A NOTE has been added to this issue. ====================================================================== https://austingroupbugs.net/view.php?id=1798 ====================================================================== Reported By: eblake Assigned To: ====================================================================== Project: Issue 8 drafts Issue ID: 1798 Category: System Interfaces Type: Clarification Requested Severity: Objection Priority: normal Status: New Name: Eric Blake Organization: Red Hat User Reference: ebb.posix_getdents Section: XSH posix_getdents Page Number: 1567 Line Number: 52609 Final Accepted Text: ====================================================================== Date Submitted: 2024-01-22 15:13 UTC Last Modified: 2024-02-29 17:27 UTC ====================================================================== Summary: Must posix_getdents remember file offsets across exec? ======================================================================
---------------------------------------------------------------------- (0006695) geoffclare (manager) - 2024-02-29 17:27 https://austingroupbugs.net/view.php?id=1798#c6695 ---------------------------------------------------------------------- Proposed interpretation (review timer to start after approval of issue 8) ... Interpretation response ------------------------ The standard states that the posix_getdents() function starts reading at the current file offset in the open file description associated with fildes, and conforming implementations must conform to this. However, concerns have been raised about this which are being referred to the sponsor. Rationale: ------------- Elsewhere the standard makes allowances for implementations where directory streams are not implemented using a file descriptor, but this was not extended to the new posix_getdents() function when it was added. Notes to the Editor (not part of this interpretation): ------------------------------------------------------- After page 920 line 31407 section fdopendir(), add a new paragraph: <blockquote>If the file descriptor specified by <i>fd</i> is associated with an open file description on which <i>posix_getdents</i>() has previously been used, the behavior is unspecified.</blockquote> After page 1567 line 52616 section posix_getdents(): <blockquote>The behavior is unspecified if <i>lseek</i>() is used to set the file offset to a value other than zero or a value returned by a previous call to <i>lseek</i>() on the same open file description.</blockquote> add these sentences: <blockquote>The behavior is unspecified if calls to <i>posix_getdents</i>() are made on different file descriptors that refer to the same open file description (for example, before and after a file descriptor is inherited across <i>fork</i>() or the <i>exec</i> family of functions, or is duplicated using <i>dup</i>() or <i>fcntl</i>()), unless <i>lseek</i>() is used to set the file offset to zero in between the calls to <i>posix_getdents</i>(). A single exception to this condition is that after a call to <i>fork</i>(), either the parent or child (but not both) can continue processing the directory using <i>posix_getdents</i>(); if both the parent and child processes use the function, the result is unspecified. Likewise, the behavior is unspecified if in between two calls to <i>posix_getdents</i>() on one file descriptor, the file offset is altered by a call made on a different file descriptor that refers to the same open file description and the new offset is not zero.</blockquote> After page 1571 line 52771 section posix_getdents(), add a new paragraph to RATIONALE: <blockquote>The restrictions on the use of different file descriptors that refer to the same open file description are needed in order to enable implementations where directory streams are not implemented using a file descriptor to maintain some internal state related to a particular file descriptor.</blockquote> At page 1858 line 61319 section readdir(), change: <blockquote>the result is undefined.</blockquote> to: <blockquote>the result is unspecified.</blockquote> Issue History Date Modified Username Field Change ====================================================================== 2024-01-22 15:13 eblake New Issue 2024-01-22 15:13 eblake Name => Eric Blake 2024-01-22 15:13 eblake Organization => Red Hat 2024-01-22 15:13 eblake User Reference => ebb.posix_getdents 2024-01-22 15:13 eblake Section => XSH posix_getdents 2024-01-22 15:13 eblake Page Number => 1567 2024-01-22 15:13 eblake Line Number => 52609 2024-01-22 15:30 eblake Note Added: 0006632 2024-01-22 15:39 eblake Note Edited: 0006632 2024-02-16 10:18 corinna_vinschenNote Added: 0006658 2024-02-29 17:27 geoffclare Note Added: 0006695 ======================================================================
