Date: Sat, 4 Oct 2025 18:42:53 GMT From: Dag-Erling =?utf-8?Q?Sm=C3=B8rgrav?= <des@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: 64f8416afd4c - main - fts: Document thread (un)safety Message-ID: <202510041842.594IgrMu084094@gitrepo.freebsd.org>
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The branch main has been updated by des: URL: https://cgit.FreeBSD.org/src/commit/?id=64f8416afd4cd042b34e3e975f84fb3493397828 commit 64f8416afd4cd042b34e3e975f84fb3493397828 Author: Dag-Erling Smørgrav <des@FreeBSD.org> AuthorDate: 2025-10-04 18:35:38 +0000 Commit: Dag-Erling Smørgrav <des@FreeBSD.org> CommitDate: 2025-10-04 18:42:19 +0000 fts: Document thread (un)safety MFC after: 3 days Sponsored by: Klara, Inc. Reviewed by: markj Differential Revision: https://reviews.freebsd.org/D52828 --- lib/libc/gen/fts.3 | 51 ++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 44 insertions(+), 7 deletions(-) diff --git a/lib/libc/gen/fts.3 b/lib/libc/gen/fts.3 index ee558b892c8c..b937607b48e0 100644 --- a/lib/libc/gen/fts.3 +++ b/lib/libc/gen/fts.3 @@ -25,7 +25,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd June 30, 2025 +.Dd October 1, 2025 .Dt FTS 3 .Os .Sh NAME @@ -376,7 +376,44 @@ The .Fa fts_name field is always .Dv NUL Ns -terminated . -.Sh FTS_OPEN +.Ss Thread Safety +The +.Nm +functions can safely be used in multi-threaded programs provided no +two threads access the same +.Vt FTS +or +.Vt FTSENT +structure simultaneously. +However, unless the +.Dv FTS_NOCHDIR +flag was passed to +.Fn fts_open +or +.Fn fts_open_b , +calls to +.Fn fts_read +and +.Fn fts_children +may change the current working directory, which will affect all +threads. +Conversely, changing the current working directory either during or +between calls to +.Fn fts_read +or +.Fn fts_children +(even in a single-thread program) may cause +.Nm +to malfunction unless the +.Dv FTS_NOCHDIR +flag was passed to +.Fn fts_open +or +.Fn fts_open_b +and all paths in +.Va path_argv +were absolute. +.Ss Fn fts_open The .Fn fts_open function takes a pointer to an array of character pointers naming one @@ -545,7 +582,7 @@ the directory traversal order is in the order listed in .Fa path_argv for the root paths, and in the order listed in the directory for everything else. -.Sh FTS_OPEN_B +.Ss Fn fts_open_b The .Fn fts_open_b function is identical to @@ -554,7 +591,7 @@ except that it takes a block pointer instead of a function pointer. The block is copied before .Fn fts_open_b returns, so the original can safely go out of scope or be released. -.Sh FTS_READ +.Ss Fn fts_read The .Fn fts_read function returns a pointer to an @@ -605,7 +642,7 @@ after the structure has been returned by the function .Fn fts_read in post-order. -.Sh FTS_CHILDREN +.Ss Fn fts_children The .Fn fts_children function returns a pointer to an @@ -679,7 +716,7 @@ and .Fa fts_namelen fields. .El -.Sh FTS_SET +.Ss Fn fts_set The function .Fn fts_set allows the user application to determine further processing for the @@ -749,7 +786,7 @@ The file may be one of those most recently returned by either or .Fn fts_read . .El -.Sh FTS_CLOSE +.Ss Fn fts_close The .Fn fts_close function closes a file hierarchy stream
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