[committed] libstdc++: Handle EMLINK and EFTYPE in std::filesystem::remove_all

[committed] libstdc++: Handle EMLINK and EFTYPE in std::filesystem::remove_all

[Jonathan Wakely]

Tested x86_64-linux and x86_64-freebsd14. Pushed to trunk.

-- >8 --

Although POSIX requires ELOOP, FreeBSD documents that openat with
O_NOFOLLOW returns EMLINK if the last component of a filename is a
symbolic link.  Check for EMLINK as well as ELOOP, so that the TOCTTOU
mitigation in remove_all works correctly.

See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=214633 or the
FreeBSD man page for reference.

According to its man page, DragonFlyBSD also uses EMLINK for this error,
and NetBSD uses its own EFTYPE. OpenBSD follows POSIX and uses EMLINK.

This fixes these failures on FreeBSD:
FAIL: 27_io/filesystem/operations/remove_all.cc  -std=gnu++17 execution test
FAIL: experimental/filesystem/operations/remove_all.cc  -std=gnu++17 execution test

libstdc++-v3/ChangeLog:

	* src/c++17/fs_ops.cc (remove_all) [__FreeBSD__ || __DragonFly__]:
	Check for EMLINK as well as ELOOP.
	[__NetBSD__]: Check for EFTYPE as well as ELOOP.
---
 libstdc++-v3/src/c++17/fs_ops.cc | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/libstdc++-v3/src/c++17/fs_ops.cc b/libstdc++-v3/src/c++17/fs_ops.cc
index 61df19753ef..07bc2a0fa88 100644
--- a/libstdc++-v3/src/c++17/fs_ops.cc
+++ b/libstdc++-v3/src/c++17/fs_ops.cc
@@ -1312,7 +1312,13 @@ fs::remove_all(const path& p)
     // Our work here is done.
     return 0;
   case ENOTDIR:
-  case ELOOP:
+  case ELOOP:  // POSIX says openat with O_NOFOLLOW sets ELOOP for a symlink.
+#if defined __FreeBSD__ || defined __DragonFly__
+  case EMLINK: // Used instead of ELOOP
+#endif
+#if defined __NetBSD__ && defined EFTYPE
+  case EFTYPE: // Used instead of ELOOP
+#endif
     // Not a directory, will remove below.
     break;
 #endif
@@ -1352,7 +1358,13 @@ fs::remove_all(const path& p, error_code& ec)
     ec.clear();
     return 0;
   case ENOTDIR:
-  case ELOOP:
+  case ELOOP:  // POSIX says openat with O_NOFOLLOW sets ELOOP for a symlink.
+#if defined __FreeBSD__ || defined __DragonFly__
+  case EMLINK: // Used instead of ELOOP
+#endif
+#if defined __NetBSD__ && defined EFTYPE
+  case EFTYPE: // Used instead of ELOOP
+#endif
     // Not a directory, will remove below.
     break;
 #endif
-- 
2.44.0