git: d04415c520b0 - main - loader: lua: remove the default kernel if it doesn't exist

The branch main has been updated by kevans:

URL: https://cgit.FreeBSD.org/src/commit/?id=d04415c520b031fb8eb93cb252e4acee66149c87

commit d04415c520b031fb8eb93cb252e4acee66149c87
Author:     Kyle Evans <kevans@FreeBSD.org>
AuthorDate: 2023-12-13 16:52:14 +0000
Commit:     Kyle Evans <kevans@FreeBSD.org>
CommitDate: 2023-12-13 16:52:14 +0000

    loader: lua: remove the default kernel if it doesn't exist
    
    The `kernel` env var provides the default kernel, usually "kernel".  It
    may be the case that the user doesn't have a "kernel" kernel, just
    "kernel.*" kernels, but have left `kernel` to the default because we
    autodetect entries by default anyways.
    
    If we're doing autodetection, take note of whether the default kernel
    exists or not and remove it from the list if it doesn't and we had found
    any other kernels.  We avoid it in the #kernels == 1 case because
    something fishy has likely happened and we should just trust the
    configuration.
    
    Reviewed by:    imp, manu
    Differential Revision:  https://reviews.freebsd.org/D42967
---
 stand/lua/core.lua | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/stand/lua/core.lua b/stand/lua/core.lua
index c7581b296b8f..9226de564348 100644
--- a/stand/lua/core.lua
+++ b/stand/lua/core.lua
@@ -201,17 +201,18 @@ function core.kernelList()
 		return core.cached_kernels
 	end
 
-	local k = loader.getenv("kernel")
+	local default_kernel = loader.getenv("kernel")
 	local v = loader.getenv("kernels")
 	local autodetect = loader.getenv("kernels_autodetect") or ""
 
 	local kernels = {}
 	local unique = {}
 	local i = 0
-	if k ~= nil then
+
+	if default_kernel then
 		i = i + 1
-		kernels[i] = k
-		unique[k] = true
+		kernels[i] = default_kernel
+		unique[default_kernel] = true
 	end
 
 	if v ~= nil then
@@ -239,6 +240,8 @@ function core.kernelList()
 		return core.cached_kernels
 	end
 
+	local present = {}
+
 	-- Automatically detect other bootable kernel directories using a
 	-- heuristic.  Any directory in /boot that contains an ordinary file
 	-- named "kernel" is considered eligible.
@@ -267,8 +270,25 @@ function core.kernelList()
 			unique[file] = true
 		end
 
+		present[file] = true
+
 		::continue::
 	end
+
+	-- If we found more than one kernel, prune the "kernel" specified kernel
+	-- off of the list if it wasn't found during traversal.  If we didn't
+	-- actually find any kernels, we just assume that they know what they're
+	-- doing and leave it alone.
+	if default_kernel and not present[default_kernel] and #kernels > 1 then
+		for i = 1, #kernels do
+			if i == #kernels then
+				kernels[i] = nil
+			else
+				kernels[i] = kernels[i + 1]
+			end
+		end
+	end
+
 	core.cached_kernels = kernels
 	return core.cached_kernels
 end