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/* GNU Mailutils -- a suite of utilities for electronic mail
Copyright (C) 2016-2025 Free Software Foundation, Inc.
GNU Mailutils is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GNU Mailutils is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Mailutils. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
#include <mailutils/util.h>
/* Return 1 if file name STR is safe, or 0 otherwise.
The name is not safe if it begins with .. or contains /../
*/
int
mu_file_name_is_safe (char const *str)
{
enum { st_init, st_slash, st_dot, st_dotdot } state;
unsigned char c;
int consume = 0;
if (!str)
return 0;
state = (*str == '.') ? st_dot : st_init;
while ((c = *str++) != 0)
{
if (consume)
consume--;
else if (c < 0xc0)
{
switch (state)
{
case st_init:
if (c == '/')
state = st_slash;
break;
case st_slash:
if (c == '.')
state = st_dot;
else if (c != '/')
state = st_init;
break;
case st_dot:
if (c == '.')
state = st_dotdot;
else if (c == '/')
state = st_slash;
else
state = st_init;
break;
case st_dotdot:
if (c == '/')
return 0;
else
state = st_init;
break;
}
}
else if (c & 0xc0)
consume = 1;
else if (c & 0xe0)
consume = 2;
else if (c & 0xf0)
consume = 3;
}
if (state == st_dotdot)
return 0;
return 1;
}
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