Previously load() returned true unconditionally on file-open success,
masking truncated or corrupt /regions2 files. Additionally, the first
field of each entry record (r->id) used the same success-chaining
pattern as subsequent fields, so a clean EOF at a record boundary set
success=false and would have been indistinguishable from real
corruption once the return value was fixed.
The r->id read is now split out: n==0 is a clean EOF (break, success
retains its prior value from the header read), n!=sizeof(r->id) is a
partial read or corruption (break, success=false). load() now returns
success instead of an unconditional true, so its return value reflects
the actual parse outcome.
Companion fix to #2372, which fixed the same return-true hardcoding
in save(). (#1891 originally reported this on load() but was closed
when #2372 landed — that PR only touched save(); this addresses the
load() side.)
jirogit
8ef369058d