1 files changed, 238 insertions, 0 deletions
diff --git a/nuttx/fs/mmap/fs_rammap.c b/nuttx/fs/mmap/fs_rammap.c
new file mode 100644
index 000000000..0eaf313b5
--- /dev/null
+++ b/nuttx/fs/mmap/fs_rammap.c
@@ -0,0 +1,238 @@
+/****************************************************************************
+ * fs/mmap/fs_rammmap.c
+ *
+ *   Copyright (C) 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sys/mman.h>
+
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/kmalloc.h>
+
+#include "fs_internal.h"
+#include "fs_rammap.h"
+
+#ifdef CONFIG_FS_RAMMAP
+
+/****************************************************************************
+ * Global Data
+ ****************************************************************************/
+
+/* This is the list of all mapped files */
+
+struct fs_allmaps_s g_rammaps;
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: rammap_initialize
+ *
+ * Description:
+ *   Verified that this capability has been initialized.
+ *
+ * Input Parameters:
+ *   None
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void rammap_initialize(void)
+{
+  if (!g_rammaps.initialized)
+    {
+      sem_init(&g_rammaps.exclsem, 0, 1);
+      g_rammaps.initialized = true;
+    }
+}
+
+/****************************************************************************
+ * Name: rammmap
+ *
+ * Description:
+ *   Support simulation of memory mapped files by copying files into RAM.
+ *
+ * Parameters:
+ *   fd      file descriptor of the backing file -- required.
+ *   length  The length of the mapping.  For exception #1 above, this length
+ *           ignored:  The entire underlying media is always accessible.
+ *   offset  The offset into the file to map
+ *
+ * Returned Value:
+ *   On success, rammmap() returns a pointer to the mapped area. On error, the
+ *   value MAP_FAILED is returned, and errno is set  appropriately.
+ *
+ *     EBADF
+ *      'fd' is not a valid file descriptor.
+ *     EINVAL
+ *       'length' or 'offset' are invalid
+ *     ENOMEM
+ *       Insufficient memory is available to map the file.
+ *
+ ****************************************************************************/
+
+FAR void *rammap(int fd, size_t length, off_t offset)
+{
+  FAR struct fs_rammap_s *map;
+  FAR uint8_t *alloc;
+  FAR uint8_t *rdbuffer;
+  ssize_t nread;
+  off_t fpos;
+  int err;
+  int ret;
+
+  /* There is a major design flaw that I have not yet thought of fix for:
+   * The goal is to have a single region of memory that represents a single
+   * file and can be shared by many threads.  That is, given a filename a
+   * thread should be able to open the file, get a file descriptor, and
+   * call mmap() to get a memory region.  Different file descriptors opened
+   * with the same file path should get the same memory region when mapped.
+   *
+   * The design flaw is that I don't have sufficient knowledge to know that
+   * these different file descriptors map to the same file.  So, for the time
+   * being, a new memory region is created each time that rammap() is called.
+   * Not very useful!
+   */
+
+  /* Allocate a region of memory of the specified size */
+
+  alloc = (FAR uint8_t *)kmalloc(sizeof(struct fs_rammap_s) + length);
+  if (!alloc)
+    {
+      fdbg("Region allocation failed, length: %d\n", (int)length);
+      err = ENOMEM;
+      goto errout;
+    }
+
+  /* Initialize the region */
+
+  map         = (FAR struct fs_rammap_s *)alloc;
+  memset(map, 0, sizeof(struct fs_rammap_s));
+  map->addr   = alloc + sizeof(struct fs_rammap_s);
+  map->length = length;
+  map->offset = offset;
+
+  /* Seek to the specified file offset */
+
+  fpos = lseek(fd, offset,  SEEK_SET);
+  if (fpos == (off_t)-1)
+    {
+      /* Seek failed... errno has already been set, but EINVAL is probably
+       * the correct response.
+       */
+
+      fdbg("Seek to position %d failed\n", (int)offset);
+      err = ENOMEM;
+      goto errout_with_region;
+    }
+
+  /* Read the file data into the memory region */
+
+  rdbuffer = map->addr;
+  while (length > 0)
+    {
+      nread = read(fd, rdbuffer, length);
+      if (nread < 0)
+        {
+           /* Handle the special case where the read was interrupted by a
+            * signal.
+            */
+
+           if (nread != EINTR)
+             {
+               /* All other read errors are bad.  errno is already set.
+                * (but maybe should be forced to EINVAL?)
+                */
+
+               fdbg("Read failed: %d\n", (int)offset);
+               goto errout_with_errno;
+             }
+
+           /* Check for end of file. */
+
+           if (nread == 0)
+             {
+               break;
+             }
+
+           /* Increment number of bytes read */
+
+           rdbuffer += nread;
+           length   -= nread;
+        }
+    }
+
+  /* Zero any memory beyond the amount read from the file */
+
+  memset(rdbuffer, 0, length);
+
+  /* Add the buffer to the list of regions */
+
+  rammap_initialize();
+  ret = sem_wait(&g_rammaps.exclsem);
+  if (ret < 0)
+    {
+      goto errout_with_errno;
+    }
+
+  map->flink  = g_rammaps.head;
+  g_rammaps.head = map;
+
+  sem_post(&g_rammaps.exclsem);
+  return map->addr;
+
+errout_with_region:
+  kfree(alloc);
+errout:
+  errno = err;
+  return MAP_FAILED;
+
+errout_with_errno:
+  kfree(alloc);
+  return MAP_FAILED;
+}
+
+#endif /* CONFIG_FS_RAMMAP */