It appears that the glibc version of asprintf() is braindamaged, and
doesn't set the target pointer to NULL in the event of an error (only
returns -1).  Therefore we need to check the return value.  Just in
case someone else made the *opposite* error, also check the pointer.

Bleh.  The glibc documentation states that *BSD sets the pointer to
NULL, but instead of following that, the glibc people put
warn_unused_result on asprintf.  Sigh.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

RHEL4 had a 2.6.9 kernel, but 2.4.20 Linux kernel headers, so put in a
workaround for 2.4 kernel headers.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Some versions of glibc have broken versions of <linux/loop.h>, so
include our own canned version.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

If we are on a loop device, set bsHidden based on the loopback device
offset.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

Make it possible to distinguish ENOENT from other "non-fatal" errors
in read_adv(), so we can try more than one filename.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

modify_adv() should be used by any installer which uses the common
CLI, so it should go into syslxopt.c.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

This file does not need <sys/types.h>.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Install an empty ADV in the Windows installer to keep it from being
broken.  In order to do that, separate the Unix-specific ADV I/O
functions from the generic data structure manipulation.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

Merge the SYSLINUX and EXTLINUX patching code and core code, removing
EXTLINUX as a separate derivative.  All the disk-based systems now use
the same code.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>