1 /* Variable-sized buffer with on-stack default allocation. 2 Copyright (C) 2015-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #ifndef _LIBC 20 # include <libc-config.h> 21 #endif 22 23 #include <scratch_buffer.h> 24 #include <errno.h> 25 #include <limits.h> 26 27 bool __libc_scratch_buffer_set_array_size(struct scratch_buffer * buffer,size_t nelem,size_t size)28__libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer, 29 size_t nelem, size_t size) 30 { 31 size_t new_length = nelem * size; 32 33 /* Avoid overflow check if both values are small. */ 34 if ((nelem | size) >> (sizeof (size_t) * CHAR_BIT / 2) != 0 35 && nelem != 0 && size != new_length / nelem) 36 { 37 /* Overflow. Discard the old buffer, but it must remain valid 38 to free. */ 39 scratch_buffer_free (buffer); 40 scratch_buffer_init (buffer); 41 __set_errno (ENOMEM); 42 return false; 43 } 44 45 if (new_length <= buffer->length) 46 return true; 47 48 /* Discard old buffer. */ 49 scratch_buffer_free (buffer); 50 51 char *new_ptr = malloc (new_length); 52 if (new_ptr == NULL) 53 { 54 /* Buffer must remain valid to free. */ 55 scratch_buffer_init (buffer); 56 return false; 57 } 58 59 /* Install new heap-based buffer. */ 60 buffer->data = new_ptr; 61 buffer->length = new_length; 62 return true; 63 } 64 libc_hidden_def (__libc_scratch_buffer_set_array_size) 65