL_USER} access to schema ${MYSQL_DATABASE}"
-			docker_process_sql --database=mysql <<<"GRANT ALL ON \`$MYSQL_DATABASE\`.* TO '$MYSQL_USER'@'%' ;"
+			docker_process_sql --database=mysql <<<"GRANT ALL ON \`${MYSQL_DATABASE//_/\\_}\`.* TO '$MYSQL_USER'@'%' ;"
 		fi
 
 		docker_process_sql --database=mysql <<<"FLUSH PRIVILEGES ;"

8.0/docker-entrypoint.sh

@@ -284,7 +284,7 @@ docker_setup_db() {
 
 		if [ -n "$MYSQL_DATABASE" ]; then
 			mysql_note "Giving user ${MYSQL_USER} access to schema ${MYSQL_DATABASE}"
-			docker_process_sql --database=mysql <<<"GRANT ALL ON \`$MYSQL_DATABASE\`.* TO '$MYSQL_USER'@'%' ;"
+			docker_process_sql --database=mysql <<<"GRANT ALL ON \`${MYSQL_DATABASE//_/\\_}\`.* TO '$MYSQL_USER'@'%' ;"
 		fi
 
 		docker_process_sql --database=mysql <<<"FLUSH PRIVILEGES ;"