make mksquashfs fail on error

it doesn't work the same way as in nixos, so don't name it the same way

STYLE.md

@@ -23,3 +23,10 @@ expression or there is more than one reference to `up`, `down` etc.
 
   * where a `let` form defines multiple names, put a newline after the
   token `let`, and indent each name two characters
+
+* should it be a package or a module? packages are self-contained -
+  they live in /nix/store/eeeeeee-name and don't directly change
+  system behaviour by their presence or absense. modules can add to
+  /etc or /bin or other global state, create services, all that
+  side-effecty stuff.  generally it should be a package unless it
+  can't be.

THOUGHTS.txt

@@ -129,3 +129,85 @@ DONE 17) rename nixwrt references in kernel builder
 19) syslogd - use busybox or s6?
 
 chat -s -S ogin:--ogin: root / "ip address show dev ppp0 | grep ppp0" 192.168.100.1  "/nix/store/*-s6-linux-init-*/bin/s6-linux-init-hpr -p"
+
+
+Working towards a general goal of having a derivation we can
+usefully run `nix path-info` on - or some other tool that will
+tell us what's making the images big. The squashfs doesn't
+have this information.
+
+Towards that end (really? can't remember how ...) what would be a
+way for packages to declare "I want to add files to /etc"? Is that
+even a good idea?
+
+Thinking we should turn s6-init-files back into a real derivation.
+
+Tue Sep 27 00:31:45 BST 2022
+
+> Thinking we should turn s6-init-files back into a real derivation.
+
+This turns out to be Not That Simple, because it contains weird shit
+(sticky bits and fifos).
+
+Tue Sep 27 09:50:44 BST 2022
+
+* allow modules to register activation scripts that are run on the
+root filesystem once all packages are installed
+
+  - do they run on build or on host? if we're upgrading in place
+  how do we ship filesystem changes to the host?
+
+or:
+
+* allow modules to declare environment.*, use pseudofile on build and
+create real files on host. will need to keep the implementation on
+  host faily simple because restricted environment
+
+Tue Sep 27 16:14:18 BST 2022
+
+TODO list is getting both longer and shorter, though longer on
+average.
+
+DONE 1) rename config.environment as .filesystem. and add module
+types for it
+
+2) perhaps we shouldn't use process-based services like [ou]dhcp as
+queryable endpoint for interface addresses (e.g. when adding routes).
+Instead have a separate service for interface address that depends on
+the *dhcp and uses its output
+
+3) when I killed ppp it restarted, but I don't think it reran
+defaultroute which is supposed to depend on it. (Might be important
+e.g. if we'd been assigned a different IP address). Investigate
+semantics of s6-rc service dependencies
+
+4) figure out a nice way to fit ppp into this model as it actually
+creates the interface instead of using an existing unconfigured one
+
+5) write a test for udhcp
+
+6) squashfs size is ~ 14MB for a configuration with not much in it,
+look for obvious wastes of space
+
+7) some of the pppoe config should be moved into a ppp service
+
+8) some of configuration.nix (e.g. defining routes) should be moved into
+tools
+
+11) haven't done (overlayfs) overlays at all
+
+13) upgrade ppp to something with an ipv6-up-script option, move ppp and pppoe derivations into their own files
+
+14) add ipv6 support generally
+
+15) "ip address add" seems to magically recognise v4 vs v6 but
+is that specified or fluke?
+
+18) maybe stop suffixing all the service names with .service
+
+19) syslogd - use busybox or s6?
+
+20) The option currently called defaultPackages needs a better name as
+it doesn't have the same semantics as nixos
+environment.defaultPackages.  maybe call it packagesInProfile or
+packagesOnPath. or defaultProfile.packages

default.nix

@@ -4,19 +4,16 @@
 let
   overlay = import ./overlay.nix;
   nixpkgs = import <nixpkgs> ( device.system // {overlays = [overlay]; });
+  inherit (nixpkgs.pkgs) callPackage liminix;
   config = (import ./merge-modules.nix) [
     ./modules/base.nix
     ({ lib, ... } : { config = { inherit (device) kernel; }; })
     <liminix-config>
+    ./modules/s6
   ] nixpkgs.pkgs;
-  finalConfig = config // {
-    packages = (with nixpkgs.pkgs; [ s6-init-files s6-rc ]) ++
-               config.systemPackages ++
-               (builtins.attrValues config.services);
-  };
-  squashfs = (nixpkgs.pkgs.callPackage ./make-image.nix {}) finalConfig;
-  kernel = nixpkgs.pkgs.callPackage ./kernel {
-    inherit (finalConfig.kernel) config;
+  squashfs = liminix.builders.squashfs config;
+  kernel = callPackage ./kernel {
+    inherit (config.kernel) config;
   };
 in {
   outputs = {

