source: bootcd/isolinux/syslinux-6.03/com32/lib/sys/module/exec.c

/*
 * exec.c
 *
 *  Created on: Aug 14, 2008
 *      Author: Stefan Bucur <stefanb@zytor.com>
 */

#include <sys/module.h>
#include <sys/exec.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <setjmp.h>
#include <setjmp.h>
#include <alloca.h>
#include <dprintf.h>

#define DBG_PRINT(fmt, args...) dprintf("[EXEC] " fmt, ##args)

struct elf_module *__syslinux_current = NULL;

int get_module_type(struct elf_module *module)
{
        if(module->main_func) return EXEC_MODULE;
        return LIB_MODULE;
}

jmp_buf __process_exit_jmp;

#if 0
int spawnv(const char *name, const char **argv)
{
        int res, ret_val = 0;
        const char **arg;
        int argc;
        char **argp, **args;
        struct elf_module *previous;
        malloc_tag_t prev_mem_tag;

        struct elf_module *module = module_alloc(name);

        if (module == NULL)
                return -1;

        res = module_load(module);
        if (res != 0) {
                module_unload(module);
                return res;
        }

        if (module->main_func == NULL) {
                // We can't execute without a main function
                module_unload(module);
                return -1;
        }
        /*if (module->main_func != NULL) {
                const char **last_arg = argv;
                void *old_tag;
                while (*last_arg != NULL)
                        last_arg++;

                // Setup the memory allocation context
                old_tag = __mem_get_tag_global();
                __mem_set_tag_global(module);

                // Execute the program
                ret_val = (*(module->main_func))(last_arg - argv, argv);

                // Clean up the allocation context
                __free_tagged(module);
                // Restore the allocation context
                __mem_set_tag_global(old_tag);
        } else {
                // We can't execute without a main function
                module_unload(module);
                return -1;
        }*/
        // Set up the process context
        previous = __syslinux_current;
        prev_mem_tag = __mem_get_tag_global();

        // Setup the new process context
        __syslinux_current = module;
        __mem_set_tag_global((malloc_tag_t)module);

        // Generate a new process copy of argv (on the stack)
        argc = 0;
        for (arg = argv; *arg; arg++)
                argc++;

        args = alloca((argc+1) * sizeof(char *));

        for (arg = argv, argp = args; *arg; arg++, argp++) {
                size_t l = strlen(*arg)+1;
                *argp = alloca(l);
                memcpy(*argp, *arg, l);
        }

        *args = NULL;

        // Execute the program
        ret_val = setjmp(module->u.x.process_exit);

        if (ret_val)
                ret_val--;              /* Valid range is 0-255 */
        else if (!module->main_func)
                ret_val = -1;
        else
                exit((module->main_func)(argc, args)); /* Actually run! */

        // Clean up the allocation context
        __free_tagged(module);
        // Restore the allocation context
        __mem_set_tag_global(prev_mem_tag);
        // Restore the process context
        __syslinux_current = previous;

        res = module_unload(module);

        if (res != 0) {
                return res;
        }

        return ((unsigned int)ret_val & 0xFF);
}

int spawnl(const char *name, const char *arg, ...)
{
        /*
         * NOTE: We assume the standard ABI specification for the i386
         * architecture. This code may not work if used in other
         * circumstances, including non-variadic functions, different
         * architectures and calling conventions.
         */
        return spawnv(name, &arg);
}
#endif

/*
 * Load a module and runs its start function.
 *
 * For library modules the start function is module->init_func and for
 * executable modules its module->main_func.
 *
 * "name" is the name of the module to load.
 *
 * "argv" and "argc" are only passed to module->main_func, for library
 * modules these arguments can be NULL and 0, respectively.
 *
 * "argv" is an array of arguments to pass to module->main_func.
 * argv[0] must be a pointer to "name" and argv[argc] must be NULL.
 *
 * "argc" is the number of arguments in "argv".
 */
int spawn_load(const char *name, int argc, char **argv)
{
        int res, ret_val = 0;
        struct elf_module *previous;
        //malloc_tag_t prev_mem_tag;
        struct elf_module *module = module_alloc(name);
        struct elf_module *cur_module;
        int type;

        dprintf("enter: name = %s", name);

        if (module == NULL)
                return -1;

        if (get_module_type(module) == EXEC_MODULE) {
                if (!argc || !argv || strcmp(argv[0], name)) {
                        dprintf("invalid args for %s\n", name);
                        res = -1;
                        goto out;
                }
        }

        cur_module = module_current();
        if (!strcmp(cur_module->name, module->name)) {
                dprintf("We is running this module %s already!", module->name);

                module_unload(cur_module);
        }

        res = module_load(module);
        if (res != 0) {
                dprintf("failed to load module %s\n", module->name);
                goto out;
        }

        type = get_module_type(module);

        dprintf("type = %d, prev = %s, cur = %s",
                type, cur_module->name, module->name);

        if(type==EXEC_MODULE)
        {
                previous = __syslinux_current;
                //prev_mem_tag = __mem_get_tag_global();

                // Setup the new process context
                __syslinux_current = module;
                //__mem_set_tag_global((malloc_tag_t)module);

                // Execute the program
                ret_val = setjmp(module->u.x.process_exit);

                if (ret_val)
                        ret_val--;              /* Valid range is 0-255 */
                else if (!module->main_func)
                        ret_val = -1;
                else
                        exit((module->main_func)(argc, argv)); /* Actually run! */

                // Clean up the allocation context
                //__free_tagged(module);
                // Restore the allocation context
                //__mem_set_tag_global(prev_mem_tag);
                // Restore the process context
                __syslinux_current = previous;

                res = module_unload(module);

                if (res != 0)
                        goto out;
        }

out:
        if (res)
                _module_unload(module);
        return res;
}

void exec_term(void)
{
        modules_term();
}