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author | jilles <jilles@FreeBSD.org> | 2016-09-07 21:03:11 +0000 |
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committer | jilles <jilles@FreeBSD.org> | 2016-09-07 21:03:11 +0000 |
commit | f0d89c26193ca3c296ea081129d48e90906d5223 (patch) | |
tree | 9bef2b19eb421ab08e87c289826873233f6664e3 /lib | |
parent | 3d6ef0e370cc6b7fa08ca5b6e64a863200a84501 (diff) | |
download | FreeBSD-src-f0d89c26193ca3c296ea081129d48e90906d5223.zip FreeBSD-src-f0d89c26193ca3c296ea081129d48e90906d5223.tar.gz |
MFC r305154: 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, although 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.
Diffstat (limited to 'lib')
-rw-r--r-- | lib/libc/gen/directory.3 | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/lib/libc/gen/directory.3 b/lib/libc/gen/directory.3 index 3919805..4b6d0a1 100644 --- a/lib/libc/gen/directory.3 +++ b/lib/libc/gen/directory.3 @@ -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 |