make-image.nix

@@ -1,67 +0,0 @@
-{
-  stdenv
-, busybox
-, buildPackages
-, callPackage
-, execline
-, lib
-, runCommand
-, s6-init-bin
-, s6-init-files
-, s6-linux-init
-, s6-rc
-, s6-rc-database
-, stdenvNoCC
-, writeScript
-, writeText
-} : config :
-let
-  s6-rc-db = s6-rc-database.override {
-    services = builtins.attrValues config.services;
-  };
-
-  profile  = writeScript ".profile" ''
-    PATH=${lib.makeBinPath ([ s6-init-bin busybox execline s6-linux-init s6-rc])}
-    export PATH
-  '';
-
-  pseudofiles = writeText "pseudofiles" ''
-     / d 0755 0 0
-     /bin d 0755 0 0
-     /etc d 0755 0 0
-     /run d 0755 0 0
-     /dev d 0755 0 0
-     /dev/null c 0666 root root 1 3
-     /dev/zero c 0666 root root 1 5
-     /dev/tty1 c 0777 root root 4 1
-     /dev/tty2 c 0777 root root 4 2
-     /dev/tty3 c 0777 root root 4 3
-     /dev/tty4 c 0777 root root 4 4
-     /dev/tty c 0777 root root 5 0
-     /dev/console c 0600 root root 5 1
-     /proc d 0555 root root
-     /sys d 0555 root root
-     /dev/pts d 0755 0 0
-     /etc/init.d d 0755 0 0
-     /bin/init s 0755 0 0 ${s6-init-bin}/bin/init
-     /bin/sh s 0755 0 0 ${busybox}/bin/sh
-     /bin/busybox s 0755 0 0 ${busybox}/bin/busybox
-     /etc/s6-rc d 0755 0 0
-     /etc/s6-rc/compiled s 0755 0 0 ${s6-rc-db}/compiled
-     /etc/passwd f 0644 0 0 echo  "root::0:0:root:/:/bin/sh"
-     /.profile s 0644 0 0 ${profile}
-  '';
-  storefs = callPackage <nixpkgs/nixos/lib/make-squashfs.nix> {
-    # add pseudofiles to store so that the packages they
-    # depend on are also added
-    storeContents = [ pseudofiles s6-init-files ] ++ config.packages ;
-  };
-in runCommand "frob-squashfs" {
-    nativeBuildInputs = with buildPackages; [ squashfsTools qprint ];
-  } ''
-    cp ${storefs} ./store.img
-    chmod +w store.img
-    mksquashfs - store.img -no-recovery -quiet -no-progress  -root-becomes store -p "/ d 0755 0 0"
-    mksquashfs - store.img -no-recovery -quiet -no-progress  -root-becomes nix  -pf ${pseudofiles} -pf ${s6-init-files}
-    cp store.img $out
-  ''

modules/base.nix

@@ -1,6 +1,9 @@
-{ lib, ...}:
+{ lib, pkgs, config, ...}:
 let
   inherit (lib) mkEnableOption mkOption types isDerivation hasAttr ;
+  inherit (pkgs.pseudofile) dir symlink;
+  inherit (pkgs) busybox;
+
   type_service = types.package // {
     name = "service";
     description = "s6-rc service";
@@ -9,12 +12,17 @@ let
 
 in {
   options = {
-    systemPackages = mkOption {
-      type = types.listOf types.package;
+    # analogous to nixos systemPackages, but we don't symlink into
+    # /run/current-system, we just add the paths in /etc/profile
+    defaultProfile = {
+      packages = mkOption {
+        type = types.listOf types.package;
+      };
     };
     services = mkOption {
       type = types.attrsOf type_service;
     };
+    filesystem = mkOption { type = types.anything; };
     kernel = {
       config = mkOption {
         # mostly the values are y n or m, but sometimes
@@ -26,4 +34,35 @@ in {
       };
     };
   };
+  config = {
+    defaultProfile.packages = with pkgs;
+      [ s6-init-bin busybox execline s6-linux-init s6-rc ];
+    filesystem = dir {
+      bin = dir {
+        sh = symlink "${busybox}/bin/sh";
+        busybox = symlink "${busybox}/bin/busybox";
+      };
+      dev =
+        let node = type: major: minor: mode : { inherit type major minor mode; };
+        in dir {
+          null =    node "c" "1" "3" "0666";
+          zero =    node "c" "1" "5" "0666";
+          tty =     node "c" "5" "0" "0666";
+          console = node "c" "5" "1" "0600";
+          pts =     dir {};
+        };
+      etc = dir {
+        profile = symlink
+          (pkgs.writeScript ".profile" ''
+            PATH=${lib.makeBinPath config.defaultProfile.packages}
+            export PATH
+          '');
+        passwd = { file = "root::0:0:root:/:/bin/sh\n"; };
+        group = { file = "root::0:\n"; };
+      };
+      proc = dir {};
+      run = dir {};
+      sys = dir {};
+    };
+  };
 }

