View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000401 | 1003.1(2008)/Issue 7 | System Interfaces | public | 2011-03-31 16:50 | 2013-04-16 13:06 |
| Reporter | eblake | Assigned To | ajosey | ||
| Priority | normal | Severity | Objection | Type | Omission |
| Status | Closed | Resolution | Accepted As Marked | ||
| Name | Eric Blake | ||||
| Organization | Red Hat | ||||
| User Reference | ebb.ferror | ||||
| Section | ferror | ||||
| Page Number | 835 | ||||
| Line Number | 27871 | ||||
| Interp Status | Approved | ||||
| Final Accepted Text | 0000401:0000747 | ||||
| Summary | 0000401: ferror should not modify errno | ||||
| Description | The standard states that unless explicitly documented otherwise, the value of errno is unspecified after a successful function call. However, it is common to use ferror() to check whether other stream-based functions failed, and is commonly implemented without modifying errno, therefore it would be nice to guarantee that errno is unchanged over a successful call, rather than requiring that applications save errno before ferror() and then rely on a non-zero result to learn whether the previously saved value is useful. For consistency, feof() and clearerr() can be given the same treatment. Note that as an extension, an implementation may guarantee that ferror will fail and set errno on detection of an invalid stream argument, but this is already unspecified behavior and does not need further mention in the standard. There is still no return value nor errno value reserved for this case in the standard, so an implementation providing such an extension would also document that setting errno to 0 prior to ferror() and observing a change in errno could be used to detect such failures. | ||||
| Desired Action | At line 22502 [XSH clearerr DESCRIPTION], add a sentence with CX shading: <CX>The clearerr() function shall not change the setting of errno if stream is valid.</CX> At line 27807 [XSH feof DESCRIPTION], add a sentence with CX shading: <CX>The feof() function shall not change the setting of errno if stream is valid.</CX> At line 27871 [XSH ferror DESCRIPTION], add a sentence with CX shading: <CX>The ferror() function shall not change the setting of errno if stream is valid.</CX> Optional: If this is approved at the same time as 0000389 and 0000399, then those resolutions should also be simplified accordingly: For 0000389, change the proposed wording at line 45791 to: ... an application wishing to check for error situations should call clearerr(stderr) before calling perror(), then if ferror(stderr) returns non-zero, the value of errno indicates which error occurred. and delete the first proposed sentence at 45810 (When using ferror() to detect whether perror() encountered an error, it is necessary to save the value of errno before the call to ferror() since this call can change the value of errno.) For 0000399, change the proposed wording at line 49339 to: ... An application wishing to use this method to check for error situations should call clearerr(stderr) before calling psiginfo() or psignal(), then if ferror(stderr) returns non-zero, the value of errno indicates which error occurred. | ||||
| Tags | tc1-2008 | ||||
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Interpretation response ------------------------ The standard does not speak to this issue, and as such no conformance distinction can be made between alternative implementations based on this. This is being referred to the sponsor. Rationale: ------------- This change should not break any known existing implementations, and will aid application developers. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- Use the instructions in the Desired Action section, including the optional sections. |
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Interpretation proposed 16 June 2011 for final 30 day review |
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The interpretation is now approved. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2011-03-31 16:50 | eblake | New Issue | |
| 2011-03-31 16:50 | eblake | Status | New => Under Review |
| 2011-03-31 16:50 | eblake | Assigned To | => ajosey |
| 2011-03-31 16:50 | eblake | Name | => Eric Blake |
| 2011-03-31 16:50 | eblake | Organization | => Red Hat |
| 2011-03-31 16:50 | eblake | User Reference | => ebb.ferror |
| 2011-03-31 16:50 | eblake | Section | => ferror |
| 2011-03-31 16:50 | eblake | Page Number | => 835 |
| 2011-03-31 16:50 | eblake | Line Number | => 27871 |
| 2011-03-31 16:50 | eblake | Interp Status | => --- |
| 2011-03-31 16:51 | eblake | Relationship added | related to 0000389 |
| 2011-03-31 16:51 | eblake | Relationship added | related to 0000399 |
| 2011-03-31 16:53 | eblake | Desired Action Updated | |
| 2011-04-21 15:40 | msbrown | Interp Status | --- => Pending |
| 2011-04-21 15:40 | msbrown | Note Added: 0000747 | |
| 2011-04-21 15:40 | msbrown | Type | Omission => Enhancement Request |
| 2011-04-21 15:40 | msbrown | Status | Under Review => Interpretation Required |
| 2011-04-21 15:40 | msbrown | Resolution | Open => Future Enhancement |
| 2011-04-21 15:41 | msbrown | Final Accepted Text | => 0000401:0000747 |
| 2011-04-21 15:41 | msbrown | Type | Enhancement Request => Omission |
| 2011-04-21 15:41 | msbrown | Resolution | Future Enhancement => Accepted As Marked |
| 2011-04-21 15:43 | nick | Tag Attached: tc1-2008 | |
| 2011-06-16 10:16 | ajosey | Interp Status | Pending => Proposed |
| 2011-06-16 10:16 | ajosey | Note Added: 0000846 | |
| 2011-07-29 06:14 | ajosey | Interp Status | Proposed => Approved |
| 2011-07-29 06:14 | ajosey | Note Added: 0000906 | |
| 2013-04-16 13:06 | ajosey | Status | Interpretation Required => Closed |
| 2016-07-28 15:06 | eblake | Relationship added | related to 0000384 |
