fix ipmitool crash with fru edit #12

The current implementation of ipmitool fru edit does not perform proper
checks when attempting to resize the FRU. This results in undesireable
changes to the FRU in several instances:
1. If the FRU is shrinking and a FRU area does not exist (offset 0),
ipmitool may attempt to shift it forwards (decrementing the offset).
This results in a wraparound to 0xFF, leaving an erroneous field offset.
2. If the areas are not in the exact order given as an example in the
FRU spec, ipmitool may shift the wrong fields, which would cause data
loss. (the FRU spec does not specify a required order for FRU fields)
3. If the FRU is being enlarged after a fru field edit, the FRU size is
not properly modified before writing the FRU, so the end of the FRU
becomes truncated, resulting in data loss.
This commit addresses these three issues by:
1. Confirming that a area's does not have an offset of 0x00 before
attempting to shift it.
2. Ensuring that the area's offset is after the area that was modified
before attempting to shift it.
3. Properly edit the size of the FRU before the FRU is written.
Tested:
Shrinking a FRU was tested with and without the change:
New Header without change:
01 00 00 01 0a ff 00 f5
 ^^
Note that the Multi Record area now has an offset of 0xFF.
New Header with change:
01 00 00 01 0a 00 00 f4
 ^^
Note that the Multi Record area retains its offset of 0x00.
This change also includes printouts specifying what offsets are found
and when they are being shifted, as well as data being erased if the FRU
is being shrunk:
Offset: 0
Offset: 0
Offset: 8
Offset: 88 moving by -8 bytes.
Offset: 0
Erasing leftover data from 200 to 208
After shrinking the FRU, the FRU was reverted to its original state with
the fix in place:
01 00 00 01 0b 00 00 f3
 ^^
This resulted in only the product area offset being updated as expected.
Offset: 0
Offset: 0
Offset: 8
Offset: 80 moving by 8 bytes.
Offset: 0
The implementation of IPMI FRU write used in these tests errors out
without writing the FRU if a checksum fails to pass, so without this
fix, it was impossible to enlarge the FRU. This is because without the
change, the last 8 bytes of the FRU would be truncated which would
result in the checksum of the final FRU area being lost which would thus
trigger this FRU write failure.
Signed-off-by: Alex Schendel <alex.schendel@intel.com>

Replaced literal int with macro and fixed formatting errors.
Signed-off-by: Schendel <alex.schendel@intel.com>

fru edit command can increase fru size. Allocate new fru data with
the bigger size. This fixes ipmitool crash when fru edit increases fru
size.
Tested:
fru edit command that increases fru size complete successfully.
Signed-off-by: Zhikui Ren <zhikui.ren@intel.com>

Reviewed-on: ZhikuiRen/ipmitool#1