Bug#751409: libc6-dev: endian.h macros don't always return the correct type

[Plamen Alexandrov <plamen@aomeda.com>]

Package: libc6-dev
Version: 2.19-1
Severity: normal

Depending on the endian of the system, the macros le64toh(), be64toh(), htole64(), htobe64(), etc. could not return a 64-bit type. This can lead to issues ranging from compilation errors to runtime crashes.

Here is a simple example:

#include <endian.h>
#include <stdio.h>
int main(void)
{
	printf("%u\n", (unsigned)sizeof(htobe64(1)));
	return 0;
}

On a little endian system this will print 8 while on a big endian system it will print 4. The reason is that on a big endian system the printf line expands to:

printf("%u\n", (unsigned)sizeof((1)));

This can cause many different types of errors (e.g. when passing arguments to a varargs function).

The simplest solution is to change the macros in endian.h to cast the result to the expected type. For example change this:
#define htobe64(x) (x)
to this:
#define htobe64(x) (uint64_t)(x)

I'm going to create a patch for this.


-- System Information:
Debian Release: jessie/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: mips (mips64)

Kernel: Linux 3.2.0-4-5kc-malta
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages libc6-dev depends on:
ii  libc-dev-bin    2.19-1
ii  libc6           2.19-1
ii  linux-libc-dev  3.14.4-1

Versions of packages libc6-dev recommends:
ii  gcc [c-compiler]      4:4.8.2-4
ii  gcc-4.8 [c-compiler]  4.8.3-2

Versions of packages libc6-dev suggests:
pn  glibc-doc     <none>
ii  manpages-dev  3.65-1

-- no debconf information