root/fs/binfmt_script.c

DEFINITIONS

1. load_script
2. init_script_binfmt
3. exit_script_binfmt

/*
 *  linux/fs/binfmt_script.c
 *
 *  Copyright (C) 1996  Martin von Löwis
 *  original #!-checking implemented by tytso.
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/binfmts.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/err.h>
#include <linux/fs.h>

static int load_script(struct linux_binprm *bprm,struct pt_regs *regs)
{
        char *cp, *i_name, *i_arg;
        struct file *file;
        char interp[BINPRM_BUF_SIZE];
        int retval;

        if ((bprm->buf[0] != '#') || (bprm->buf[1] != '!') || (bprm->sh_bang)) 
                return -ENOEXEC;
        /*
         * This section does the #! interpretation.
         * Sorta complicated, but hopefully it will work.  -TYT
         */

        bprm->sh_bang = 1;
        allow_write_access(bprm->file);
        fput(bprm->file);
        bprm->file = NULL;

        bprm->buf[BINPRM_BUF_SIZE - 1] = '\0';
        if ((cp = strchr(bprm->buf, '\n')) == NULL)
                cp = bprm->buf+BINPRM_BUF_SIZE-1;
        *cp = '\0';
        while (cp > bprm->buf) {
                cp--;
                if ((*cp == ' ') || (*cp == '\t'))
                        *cp = '\0';
                else
                        break;
        }
        for (cp = bprm->buf+2; (*cp == ' ') || (*cp == '\t'); cp++);
        if (*cp == '\0') 
                return -ENOEXEC; /* No interpreter name found */
        i_name = cp;
        i_arg = NULL;
        for ( ; *cp && (*cp != ' ') && (*cp != '\t'); cp++)
                /* nothing */ ;
        while ((*cp == ' ') || (*cp == '\t'))
                *cp++ = '\0';
        if (*cp)
                i_arg = cp;
        strcpy (interp, i_name);
        /*
         * OK, we've parsed out the interpreter name and
         * (optional) argument.
         * Splice in (1) the interpreter's name for argv[0]
         *           (2) (optional) argument to interpreter
         *           (3) filename of shell script (replace argv[0])
         *
         * This is done in reverse order, because of how the
         * user environment and arguments are stored.
         */
        retval = remove_arg_zero(bprm);
        if (retval)
                return retval;
        retval = copy_strings_kernel(1, &bprm->interp, bprm);
        if (retval < 0) return retval; 
        bprm->argc++;
        if (i_arg) {
                retval = copy_strings_kernel(1, &i_arg, bprm);
                if (retval < 0) return retval; 
                bprm->argc++;
        }
        retval = copy_strings_kernel(1, &i_name, bprm);
        if (retval) return retval; 
        bprm->argc++;
        bprm->interp = interp;

        /*
         * OK, now restart the process with the interpreter's dentry.
         */
        file = open_exec(interp);
        if (IS_ERR(file))
                return PTR_ERR(file);

        bprm->file = file;
        retval = prepare_binprm(bprm);
        if (retval < 0)
                return retval;
        return search_binary_handler(bprm,regs);
}

static struct linux_binfmt script_format = {
        .module         = THIS_MODULE,
        .load_binary    = load_script,
};

static int __init init_script_binfmt(void)
{
        return register_binfmt(&script_format);
}

static void __exit exit_script_binfmt(void)
{
        unregister_binfmt(&script_format);
}

core_initcall(init_script_binfmt);
module_exit(exit_script_binfmt);
MODULE_LICENSE("GPL");