Modules: Move first five of many C files from sched/module to libc/modlib

libc/modlib/modlib_depend.c

@@ -0,0 +1,198 @@
+/****************************************************************************
+ * libc/modlib/modlib_depend.c
+ *
+ *   Copyright (C) 2017 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 <stdlib.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/module.h>
+#include <nuttx/lib/modlib.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: modlib_depend
+ *
+ * Description:
+ *   Set up module dependencies between the exporter and the importer of a
+ *   symbol.  The happens when the module is installed via insmod and a
+ *   symbol is imported from another module.
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ * Assumptions:
+ *   Caller holds the registry lock.
+ *
+ ****************************************************************************/
+
+int modlib_depend(FAR struct module_s *importer, FAR struct module_s *exporter)
+{
+#if CONFIG_MODLIB_MAXDEPEND > 0
+  int freendx;
+  int i;
+
+  DEBUGASSERT(importer != NULL && exporter != NULL);
+
+  /* First checker if the exported is already in our list if dependencies.
+   * This would happen if we are importing multiple symbols from the same
+   * exporting module.  In that case, the module would already be in the
+   * list of dependencies.
+   *
+   * The list dependency list is a a dumb, upacked array of pointers.  This
+   * should not be too inefficient if the number of CONFIG_MODLIB_MAXDEPEND
+   * is small.  Otherwise, a more dynamic data structure would be in order.
+   */
+
+  for (i = 0, freendx = -1; i < CONFIG_MODLIB_MAXDEPEND; i++)
+    {
+      FAR const struct module_s *modp;
+
+      /* Check if this dependency slot is available. */
+
+      modp = importer->dependencies[i];
+      if (modp == NULL)
+        {
+          /* Remember this slot for use the module is NOT already in the
+           * list of dependencies.
+           */
+
+          freendx = i;
+        }
+      else if (modp == exporter)
+        {
+          /* Yes, we are already importing symbols from this module.  Nothing
+           * more needs to be done.
+           */
+
+          return OK;
+        }
+    }
+
+  /* If we get here, then (1) this is a new exporting module that does not
+   * already appear in the list of dependencies, and (2) freendx is the
+   * index to the last free slot in the dependency list.  If freendx is
+   * negative, then the dependency list is full.
+   */
+
+  if (freendx >= 0)
+    {
+      /* Increment the count of dependencies on the exporter module */
+
+      DEBUGASSERT(exporter->dependents < UINT8_MAX);
+      if (exporter->dependents >= UINT8_MAX)
+        {
+          return -ENOSPC;
+        }
+
+      exporter->dependents++;
+
+      /* And remember the exporter so that we can decrement the count of
+       * dependents if the importer is removed.
+       */
+
+       DEBUGASSERT(importer->dependencies[freendx] == NULL);
+       importer->dependencies[freendx] = exporter;
+       return OK;
+    }
+
+  /* If we get there then the list of dependencies is full. */
+
+  DEBUGPANIC();
+  return -ENFILE;
+
+#else
+  return OK;
+#endif
+}
+
+/****************************************************************************
+ * Name: modlib_undepend
+ *
+ * Description:
+ *   Tear down module dependencies between the exporters and the importer of
+ *   symbols.  This happens when the module is removed via rmmod (and on
+ *   error handling cases in insmod).
+ *
+ * Returned Value:
+ *   0 (OK) is returned on success and a negated errno is returned on
+ *   failure.
+ *
+ * Assumptions:
+ *   Caller holds the registry lock.
+ *
+ ****************************************************************************/
+
+int modlib_undepend(FAR struct module_s *importer)
+{
+#if CONFIG_MODLIB_MAXDEPEND > 0
+  FAR struct module_s *exporter;
+  int i;
+
+  DEBUGASSERT(importer != NULL && importer->dependents == 0);
+
+  /* Decrement the dependency count on each of exporters of symbols used by
+   * this importer module.  This is an upacked array of pointers.  This
+   * should not be too inefficient if the number of CONFIG_MODLIB_MAXDEPEND
+   * is small.  Otherwise, a more dynamic data structure would be in order.
+   */
+
+  for (i = 0; i < CONFIG_MODLIB_MAXDEPEND; i++)
+    {
+      exporter = importer->dependencies[i];
+      if (exporter != NULL)
+        {
+          DEBUGASSERT(exporter->dependents > 0);
+          if (exporter->dependents > 0)
+            {
+              exporter->dependents--;
+            }
+
+          importer->dependencies[i] = NULL;
+        }
+    }
+#endif
+
+  return OK;
+}