[M] Change in flashrom[main]: erasure_layout: don't copy region buffers if they're null/zero-size

[Anastasia Klimchuk (Code Review)]

Attention is currently required from: Aarya, Alexander Goncharov, Nikolai Artemiev.

Anastasia Klimchuk has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/81548?usp=email )

Change subject: erasure_layout: don't copy region buffers if they're null/zero-size
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Patch Set 2:

(4 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/81548/comment/fd0cc90d_526bab2a :
PS2, Line 10: the pointer is null
I think from the meaning of the patch, you meant to say
`the pointer is non-null`

File erasure_layout.c:

https://review.coreboot.org/c/flashrom/+/81548/comment/7680b945_70a9f658 :
PS1, Line 263: 	old_start_buf = (uint8_t *)malloc(old_start - region_start);
             : 	if (!old_start_buf) {
             : 		msg_cerr("Not enough memory!\n");
             : 		ret = -1;
             : 		goto _end;
             : 	}
             : 	old_end_buf = (uint8_t *)malloc(region_end - old_end);
             : 	if (!old_end_buf) {
             : 		msg_cerr("Not enough memory!\n");
             : 		ret = -1;
             : 		goto _end;
             : 	}
> Sorry it took longer than I expected. […]

Great! this is what I was thinking about! I am resolving this comment.
I added few more other comments though :)

File erasure_layout.c:

https://review.coreboot.org/c/flashrom/+/81548/comment/dd093a22_69ec2718 :
PS2, Line 263: size_t old_start_len
This can be const, but also

maybe rename it into `start_buf_len` ?
I think that "old" suffix doesn't really explain anything. What do you think?

https://review.coreboot.org/c/flashrom/+/81548/comment/47062ded_d9a3f306 :
PS2, Line 264: size_t old_end_len
And this can be const and `end_buf_len`