142 lines
5.5 KiB
C
142 lines
5.5 KiB
C
/****************************************************************************
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* sched/task/task_execv.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 <stdlib.h>
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#include <unistd.h>
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#include <errno.h>
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#include <debug.h>
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#include <nuttx/binfmt/binfmt.h>
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#include <nuttx/binfmt/symtab.h>
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#ifdef CONFIG_LIBC_EXECFUNCS
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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/****************************************************************************
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* Private Data
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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: execv
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*
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* Description:
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* The standard 'exec' family of functions will replace the current process
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* image with a new process image. The new image will be constructed from a
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* regular, executable file called the new process image file. There will
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* be no return from a successful exec, because the calling process image
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* is overlaid by the new process image.
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*
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* Simplified 'execl()' and 'execv()' functions are provided by NuttX for
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* compatibility. NuttX is a tiny embedded RTOS that does not support
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* processes and hence the concept of overlaying a tasks process image with
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* a new process image does not make any sense. In NuttX, these functions
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* are wrapper functions that:
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*
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* 1. Call the non-standard binfmt function 'exec', and then
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* 2. exit(0).
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*
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* Note the inefficiency when 'exec[l|v]()' is called in the normal, two-
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* step process: (1) first call vfork() to create a new thread, then (2)
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* call 'exec[l|v]()' to replace the new thread with a program from the
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* file system. Since the new thread will be terminated by the
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* 'exec[l|v]()' call, it really served no purpose other than to support
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* Unix compatility.
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*
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* The non-standard binfmt function 'exec()' needs to have (1) a symbol
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* table that provides the list of symbols exported by the base code, and
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* (2) the number of symbols in that table. This information is currently
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* provided to 'exec()' from 'exec[l|v]()' via NuttX configuration
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* settings:
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*
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* CONFIG_LIBC_EXECFUNCS : Enable exec[l|v] support
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* CONFIG_EXECFUNCS_HAVE_SYMTAB : Defined if there is a pre-defined
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* symbol table
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* CONFIG_EXECFUNCS_SYMTAB_ARRAY : Symbol table name used by exec[l|v]
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* CONFIG_EXECFUNCS_NSYMBOLS_VAR : Variable holding number of symbols
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* in the table
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*
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* As a result of the above, the current implementations of 'execl()' and
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* 'execv()' suffer from some incompatibilities that may or may not be
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* addressed in a future version of NuttX. Other than just being an
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* inefficient use of MCU resource, the most serious of these is that
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* the exec'ed task will not have the same task ID as the vfork'ed
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* function. So the parent function cannot know the ID of the exec'ed
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* task.
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*
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* Input Parameters:
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* path - The path to the program to be executed. If CONFIG_LIBC_ENVPATH
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* is defined in the configuration, then this may be a relative path
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* from the current working directory. Otherwise, path must be the
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* absolute path to the program.
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* argv - A pointer to an array of string arguments. The end of the
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* array is indicated with a NULL entry.
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*
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* Returned Value:
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* This function does not return on success. On failure, it will return
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* -1 (ERROR) and will set the 'errno' value appropriately.
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*
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****************************************************************************/
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int execv(FAR const char *path, FAR char * const argv[])
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{
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FAR const struct symtab_s *symtab;
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int nsymbols;
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int ret;
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/* Get the current symbol table selection */
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exec_getsymtab(&symtab, &nsymbols);
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/* Start the task */
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ret = exec(path, (FAR char * const *)argv, symtab, nsymbols);
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if (ret < 0)
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{
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serr("ERROR: exec failed: %d\n", get_errno());
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return ERROR;
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}
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/* Then exit */
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exit(0);
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/* We should not get here, but might be needed by some compilers. Other,
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* smarter compilers might complain that this code is unreachable. You
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* just can't win.
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*/
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return ERROR;
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}
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#endif /* CONFIG_LIBC_EXECFUNCS */
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