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| ID | Category | Severity | Type | Date Submitted | Last Update | ||
| 0000396 | [1003.1(2008)/Issue 7] System Interfaces | Objection | Error | 2011-03-17 18:11 | 2013-04-16 13:06 | ||
| Reporter | eblake | View Status | public | ||||
| Assigned To | ajosey | ||||||
| Priority | normal | Resolution | Accepted | ||||
| Status | Closed | ||||||
| Name | Eric Blake | ||||||
| Organization | Red Hat | ||||||
| User Reference | ebb.fmemopen | ||||||
| Section | fmemopen | ||||||
| Page Number | 866 | ||||||
| Line Number | 28743 | ||||||
| Interp Status | Approved | ||||||
| Final Accepted Text | See Note: 0000795 | ||||||
| Summary | 0000396: fmemopen vs. 'b' mode flag | ||||||
| Description |
When fmemopen was first proposed for addition in the standard during the 2006 Extended API Set documents, it was derived from the glibc implementation, which at that time silently ignored the 'b' flag in the mode argument. However, before POSIX 2008 was ratified, the glibc implementation changed behavior to give the 'b' flag a specific meaning: http://sourceware.org/bugzilla/show_bug.cgi?id=6544 [^] (Aug 2008) with the current glibc documentation of: Since glibc 2.9, the letter 'b' may be specified as the second character in mode. This provides "binary" mode: writes don't implicitly add a terminating null byte, and fseek(3) SEEK_END is relative to the end of the buffer (i.e., the value specified by the size argument), rather than the current string length. When this was pointed out to the glibc maintainers, they argued that since the POSIX specification of fmemopen used the glibc implementation as the reference, then POSIX rather than glibc should be changed to permit the glibc behavior that was in effect at the time POSIX 2008 was ratified: http://sourceware.org/bugzilla/show_bug.cgi?id=12503 [^] The desired action for this bug is designed for TC1, to permit current glibc behavior without penalizing other implementations that implemented what was standardized (most other implementations documented fmemopen mode flags based on POSIX wording, so the new wording can require implementation-defined rather than unspecified behavior). However, given that glibc has determined that binary string processing seems useful, we should probably also open consider a separate proposal for Issue 8 that mandates the new glibc behavior (although possibly with a new mode flag, rather than 'b'). |
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| Desired Action |
At lines 28743-28749 [XSH fmemopen DESCRIPTION], change the first column: r or rb w or wb a or ab r+ or rb+ or r+b w+ or wb+ or w+b a+ or ab+ or a+b to: r w a r+ w+ a+ At line 28751, replace: The character ’b’ shall have no effect. with: Implementations shall accept all mode strings allowed by fopen(), but the use of the character 'b' shall produce implementation-defined results, where the resulting FILE * need not behave the same as if 'b' were omitted. At line 28824 [FUTURE DIRECTIONS], change "None." to: A future revision of this standard may mandate specific behavior when the mode argument includes 'b'. |
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| Tags | tc1-2008 | ||||||
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Notes |
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(0000795) nick (manager) 2011-05-26 15:42 |
Interpretation response ------------------------ The standard states that the character 'b' shall have no effect, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor. Rationale: ------------- Existing practice at the time of final acceptance of POSIX.1:2008 had expanded to include use of the letter 'b' as the second character in mode. This provides "binary" mode: writes don't implicitly add a terminating null byte, and fseek(3) SEEK_END is relative to the end of the buffer (i.e., the value specified by the size argument), rather than the current string length. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- See Desired Action. |
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(0000842) ajosey (manager) 2011-06-16 10:15 |
Interpretation proposed 16 June 2011 for final 30 day review |
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(0000910) ajosey (manager) 2011-07-29 06:15 |
The interpretation is now approved. |
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Issue History |
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| Date Modified | Username | Field | Change |
| 2011-03-17 18:11 | eblake | New Issue | |
| 2011-03-17 18:11 | eblake | Status | New => Under Review |
| 2011-03-17 18:11 | eblake | Assigned To | => ajosey |
| 2011-03-17 18:11 | eblake | Name | => Eric Blake |
| 2011-03-17 18:11 | eblake | Organization | => Red Hat |
| 2011-03-17 18:11 | eblake | User Reference | => ebb.fmemopen |
| 2011-03-17 18:11 | eblake | Section | => fmemopen |
| 2011-03-17 18:11 | eblake | Page Number | => 866 |
| 2011-03-17 18:11 | eblake | Line Number | => 28743 |
| 2011-03-17 18:11 | eblake | Interp Status | => --- |
| 2011-05-26 15:42 | nick | Note Added: 0000795 | |
| 2011-05-26 15:43 | nick | Interp Status | --- => Pending |
| 2011-05-26 15:43 | nick | Final Accepted Text | => See Note: 0000795 |
| 2011-05-26 15:43 | nick | Status | Under Review => Interpretation Required |
| 2011-05-26 15:43 | nick | Resolution | Open => Accepted |
| 2011-05-26 15:43 | nick | Tag Attached: tc1-2008 | |
| 2011-06-02 19:11 | eblake | Desired Action Updated | |
| 2011-06-02 19:12 | eblake | Relationship added | parent of 0000456 |
| 2011-06-07 21:00 | eblake | Relationship added | related to 0000461 |
| 2011-06-16 10:15 | ajosey | Interp Status | Pending => Proposed |
| 2011-06-16 10:15 | ajosey | Note Added: 0000842 | |
| 2011-07-29 06:15 | ajosey | Interp Status | Proposed => Approved |
| 2011-07-29 06:15 | ajosey | Note Added: 0000910 | |
| 2013-02-14 16:55 | eblake | Relationship added | related to 0000657 |
| 2013-04-16 13:06 | ajosey | Status | Interpretation Required => Closed |
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