Re: sizeof(dev_t) between lomount.c and loop.c

[Pavel Minev Penev <kal_pav@sz.techno-link.com>]

On Thu, Jan 17, 2002 at 03:36:53PM -0500, Michael Zhu wrote:
> In losetup:
> The sizeof(struct loop_info) is 148.
> The sizeof(dev_t) is 8.
> 
> In loop:
> The sizeof(struct loop_info) is 136.
> The sizeof(dev_t) is 2.

Unfortunately dev_t is rather OS-specific, and, therefore, it is a bit
harder to have it defined to the proper type. In util-linux 2.11 a shell
script (attached) is used. It will output a loop.h file which will have
dev_t defined to the correct type.

Hope this helps,
-- 
Pav
#!/bin/sh
#
# Figure out (i) the type of dev_t (ii) the defines for loop stuff
#

rm -f loop.h

# Since 1.3.79 there is an include file <asm/posix_types.h>
# that defines __kernel_dev_t.
# (The file itself appeared in 1.3.78, but there it defined __dev_t.)
# If it exists, we use it, or, rather, <linux/posix_types.h> which
# avoids namespace pollution.  Otherwise we guess that __kernel_dev_t
# is an unsigned short (which is true on i386, but false on alpha).

if [ -f /usr/include/linux/posix_types.h ]; then
   echo '#include <linux/posix_types.h>' >> loop.h
   echo '#undef dev_t' >> loop.h
   echo '#define dev_t __kernel_dev_t' >> loop.h
else
   echo '#undef dev_t' >> loop.h
   echo '#define dev_t unsigned short' >> loop.h
fi

# Next we have to find the loop stuff itself.
# First try kernel source, then a private version.

if [ -f /usr/include/linux/loop.h ]; then
   echo '#include <linux/loop.h>' >> loop.h
else
   echo '#include "h/loop.h"' >> loop.h
fi

echo '#undef dev_t' >> loop.h