diff options
-rw-r--r-- | lib/modules.nix | 11 | ||||
-rw-r--r-- | lib/options.nix | 2 | ||||
-rw-r--r-- | nixos/doc/manual/options-to-docbook.xsl | 4 | ||||
-rw-r--r-- | nixos/modules/misc/version.nix | 4 |
4 files changed, 16 insertions, 5 deletions
diff --git a/lib/modules.nix b/lib/modules.nix index d7037abfbef03..50827e18f1050 100644 --- a/lib/modules.nix +++ b/lib/modules.nix @@ -261,11 +261,16 @@ rec { evalOptionValue = loc: opt: defs: let # Add in the default value for this option, if any. - defs' = (optional (opt ? default) - { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs; + defs' = + (optional (opt ? default) + { file = head opt.declarations; value = mkOptionDefault opt.default; }) ++ defs; # Handle properties, check types, and merge everything together. - res = mergeDefinitions loc opt.type defs'; + res = + if opt.readOnly or false && length defs' > 1 then + throw "The option `${showOption loc}' is read-only, but it's set multiple times." + else + mergeDefinitions loc opt.type defs'; # Check whether the option is defined, and apply the ‘apply’ # function to the merged value. This allows options to yield a diff --git a/lib/options.nix b/lib/options.nix index 5c543f56bcf36..444ec37e6eaf3 100644 --- a/lib/options.nix +++ b/lib/options.nix @@ -19,6 +19,7 @@ rec { , apply ? null # Function that converts the option value to something else. , internal ? null # Whether the option is for NixOS developers only. , visible ? null # Whether the option shows up in the manual. + , readOnly ? null # Whether the option can be set only once , options ? null # Obsolete, used by types.optionSet. } @ attrs: attrs // { _type = "option"; }; @@ -90,6 +91,7 @@ rec { declarations = filter (x: x != unknownModule) opt.declarations; internal = opt.internal or false; visible = opt.visible or true; + readOnly = opt.readOnly or false; type = opt.type.name or null; } // (if opt ? example then { example = scrubOptionValue opt.example; } else {}) diff --git a/nixos/doc/manual/options-to-docbook.xsl b/nixos/doc/manual/options-to-docbook.xsl index f588a019e639a..3d6ea9427016e 100644 --- a/nixos/doc/manual/options-to-docbook.xsl +++ b/nixos/doc/manual/options-to-docbook.xsl @@ -39,6 +39,10 @@ <emphasis>Type:</emphasis> <xsl:text> </xsl:text> <xsl:apply-templates select="attr[@name = 'type']" mode="top" /> + <xsl:if test="attr[@name = 'readOnly']/bool/@value = 'true'"> + <xsl:text> </xsl:text> + <emphasis>(read only)</emphasis> + </xsl:if> </para> </xsl:if> diff --git a/nixos/modules/misc/version.nix b/nixos/modules/misc/version.nix index 8a52df42dd80f..dc8eb4e88329d 100644 --- a/nixos/modules/misc/version.nix +++ b/nixos/modules/misc/version.nix @@ -29,7 +29,7 @@ with lib; }; system.nixosRelease = mkOption { - internal = true; + readOnly = true; type = types.str; default = readFile "${toString pkgs.path}/.version"; description = "NixOS release."; @@ -48,7 +48,7 @@ with lib; }; system.nixosCodeName = mkOption { - internal = true; + readOnly = true; type = types.str; description = "NixOS release code name."; }; |