mkvparser: validate results in EBMLHeader::Parse.

Return an error when DocType, DocTypeReadVersion, DocTypeVersion
EBMLMaxIDLength or EBMLMaxSizeLength are invalid or cannot be
handled by mkvparser.

Update samples to respect the return value from EBMLHeader::Parse.

BUG=https://code.google.com/p/webm/issues/detail?id=1057

Change-Id: I9337f13c1d5fa366b1101e48fe6bc46eb5b2ee97

mkvparser.cpp

@@ -630,6 +630,15 @@ long long EBMLHeader::Parse(IMkvReader* pReader, long long& pos) {
   if (pos != end)
     return E_FILE_FORMAT_INVALID;
 
+  // Make sure DocType, DocTypeReadVersion, and DocTypeVersion are valid.
+  if (m_docType == NULL || m_docTypeReadVersion <= 0 || m_docTypeVersion <= 0)
+    return E_FILE_FORMAT_INVALID;
+
+  // Make sure EBMLMaxIDLength and EBMLMaxSizeLength are valid.
+  if (m_maxIdLength <= 0 || m_maxIdLength > 4 ||
+      m_maxSizeLength <= 0 || m_maxSizeLength > 8)
+    return E_FILE_FORMAT_INVALID;
+
   return 0;
 }
 

sample.cpp

@@ -83,7 +83,11 @@ int main(int argc, char* argv[]) {
 
   EBMLHeader ebmlHeader;
 
-  ebmlHeader.Parse(&reader, pos);
+  long long ret = ebmlHeader.Parse(&reader, pos);
+  if (ret < 0) {
+    printf("\n EBMLHeader::Parse() failed.");
+    return -1;
+  }
 
   printf("\t\t\t    EBML Header\n");
   printf("\t\tEBML Version\t\t: %lld\n", ebmlHeader.m_version);
@@ -95,7 +99,7 @@ int main(int argc, char* argv[]) {
   typedef mkvparser::Segment seg_t;
   seg_t* pSegment_;
 
-  long long ret = seg_t::CreateInstance(&reader, pos, pSegment_);
+  ret = seg_t::CreateInstance(&reader, pos, pSegment_);
   if (ret) {
     printf("\n Segment::CreateInstance() failed.");
     return -1;

sample_muxer.cpp

@@ -248,11 +248,14 @@ int main(int argc, char* argv[]) {
 
   long long pos = 0;
   mkvparser::EBMLHeader ebml_header;
-  ebml_header.Parse(&reader, pos);
+  long long ret = ebml_header.Parse(&reader, pos);
+  if (ret) {
+    printf("\n EBMLHeader::Parse() failed.");
+    return EXIT_FAILURE;
+  }
 
   mkvparser::Segment* parser_segment_;
-  long long ret =
+  ret = mkvparser::Segment::CreateInstance(&reader, pos, parser_segment_);
-      mkvparser::Segment::CreateInstance(&reader, pos, parser_segment_);
   if (ret) {
     printf("\n Segment::CreateInstance() failed.");
     return EXIT_FAILURE;

vttdemux.cc

@@ -345,7 +345,7 @@ bool vttdemux::ParseHeader(mkvparser::IMkvReader* reader, mkvpos_t* pos) {
     return false;
   }
 
-  if (strcmp(h.m_docType, "webm") != 0) {
+  if (h.m_docType == NULL || strcmp(h.m_docType, "webm") != 0) {
     printf("bad doctype\n");
     return false;
   }