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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *  * Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  *  * Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in
     12  *    the documentation and/or other materials provided with the
     13  *    distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
     19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
     20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
     21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
     22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
     23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
     24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
     25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26  * SUCH DAMAGE.
     27  */
     28 
     29 #include <stdio.h>
     30 #include <stdlib.h>
     31 #include "libc_logging.h"
     32 
     33 /*
     34  * __fgets_chk. Called in place of fgets() when we know the
     35  * size of the buffer we're writing into.
     36  *
     37  * See
     38  *   http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html
     39  * for details.
     40  *
     41  * This fgets check is called if _FORTIFY_SOURCE is defined and
     42  * greater than 0.
     43  */
     44 extern "C" char *__fgets_chk(char *dest, int supplied_size,
     45                   FILE *stream, size_t dest_len_from_compiler)
     46 {
     47     if (supplied_size < 0) {
     48         __fortify_chk_fail("fgets buffer size less than 0", 0);
     49     }
     50 
     51     if (((size_t) supplied_size) > dest_len_from_compiler) {
     52         __fortify_chk_fail("fgets buffer overflow", 0);
     53     }
     54 
     55     return fgets(dest, supplied_size, stream);
     56 }
     57