split out reexec from mds-registry

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 180 insertions, 0 deletions

diff --git a/src/mds-registry/reexec.c b/src/mds-registry/reexec.c
new file mode 100644
index 0000000..dafbff1
--- /dev/null
+++ b/src/mds-registry/reexec.c
@@ -0,0 +1,180 @@
+/**
+ * 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 "reexec.h"
+
+#include "util.h"
+#include "globals.h"
+
+#include <libmdsserver/macros.h>
+#include <libmdsserver/hash-help.h>
+#include <libmdsserver/client-list.h>
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+
+
+/**
+ * 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)
+{
+  size_t i, rc = 2 * sizeof(int) + sizeof(int32_t) + 3 * sizeof(size_t);
+  hash_entry_t* entry;
+  
+  rc += mds_message_marshal_size(&received);
+  
+  foreach_hash_table_entry (reg_table, i, entry)
+    {
+      char* command = (char*)(void*)(entry->key);
+      size_t len = strlen(command) + 1;
+      client_list_t* list = (client_list_t*)(void*)(entry->value);
+      
+      rc += len + sizeof(size_t) + client_list_marshal_size(list);
+    }
+  
+  return rc;
+}
+
+
+/**
+ * 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)
+{
+  size_t i, n = mds_message_marshal_size(&received);
+  hash_entry_t* entry;
+  
+  buf_set_next(state_buf, int, MDS_REGISTRY_VARS_VERSION);
+  buf_set_next(state_buf, int, connected);
+  buf_set_next(state_buf, int32_t, message_id);
+  buf_set_next(state_buf, size_t, n);
+  mds_message_marshal(&received, state_buf);
+  state_buf += n / sizeof(char);
+  
+  buf_set_next(state_buf, size_t, reg_table.capacity);
+  buf_set_next(state_buf, size_t, reg_table.size);
+  foreach_hash_table_entry (reg_table, i, entry)
+    {
+      char* command = (char*)(void*)(entry->key);
+      size_t len = strlen(command) + 1;
+      client_list_t* list = (client_list_t*)(void*)(entry->value);
+      
+      memcpy(state_buf, command, len * sizeof(char));
+      state_buf += len;
+      
+      n = client_list_marshal_size(list);
+      buf_set_next(state_buf, size_t, n);
+      client_list_marshal(list, state_buf);
+      state_buf += n / sizeof(char);
+    }
+  
+  hash_table_destroy(&reg_table, (free_func*)reg_table_free_key, (free_func*)reg_table_free_value);
+  mds_message_destroy(&received);
+  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)
+{
+  char* command;
+  client_list_t* list;
+  size_t i, n, m;
+  int stage = 0;
+  
+  /* buf_get_next(state_buf, int, MDS_REGISTRY_VARS_VERSION); */
+  buf_next(state_buf, int, 1);
+  buf_get_next(state_buf, int, connected);
+  buf_get_next(state_buf, int32_t, message_id);
+  buf_get_next(state_buf, size_t, n);
+  fail_if (mds_message_unmarshal(&received, state_buf));
+  state_buf += n / sizeof(char);
+  stage = 1;
+  
+  buf_get_next(state_buf, size_t, n);
+  fail_if (hash_table_create_tuned(&reg_table, n));
+  buf_get_next(state_buf, size_t, n);
+  for (i = 0; i < n; i++)
+    {
+      stage = 1;
+      fail_if ((command = strdup(state_buf)) == NULL);
+      state_buf += strlen(command) + 1;
+      
+      stage = 2;
+      fail_if ((list = malloc(sizeof(client_list_t))) == NULL);
+      buf_get_next(state_buf, size_t, m);
+      stage = 3;
+      fail_if (client_list_unmarshal(list, state_buf));
+      state_buf += m / sizeof(char);
+      
+      hash_table_put(&reg_table, (size_t)(void*)command, (size_t)(void*)list);
+      fail_if (errno);
+    }
+  
+  reg_table.key_comparator = (compare_func*)string_comparator;
+  reg_table.hasher = (hash_func*)string_hash;
+  
+  return 0;
+ pfail:
+  perror(*argv);
+  mds_message_destroy(&received);
+  if (stage >= 1)
+    hash_table_destroy(&reg_table, (free_func*)reg_table_free_key, (free_func*)reg_table_free_value);
+  if (stage >= 2)
+    free(command);
+  if (stage >= 3)
+    {
+      client_list_destroy(list);
+      free(list);
+    }
+  abort();
+  return -1;
+}
+
+
+/**
+ * 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;
+}
+