101 lines
4.0 KiB
C
101 lines
4.0 KiB
C
/****************************************************************************
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* libs/libc/dlfcn/lib_dlsym.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <dlfcn.h>
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#include <nuttx/lib/modlib.h>
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: dlsym
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*
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* Description:
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* dlsym() allows a process to obtain the address of a symbol defined
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* within an object made accessible through a dlopen() call. handle is the
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* value returned from a call to dlopen() (and which has not since been
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* released via a call to dlclose()), name is the symbol's name as a
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* character string.
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*
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* dlsym() will search for the named symbol in all objects loaded
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* automatically as a result of loading the object referenced by handle
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* (see dlopen()). Load ordering is used in dlsym() operations upon the
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* global symbol object. The symbol resolution algorithm used will be
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* dependency order as described in dlopen().
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*
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* Input Parameters:
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* handle - The opaque, non-NULL value returned by a previous successful
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* call to dlopen().
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* name - A pointer to the symbol name string.
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*
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* Returned Value:
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* If handle does not refer to a valid object opened by dlopen(), or if
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* the named symbol cannot be found within any of the objects associated
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* with handle, dlsym() will return NULL. More detailed diagnostic
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* information will be available through dlerror().
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*
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* Reference: OpenGroup.org
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*
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****************************************************************************/
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FAR void *dlsym(FAR void *handle, FAR const char *name)
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{
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#if defined(CONFIG_BUILD_FLAT) || defined(CONFIG_BUILD_PROTECTED)
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/* In the FLAT build, a shared library is essentially the same as a kernel
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* module.
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*
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* The PROTECTED build is equivalent to the FLAT build EXCEPT that there
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* must be two copies of the module logic: One residing in kernel
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* space and using the kernel symbol table and one residing in user space
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* using the user space symbol table.
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*
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* dlgetsem() is essentially a clone of modsym().
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*/
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return (FAR void *)modlib_getsymbol(handle, name);
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#else /* if defined(CONFIG_BUILD_KERNEL) */
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/* The KERNEL build is considerably more complex: In order to be shared,
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* the .text portion of the module must be (1) build for PIC/PID operation
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* and (2) must like in a shared memory region accessible from all
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* processes. The .data/.bss portion of the module must be allocated in
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* the user space of each process, but must lie at the same virtual address
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* so that it can be referenced from the one copy of the text in the shared
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* memory region.
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*/
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/* #warning Missing logic */
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return NULL;
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#endif
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}
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