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/*
* exec.h
*
* Created on: Aug 14, 2008
* Author: Stefan Bucur <stefanb@zytor.com>
*/
#ifndef EXEC_H_
#define EXEC_H_
#include <sys/module.h>
/**
* EXEC_ROOT_NAME - The name of the ELF module associated with the COM32 module.
*
* This is a shallow ELF module, that contains only the symbol table for
* the code and data sections of the loaded COM32 root module.
*/
#define EXEC_ROOT_NAME "_root_.dyn"
/**
* EXEC_DIRECTORY - The base path for all dynamic linked modules.
*/
#define EXEC_DIRECTORY "/dyn/"
/**
* exec_init - Initialize the dynamic execution environment.
*
* Among others, it initializes the module subsystem and loads the root
* module into memory. You should note the difference between the module
* management API, and the execution API:
* - the module system is a static one - it only manages the data structures
* and their relationship. It does not describe the way modules are executed,
* when and how they are loaded/unloaded, etc. It acts as a service layer for
* the execution API.
* - the execution environment is the dynamic part of the SYSLINUX dynamic
* module API - it implements the behavior of the modules: it
* triggers the execution of initialization and termination functions for
* libraries, executes the modules marked as executable, handles dynamic
* memory cleanup, etc. In other words, at this layer the code and data
* loaded by the lower module layer gets to be executed by the CPU,
* thus becoming part of the SYSLINUX environment.
*/
extern int exec_init();
/**
* load_library - Loads a dynamic library into the environment.
* @name: the name of the library to load, including the extension
* (e.g. 'sort.dyn')
*
* A dynamic library is an ELF module that may contain initialization and
* termination routines, but not a main routine. At the same time, any memory
* allocations using malloc() and its derivatives are made on behalf of the
* currently executing program or the COM32 root module. If the library
* is unloaded, no memory cleanup is performed.
*/
extern int load_library(const char *name);
/**
* unload_library - unloads a library from the environment.
* @name: the name of the library to unload, including the extension
* (e.g. 'sort.dyn')
*
* Note that no memory allocated by the library code is cleaned up, as the
* allocations belong to the innermost calling program in the call stack.
*/
extern int unload_library(const char *name);
/**
* spawnv - Executes a program in the current environment.
* @name: the name of the program to spawn, including the extension
* (e.g. 'hello.dyn')
* @argv: a NULL-terminated vector of string arguments, starting with
* the program name.
*
* A program is an ELF module that contains a main routine. A program is
* loaded into memory, executed, then unloaded, thus remaining in memory only
* while the main() function is executing. A program also defines a
* memory allocation context, and a simple garbage collection mechanism
* it thus provided. This is done by internally associating with the program
* module each pointer returned by malloc(). After the program finishes
* its execution, all the unallocated memory pertaining to the program
* is automatically cleaned up.
*
* Note that this association takes place both for the allocations happening
* directly in the program, or indirectly through a library function. Libraries
* do not create allocation contexts, thus each allocation they made belong
* to the innermost calling program.
*/
extern int spawnv(const char *name, const char **argv);
/**
* spawnl - Executes a program in the current environment.
* @name: the name of the program to spawn, including the extension
* (e.g. 'hello.dyn')
* @arg: the first argument (argv[0]) to be passed to the main function
* of the program
* @...: optional subsequent arguments that are passed o the main function
* of the program
*
* This is another version of the spawn routine. Please see 'spawnv' for
* a full presentation.
*/
extern int spawnl(const char *name, const char *arg, ...);
/**
* exec_term - Releases the resources of the execution environment.
*/
extern void exec_term();
#endif /* EXEC_H_ */
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