ipc message class, does not do reading yet

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

1 files changed, 219 insertions, 0 deletions

diff --git a/src/libmdsserver/mds-message.c b/src/libmdsserver/mds-message.c
new file mode 100644
index 0000000..94e9e63
--- /dev/null
+++ b/src/libmdsserver/mds-message.c
@@ -0,0 +1,219 @@
+/**
+ * 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-message.h"
+
+#include <stdlib.h>
+#include <string.h>
+
+
+/**
+ * Initialsie a message slot so that it can
+ * be used by `mds_message_read`.
+ * 
+ * @param   this  Memory slot in which to store the new message
+ * @return        Non-zero on error, errno will be set accordingly.
+ *                Destroy the message on error.
+ */
+int mds_message_initialise(mds_message_t* this)
+{
+  this->headers = NULL;
+  this->header_count = 0;
+  this->payload = NULL;
+  this->payload_size = 0;
+  this->buffer = NULL;
+  this->buffer_size = 128;
+  this->buffer_ptr = 0;
+  this->buffer = malloc(this->buffer_size * sizeof(char));
+  if (this->buffer == NULL)
+    return -1;
+  return 0;
+}
+
+
+/**
+ * Release all resources in a message, should
+ * be done even if initialisation fails
+ * 
+ * @param  this  The message
+ */
+void mds_message_destroy(mds_message_t* this)
+{
+  if (this->headers != NULL)
+    {
+      size_t i;
+      for (i = 0; i < this->header_count; i++)
+	if (this->headers[i] != NULL)
+	  free(this->headers[i]);
+      free(this->headers);
+    }
+  
+  if (this->payload != NULL)
+    free(this->payload);
+  
+  if (this->buffer != NULL)
+    free(this->buffer);
+}
+
+
+/**
+ * Read the next message from a file descriptor
+ * 
+ * @param   this  Memory slot in which to store the new message
+ * @param   fd    The file descriptor
+ * @return        Non-zero on error, errno will be set accordingly.
+ *                Destroy the message on error.
+ */
+int mds_message_read(mds_message_t* this, int fd)
+{
+  return 0;
+}
+
+
+/**
+ * Get the required allocation size for `data` of the
+ * function `mds_message_marshal`
+ * 
+ * @param   this            The message
+ * @param   include_buffer  Whether buffer should be marshalled (state serialisation, not communication)
+ * @return                  The size of the message when marshalled
+ */
+size_t mds_message_marshal_size(mds_message_t* this, int include_buffer)
+{
+  size_t rc = (include_buffer ? 3 : 2) + this->header_count + this->payload_size;
+  size_t i;
+  for (i = 0; i < this->header_count; i++)
+    rc += strlen(this->headers[i]);
+  return rc * sizeof(char);
+}
+
+
+/**
+ * Marshal a message, this can be used both when serialising
+ * the servers state or to get the byte stream to send to
+ * the recipient of the message
+ * 
+ * @param  this            The message
+ * @param  data            Output buffer for the marshalled data
+ * @param  include_buffer  Whether buffer should be marshalled (state serialisation, not communication)
+ */
+void mds_message_marshal(mds_message_t* this, char* data, int include_buffer)
+{
+  size_t i, n;
+  
+  ((size_t*)data)[0] = this->header_count;
+  ((size_t*)data)[1] = this->payload_size;
+  if (include_buffer)
+    ((size_t*)data)[2] = this->buffer_ptr;
+  data += (include_buffer ? 3 : 2) * sizeof(size_t) / sizeof(char);
+  
+  for (i = 0; i < this->header_count; i++)
+    {
+      n = strlen(this->headers[i]) + 1;
+      memcpy(data, this->headers[i], n * sizeof(char));
+      data += n;
+    }
+  
+  memcpy(data, this->payload, this->payload_size * sizeof(char));
+  
+  if (include_buffer)
+    {
+      data += this->payload_size;
+      memcpy(data, this->buffer, this->buffer_ptr * sizeof(char));
+    }
+}
+
+
+/**
+ * Unmarshal a message, it is assumed that the buffer is marshalled
+ * 
+ * @param  this  Memory slot in which to store the new message
+ * @param  data  In buffer with the marshalled data
+ * @return       Non-zero on error, errno will be set accordingly.
+ *               Destroy the message on error.
+ */
+int mds_message_unmarshal(mds_message_t* this, char* data)
+{
+  size_t i, n, header_count;
+  
+  header_count = ((size_t*)data)[0];
+  this->header_count = 0;
+  this->payload_size = ((size_t*)data)[1];
+  this->buffer_ptr = ((size_t*)data)[2];
+  this->buffer_size = this->buffer_ptr;
+  this->headers = NULL;
+  this->payload = NULL;
+  this->buffer = NULL;
+  
+  data += 3 * sizeof(size_t) / sizeof(char);
+  
+  /* To 2-power-multiple of 128 bytes. */
+  this->buffer_size >>= 7;
+  if (this->buffer_size == 0)
+    this->buffer_size = 1;
+  else
+    {
+      this->buffer_size -= 1;
+      this->buffer_size |= this->buffer_size >> 1;
+      this->buffer_size |= this->buffer_size >> 2;
+      this->buffer_size |= this->buffer_size >> 4;
+      this->buffer_size |= this->buffer_size >> 8;
+      this->buffer_size |= this->buffer_size >> 16;
+#if __WORDSIZE == 64
+      this->buffer_size |= this->buffer_size >> 32;
+#endif
+      this->buffer_size += 1;
+    }
+  this->buffer_size <<= 7;
+  
+  if (header_count > 0)
+    {
+      this->headers = malloc(header_count * sizeof(char*));
+      if (this->headers == NULL)
+	return -1;
+    }
+  
+  if (this->payload_size > 0)
+    {
+      this->payload = malloc(this->payload_size * sizeof(char));
+      if (this->payload == NULL)
+	return -1;
+    }
+  
+  this->buffer = malloc(this->buffer_size * sizeof(char));
+  if (this->buffer == NULL)
+    return -1;
+  
+  for (i = 0; i < this->header_count; i++)
+    {
+      n = strlen(data) + 1;
+      this->headers[i] = malloc(n * sizeof(char));
+      if (this->headers[i] == NULL)
+	return -1;
+      memcpy(this->headers[i], data, n * sizeof(char));
+      data += n;
+      this->header_count++;
+    }
+  
+  memcpy(this->payload, data, this->payload_size * sizeof(char));
+  data += this->payload_size;
+  
+  memcpy(this->buffer, data, this->buffer_ptr * sizeof(char));
+  
+  return 0;
+}
+