Merge pull request #553 from nix-community/long_device_names

types gpt: hash long device names

example/long-device-name.nix

@@ -0,0 +1,34 @@
+{
+  disko.devices = {
+    disk = {
+      vdb = {
+        device = "/dev/disk/by-id/some-disk-id";
+        name = "this-is-some-super-long-name-to-test-what-happens-when-the-name-is-too-long";
+        type = "disk";
+        content = {
+          type = "gpt";
+          partitions = {
+            ESP = {
+              type = "EF00";
+              size = "500M";
+              content = {
+                type = "filesystem";
+                format = "vfat";
+                mountpoint = "/boot";
+              };
+            };
+            root = {
+              size = "100%";
+              content = {
+                type = "filesystem";
+                format = "ext4";
+                mountpoint = "/";
+              };
+            };
+          };
+        };
+      };
+    };
+  };
+}
+

lib/tests.nix

@@ -223,10 +223,15 @@ let
                   disk_flags += f' -drive file={oldmachine.state_dir}/empty{i}.qcow2,id=drive{i + 1},if=none,index={i + 1},werror=report'
                   disk_flags += f' -device virtio-blk-pci,drive=drive{i + 1}'
               return disk_flags
-          def create_test_machine(oldmachine=None, args={}): # taken from <nixpkgs/nixos/tests/installer.nix>
+          def create_test_machine(oldmachine, args={}): # taken from <nixpkgs/nixos/tests/installer.nix>
+              startCommand = "${pkgs.qemu_test}/bin/qemu-kvm"
+              startCommand += " -cpu max -m 1024 -virtfs local,path=/nix/store,security_model=none,mount_tag=nix-store"
+              startCommand += disks(oldmachine, ${toString num-disks})
+              ${lib.optionalString efi ''
+                startCommand +=" -drive if=pflash,format=raw,unit=0,readonly=on,file=${pkgs.OVMF.firmware} -drive if=pflash,format=raw,unit=1,readonly=on,file=${pkgs.OVMF.variables}"
+              ''}
               machine = create_machine({
-                "qemuFlags": "-cpu max -m 1024 -virtfs local,path=/nix/store,security_model=none,mount_tag=nix-store" + disks(oldmachine, ${toString num-disks}),
-                ${lib.optionalString efi ''"bios": "${pkgs.OVMF.fd}/FV/OVMF.fd",''}
+                "startCommand": startCommand,
               } | args)
               driver.machines.append(machine)
               return machine

lib/types/gpt.nix

@@ -55,7 +55,15 @@ in
           };
           label = lib.mkOption {
             type = lib.types.str;
-            default = "${config._parent.type}-${config._parent.name}-${partition.config.name}";
+            default = let
+              # 72 bytes is the maximum length of a GPT partition name
+              # the labels seem to be in UTF-16, so 2 bytes per character
+              limit = 36;
+              label = "${config._parent.type}-${config._parent.name}-${partition.config.name}"; 
+            in if (lib.stringLength label) > limit then
+              builtins.substring 0 limit (builtins.hashString "sha256" label)
+            else
+              label;
           };
           size = lib.mkOption {
             type = lib.types.either (lib.types.enum [ "100%" ]) (lib.types.strMatching "[0-9]+[KMGTP]?");

tests/long-device-name.nix

@@ -0,0 +1,11 @@
+{ pkgs ? import <nixpkgs> { }
+, diskoLib ? pkgs.callPackage ../lib { }
+}:
+diskoLib.testLib.makeDiskoTest {
+  inherit pkgs;
+  name = "long-device-name";
+  disko-config = ../example/long-device-name.nix;
+  extraTestScript = ''
+    machine.succeed("mountpoint /");
+  '';
+}