/* GStreamer
 * Copyright (C) 2014 William Manley <will@williammanley.net>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public
 * License along with this library; if not, write to the
 * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */

#define _GNU_SOURCE

#include "gsttmpfileallocator.h"
#include <gst/allocators/gstfdmemory.h>

#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#define PAGE_ALIGN 4095

#define GST_TYPE_TMPFILE_ALLOCATOR    (gst_tmpfile_allocator_get_type ())

typedef struct
{
  GstFdAllocator parent;
} GstTmpFileAllocator;

typedef struct
{
  GstFdAllocatorClass parent_class;
} GstTmpFileAllocatorClass;

GType gst_tmpfile_allocator_get_type (void);
G_DEFINE_TYPE (GstTmpFileAllocator, gst_tmpfile_allocator, GST_TYPE_FD_ALLOCATOR);

static int
tmpfile_create (GstTmpFileAllocator * allocator, gsize size)
{
  char filename[] = "/dev/shm/tmpfilepay.XXXXXX";
  int fd, result;

  GST_DEBUG_OBJECT (allocator, "tmpfile_create");

  fd = mkostemp (filename, O_CLOEXEC);
  if (fd == -1) {
    GST_WARNING_OBJECT (allocator, "Failed to create temporary file: %s",
        strerror (errno));
    return -1;
  }
  unlink (filename);

  result = ftruncate (fd, size);
  if (result == -1) {
    GST_WARNING_OBJECT (allocator, "Failed to resize temporary file: %s",
        strerror (errno));
    close (fd);
    return -1;
  }

  return fd;
}


inline static gsize
pad (gsize off, gsize align)
{
  return (off + align) / (align + 1) * (align + 1);
}

static GstMemory *
gst_tmpfile_allocator_alloc (GstAllocator * allocator, gsize size,
    GstAllocationParams * params)
{
  GstTmpFileAllocator *alloc = (GstTmpFileAllocator *) allocator;
  GstFdAllocator *fdalloc = GST_FD_ALLOCATOR_CAST (allocator);
  GstFdAllocatorClass *klass = GST_FD_ALLOCATOR_GET_CLASS (alloc);
  GstMemory *mem;
  int fd;
  gsize maxsize;

  g_return_val_if_fail (params != NULL, NULL);

  maxsize =
      pad (size + pad (params->prefix, params->align) + params->padding,
      PAGE_ALIGN);

  fd = tmpfile_create (alloc, maxsize);
  if (fd < 0)
    return NULL;

  mem = klass->alloc (fdalloc, fd, maxsize, GST_FD_MEMORY_FLAG_NONE);
  gst_memory_resize (mem, pad (params->prefix, params->align), size);

  return mem;
}

static void
gst_tmpfile_allocator_class_init (GstTmpFileAllocatorClass * klass)
{
  GstAllocatorClass *allocator_class;

  allocator_class = (GstAllocatorClass *) klass;

  allocator_class->alloc = gst_tmpfile_allocator_alloc;
}

static void
gst_tmpfile_allocator_init (GstTmpFileAllocator * allocator)
{
  GstAllocator *alloc = GST_ALLOCATOR_CAST (allocator);

  alloc->mem_type = GST_ALLOCATOR_TMPFILE;
}

GstAllocator *
gst_tmpfile_allocator_new (void)
{
  return g_object_new (GST_TYPE_TMPFILE_ALLOCATOR, NULL);
}

gint
gst_tmpfile_memory_get_fd (GstMemory * mem)
{
  g_return_val_if_fail (gst_is_tmpfile_memory (mem), -1);

  return gst_fd_memory_get_fd (mem);
}

gboolean
gst_is_tmpfile_memory (GstMemory * mem)
{
  return gst_memory_is_type (mem, GST_ALLOCATOR_TMPFILE);
}