Date: Wed, 31 Aug 2016 20:38:40 +0000 (UTC) From: Jilles Tjoelker <jilles@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r305154 - head/lib/libc/gen Message-ID: <201608312038.u7VKce8M099047@repo.freebsd.org>
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Author: jilles Date: Wed Aug 31 20:38:40 2016 New Revision: 305154 URL: https://svnweb.freebsd.org/changeset/base/305154 Log: directory(3): Deprecate readdir_r(). Clarify dirent buffers. In existing implementations including FreeBSD, there is no reason to use readdir_r() in the common case where potentially multiple threads each list their own directory. Code using readdir() is simpler. What's more, lthough readdir_r() can safely be used on FreeBSD because NAME_MAX is forced to 255, it cannot be used safely on systems where {NAME_MAX} is not fixed. As a concrete example, FAT/NTFS filenames can be up to 255 UTF-16 code units long, which can be up to 765 UTF-8 bytes. Deprecating readdir_r() in POSIX has been proposed in http://www.austingroupbugs.net/view.php?id=696 and glibc wants to deprecate it as well. Reviewed by: ed, wblock MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D7678 Modified: head/lib/libc/gen/directory.3 Modified: head/lib/libc/gen/directory.3 ============================================================================== --- head/lib/libc/gen/directory.3 Wed Aug 31 20:33:59 2016 (r305153) +++ head/lib/libc/gen/directory.3 Wed Aug 31 20:38:40 2016 (r305154) @@ -28,7 +28,7 @@ .\" @(#)directory.3 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd February 19, 2016 +.Dd August 31, 2016 .Dt DIRECTORY 3 .Os .Sh NAME @@ -68,6 +68,15 @@ .Ft int .Fn dirfd "DIR *dirp" .Sh DESCRIPTION +.Bf -symbolic +The +.Fn readdir_r +interface is deprecated +because it cannot be used correctly unless +.Brq Va NAME_MAX +is a fixed value. +.Ef +.Pp The .Fn opendir function @@ -122,7 +131,13 @@ The .Fn readdir function returns a pointer to the next directory entry. -It returns +The directory entry remains valid until the next call to +.Fn readdir +or +.Fn closedir +on the same +.Em directory stream . +The function returns .Dv NULL upon reaching the end of the directory or on error. In the event of an error, @@ -139,6 +154,13 @@ provides the same functionality as but the caller must provide a directory .Fa entry buffer to store the results in. +The buffer must be large enough for a +.Vt struct dirent +with a +.Va d_name +array with +.Brq Va NAME_MAX ++ 1 elements. If the read succeeds, .Fa result is pointed at the
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