Paul H. Hargrove wrote:
Quoting from a different manpage for ftruncate:
[T]he POSIX standard allows two behaviours for ftruncate
when length exceeds the file length [...]: either returning an
error, or
extending the file.
So, if that is to be trusted, it is not legal by POSIX to *silently*
not extend the file.
On a Solaris system, the ftruncate man page says:
truncate, ftruncate - set a file to a specified length
The truncate() function causes the regular file named by
path to have a size equal to length bytes.
If the file previously was larger than length, the extra
data is discarded. If the file was previously shorter than
length, its size is increased, and the extended area appears
as if it were zero-filled.
So, the sense is not of "truncating" (shortening) per se, but of fixing
a new length, whether that length is longer or shorter.
I guess we could try to track down the ftruncate behavior on the systems
in question, but (IMHO) this doesn't feel like the correct explanation.
