5.6.1 Portability of Headers

This section documents some collected knowledge about common headers, and the problems they cause. By definition, this list always requires additions. A much more complete list is maintained by the Gnulib project (see Gnulib), covering Posix Headers and Glibc Headers. Please help us keep the gnulib list as complete as possible.

limits.h

C99 says that limits.h defines LLONG_MIN, LLONG_MAX, and ULLONG_MAX, but many almost-C99 environments (e.g., default GCC 4.0.2 + glibc 2.4) do not define them.

inttypes.h vs. stdint.h

The C99 standard says that inttypes.h includes stdint.h, so there's no need to include stdint.h separately in a standard environment. Some implementations have inttypes.h but not stdint.h (e.g., Solaris 7), but we don't know of any implementation that has stdint.h but not inttypes.h.

linux/irda.h

It requires linux/types.h and sys/socket.h.

linux/random.h

It requires linux/types.h.

net/if.h

On Darwin, this file requires that sys/socket.h be included beforehand. One should run:

          AC_CHECK_HEADERS([sys/socket.h])
          AC_CHECK_HEADERS([net/if.h], [], [],
          [#include <stdio.h>
          #ifdef STDC_HEADERS
          # include <stdlib.h>
          # include <stddef.h>
          #else
          # ifdef HAVE_STDLIB_H
          #  include <stdlib.h>
          # endif
          #endif
          #ifdef HAVE_SYS_SOCKET_H
          # include <sys/socket.h>
          #endif
          ])

netinet/if_ether.h

On Darwin, this file requires that stdio.h and sys/socket.h be included beforehand. One should run:

          AC_CHECK_HEADERS([sys/socket.h])
          AC_CHECK_HEADERS([netinet/if_ether.h], [], [],
          [#include <stdio.h>
          #ifdef STDC_HEADERS
          # include <stdlib.h>
          # include <stddef.h>
          #else
          # ifdef HAVE_STDLIB_H
          #  include <stdlib.h>
          # endif
          #endif
          #ifdef HAVE_SYS_SOCKET_H
          # include <sys/socket.h>
          #endif
          ])

stdint.h

See above, item inttypes.h vs. stdint.h.

stdlib.h

On many systems (e.g., Darwin), stdio.h is a prerequisite.

sys/mount.h

On FreeBSD 4.8 on ia32 and using gcc version 2.95.4, sys/params.h is a prerequisite.

sys/ptem.h

On Solaris 8, sys/stream.h is a prerequisite.

sys/socket.h

On Darwin, stdlib.h is a prerequisite.

sys/ucred.h

On Tru64 5.1, sys/types.h is a prerequisite.

X11/extensions/scrnsaver.h

Using XFree86, this header requires X11/Xlib.h, which is probably so required that you might not even consider looking for it.

          AC_CHECK_HEADERS([X11/extensions/scrnsaver.h], [], [],
          [[#include <X11/Xlib.h>
          ]])