0000063: EPERM error under futimens() appears to be faulty

Austin Group Defect Tracker

Aardvark Mark III

Viewing Issue Simple Details [ Jump to Notes ]

[ Issue History ] [ Print ]

Category

Severity

Type

Date Submitted

Last Update

0000063

[1003.1(2008)/Issue 7] System Interfaces

Comment

Error

2009-06-26 14:14

2009-10-09 16:29

Reporter

msbrown

View Status

public

Assigned To

ajosey

Priority

normal

Resolution

Accepted

Status

Interpretation Required

Name

Mark Brown

Organization

IBM

User Reference

Section

futimens

Page Number

969

Line Number

32433

Interp Status

Approved

Final Accepted Text

Note: 0000229

Summary

0000063: EPERM error under futimens() appears to be faulty

Description

COMMENT Enhancement Request Number 1
michael.kerrisk:xxxxxxxxx Bug in XSHd5 futimens (rdvk# 1)
{utimensat-errs} Wed, 14 May 2008 22:43:49 +0100 (BST)
---------------------
The text describing the EPERM error under futimens() appears to be faulty.

Consider the following table, which describes the three parameters
affecting the success or failure of these interfaces. In the table,
the columns are:
[a] Is the time argument NULL (or in the case of futimens() and
utimnensat() points to a structure in which both fields are UTIME_NOW
or both are UTIME_OMIT), or does it point to a structure containing
timestamps?
[b] Does the caller's effective UID match the owner of the file?
[c] Is the file writable by the caller's effective UID?

  [a]    [b]      [c]
 times  file     file
 arg.    UID      is
 NULL   owner   writable        Result
 !NULL  !owner  !writable

 N      o          w            success
 N      o          !w           success
 N      !          w            success
 N      !o         !w           EACCES [1]
 !N     o          w            success
 !N     o          !w           success
 !N     !o         w            EPERM [2]
 !N     !o         !w           EPERM [3]

The fourth column shows the expected result of calling the interface.
However, the text describing the errors does not cover all three error
cases above:

Error case [1] is covered by the EACCES description:
[EACCES]
The times argument is a null pointer, or both tv_nsec values are
UTIME_NOW, and the effective user ID of the process does not match the
owner of the file and write access is denied.

Error case [2] is covered by the EPERM description:
[EPERM]
The times argument is not a null pointer, does not have both tv_nsec
fields set to UTIME_NOW, does not have both tv_nsec fields set to
UTIME_OMIT, the calling process effective user ID has write access to
the file but does not match the owner of the file, and the calling
process does not have appropriate privileges.

Error case [3] is not covered by either of the above descriptions.

Lines 32400-32403 of the draft say :

     Only a process with the effective user ID equal to the
     user ID of the file or with appropriate privileges may
     use futimens() or utimensat() with a non-null times
     argument that does not have both tv_nsec fields set to
     UTIME_NOW and does not have both tv_nsec fields set to
     UTIME_OMIT.

Looking at these lines suggests that the text for the EPERM error
should remove discussion of write access to the file, since the error
applies regardless of whether the file is writable.

Desired Action

Replace lines 32431 to 32435 with the following:

[EPERM]
The times argument is not a null pointer, does not have both tv_nsec
fields set to UTIME_NOW, does not have both tv_nsec fields set to
UTIME_OMIT, the calling process effective user ID does not match the
owner of the file, and the calling process does not have appropriate
privileges.

Tags

No tags attached.

Attached Files

Relationships

Notes
(0000229) ajosey (manager) 2009-09-17 15:16	Interpretation response ------------------------ The standard is unclear on this issue, and no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor. Rationale: ------------- None. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- Make the change suggested by the submitter

Issue History
Date Modified	Username	Field	Change
2009-06-26 14:14	msbrown	New Issue
2009-06-26 14:14	msbrown	Status	New => Under Review
2009-06-26 14:14	msbrown	Assigned To	=> ajosey
2009-06-26 14:14	msbrown	Name	=> Mark Brown
2009-06-26 14:14	msbrown	Organization	=> IBM
2009-06-26 14:14	msbrown	Section	=> futimens
2009-06-26 14:14	msbrown	Page Number	=> 969
2009-06-26 14:14	msbrown	Line Number	=> 32433
2009-06-26 14:15	msbrown	Status	Under Review => Resolved
2009-06-26 14:15	msbrown	Resolution	Open => Accepted
2009-07-30 16:26	msbrown	Status	Resolved => Interpretation Required
2009-07-30 16:26	msbrown	Description Updated
2009-08-11 16:27	Don Cragun	Interp Status	=> Pending
2009-09-17 15:16	ajosey	Note Added: 0000229
2009-09-17 15:17	ajosey	Final Accepted Text	=> Note: 0000229
2009-09-17 15:41	nick	Interp Status	Pending => Proposed
2009-10-09 16:29	ajosey	Interp Status	Proposed => Approved

Mantis 1.1.6[^]