[XS] Change in flashrom[main]: Add clarification to struct flash_region on chipoff_t

[Peter Marheine (Code Review)]

Peter Marheine has uploaded this change for review. ( https://review.coreboot.org/c/flashrom/+/82677?usp=email )

Change subject: Add clarification to struct flash_region on chipoff_t
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Add clarification to struct flash_region on chipoff_t

Although chipoff_t is fairly clearly documented on its own, it seems
fairly frequent that developers will treat the end address of a flash
region as an exclusive upper bound rather than the inclusive one it
should be; for example CB:82496 fixes an incorrect use that affected
multiple sites, and CB:73571 stemmed from a similar cause. Add a
clarifying comment to call attention to this, to help programmers avoid
making similar mistakes in the future.

Change-Id: I80b61a87ca31bd5a116224aadb4e211ee6841e1f
Signed-off-by: Peter Marheine 
---
M include/layout.h
1 file changed, 5 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/77/82677/1

diff --git a/include/layout.h b/include/layout.h
index 5614bea..d03a15b 100644
--- a/include/layout.h
+++ b/include/layout.h
@@ -37,6 +37,11 @@

struct flash_region {
    char *name;
+	/*
+	 * Note that because start and end are chipoff_t, end is an inclusive upper
+	 * bound: the length of a region is (end - start + 1) bytes and it is
+	 * impossible to represent a region with zero length.
+	 */
    chipoff_t start;
    chipoff_t end;
    bool read_prot;