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Diffstat (limited to '')
| -rw-r--r-- | src/mds-echo.c | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/src/mds-echo.c b/src/mds-echo.c new file mode 100644 index 0000000..7b1a0ac --- /dev/null +++ b/src/mds-echo.c @@ -0,0 +1,262 @@ +/** + * mds — A micro-display server + * Copyright © 2014 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include "mds-echo.h" + +#include <libmdsserver/macros.h> +#include <libmdsserver/util.h> +#include <libmdsserver/mds-message.h> + +#include <errno.h> +#include <stdint.h> +#include <string.h> +#include <stdio.h> +#define reconnect_to_display() -1 /* TODO */ + + + +#define MDS_ECHO_VARS_VERSION 0 + + + +/** + * This variable should declared by the actual server implementation. + * It must be configured before `main` is invoked. + * + * This tells the server-base how to behave + */ +server_characteristics_t server_characteristics = + { + .require_privileges = 0, + .require_display = 1, + .require_respawn_info = 1, + .sanity_check_argc = 1 + }; + + + +/** + * Value of the ‘Message ID’ header for the next message + */ +static int32_t message_id = 1; + +/** + * Buffer for received messages + */ +static mds_message_t received; + +/** + * Whether the server is connected to the display + */ +static int connected = 1; + + + +/** + * This function will be invoked before `initialise_server` (if not re-exec:ing) + * or before `unmarshal_server` (if re-exec:ing) + * + * @return Non-zero on error + */ +int __attribute__((const)) preinitialise_server(void) +{ + return 0; +} + + +/** + * This function should initialise the server, + * and it not invoked after a re-exec. + * + * @return Non-zero on error + */ +int initialise_server(void) +{ + const char* message = + "Command: intercept\n" + "Message ID: 0\n" + "Length: 13\n" + "\n" + "Command: echo"; + size_t length = strlen(message); + size_t sent; + + while (length > 0) + { + sent = send_message(socket_fd, message, length); + if (sent > length) + { + eprint("Sent more of a message than exists in the message, aborting."); + return 1; + } + else if ((sent < length) && (errno != EINTR)) + { + perror(*argv); + return 1; + } + message += sent; + length -= sent; + } + + mds_message_initialise(&received); + return 0; +} + + +/** + * This function will be invoked after `initialise_server` (if not re-exec:ing) + * or after `unmarshal_server` (if re-exec:ing) + * + * @return Non-zero on error + */ +int postinitialise_server(void) +{ + if (connected) + return 0; + + if (reconnect_to_display()) + { + mds_message_destroy(&received); + return 1; + } + connected = 1; + return 0; +} + + +/** + * Calculate the number of bytes that will be stored by `marshal_server` + * + * On failure the program should `abort()` or exit by other means. + * However it should not be possible for this function to fail. + * + * @return The number of bytes that will be stored by `marshal_server` + */ +size_t marshal_server_size(void) +{ + return 2 * sizeof(int) + sizeof(int32_t) + mds_message_marshal_size(&received); +} + + +/** + * Marshal server implementation specific data into a buffer + * + * @param state_buf The buffer for the marshalled data + * @return Non-zero on error + */ +int marshal_server(char* state_buf) +{ + buf_set_next(state_buf, int, MDS_ECHO_VARS_VERSION); + buf_set_next(state_buf, int, connected); + buf_set_next(state_buf, int32_t, message_id); + mds_message_marshal(&received, state_buf); + return 0; +} + + +/** + * Unmarshal server implementation specific data and update the servers state accordingly + * + * On critical failure the program should `abort()` or exit by other means. + * That is, do not let `reexec_failure_recover` run successfully, if it unrecoverable + * error has occurred or one severe enough that it is better to simply respawn. + * + * @param state_buf The marshalled data that as not been read already + * @return Non-zero on error + */ +int unmarshal_server(char* state_buf) +{ + int r; + /* buf_get_next(state_buf, int, MDS_ECHO_VARS_VERSION); */ + buf_next(state_buf, int, 1); + buf_get_next(state_buf, int, connected); + buf_get_next(state_buf, int32_t, message_id); + r = mds_message_unmarshal(&received, state_buf); + if (r) + mds_message_destroy(&received); + return r; +} + + +/** + * Attempt to recover from a re-exec failure that has been + * detected after the server successfully updated it execution image + * + * @return Non-zero on error + */ +int __attribute__((const)) reexec_failure_recover(void) +{ + return -1; +} + + +/** + * Perform the server's mission + * + * @return Non-zero on error + */ +int master_loop(void) +{ + while (!reexecing && !terminating) + { + int r = mds_message_read(&received, socket_fd); + if (r == 0) + { + r = echo_message(); + if (r == 0) + continue; + } + if (r == -2) + { + eprint("corrupt message received, aborting."); + goto fail; + } + else if (errno == EINTR) + continue; + else if (errno != ECONNRESET) + goto pfail; + + eprint("lost connection to server."); + mds_message_destroy(&received); + mds_message_initialise(&received); + connected = 0; + if (reconnect_to_display()) + goto fail; + connected = 1; + } + + mds_message_destroy(&received); + return 0; + pfail: + perror(*argv); + fail: + mds_message_destroy(&received); + return 1; +} + + +/** + * Echo the received message payload + * + * @return Zero on success -1 on error or interruption, + * errno will be set accordingly + */ +int echo_message(void) +{ + return 0; /* TODO */ +} + |