modules/s6/default.nix

@@ -0,0 +1,158 @@
+{ config, pkgs, ... }:
+let
+  inherit (pkgs)
+    busybox
+    execline
+    s6
+    s6-init-bin
+    s6-linux-init
+    stdenvNoCC;
+  inherit (pkgs.pseudofile) dir symlink;
+
+  s6-rc-db = pkgs.s6-rc-database.override {
+    services = builtins.attrValues config.services;
+  };
+  s6-init-scripts = stdenvNoCC.mkDerivation {
+    name = "s6-scripts";
+    src = ./scripts;
+    phases = ["unpackPhase" "installPhase" ];
+    buildInputs = [busybox];
+    installPhase = ''
+      mkdir $out
+      cp -r $src $out/scripts
+      chmod -R +w $out
+      patchShebangs $out/scripts
+    '';
+  };
+  service = dir  {
+    s6-linux-init-runleveld = dir {
+      notification-fd = { file = "3"; };
+      run = {
+        file = ''
+              #!${execline}/bin/execlineb -P
+              ${execline}/bin/fdmove -c 2 1
+              ${execline}/bin/fdmove 1 3
+              ${s6}/bin/s6-ipcserver -1 -a 0700 -c 1 -- s
+              ${s6}/bin/s6-sudod -dt30000 -- "/etc/s6-linux-init/current"/scripts/runlevel
+            '';
+        mode = "0755";
+      };
+    };
+    s6-linux-init-shutdownd = dir {
+      fifo = {
+        type = "i";
+        subtype = "f";
+        mode = "0600";
+      };
+      run = {
+        file = ''
+              #!${execline}/bin/execlineb -P
+              ${s6-linux-init}/bin/s6-linux-init-shutdownd -c  "/etc/s6-linux-init/current" -g 3000
+            '';
+        mode = "0755";
+      };
+    };
+    s6-svscan-log = dir {
+      fifo = {
+        type = "i";
+        subtype = "f";
+        mode = "0600";
+      };
+      notification-fd = { file = "3"; };
+      run = {
+        file = ''
+              #!${execline}/bin/execlineb -P
+              ${execline}/bin/redirfd -w 1 /dev/null
+              ${execline}/bin/redirfd -rnb 0 fifo
+              ${s6}/bin/s6-log -bpd3 -- t /run/uncaught-logs
+          '';
+        mode = "0755";
+      };
+    };
+    getty = dir {
+      run = {
+        file = ''
+              #!${execline}/bin/execlineb -P
+              ${busybox}/bin/getty -l ${busybox}/bin/login 38400 /dev/console
+          '';
+        mode = "0755";
+      };
+    };
+    ".s6-svscan" =
+      let
+        quit = message: ''
+              #!${execline}/bin/execlineb -P
+              ${execline}/bin/redirfd -w 2 /dev/console
+              ${execline}/bin/fdmove -c 1 2
+              ${execline}/bin/foreground { ${s6-linux-init}/bin/s6-linux-init-echo -- ${message} }
+              ${s6-linux-init}/bin/s6-linux-init-hpr -fr
+            '';
+        shutdown = action: ''
+              #!${execline}/bin/execlineb -P
+              ${s6-linux-init}/bin/s6-linux-init-hpr -a #{action} -- now
+            '';
+        empty = "#!${execline}/bin/execlineb -P\n";
+      in dir {
+        crash = {
+          file = quit "s6-svscan crashed. Rebooting.";
+          mode = "0755";
+        };
+        finish = {
+          file = quit "s6-svscan exited. Rebooting.";
+          mode = "0755";
+        };
+        SIGINT = {
+          file = shutdown "-r";
+          mode = "0755";
+        };
+        SIGPWR = {
+          file = shutdown "-p";
+          mode = "0755";
+        };
+        SIGQUIT = {
+          file = empty;
+          mode = "0755";
+        };
+        SIGTERM = {
+          file = empty;
+          mode = "0755";
+        };
+        SIGUSR1 = {
+          file = shutdown "-p";
+          mode = "0755";
+        };
+        SIGUSR2 = {
+          file = shutdown "-h";
+          mode = "0755";
+        };
+        SIGWINCH = {
+          file = empty;
+          mode = "0755";
+        };
+
+      };
+  };
+in {
+  config = {
+    filesystem = dir {
+      etc = dir {
+        s6-rc = dir {
+          compiled = symlink "${s6-rc-db}/compiled";
+        };
+        s6-linux-init = dir {
+          current = dir {
+            scripts = symlink "${s6-init-scripts}/scripts";
+            env = dir {};
+            run-image = dir {
+              uncaught-logs = (dir {}) // {mode = "2750";};
+              inherit service;
+            };
+          };
+        };
+      };
+      bin = dir {
+        init = symlink "${s6-init-bin}/bin/init";
+      };
+    };
+  };
+}

