This patch makes hexdump return the number of bytes placed in the buffer
excluding trailing NUL.  In the case of overflow it returns the desired
amount of bytes to produce the entire dump.  Thus, it mimics snprintf().

This will be useful for users that would like to repeat with a bigger
buffer.

[akpm@linux-foundation.org: fix printk warning]
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Test different scenarios of function calls located in lib/hexdump.c.

Currently hex_dump_to_buffer() is only tested and test data is provided
for little endian CPUs.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>