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37d7439ef9
There's probably a number of other places where the bh_leb_read could be used (e.g. aot loader) but I'm making the change as small as possible. Further refactoring can be done later.
77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
/*
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* Copyright (C) 2019 Intel Corporation. All rights reserved.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*/
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#include "bh_leb128.h"
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bh_leb_read_status_t
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bh_leb_read(const uint8 *buf, const uint8 *buf_end, uint32 maxbits, bool sign,
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uint64 *p_result, size_t *p_offset)
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{
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uint64 result = 0;
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uint32 shift = 0;
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uint32 offset = 0, bcnt = 0;
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uint64 byte;
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while (true) {
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/* uN or SN must not exceed ceil(N/7) bytes */
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if (bcnt + 1 > (maxbits + 6) / 7) {
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return BH_LEB_READ_TOO_LONG;
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}
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if ((uintptr_t)buf + offset + 1 < (uintptr_t)buf
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|| (uintptr_t)buf + offset + 1 > (uintptr_t)buf_end) {
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return BH_LEB_READ_UNEXPECTED_END;
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}
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byte = buf[offset];
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offset += 1;
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result |= ((byte & 0x7f) << shift);
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shift += 7;
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bcnt += 1;
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if ((byte & 0x80) == 0) {
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break;
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}
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}
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if (!sign && maxbits == 32 && shift >= maxbits) {
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/* The top bits set represent values > 32 bits */
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if (((uint8)byte) & 0xf0)
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return BH_LEB_READ_OVERFLOW;
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}
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else if (sign && maxbits == 32) {
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if (shift < maxbits) {
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/* Sign extend, second-highest bit is the sign bit */
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if ((uint8)byte & 0x40)
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result |= (~((uint64)0)) << shift;
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}
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else {
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/* The top bits should be a sign-extension of the sign bit */
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bool sign_bit_set = ((uint8)byte) & 0x8;
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int top_bits = ((uint8)byte) & 0xf0;
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if ((sign_bit_set && top_bits != 0x70)
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|| (!sign_bit_set && top_bits != 0))
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return BH_LEB_READ_OVERFLOW;
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}
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}
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else if (sign && maxbits == 64) {
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if (shift < maxbits) {
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/* Sign extend, second-highest bit is the sign bit */
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if ((uint8)byte & 0x40)
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result |= (~((uint64)0)) << shift;
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}
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else {
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/* The top bits should be a sign-extension of the sign bit */
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bool sign_bit_set = ((uint8)byte) & 0x1;
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int top_bits = ((uint8)byte) & 0xfe;
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if ((sign_bit_set && top_bits != 0x7e)
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|| (!sign_bit_set && top_bits != 0))
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return BH_LEB_READ_OVERFLOW;
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}
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}
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*p_offset = offset;
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*p_result = result;
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return BH_LEB_READ_SUCCESS;
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} |