added a FIFO implementation

1 files changed, 164 insertions, 0 deletions

diff --git a/common/fifo.c b/common/fifo.c
new file mode 100644
index 00000000..5e94694d
--- /dev/null
+++ b/common/fifo.c
@@ -0,0 +1,164 @@
+/**
+ * xrdp: A Remote Desktop Protocol server.
+ *
+ * Copyright (C) Laxmikant Rashinkar 2004-2014
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * FIFO implementation to store pointer to data struct
+ */
+
+#include "fifo.h"
+#include "common/os_calls.h"
+
+/**
+ * Create new fifo data struct
+ * 
+ * @return pointer to new FIFO or NULL if system out of memory
+ *****************************************************************************/
+ 
+FIFO *fifo_create()
+{
+    return (FIFO *) g_malloc(sizeof(FIFO), 1);
+}
+
+/**
+ * Delete specified FIFO
+ *****************************************************************************/
+ 
+void fifo_delete(FIFO *self)
+{
+    USER_DATA *udp;
+    
+    if (!self)
+        return;
+
+     if (!self->head)
+     {
+         /* FIFO is empty */
+         g_free(self);
+         return;
+     }
+     
+    if (self->head == self->tail)
+    {
+        /* only one item in FIFO */
+        if (self->auto_free)
+            g_free(self->head->item);
+            
+        g_free(self->head);
+        g_free(self);
+        return;
+    }
+    
+    /* more then one item in FIFO */
+    while (self->head)
+    {
+        udp = self->head;
+        
+        if (self->auto_free)
+            g_free(udp->item);
+        
+        self->head = udp->next;
+        g_free(udp);
+    }
+    
+    g_free(self);
+}
+
+/**
+ * Add an item to the specified FIFO
+ * 
+ * @param self FIFO to operate on
+ * @param item item to add to specified FIFO
+ * 
+ * @return 0 on success, -1 on error
+ *****************************************************************************/ 
+ 
+int fifo_add_item(FIFO *self, void *item)
+{
+    USER_DATA *udp;
+    
+    if (!self || !item)
+        return -1;
+
+    if ((udp = (USER_DATA *) g_malloc(sizeof(USER_DATA), 0)) == 0)
+        return -1;
+        
+    udp->item = item;
+    udp->next = 0;
+    
+    /* if fifo is empty, add to head */
+    if (!self->head)
+    {
+        self->head = udp;
+        self->tail = udp;
+        return 0;
+    }
+    
+    /* add to tail */
+    self->tail->next = udp;
+    self->tail = udp;
+    
+    return 0;
+}
+
+/**
+ * Return an item from top of FIFO
+ * 
+ * @param self FIFO to operate on
+ * 
+ * @return top item from FIFO or NULL if FIFO is empty
+ *****************************************************************************/ 
+ 
+void *fifo_remove_item(FIFO *self)
+{
+    void      *item;
+    USER_DATA *udp;
+    
+    if (!self || !self->head)
+        return 0;
+        
+    if (self->head == self->tail)
+    {
+        /* only one item in FIFO */
+        item = self->head->item;
+        g_free(self->head);
+        self->head = 0;
+        self->tail = 0;
+        return item;
+    }
+    
+    /* more then one item in FIFO */
+    udp = self->head;
+    item = self->head->item;
+    self->head = self->head->next;
+    g_free(udp);
+    return item;
+}
+
+/**
+ * Return FIFO status
+ * 
+ * @param self FIFO to operate on
+ * 
+ * @return true if FIFO is empty, false otherwise
+ *****************************************************************************/ 
+ 
+int fifo_is_empty(FIFO *self)
+{
+    if (!self)
+        return 1;
+        
+    return (self->head == 0);
+}