of repeating unsuccessful lseek call on each write (original stdio bug).
2) Save errno accross _sseek call in _swrite to not touch it in case write
success (original stdio bug).
3) Add _sseek error checking back, but only for __SOPT mode now.
with non-seekable streams. Now here is what here was originally, but it is
ugly, producing unneded seek syscall on each non-seekable stream write. I'll
think about proper solution later.
plain regular files, i.e. files with __SOPT flag set. Fix it, so ftell(stdout)
always returns the same as lseek(1, 0, 1) now.
NOTE: this bug was in original stdio code
__swrite() and __sseek() to higher level. According to funopen(3) they all
are just wrappers to something like standard read(2), write(2) and
lseek(2), i.e. must not touch stdio internals because they are replaceable
with any other functions knows nothing about stdio internals. See example
of funopen(3) usage in sendmail sources f.e.
NOTE: this is original stdio bug, not result of my range checkin added.
internal functions there may fail and set (i.e. overwrite) errno in normal
(not error) situation). In original variant errno testing after call
(as POSIX suggest) is wrong when errno overwrite happens.
0, return that we can't specify it, i.e. error with ESPIPE.
(hint from: "Peter S. Housel" <housel@acm.org>)
Back out sinit() addition, not needed after various code simplifications.
When file offset tends to be negative due to internal and ungetc buffers
additions counted, try to discard some ungetc data first, then return EBADF.
Later one can happens if lseek(fileno(fd),...) called f.e. POSIX says that
ungetc beyond beginning of the file results are undefined, so we can just
discard some of ungetc data in that case.
Don't rely on gcc cast when checking for overflow, use OFF_MAX.
Cosmetique.
Resulting fseek() offset must fit in long, required by POSIX (pointed by bde),
so add LONG_MAX and final tests for it.
rewind.c:
1) add missing __sinit() as in fseek() it pretends to be.
2) use clearerr_unlocked() since we already lock stream before _fseeko()
3) don't zero errno at the end, it explicitely required by POSIX as the
only one method to test rewind() error condition.
4) don't clearerr() if error happens in _fseeko()
"[EINVAL] ... The resulting file-position indicator would be set to a
negative value."
Moreover, in real life negative seek in stdio cause EOF indicator cleared
and not set again forever even if EOF returned.
2) Catch few possible off_t overflows.
Reviewed by: arch discussion
