No, you are right. The copying is a bad bug. Using sizeof(char) is mostly a coding style question. The casting of the malloc() return value is something reason

No, you are right. The copying is a bad bug. Using sizeof(char) is mostly a coding style question. The casting of the malloc() return value is something reasonable people can disagree about (by which I mean nerds can endlessly flame each other about). But here are some points: * In C++, which Mozilla is written in, it is a compile time error to not cast, so most likely this blog post is just wrong. Conceivably, the file could have been a C file in an otherwise C++ project, but even in that case, it's at least understandable why the cast is there. * If you have a macro that takes the type as a parameter: #define alloc(type) ((type *)malloc(sizeof(type))) then the casting is a good thing because it makes the compiler warn if you try to assign the result to the wrong pointer type. * It is true that if you forget to include the stdlib.h header, the cast will silence a useful warning about converting int to pointer.