ref: f6a002f2a67579cce9d53a4314f0676228517c12
dir: /third_party/libyuv/source/mjpeg_validate.cc/
/* * Copyright 2012 The LibYuv Project Authors. All rights reserved. * * Use of this source code is governed by a BSD-style license * that can be found in the LICENSE file in the root of the source * tree. An additional intellectual property rights grant can be found * in the file PATENTS. All contributing project authors may * be found in the AUTHORS file in the root of the source tree. */ #include "libyuv/mjpeg_decoder.h" #include <string.h> // For memchr. #ifdef __cplusplus namespace libyuv { extern "C" { #endif // Helper function to scan for EOI marker (0xff 0xd9). static LIBYUV_BOOL ScanEOI(const uint8_t* sample, size_t sample_size) { if (sample_size >= 2) { const uint8_t* end = sample + sample_size - 1; const uint8_t* it = sample; while (it < end) { // TODO(fbarchard): scan for 0xd9 instead. it = (const uint8_t*)(memchr(it, 0xff, end - it)); if (it == NULL) { break; } if (it[1] == 0xd9) { return LIBYUV_TRUE; // Success: Valid jpeg. } ++it; // Skip over current 0xff. } } // ERROR: Invalid jpeg end code not found. Size sample_size return LIBYUV_FALSE; } // Helper function to validate the jpeg appears intact. LIBYUV_BOOL ValidateJpeg(const uint8_t* sample, size_t sample_size) { // Maximum size that ValidateJpeg will consider valid. const size_t kMaxJpegSize = 0x7fffffffull; const size_t kBackSearchSize = 1024; if (sample_size < 64 || sample_size > kMaxJpegSize || !sample) { // ERROR: Invalid jpeg size: sample_size return LIBYUV_FALSE; } if (sample[0] != 0xff || sample[1] != 0xd8) { // SOI marker // ERROR: Invalid jpeg initial start code return LIBYUV_FALSE; } // Look for the End Of Image (EOI) marker near the end of the buffer. if (sample_size > kBackSearchSize) { if (ScanEOI(sample + sample_size - kBackSearchSize, kBackSearchSize)) { return LIBYUV_TRUE; // Success: Valid jpeg. } // Reduce search size for forward search. sample_size = sample_size - kBackSearchSize + 1; } // Step over SOI marker and scan for EOI. return ScanEOI(sample + 2, sample_size - 2); } #ifdef __cplusplus } // extern "C" } // namespace libyuv #endif