[haiku-bugs] Re: [Haiku] #3145: fseek does not discard ungetc buffer
- From: "zooey" <trac@xxxxxxxxxxxx>
- Date: Wed, 29 Dec 2010 22:24:24 -0000
#3145: fseek does not discard ungetc buffer
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Reporter: bhaible | Owner: zooey
Type: bug | Status: in-progress
Priority: normal | Milestone: R1
Component: System/libroot.so | Version: R1/pre-alpha1
Resolution: | Keywords:
Blocked By: | Has a Patch: 1
Platform: All | Blocking:
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Comment (by zooey):
Replying to [comment:6 hamish]:
> _IO_buf_base points to the start of the entire stream buffer, while
_IO_read_base points to the start of the read part of the stream buffer.
ungetc() and friends store characters in the bytes between _IO_buf_base
and _IO_read_base, so the seek function must take these into account and
skip them.
Not quite, no: ungetc() invokes _IO_sputbackc(), which puts back
characters between _IO_read_ptr and _IO_read_base - _IO_buf_base doesn't
play any role there.
That's why I still fail to understand what exactly your patch does that
causes the good effect. More importantly, I'm not at all sure it doesn't
actually break other use cases. Have you tried running all gnulib tests to
see if applying your patch doesn't introduce new problems?
--
Ticket URL: <http://dev.haiku-os.org/ticket/3145#comment:7>
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