/**************************************************************************** * libc/unistd/lib_execl.c * * Copyright (C) 2013, 2015 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #ifdef CONFIG_LIBC_EXECFUNCS /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* This is an artificial limit to detect error conditions where an argv[] * list is not properly terminated. */ #define MAX_EXECL_ARGS 256 /**************************************************************************** * Global Variables ****************************************************************************/ /**************************************************************************** * Private Variables ****************************************************************************/ /**************************************************************************** * Global Functions ****************************************************************************/ /**************************************************************************** * Name: execl * * Description: * The standard 'exec' family of functions will replace the current process * image with a new process image. The new image will be constructed from a * regular, executable file called the new process image file. There will * be no return from a successful exec, because the calling process image * is overlaid by the new process image. * * Simplified 'execl()' and 'execv()' functions are provided by NuttX for * compatibility. NuttX is a tiny embedded RTOS that does not support * processes and hence the concept of overlaying a tasks process image with * a new process image does not make any sense. In NuttX, these functions * are wrapper functions that: * * 1. Call the non-standard binfmt function 'exec', and then * 2. exit(0). * * Note the inefficiency when 'exec[l|v]()' is called in the normal, two- * step process: (1) first call vfork() to create a new thread, then (2) * call 'exec[l|v]()' to replace the new thread with a program from the * file system. Since the new thread will be terminated by the * 'exec[l|v]()' call, it really served no purpose other than to support * Unix compatility. * * The non-standard binfmt function 'exec()' needs to have (1) a symbol * table that provides the list of symbols exported by the base code, and * (2) the number of symbols in that table. This information is currently * provided to 'exec()' from 'exec[l|v]()' via NuttX configuration settings: * * CONFIG_LIBC_EXECFUNCS : Enable exec[l|v] support * CONFIG_EXECFUNCS_SYMTAB : Symbol table used by exec[l|v] * CONFIG_EXECFUNCS_NSYMBOLS : Number of symbols in the table * * As a result of the above, the current implementations of 'execl()' and * 'execv()' suffer from some incompatibilities that may or may not be * addressed in a future version of NuttX. Other than just being an * inefficient use of MCU resource, the most serious of these is that * the exec'ed task will not have the same task ID as the vfork'ed * function. So the parent function cannot know the ID of the exec'ed * task. * * Input Parameters: * path - The path to the program to be executed. If CONFIG_BINFMT_EXEPATH * is defined in the configuration, then this may be a relative path * from the current working directory. Otherwise, path must be the * absolute path to the program. * ... - A list of the string arguments to be recevied by the * program. Zero indicates the end of the list. * * Returned Value: * This function does not return on success. On failure, it will return * -1 (ERROR) and will set the 'errno' value appropriately. * ****************************************************************************/ int execl(FAR const char *path, ...) { FAR char **argv = (FAR char **)NULL; FAR char *arg; size_t nargs; va_list ap; int argc; int ret; /* Count the number of arguments */ va_start(ap, path); nargs = 0; do { /* Check if the next argument is present */ arg = va_arg(ap, FAR char *); if (arg) { /* Yes.. increment the number of arguments. Here is a sanity * check to prevent running away with an unterminated argv[] list. * MAX_EXECL_ARGS should be sufficiently large that this never * happens in normal usage. */ if (++nargs > MAX_EXECL_ARGS) { set_errno(E2BIG); va_end(ap); return ERROR; } } } while (arg); va_end(ap); /* Allocate a temporary argv[] array */ if (nargs > 0) { argv = (FAR char **)malloc((nargs + 1) * sizeof(FAR char *)); if (argv == (FAR char **)NULL) { set_errno(ENOMEM); return ERROR; } /* Collect the arguments into the argv[] array */ va_start(ap, path); for (argc = 0; argc < nargs; argc++) { argv[argc] = va_arg(ap, FAR char *); } argv[nargs] = NULL; va_end(ap); } /* Then let execv() do the real work */ ret = execv(path, (FAR char * const *)argv); /* Free the allocated argv[] list */ if (argv) { free(argv); } return ret; } #endif /* CONFIG_LIBC_EXECFUNCS */