This is a copy of my shell interaction:

$ ls -l
total 13
-rw-r--r--  1 Dan all  1980 Mar  5 17:56 shortnsweet.c
-rw-r--r--  1 Dan all 10962 Mar  5 17:48 writetest.c
$ gcc shortnsweet.c -o shortnsweet
$ ./shortnsweet
chkwrite:: extra bytes written (according to lseek)
        supposed to be     : 1 byte(s)
        actual             : 2 byte(s)
        file pos (pre-wr  ): 10
        file pos (post-wr ): 12
        file size (fstat)  : 12
$ ls -l tstfile
-rw-r--r--  1 Dan all 16 Mar  5 18:05 tstfile
$ gcc writetest.c -o writetest
$ ./writetest
chkwrite:: extra bytes written (according to lseek)
        supposed to be     : 1 byte(s)
        actual             : 2 byte(s)
        total bytes written: 11
        file pos (pre-wr  ): 10
        file pos (post-wr ): 12
        file size (fstat)  : 12
        wrote              : 0xa
        read back          : 0xa
inconsistency:: showing chkread errors:
chkread:: too few bytes read (according to return value of read)
        supposed to be     : 2 byte(s)
        actual             : 1 byte(s)
        file pos (pre-rd)  : 10
        file pos (post-rd) : 12
        read               : 0xa
examine_inconsistency:: read 1 (extra bytes) bytes:: 0xa
examine_inconsistency:: showing chkread errors (intended):
chkread:: extra bytes read (according to lseek)
        supposed to be     : 1 byte(s)
        actual             : 2 byte(s)
        file pos (pre-read): 10
        file pos (post-rd) : 12
        read               : 0xa
examine_inconsistency:: showing chkread errors (intended and extra):
chkread:: too few bytes read (according to return value of read)
        supposed to be     : 2 byte(s)
        actual             : 1 byte(s)
        file pos (pre-rd)  : 10
        file pos (post-rd) : 12
        read               : 0xa
examine_inconsistency:: showing chkread errors (intended and extra+1):
chkread:: too few bytes read (according to return value of read)
        supposed to be     : 3 byte(s)
        actual             : 2 byte(s)
        file pos (pre-rd)  : 10
        file pos (post-rd) : 13
        read               : 0xa 0xb
read_and_fprint_file:: showing chkread errors (entire file):
chkread:: too few bytes read (according to return value of read)
        supposed to be     : 16 byte(s)
        actual             : 15 byte(s)
        file pos (pre-rd)  : 0
        file pos (post-rd) : 16
        read               : 0 0x1 0x2 0x3 0x4 0x5 0x6 0x7 0x8 0x9 0xa 0xb 0xc 0xd 0xe
chklseek_then_read_byte:: read 0 at pos 0
chklseek_then_read_byte:: read 0x1 at pos 0x1
chklseek_then_read_byte:: read 0x2 at pos 0x2
chklseek_then_read_byte:: read 0x3 at pos 0x3
chklseek_then_read_byte:: read 0x4 at pos 0x4
chklseek_then_read_byte:: read 0x5 at pos 0x5
chklseek_then_read_byte:: read 0x6 at pos 0x6
chklseek_then_read_byte:: read 0x7 at pos 0x7
chklseek_then_read_byte:: read 0x8 at pos 0x8
chklseek_then_read_byte:: read 0x9 at pos 0x9
chklseek_then_read_byte:: read 0xa at pos 0xa
chklseek_then_read_byte:: read 0xa at pos 0xb
chklseek_then_read_byte:: read 0xb at pos 0xc
chklseek_then_read_byte:: read 0xc at pos 0xd
chklseek_then_read_byte:: read 0xd at pos 0xe
$ ls -l tstfile
-rw-r--r--  1 Dan all 16 Mar  5 18:07 tstfile