svn commit: r268984 - head/lib/libc/stdio

[Andrey Chernov]

On 22.07.2014 21:08, Andrey Chernov wrote:
> On 22.07.2014 20:44, Andrey Chernov wrote:
>> Producing physical writes on ftell cause great performance degradation.
>> You should check for __SAPP flag before calling sflush to do this only
>> for append-mode files.
> 
> BTW, I believe that sflush() should be completely eliminated even for
> _SAPP case. Something like that instead:

Proper patch to the old version:

--- ftell.c.bak	2014-07-22 21:25:46.000000000 +0400
+++ ftell.c	2014-07-22 21:28:01.000000000 +0400
@@ -118,6 +118,11 @@
 		if (HASUB(fp))
 			pos -= fp->_r;  /* Can be negative at this point. */
 	} else if ((fp->_flags & __SWR) && fp->_p != NULL) {
+		if (fp->_flags & __SAPP) {
+			pos = _sseek(fp, (fpos_t)0, SEEK_END);
+			if (pos == -1)
+				return (1);
+		}
 		/*
 		 * Writing.  Any buffered characters cause the
 		 * position to be greater than that in the

Forget the code below, it breaks reading:

> if (fp->_flags & __SAPP) {
> 	pos = _sseek(fp, (fpos_t)0, SEEK_END);
> 	if (pos == -1)
>      		return (1);
> } else if (fp->_flags & __SOFF)
> 	pos = fp->_offset;
> else {
>         pos = _sseek(fp, (fpos_t)0, SEEK_CUR);
> 	if (pos == -1)
>      		return (1);
> }
> 
>>
>> On 22.07.2014 20:19, Pedro F. Giffuni wrote:
>>> Author: pfg
>>> Date: Tue Jul 22 16:19:01 2014
>>> New Revision: 268984
>>> URL: http://svnweb.freebsd.org/changeset/base/268984
>>>
>>> Log:
>>>   ftello: return 1 when seeking offset on an append stream.
>>>   
>>>   Obtained from:	Apple Inc. (Libc 997.90.3)
>>>   Phabric:	D442
>>>   MFC after:	2 weeks
>>>
>>> Modified:
>>>   head/lib/libc/stdio/ftell.c
>>>
>>> Modified: head/lib/libc/stdio/ftell.c
>>> ==============================================================================
>>> --- head/lib/libc/stdio/ftell.c	Tue Jul 22 16:10:56 2014	(r268983)
>>> +++ head/lib/libc/stdio/ftell.c	Tue Jul 22 16:19:01 2014	(r268984)
>>> @@ -97,6 +97,8 @@ _ftello(FILE *fp, fpos_t *offset)
>>>  	 * Find offset of underlying I/O object, then
>>>  	 * adjust for buffered bytes.
>>>  	 */
>>> +	if (__sflush(fp))	/* may adjust seek offset on append stream */
>>> +		return (1);
>>>  	if (fp->_flags & __SOFF)
>>>  		pos = fp->_offset;
>>>  	else {
>>>
>>
>>
> 
> 


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