Fix some empty vector references

sipa · sipa · commit f478d98fe49d · 2017-04-21T05:58:31.000-07:00
streams.h has some methods that can be tricked into dereferencing
null pointers or end() iterators. Fix this.
diff --git a/src/streams.h b/src/streams.h
@@ -248,7 +248,8 @@ class CDataStream
 
     void insert(iterator it, std::vector<char>::const_iterator first, std::vector<char>::const_iterator last)
     {
-        assert(last - first >= 0);
+        if (last == first) return;
+        assert(last - first > 0);
         if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)
         {
             // special case for inserting at the front when there's room
@@ -261,7 +262,8 @@ class CDataStream
 
     void insert(iterator it, const char* first, const char* last)
     {
-        assert(last - first >= 0);
+        if (last == first) return;
+        assert(last - first > 0);
         if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)
         {
             // special case for inserting at the front when there's room
@@ -339,6 +341,8 @@ class CDataStream
 
     void read(char* pch, size_t nSize)
     {
+        if (nSize == 0) return;
+
         // Read from the beginning of the buffer
         unsigned int nReadPosNext = nReadPos + nSize;
         if (nReadPosNext >= vch.size())

Original file line number	Diff line number	Diff line change
`@@ -248,7 +248,8 @@ class CDataStream`
`248`	`248`
`249`	`249`	`void insert(iterator it, std::vector<char>::const_iterator first, std::vector<char>::const_iterator last)`
`250`	`250`	`{`
`251`		`- assert(last - first >= 0);`
	`251`	`+ if (last == first) return;`
	`252`	`+ assert(last - first > 0);`
`252`	`253`	`if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)`
`253`	`254`	`{`
`254`	`255`	`// special case for inserting at the front when there's room`
`@@ -261,7 +262,8 @@ class CDataStream`
`261`	`262`
`262`	`263`	`void insert(iterator it, const char* first, const char* last)`
`263`	`264`	`{`
`264`		`- assert(last - first >= 0);`
	`265`	`+ if (last == first) return;`
	`266`	`+ assert(last - first > 0);`
`265`	`267`	`if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)`
`266`	`268`	`{`
`267`	`269`	`// special case for inserting at the front when there's room`
`@@ -339,6 +341,8 @@ class CDataStream`
`339`	`341`
`340`	`342`	`void read(char* pch, size_t nSize)`
`341`	`343`	`{`
	`344`	`+ if (nSize == 0) return;`
	`345`	`+`
`342`	`346`	`// Read from the beginning of the buffer`
`343`	`347`	`unsigned int nReadPosNext = nReadPos + nSize;`
`344`	`348`	`if (nReadPosNext >= vch.size())`