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|ID||Category||Severity||Type||Date Submitted||Last Update|
|0000590||[1003.1(2008)/Issue 7] System Interfaces||Objection||Clarification Requested||2012-06-26 22:54||2012-07-12 15:56|
|Section||dup, dup2 - duplicate an open file descriptor|
|Final Accepted Text||see Note: 0001270|
|Summary||0000590: dup2 and signals|
|Description||The standard does not specify what the state of the file descriptor is when dup2 is interrupted by a signal.|
I expect that in most cases, dup2 is implemented using close and fcntl. The former has been settled by a different bug report, and the latter does not permit EINTR when used with F_DUPFD. Hence, the logical solution would be to always close the descriptor if implementations agree.
The dup2() function was interrupted by a signal.
The dup2() function was interrupted by a signal and fildes2 was closed.
If you agree with the above, I will open a new proposal for posix_dup2 which would work in a similar fashion as posix_close.
|Tags||No tags attached.|
The standard is already clear that:
"If the close operation fails to close fildes2, dup2( ) shall return −1 without changing the open file description to which fildes2 refers." (line 24875)
That is, if dup2() is interrupted by a signal, then fildes2 was not closed.
Furthermore, the standard requires that dup2() be atomic with respect to all other functions in the standard by virtue of the fact that dup2() is async-signal-safe (line 16744); an implementation that implements dup2() by first calling close() and then calling dup() in such a manner that another thread or interrupt handler can see the state between the close operation and subsequent dup is not compliant. I don't think we have an issue here.
I will also point out that we have already have proposed the addition of dup3() as part of 0000411, that already provides a flag argument with enough spare bits that if any functionality is deemed necessary to fine-tune what happens when a dup operation is interrupted, we can implement it by defining one of those bits, instead of adding yet another function named posix_dup2(). But you first have to convince me that we even have an issue where it is even worth fine-tuning dup3() failure with regards to interrupts.
|2012-06-26 22:54||Love4Boobies||New Issue|
|2012-06-26 22:54||Love4Boobies||Status||New => Under Review|
|2012-06-26 22:54||Love4Boobies||Assigned To||=> ajosey|
|2012-06-26 22:54||Love4Boobies||Name||=> Bogdan Barbu|
|2012-06-26 22:54||Love4Boobies||Section||=> dup, dup2 - duplicate an open file descriptor|
|2012-06-26 22:54||Love4Boobies||Page Number||=> ?|
|2012-06-26 22:54||Love4Boobies||Line Number||=> ?|
|2012-06-26 23:14||eblake||Note Added: 0001270|
|2012-06-26 23:15||eblake||Relationship added||related to 0000411|
|2012-06-26 23:15||eblake||Relationship added||related to 0000529|
|2012-07-12 15:56||eblake||Interp Status||=> ---|
|2012-07-12 15:56||eblake||Final Accepted Text||=> see Note: 0001270|
|2012-07-12 15:56||eblake||Status||Under Review => Closed|
|2012-07-12 15:56||eblake||Resolution||Open => Rejected|
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