For the following tests I use
mkfile program from OS4Depot.
Using JXFS partition:
8.Work:> mkfile test 64000000
8.Work:> list test
test 64000000 ----rw-d Today 18:46:34
1 file - 61M bytes - 125001 blocks used
8.Work:> mkfile test 63995904
8.Work:> list test
test 64000000 ----rw-d Today 18:49:49
1 file - 61M bytes - 125001 blocks used
8.Work:> mkfile test 6389760
test: Error 73442
8.Work:> list test
test 64000000 ----rw-d Today 18:49:49
1 file - 61M bytes - 125001 blocks used
8.Work:> mkfile test 32000000
test: Error 73442
8.Work:> list test
test 64000000 ----rw-d Today 18:49:49
1 file - 61M bytes - 125001 blocks used
8.Work:>
Using SFS\0 partition (or any other FS):
8.OS4.1:> mkfile test 64000000
8.OS4.1:> list test
test 64000000 ----rwed Today 18:50:37
1 file - 61M bytes - 125001 blocks used
8.OS4.1:> mkfile test 63995904
8.OS4.1:> list test
test 63995904 ----rwed Today 18:50:42
1 file - 61M bytes - 124993 blocks used
8.OS4.1:> mkfile test 6389760
8.OS4.1:> list test
test 6389760 ----rwed Today 18:50:53
1 file - 6240K bytes - 12481 blocks used
8.OS4.1:>
The code that is used in mkfile to change the file size is just a simple ChangeFileSize call like:
IDOS->ChangeFileSize(file, newsize, OFFSET_BEGINNING);