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POImplementing a queue in C
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copied!<p>I am trying to implement a custom queue for Gstreamer buffers. The problem is that when I try to dequeue, it seems that I am loosing the head of the queue. Whenever I try to dequeue twice, I get a segmentation fault. I have also noticed that head is always equal than head->next. Now I'm not sure if there's something wrong with enqueue or dequeue. Please help me out. Thank you.</p> <pre><code>typedef struct _GstBUFFERQUEUE GstBufferQueue; struct _GstBUFFERQUEUE { GstBuffer *buf; guint buf_size; struct _GstBUFFERQUEUE *next; }; void enqueue_gstbuffer(GstBufferQueue **head, GstBufferQueue **tail, guint *queue_size, GstBuffer *buf) { if (*queue_size == 0) { *head = malloc(sizeof(GstBufferQueue)); (*head)->buf = gst_buffer_try_new_and_alloc (GST_BUFFER_SIZE(buf)); (*head)->buf = gst_buffer_copy(buf); *tail = *head; } else { if ((*tail)->next = malloc(sizeof(GstBufferQueue))) { (*tail)->next->buf = gst_buffer_try_new_and_alloc (GST_BUFFER_SIZE(buf)); (*tail)->next->buf = gst_buffer_copy(buf); (*tail) = (*tail)->next; } else { GST_WARNING("Error allocating memory for new buffer in queue"); } } (*tail)->next = NULL; (*queue_size)++; } void dequeue_gstbuffer(GstBufferQueue **head, GstBufferQueue **tail, guint *queue_size, GstBuffer **buf) { GstBufferQueue **tmpPtr = head; GstBufferQueue **nextPtr; *nextPtr = (*head)->next; *buf = gst_buffer_try_new_and_alloc (GST_BUFFER_SIZE((*tmpPtr)->buf)); *buf = gst_buffer_copy((*tmpPtr)->buf); gst_buffer_unref((*tmpPtr)->buf); free((*tmpPtr)); *head = *nextPtr; if ((*head) == NULL) (*tail) = NULL; (*queue_size)--; } </code></pre>

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