In particular, when asked to read an empty file, this function
calls malloc() with a zero size allocation request. Standard C
says that the behaviour of malloc() in this case is implementation
defined.

[C99, 7.20.3 says "... If the size of the space requested is zero,
the behavior is implementation-defined: either a null pointer is
returned, or the behavior is as if the size were some nonzero
value, except that the returned pointer shall not be used to
access an object."]

Finesse the issue by over-allocating by one byte. Setting the extra
byte to '\0' may also provide a useful sentinel for text files.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>