git: bf0881060ecd - main - lualoader: allow the local module to filter out the BE list

The branch main has been updated by kevans:

URL: https://cgit.FreeBSD.org/src/commit/?id=bf0881060ecd75ce79683b82ebcd4809eadf7cf5

commit bf0881060ecd75ce79683b82ebcd4809eadf7cf5
Author:     Kyle Evans <kevans@FreeBSD.org>
AuthorDate: 2026-04-08 12:49:18 +0000
Commit:     Kyle Evans <kevans@FreeBSD.org>
CommitDate: 2026-04-08 12:49:58 +0000

    lualoader: allow the local module to filter out the BE list
    
    This allows something like the following local.lua to install a filter
    to implement its own notion of hidden BEs using a naming convention of
    a leading dot to hide them:
    
    -- file: /boot/lua/local.lua
    local core = require("core")
    
    local function be_hide(be)
        if core.isSingleUserBoot() then
            -- All BEs are accepted for single-user
            return true
        end
    
        local name = be:match("/([^/]+)$")
        if not name then
            -- Accept malformed BEs, for whatever reason
            return true
        end
    
        return name:match("^%.") == nil
    end
    
    if core.bootenvFilter then
        -- Just in case we need to be compatible with older versions of
        -- core.lua without the filtering functionality.
        core.bootenvFilter(be_hide)
    end
    -- EOF
    
    Requested by:   Marek Zarychta
    Reviewed by:    imp
    Differential Revision:  https://reviews.freebsd.org/D55359
---
 stand/lua/core.lua   | 20 ++++++++++++++++++--
 stand/lua/core.lua.8 | 13 ++++++++++++-
 2 files changed, 30 insertions(+), 3 deletions(-)

diff --git a/stand/lua/core.lua b/stand/lua/core.lua
index 92cbd20b25a0..471e579619c7 100644
--- a/stand/lua/core.lua
+++ b/stand/lua/core.lua
@@ -305,6 +305,15 @@ function core.bootenvDefault()
 	return loader.getenv("zfs_be_active")
 end
 
+function core.bootenvFilter(func)
+	local oldf = core.bootenv_filter
+
+	-- Filter contract: returns true if the BE should be kept, false if it
+	-- should be hidden.
+	core.bootenv_filter = func
+	return oldf
+end
+
 function core.bootenvList()
 	local bootenv_count = tonumber(loader.getenv(bootenv_list .. "_count"))
 	local bootenvs = {}
@@ -332,11 +341,18 @@ function core.bootenvList()
 	for curenv_idx = 0, bootenv_count - 1 do
 		curenv = loader.getenv(bootenv_list .. "[" .. curenv_idx .. "]")
 		if curenv ~= nil and unique[curenv] == nil then
-			envcount = envcount + 1
-			bootenvs[envcount] = curenv
 			unique[curenv] = true
+
+			-- If we have a filter installed (by a local module), we
+			-- give it a chance to veto the BE.
+			if not core.bootenv_filter or
+			    core.bootenv_filter(curenv) then
+				envcount = envcount + 1
+				bootenvs[envcount] = curenv
+			end
 		end
 	end
+
 	return bootenvs
 end
 
diff --git a/stand/lua/core.lua.8 b/stand/lua/core.lua.8
index de43d3e2b220..325320b2fce8 100644
--- a/stand/lua/core.lua.8
+++ b/stand/lua/core.lua.8
@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 29, 2025
+.Dd April 8, 2026
 .Dt CORE.LUA 8
 .Os
 .Sh NAME
@@ -164,6 +164,17 @@ is set in
 kernels will be autodetected from the current system.
 .It Fn core.bootenvDefault
 Returns the default boot environment, nil if unset.
+.It Fn core.bootenvFilter func
+Installs a filter
+.Fa func
+into
+.Fn core.bootenvList .
+If the
+.Fa func
+returns true, then the boot environment is retained in the list.
+Otherwise, the boot environment is hidden.
+The old filter, if any, is returned to allow the caller to compose a filter on
+top of another filter.
 .It Fn core.bootenvList
 Returns a table of boot environments, or an empty table.
 These will be picked up using the