overlay.nix

@@ -1,15 +1,15 @@
 final: prev: {
   pseudofile = final.callPackage ./pkgs/pseudofile {};
-  s6-init-files = final.callPackage ./pkgs/s6-init-files {};
   strace = prev.strace.override { libunwind = null; };
   liminix = {
     services = final.callPackage ./pkgs/liminix-tools/services {};
     networking =  final.callPackage ./pkgs/liminix-tools/networking {};
+    builders =  {
+      squashfs = final.callPackage ./pkgs/liminix-tools/builders/squashfs.nix {};
+    };
   };
   writeAshScript = final.callPackage ./pkgs/write-ash-script {};
-
   s6-init-bin =  final.callPackage ./pkgs/s6-init-bin {};
-
   s6-rc-database = final.callPackage ./pkgs/s6-rc-database {};
 
   pppoe = prev.rpPPPoE.overrideAttrs (o: {

pkgs/liminix-tools/builders/squashfs.nix

@@ -0,0 +1,29 @@
+{
+  stdenv
+, busybox
+, buildPackages
+, callPackage
+, pseudofile
+, runCommand
+, writeText
+} : config :
+let
+  pseudofiles =
+    pseudofile.write "files.pf" (config.filesystem.contents);
+
+  storefs = callPackage <nixpkgs/nixos/lib/make-squashfs.nix> {
+    # 1) Every required package is referenced from somewhere
+    # outside /nix/store. 2) Every file outside the store is
+    # specified by config.filesystem. 3) Therefore, closing over
+    # the pseudofile will give us all the needed packages
+    storeContents = [ pseudofiles ];
+  };
+in runCommand "frob-squashfs" {
+    nativeBuildInputs = with buildPackages; [ squashfsTools qprint ];
+} ''
+    cp ${storefs} ./store.img
+    chmod +w store.img
+    mksquashfs - store.img -exit-on-error -no-recovery -quiet -no-progress  -root-becomes store -p "/ d 0755 0 0"
+    mksquashfs - store.img -exit-on-error -no-recovery -quiet -no-progress  -root-becomes nix  -p "/ d 0755 0 0" -pf ${pseudofiles}
+    cp store.img $out
+''

pkgs/pseudofile/default.nix

@@ -2,9 +2,7 @@
   writeText
 , lib
 }:
-filename  : attrset :
 let
-  inherit (lib.debug) traceSeqN;
   inherit (lib.attrsets) mapAttrsToList;
   visit = prefix: attrset:
     let
@@ -23,6 +21,10 @@ let
               else if attrs'.type == "d" then
                 (visit "${prefix}/${filename}" attrs.contents) +
                 "\n" + line
+              else if attrs'.type == "c" then
+                with attrs'; "${line} ${major} ${minor}"
+              else if attrs'.type == "b" then
+                with attrs'; "${line} ${major} ${minor}"
               else if attrs'.type == "s" then
                 "${line} ${attrs'.target}"
               else if attrs'.type == "l" then
@@ -33,5 +35,8 @@ let
                 line)
           attrset;
     in builtins.concatStringsSep "\n" l;
-  res =  (visit "" attrset);
-in writeText filename res
+in {
+  write = filename : attrset : writeText filename (visit "" attrset);
+  dir = contents: { type = "d"; inherit contents; };
+  symlink = target: { type = "s"; inherit target; };
+}

