View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0000711 | 1003.1(2013)/Issue7+TC1 | System Interfaces | public | 2013-06-16 22:46 | 2024-06-11 09:02 |
| Reporter | dalias | Assigned To | |||
| Priority | normal | Severity | Editorial | Type | Clarification Requested |
| Status | Closed | Resolution | Accepted As Marked | ||
| Name | Rich Felker | ||||
| Organization | musl libc | ||||
| User Reference | |||||
| Section | XSH 2.4.3 Signal Actions | ||||
| Page Number | 494 | ||||
| Line Number | 16876 | ||||
| Interp Status | Approved | ||||
| Final Accepted Text | See 0000711:0001655 | ||||
| Summary | 0000711: Are the stdarg.h macros async-signal-safe? | ||||
| Description | XSH 2.4.3 lists functions which are async-signal-safe and does not include va_* in its list; however, va_* are specified to be macros and functions are not required to exist. Thus, it seems unclear to me whether variadic functions may access their arguments from an async-signal context. | ||||
| Desired Action | Clarify whether va_* are async-signal-safe, preferably in the affirmative unless there is a significant historical reason for allowing them to be unsafe. | ||||
| Tags | issue8 | ||||
| related to | 0001302 | Closed | 1003.1(2016/18)/Issue7+TC2 | Alignment with C17 |
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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: ------------- None Notes to the Editor (not part of this interpretation): ------------------------------------------------------- At line 16841, change "or if the signal handler calls any function defined in this standard other than one of the functions listed in the following table" to "or if the signal handler calls any function or function-like macro defined in this standard other than one of the functions and macros listed in the following table" At line 16843, change "a set of functions" to "a set of functions and function-like macros" and add va_arg va_copy va_end va_start to the list in proper alphabetical order. At line 16880, change "All functions" to "All functions or function-like macros" At line 16883, change "signal interrupts an unsafe function and the signal-catching function calls an unsafe function, the behavior is undefined." to "signal interrupts an unsafe function or function-like macro and the signal-catching function calls an unsafe function or function-like macro, the behavior is undefined." |
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It's come to my attention that there are a number of other function-like macros such as FD_* (used with select) which may need to be added to this list. It may also be important to review whether there are historic implementations where said macros are not async-signal-safe, and whether requiring them to be safe is an omission that can be added in TC2 or a new requirement for the next issue. I seem to recall there being some ancient systems, albeit possibly only theoretical ones, where va_start involved allocation; otherwise, there would have been no motivation for va_end to exist. |
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We discussed 0000711:0001656 during the June 27, 2013 conference call. If additional function-like macros need to be added to the table, please submit a bug report (or reports) with the additional macros that need to be addressed. This bug is going through the interpretations track, so if some implementations have a problem with making va_* macros async-signal safe, they can note the issue during the interpretation review process. |
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Interpretation Proposed 6 Sep 2013 |
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Interpretation approved 14 October 2013 |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2013-06-16 22:46 | dalias | New Issue | |
| 2013-06-16 22:46 | dalias | Name | => Rich Felker |
| 2013-06-16 22:46 | dalias | Organization | => musl libc |
| 2013-06-16 22:46 | dalias | Section | => XSH 2.4.3 Signal Actions |
| 2013-06-16 22:46 | dalias | Page Number | => unknown |
| 2013-06-16 22:46 | dalias | Line Number | => unknown |
| 2013-06-20 15:58 | Don Cragun | Page Number | unknown => 494 |
| 2013-06-20 15:58 | Don Cragun | Line Number | unknown => 16876 |
| 2013-06-20 15:58 | Don Cragun | Interp Status | => --- |
| 2013-06-20 16:29 | nick | Note Added: 0001655 | |
| 2013-06-20 16:30 | nick | Tag Attached: issue8 | |
| 2013-06-20 19:36 | dalias | Note Added: 0001656 | |
| 2013-06-27 15:35 | nick | Note Edited: 0001655 | |
| 2013-06-27 15:37 | nick | Interp Status | --- => Pending |
| 2013-06-27 15:37 | nick | Final Accepted Text | => See 0000711:0001655 |
| 2013-06-27 15:37 | nick | Status | New => Interpretation Required |
| 2013-06-27 15:37 | nick | Resolution | Open => Accepted As Marked |
| 2013-06-27 15:38 | nick | Note Edited: 0001655 | |
| 2013-06-27 15:38 | nick | Tag Attached: tc2-2008 | |
| 2013-06-27 15:38 | nick | Tag Detached: tc2-2008 | |
| 2013-06-27 15:40 | nick | Note Edited: 0001655 | |
| 2013-06-27 15:41 | nick | Note Edited: 0001655 | |
| 2013-06-27 15:43 | nick | Note Edited: 0001655 | |
| 2013-06-27 15:45 | nick | Note Edited: 0001655 | |
| 2013-06-27 16:03 | Don Cragun | Note Added: 0001659 | |
| 2013-09-06 04:54 | ajosey | Interp Status | Pending => Proposed |
| 2013-09-06 04:54 | ajosey | Note Added: 0001806 | |
| 2013-10-14 13:07 | ajosey | Interp Status | Proposed => Approved |
| 2013-10-14 13:07 | ajosey | Note Added: 0001894 | |
| 2019-11-20 15:42 | geoffclare | Relationship added | related to 0001302 |
| 2020-03-24 15:58 | geoffclare | Status | Interpretation Required => Applied |
| 2024-06-11 09:02 | agadmin | Status | Applied => Closed |
