BINFMT: A framework to support a P-code binary format (a work in progress)

binfmt/pcode.c

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+/****************************************************************************
+ * binfmt/pcode.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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 <fcntl.h>
+#include <stdint.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/poff.h>
+#include <nuttx/binfmt/binfmt.h>
+#include <nuttx/binfmt/pcode.h>
+
+#ifdef CONFIG_PCODE
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int pcode_loadbinary(FAR struct binary_s *binp);
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static struct binfmt_s g_pcode_binfmt =
+{
+  NULL,              /* next */
+  pcode_loadbinary,  /* load */
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pcode_proxy
+ *
+ * Description:
+ *   This is the proxy program that runs and starts the P-Code interpreter.
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_NUTTX_KERNEL
+static int pcode_proxy(int argc, char **argv)
+{
+  /* REVISIT:  There are issues here when CONFIG_NUTTX_KERNEL is selected. */
+
+  bdbg("ERROR: Not implemented");
+  return EXIT_FAILURE;
+}
+#else
+#  error Missing logic for the case of CONFIG_NUTTX_KERNEL
+#endif
+
+/****************************************************************************
+ * Name: pcode_loadbinary
+ *
+ * Description:
+ *   Verify that the file is an pcode binary.
+ *
+ ****************************************************************************/
+
+static int pcode_loadbinary(struct binary_s *binp)
+{
+  FAR struct poff_fileheader_s hdr;
+  FAR const struct pcode_s *b;
+  FAR uint8_t *ptr;
+  size_t remaining;
+  ssize_t nread;
+  int fd;
+  int ret;
+
+  bvdbg("Loading file: %s\n", binp->filename);
+
+  /* Open the binary file for reading (only) */
+
+  fd = open(binp->filename, O_RDONLY);
+  if (fd < 0)
+    {
+      int errval = errno;
+      bdbg("ERROR: Failed to open binary %s: %d\n", binp->filename, errval);
+      return -errval;
+    }
+
+  /* Read the POFF file header */
+
+  for (remaining = sizeof(struct poff_fileheader_s), ptr = (FAR uint8_t *)&hdr;
+       remaining > 0; )
+    {
+      /* Read the next GULP */
+
+      nread = read(fd, ptr, remaining);
+      if (nread < 0)
+        {
+          /* If errno is EINTR, then this is not an error; the read() was
+           * simply interrupted by a signal.
+           */
+
+          int errval = errno;
+          DEBUGASSERT(errval > 0);
+
+          if (errval != EINTR)
+            {
+              bdbg("ERROR: read failed: %d\n", errval);
+              ret = -errval;
+              goto errout_with_fd;
+            }
+
+          bdbg("Interrupted by a signal\n");
+        }
+      else
+        {
+          /* Set up for the next gulp */
+
+          DEBUASSERT(nread > 0 && nread <=remaining);
+          remaining -= nread;
+          ptr += nread;
+        } 
+    }
+
+#ifdef CONFIG_PCODE_DUMPBUFFER
+  lib_dumpbuffer("POFF File Header", &hdr, sizeof(poff_fileheader_s));
+#endif
+
+  /* Verify that the file is a P-Code executable */
+
+  if (memcmp(&hdr.fh_ident, FHI_POFF_MAG, 4) != 0 || hdr.fh_type != FHT_EXEC)
+    {
+      dbg("ERROR: File is not a P-code executable: %d\n");
+      ret = -ENOEXEC;
+      goto errout_with_fd;
+    }
+
+  /* Return the load information.
+   * REVISIT:  There are issues here when CONFIG_NUTTX_KERNEL is selected.
+   */
+
+  binp->entrypt   = pcode_proxy;
+  binp->stacksize = CONFIG_PCODE_STACKSIZE;
+  binp->priority  = CONFIG_PCODE_PRIORITY;
+
+  /* Successfully identified a p-code binary */
+
+  ret = OK;
+
+errout_with_fd:
+  close(fd);
+  return ret;
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pcode_initialize
+ *
+ * Description:
+ *   P-code support is built based on the configuration.  However, in order
+ *   to use this binary format, this function must be called during system
+ *   initialization in order to register the P-Code binary format.
+ *
+ * Returned Value:
+ *   This is a NuttX internal function so it follows the convention that
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ ****************************************************************************/
+
+int pcode_initialize(void)
+{
+  int ret;
+
+  /* Register ourselves as a binfmt loader */
+
+  bvdbg("Registering P-Code Loader\n");
+
+  ret = register_binfmt(&g_pcode_binfmt);
+  if (ret != 0)
+    {
+      bdbg("Failed to register binfmt: %d\n", ret);
+    }
+
+  return ret;
+}
+
+/****************************************************************************
+ * Name: pcode_uninitialize
+ *
+ * Description:
+ *   Unregister the pcode binary loader
+ *
+ * Returned Value:
+ *   None
+ *
+ ****************************************************************************/
+
+void pcode_uninitialize(void)
+{
+  unregister_binfmt(&g_pcode_binfmt);
+}
+
+#endif /* CONFIG_PCODE */
+