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/*
* 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/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)
{
const char *i_arg, *i_name;
char *cp;
struct file *file;
char interp[BINPRM_BUF_SIZE];
int retval;

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

bprm->recursion_depth++;
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");
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