0000397: setbuf and errno - Austin Group Issue Tracker

ID	Project	Category	View Status	Date Submitted	Last Update

0000397	1003.1(2008)/Issue 7	System Interfaces	public	2011-03-17 18:36	2013-04-16 13:06

Reporter	eblake	Assigned To	ajosey
Priority	normal	Severity	Objection	Type	Error
Status	Closed	Resolution	Accepted As Marked

Name	Eric Blake
Organization	Red Hat
User Reference	ebb.setbuf
Section	setbuf
Page Number	1855
Line Number	59282
Interp Status	---
Final Accepted Text	See 0000397:0000799


Summary	0000397: setbuf and errno
Description	Since setbuf is required to be implemented in terms of setvbuf, and the latter is documented as being permitted to set errno on failure, we must document how to detect the same failure for setbuf.
Desired Action	At line 59278 [XSH setbuf DESCRIPTION], add a paragraph with CX shading: setbuf() shall not modify errno on success. Since no value is returned, an application wishing to check for error situations should set errno to 0, call setbuf(), then check errno. At line 59282 [ERRORS], replace "None." with: [CX] Refer to [xref to setvbuf()]. [/CX]
Tags	tc1-2008

geoffclare 2011-05-27 09:39 manager bugnote:0000798	This fixes the discrepancy between setbuf() and setvbuf() for errors, but it also introduces one for successful calls, since setvbuf() is allowed to set errno on success. I suggest the following changes instead of the Desired Action: At line 59272 [XSH setbuf DESCRIPTION] change: Except that it returns no value, the function call: setbuf(stream, buf) shall be equivalent to: setvbuf(stream, buf, _IOFBF, BUFSIZ) if buf is not a null pointer, or to: setvbuf(stream, buf, _IONBF, BUFSIZ) if buf is a null pointer. to: The function call: setbuf(stream, buf) shall be equivalent to: (void) setvbuf(stream, buf, _IOFBF, BUFSIZ) if buf is not a null pointer, or to: (void) setvbuf(stream, buf, _IONBF, BUFSIZ) if buf is a null pointer, [CX]except that setbuf() shall not modify errno on success[/CX]. [CX]Since no value is returned, an application wishing to check for error situations should set errno to 0, call setbuf(), then check errno.[/CX] At line 59282 [ERRORS], replace "None." with: [CX]Refer to [xref to setvbuf()].[/CX]

nick 2011-06-02 15:26 manager bugnote:0000799	Since existing implementations do not work to preserve errno values in the case of no error, the following changes should be made instead: At p 1855 line 59282, change ERRORS text from: No errors are defined. To: Although the setvbuf() interface may set errno in defined ways, the value of errno after a call to setbuf() is unspecified. At line 59289 add to Application Usage: Since errno is not required to be unchanged on success, in order to correctly detect and possibly recover from errors, applications should use setvbuf() instead of setbuf().

Date Modified	Username	Field	Change
2011-03-17 18:36	eblake	New Issue
2011-03-17 18:36	eblake	Status	New => Under Review
2011-03-17 18:36	eblake	Assigned To	=> ajosey
2011-03-17 18:36	eblake	Name	=> Eric Blake
2011-03-17 18:36	eblake	Organization	=> Red Hat
2011-03-17 18:36	eblake	User Reference	=> ebb.setbuf
2011-03-17 18:36	eblake	Section	=> setbuf
2011-03-17 18:36	eblake	Page Number	=> 1855
2011-03-17 18:36	eblake	Line Number	=> 59282
2011-03-17 18:36	eblake	Interp Status	=> ---
2011-05-26 15:50	msbrown	Tag Attached: tc1-2008
2011-05-26 15:50	msbrown	Status	Under Review => Resolved
2011-05-26 15:50	msbrown	Resolution	Open => Accepted
2011-05-27 09:39	geoffclare	Note Added: 0000798
2011-05-27 09:39	geoffclare	Status	Resolved => Under Review
2011-05-27 09:39	geoffclare	Resolution	Accepted => Reopened
2011-06-02 15:26	nick	Note Added: 0000799
2011-06-02 15:29	nick	Final Accepted Text	=> See 0000397:0000799
2011-06-02 15:29	nick	Status	Under Review => Resolved
2011-06-02 15:29	nick	Resolution	Reopened => Accepted As Marked
2013-04-16 13:06	ajosey	Status	Resolved => Closed
2016-07-28 15:08	eblake	Relationship added	related to 0000384

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