I was just asking because I observed such a call in _rw_bufcat(). It happens when the printf-like functions in tests/src/printf.cpp are creating a new buffer for formatting operations.
Brad. > -----Original Message----- > From: Martin Sebor [mailto:[EMAIL PROTECTED] On Behalf Of Martin Sebor > Sent: Thursday, April 10, 2008 7:40 PM > To: dev@stdcxx.apache.org > Subject: Re: Null src pointer in memcpy? > > This is explicitly required in 7.1.4 of C99: > > 7.1.4 Use of library functions > > -1- Each of the following statements applies unless > explicitly stated > otherwise in the detailed descriptions that follow: If > an argument > to a function has an invalid value (such as a value outside the > domain of the function, or a pointer outside the address space > of the program, or a null pointer, or a pointer to > non-modifiable > storage when the corresponding parameter is not > const-qualified) > or a type (after promotion) not expected by a function with > variable number of arguments, the behavior is undefined. ... > > Here's an answer to the same question on comp.lang.c.moderated: > http://tinyurl.com/6eqo3n > > Martin Sebor wrote: > > Eric Lemings wrote: > >> > >> Is it safe to pass a null pointer as the 2nd argument to > memcpy()? Or > >> undefined? > > > > Assuming the third argument is 0. Strictly speaking I believe it's > > undefined because memcpy(s1, s2, n) is specified to "copy n bytes > > from the object pointed to by s2 into the object pointed to by s1" > > and a null pointer doesn't point to an object. An object is defined > > as "a region of storage in the execution environment, the contents > > of which can represent values." > > > > AFAIK, most implementations allow null pointers for no-op calls to > > memcpy() but gcc issues a warning when it detects at compile time > > that a null pointer is passed as the first or second argument to > > memcpy(). > > > > Martin > > > >
