1 files changed, 71 insertions, 0 deletions
diff --git a/source/mjpeg_validate.cc b/source/mjpeg_validate.cc
new file mode 100644
index 00000000..ba0a03ab
--- /dev/null
+++ b/source/mjpeg_validate.cc
@@ -0,0 +1,71 @@
+/*
+ *  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* src_mjpg, size_t src_size_mjpg) {
+  if (src_size_mjpg >= 2) {
+    const uint8_t* end = src_mjpg + src_size_mjpg - 1;
+    const uint8_t* it = src_mjpg;
+    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 src_size_mjpg
+  return LIBYUV_FALSE;
+}
+
+// Helper function to validate the jpeg appears intact.
+LIBYUV_BOOL ValidateJpeg(const uint8_t* src_mjpg, size_t src_size_mjpg) {
+  // Maximum size that ValidateJpeg will consider valid.
+  const size_t kMaxJpegSize = 0x7fffffffull;
+  const size_t kBackSearchSize = 1024;
+  if (src_size_mjpg < 64 || src_size_mjpg > kMaxJpegSize || !src_mjpg) {
+    // ERROR: Invalid jpeg size: src_size_mjpg
+    return LIBYUV_FALSE;
+  }
+  // SOI marker
+  if (src_mjpg[0] != 0xff || src_mjpg[1] != 0xd8 || src_mjpg[2] != 0xff) {
+    // ERROR: Invalid jpeg initial start code
+    return LIBYUV_FALSE;
+  }
+
+  // Look for the End Of Image (EOI) marker near the end of the buffer.
+  if (src_size_mjpg > kBackSearchSize) {
+    if (ScanEOI(src_mjpg + src_size_mjpg - kBackSearchSize, kBackSearchSize)) {
+      return LIBYUV_TRUE;  // Success: Valid jpeg.
+    }
+    // Reduce search size for forward search.
+    src_size_mjpg = src_size_mjpg - kBackSearchSize + 1;
+  }
+  // Step over SOI marker and scan for EOI.
+  return ScanEOI(src_mjpg + 2, src_size_mjpg - 2);
+}
+
+#ifdef __cplusplus
+}  // extern "C"
+}  // namespace libyuv
+#endif