Shared libraries: Add a non-standard dllfnc.h function to set the symbol table.

include/dllfcn.h

@@ -104,6 +104,26 @@ extern "C"
 #define EXTERN extern
 #endif
 
+/****************************************************************************
+ * Name: dlsymtab
+ *
+ * Description:
+ *   dlsymtab() is a non-standard shared library interface.  It selects the
+ *   symbol table to use when binding a shared libary to the base firmware
+ *   which may be in FLASH memory.
+ *
+ * Input Parameters:
+ *   symtab   - The new symbol table.
+ *   nsymbols - The number of symbols in the symbol table.
+ *
+ * Returned Value:
+ *   Always returns OK.
+ *
+ ****************************************************************************/
+
+struct symtab_s;
+int dlsymtab(FAR const struct symtab_s *symtab, int nsymbols);
+
 /****************************************************************************
  * Name: dlopen
  *

include/nuttx/module.h

@@ -109,7 +109,7 @@ struct mod_info_s
 {
   mod_uninitializer_t uninitializer;   /* Module uninitializer */
   FAR void *arg;                       /* Uninitializer argument */
-  FAR struct symtab_s *exports;      /* Symbols exported by module */
+  FAR const struct symtab_s *exports;  /* Symbols exported by module */
   unsigned int nexports;               /* Number of symobols in exports list */
 };
 
@@ -128,7 +128,7 @@ struct mod_info_s
 
 typedef CODE int (*mod_initializer_t)(FAR struct mod_info_s *modinfo);
 
-#ifdef __KERNEL__
+#if defined(__KERNEL__) || defined(CONFIG_BUILD_FLAT)
 /* This is the type of the callback function used by mod_registry_foreach() */
 
 struct module_s;
@@ -163,7 +163,7 @@ extern "C"
  *
  ****************************************************************************/
 
-#ifdef __KERNEL__
+#if defined(__KERNEL__) || defined(CONFIG_BUILD_FLAT)
 void mod_getsymtab(FAR const struct symtab_s **symtab, FAR int *nsymbols);
 #endif
 
@@ -182,7 +182,7 @@ void mod_getsymtab(FAR const struct symtab_s **symtab, FAR int *nsymbols);
  *
  ****************************************************************************/
 
-#ifdef __KERNEL__
+#if defined(__KERNEL__) || defined(CONFIG_BUILD_FLAT)
 void mod_setsymtab(FAR const struct symtab_s *symtab, int nsymbols);
 #endif
 
@@ -301,7 +301,7 @@ FAR void *modhandle(FAR const char *name);
  *
  ****************************************************************************/
 
-#ifdef __KERNEL__
+#if defined(__KERNEL__) || defined(CONFIG_BUILD_FLAT)
 int mod_registry_foreach(mod_callback_t callback, FAR void *arg);
 #endif
 

libc/dllfcn/Make.defs

@@ -37,7 +37,7 @@ ifeq ($(CONFIG_LIBC_DLLFCN),y)
 
 # Add the dllfcn.h files to the build
 
-CSRCS += lib_dlopen.c lib_dlclose.c lib_dlsym.c lib_dlerror.c
+CSRCS += lib_dlopen.c lib_dlclose.c lib_dlsym.c lib_dlerror.c lib_dlsymtab.c
 
 # Add the dllfcn.h directory to the build
 

libc/dllfcn/lib_dlsymtab.c

@@ -0,0 +1,103 @@
+/****************************************************************************
+ * libc/dllfcn/lib_symtab.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 <dllfcn.h>
+
+#include <nuttx/module.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: dlsymtab
+ *
+ * Description:
+ *   dlsymtab() is a non-standard shared library interface.  It selects the
+ *   symbol table to use when binding a shared libary to the base firmware
+ *   which may be in FLASH memory.
+ *
+ * Input Parameters:
+ *   symtab   - The new symbol table.
+ *   nsymbols - The number of symbols in the symbol table.
+ *
+ * Returned Value:
+ *   Always returns OK.
+ *
+ ****************************************************************************/
+
+int dlsymtab(FAR const struct symtab_s *symtab, int nsymbols)
+{
+#if defined(CONFIG_BUILD_FLAT)
+  /* In the FLAT build, a shared library is essentially the same as a kernel
+   * module.
+   */
+
+  mod_setsymtab(symtab, nsymbols);
+  return OK;
+
+#elif defined(CONFIG_BUILD_PROTECTED)
+  /* The PROTECTED build is equivalent to the FLAT build EXCEPT that there
+   * must be two copies of the the module logic:  One residing in kernel
+   * space and using the kernel symbol table and one residing in user space
+   * using the user space symbol table.
+   *
+   * The brute force way to accomplish this is by just copying the kernel
+   * module code into libc/module.
+   */
+
+#warning Missing logic
+  return NULL;
+
+#else /* if defined(CONFIG_BUILD_KERNEL) */
+  /* The KERNEL build is considerably more complex:  In order to be shared,
+   * the .text portion of the module must be (1) build for PIC/PID operation
+   * and (2) must like in a shared memory region accessible from all
+   * processes.  The .data/.bss portion of the module must be allocated in
+   * the user space of each process, but must lie at the same virtual address
+   * so that it can be referenced from the one copy of the text in the shared
+   * memory region.
+   */
+
+#warning Missing logic
+  return NULL;
+#endif
+}