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Problem: API Set 1(Draft January 12, 2006)
There are three defects detected in the description of the fmemopen()
function.
1.
The description reads:
321 If a null pointer is specified as the buf argument,
fmemopen( ) shall allocate size bytes of memory
322 as if
by a call to malloc( ). This buffer shall be automatically freed when the stream
is closed.
323 Because this feature is only useful when
the stream is opened for updating (because there is no
324
way to get a pointer to the buffer) the fmemopen( ) call may fail if the mode
argument does not
325 include a ’+’.
326 The stream maintains a current position in the
buffer. This position is initially set to either the
327
begining of the buffer (for r and w modes) or to the first null byte in the
buffer (for a modes). If
328 no null byte is found in append
mode, the initial position is set to one byte after the end of
the
329 buffer.
It follows if a null pointer is specified as the buf argument and mode had
'a' as the first character,
the initial value of the current position is a random value.
Memory allocated by a call to malloc( ) contains accidental bytes. So the
first null byte in the buffer is
at a random position.
Proposed action:
Add explicit definition of the initial value of the current position
in this situation.
The begining of the buffer is the best choice in my view.
2.
The misprint is in the sentence at lines 336-337: 'The write operation
starts at the current buffer position of the stream.'
I guess it shall read: 'The read operation starts at the current
buffer position of the stream.'
334 A read operation on the stream cannot advance the
current buffer position behind the current
335 buffer
size. Reaching the buffer size in a read operation counts as "end of file". Null
bytes in the
336 buffer have no special meaning for reads.
The write operation starts at the current buffer
337
position of the stream.
338 A write operation starts either at the current
position of the stream (if mode has not specified a
339 as
the first character) or at the current size of the stream (if mode had a as the
first character). If
340 the current position at the end
of the write is larger than the current buffer size, the
current
341 buffer size is set to the current position. A
write operation on the stream cannot advance the
342
current buffer size behind the size given in the size argument.
Proposed action:
Replace
334 A read operation on the stream cannot advance the
current buffer position behind the current
335 buffer
size. Reaching the buffer size in a read operation counts as "end of file". Null
bytes in the
336 buffer have no special meaning for reads.
The write operation starts at the current buffer
337
position of the stream.
by
334 A read operation on the stream cannot advance the
current buffer position behind the current
335 buffer
size. Reaching the buffer size in a read operation counts as "end of file". Null
bytes in the
336 buffer have no special meaning for reads.
The read operation starts at the current buffer
337
position of the stream.
3.
The description
343 When a stream open for writing is flushed or closed,
a null byte is written at the end of the buffer
344 if it
fits. If a stream open for update is flushed or closed and the last write has
advanced the
345 current buffer size, a null byte is
written at the end of the buffer if it fits.
346 An
attempt to seek a memory buffer stream to a negative position or to a position
larger than the
347 buffer size given in the size argument
shall fail.
is unclear.
'the end of the buffer' can be understood in two ways: either the size of
the current contents
or the size of the buffer itself.
'if it fits' in this context is also unclear.
P.S.
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