fix ByteStreamBuffer

brian-armstrong-discord · brian-armstrong-discord · commit 40dc0bcd6395 · 2017-04-24T18:07:47.000-07:00
diff --git a/modules/imgcodecs/src/loadsave.cpp b/modules/imgcodecs/src/loadsave.cpp
@@ -70,21 +70,21 @@ class ByteStreamBuffer: public std::streambuf
                               std::ios_base::seekdir dir,
                               std::ios_base::openmode )
     {
-        // get absolute offset
-        off_type off = offset;
+        char* whence = eback();
         if (dir == std::ios_base::cur)
         {
-            off += gptr() - eback();
+            whence = gptr();
         }
         else if (dir == std::ios_base::end)
         {
-            off += egptr() - eback();
+            whence = egptr();
         }
+        char* to = whence + offset;
 
         // check limits
-        if (off >= (off_type)0 && off <= egptr() - eback())
+        if (to >= eback() && to <= egptr())
         {
-            setg(eback(), gptr() + off, egptr());
+            setg(eback(), to, egptr());
             return gptr() - eback();
         }
 

Original file line number	Diff line number	Diff line change
`@@ -70,21 +70,21 @@ class ByteStreamBuffer: public std::streambuf`
`70`	`70`	`std::ios_base::seekdir dir,`
`71`	`71`	`std::ios_base::openmode )`
`72`	`72`	`{`
`73`		`- // get absolute offset`
`74`		`- off_type off = offset;`
	`73`	`+ char* whence = eback();`
`75`	`74`	`if (dir == std::ios_base::cur)`
`76`	`75`	`{`
`77`		`- off += gptr() - eback();`
	`76`	`+ whence = gptr();`
`78`	`77`	`}`
`79`	`78`	`else if (dir == std::ios_base::end)`
`80`	`79`	`{`
`81`		`- off += egptr() - eback();`
	`80`	`+ whence = egptr();`
`82`	`81`	`}`
	`82`	`+ char* to = whence + offset;`
`83`	`83`
`84`	`84`	`// check limits`
`85`		`- if (off >= (off_type)0 && off <= egptr() - eback())`
	`85`	`+ if (to >= eback() && to <= egptr())`
`86`	`86`	`{`
`87`		`- setg(eback(), gptr() + off, egptr());`
	`87`	`+ setg(eback(), to, egptr());`
`88`	`88`	`return gptr() - eback();`
`89`	`89`	`}`
`90`	`90`