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47 lines
1.8 KiB
C
47 lines
1.8 KiB
C
/* Array allocation from a fixed-size buffer.
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Copyright (C) 2017-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <alloc_buffer.h>
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#include <libc-pointer-arith.h>
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void *
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__libc_alloc_buffer_alloc_array (struct alloc_buffer *buf, size_t element_size,
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size_t align, size_t count)
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{
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uintptr_t current = buf->__alloc_buffer_current;
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/* The caller asserts that align is a power of two. */
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uintptr_t aligned = ALIGN_UP (current, align);
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size_t size;
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bool overflow = __builtin_mul_overflow (element_size, count, &size);
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uintptr_t new_current = aligned + size;
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if (!overflow /* Multiplication did not overflow. */
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&& aligned >= current /* No overflow in align step. */
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&& new_current >= size /* No overflow in size computation. */
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&& new_current <= buf->__alloc_buffer_end) /* Room in buffer. */
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{
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buf->__alloc_buffer_current = new_current;
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return (void *) aligned;
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}
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else
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{
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alloc_buffer_mark_failed (buf);
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return NULL;
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}
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}
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libc_hidden_def (__libc_alloc_buffer_alloc_array)
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