From cfcfd4614b8b01b2782ac4dcafb21d14d74d5184 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Tue, 7 Apr 2015 11:03:43 +0200 Subject: Add struct scratch_buffer and its internal helper functions These will be used from NSS modules, so they have to be exported. --- malloc/scratch_buffer_set_array_size.c | 59 ++++++++++++++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 malloc/scratch_buffer_set_array_size.c (limited to 'malloc/scratch_buffer_set_array_size.c') diff --git a/malloc/scratch_buffer_set_array_size.c b/malloc/scratch_buffer_set_array_size.c new file mode 100644 index 0000000000..a00b520eef --- /dev/null +++ b/malloc/scratch_buffer_set_array_size.c @@ -0,0 +1,59 @@ +/* Variable-sized buffer with on-stack default allocation. + Copyright (C) 2015 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library 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 + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include + +bool +__libc_scratch_buffer_set_array_size (struct scratch_buffer *buffer, + size_t nelem, size_t size) +{ + size_t new_length = nelem * size; + + /* Avoid overflow check if both values are small. */ + if ((nelem | size) >> (sizeof (size_t) * CHAR_BIT / 2) != 0 + && nelem != 0 && size != new_length / nelem) + { + /* Overflow. Discard the old buffer, but it must remain valid + to free. */ + scratch_buffer_free (buffer); + scratch_buffer_init (buffer); + __set_errno (ENOMEM); + return false; + } + + if (new_length <= buffer->length) + return true; + + /* Discard old buffer. */ + scratch_buffer_free (buffer); + + char *new_ptr = malloc (new_length); + if (new_ptr == NULL) + { + /* Buffer must remain valid to free. */ + scratch_buffer_init (buffer); + return false; + } + + /* Install new heap-based buffer. */ + buffer->data = new_ptr; + buffer->length = new_length; + return true; +} +libc_hidden_def (__libc_scratch_buffer_set_array_size); -- cgit v1.2.3