1 //===-- stack_trace_compressor.h --------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef GWP_ASAN_STACK_TRACE_COMPRESSOR_ 10 #define GWP_ASAN_STACK_TRACE_COMPRESSOR_ 11 12 #include <stddef.h> 13 #include <stdint.h> 14 15 // These functions implement stack frame compression and decompression. We store 16 // the zig-zag encoded pointer difference between frame[i] and frame[i - 1] as 17 // a variable-length integer. This can reduce the memory overhead of stack 18 // traces by 50%. 19 20 namespace gwp_asan { 21 namespace compression { 22 23 // For the stack trace in `Unpacked` with length `UnpackedSize`, pack it into 24 // the buffer `Packed` maximum length `PackedMaxSize`. The return value is the 25 // number of bytes that were written to the output buffer. 26 size_t pack(const uintptr_t *Unpacked, size_t UnpackedSize, uint8_t *Packed, 27 size_t PackedMaxSize); 28 29 // From the packed stack trace in `Packed` of length `PackedSize`, write the 30 // unpacked stack trace of maximum length `UnpackedMaxSize` into `Unpacked`. 31 // Returns the number of full entries unpacked, or zero on error. 32 size_t unpack(const uint8_t *Packed, size_t PackedSize, uintptr_t *Unpacked, 33 size_t UnpackedMaxSize); 34 35 } // namespace compression 36 } // namespace gwp_asan 37 38 #endif // GWP_ASAN_STACK_TRACE_COMPRESSOR_ 39