pkgs/s6-init-files/default.nix

@@ -1,144 +0,0 @@
-{
-  execline
-, s6
-, s6-linux-init
-, s6-rc
-, pseudofile
-, lib
-, stdenvNoCC
-, busybox
-} :
-let
-  initscripts = stdenvNoCC.mkDerivation {
-    name = "s6-scripts";
-    src = ./scripts;
-    phases = ["unpackPhase" "installPhase" ];
-    buildInputs = [busybox];
-    installPhase = ''
-      mkdir $out
-      cp -r $src $out/scripts
-      chmod -R +w $out
-      patchShebangs $out/scripts
-    '';
-  };
-  dir = contents: { type = "d"; inherit contents; };
-  symlink = target: { type = "s"; inherit target; };
-  scripts = symlink "${initscripts}/scripts";
-  env = dir {};
-  run-image = dir {
-    service = dir {
-      s6-linux-init-runleveld = dir {
-        notification-fd = { file = "3"; };
-        run = {
-          file = ''
-              #!${execline}/bin/execlineb -P
-              ${execline}/bin/fdmove -c 2 1
-              ${execline}/bin/fdmove 1 3
-              ${s6}/bin/s6-ipcserver -1 -a 0700 -c 1 -- s
-              ${s6}/bin/s6-sudod -dt30000 -- "/etc/s6-linux-init/current"/scripts/runlevel
-            '';
-          mode = "0755";
-        };
-      };
-      s6-linux-init-shutdownd = dir {
-        fifo = {
-          type = "i";
-          subtype = "f";
-          mode = "0600";
-        };
-        run = {
-          file = ''
-              #!${execline}/bin/execlineb -P
-              ${s6-linux-init}/bin/s6-linux-init-shutdownd -c  "/etc/s6-linux-init/current" -g 3000
-            '';
-          mode = "0755";
-        };
-
-      };
-      s6-svscan-log = dir {
-        fifo = {
-          type = "i";
-          subtype = "f";
-          mode = "0600";
-        };
-        notification-fd = { file = "3"; };
-        run = {
-          file = ''
-              #!${execline}/bin/execlineb -P
-              ${execline}/bin/redirfd -w 1 /dev/null
-              ${execline}/bin/redirfd -rnb 0 fifo
-              ${s6}/bin/s6-log -bpd3 -- t /run/uncaught-logs
-          '';
-          mode = "0755";
-        };
-      };
-      getty = dir {
-        run = {
-          file = ''
-              #!${execline}/bin/execlineb -P
-              ${busybox}/bin/getty -l ${busybox}/bin/login 38400 /dev/console
-          '';
-          mode = "0755";
-        };
-      };
-      ".s6-svscan" =
-        let
-          quit = message: ''
-              #!${execline}/bin/execlineb -P
-              ${execline}/bin/redirfd -w 2 /dev/console
-              ${execline}/bin/fdmove -c 1 2
-              ${execline}/bin/foreground { ${s6-linux-init}/bin/s6-linux-init-echo -- ${message} }
-              ${s6-linux-init}/bin/s6-linux-init-hpr -fr
-            '';
-          shutdown = action: ''
-              #!${execline}/bin/execlineb -P
-              ${s6-linux-init}/bin/s6-linux-init-hpr -a #{action} -- now
-            '';
-          empty = "#!${execline}/bin/execlineb -P\n";
-        in dir {
-          crash = {
-            file = quit "s6-svscan crashed. Rebooting.";
-            mode = "0755";
-          };
-          finish = {
-            file = quit "s6-svscan exited. Rebooting.";
-            mode = "0755";
-          };
-          SIGINT = {
-            file = shutdown "-r";
-            mode = "0755";
-          };
-          SIGPWR = {
-            file = shutdown "-p";
-            mode = "0755";
-          };
-          SIGQUIT = {
-            file = empty;
-            mode = "0755";
-          };
-          SIGTERM = {
-            file = empty;
-            mode = "0755";
-          };
-          SIGUSR1 = {
-            file = shutdown "-p";
-            mode = "0755";
-          };
-          SIGUSR2 = {
-            file = shutdown "-h";
-            mode = "0755";
-          };
-          SIGWINCH = {
-            file = empty;
-            mode = "0755";
-          };
-
-        };
-    };
-    uncaught-logs = (dir {}) // {mode = "2750";};
-  };
-  structure = { etc = dir { s6-linux-init = dir { current = dir {
-    inherit scripts env run-image;
-  };};};};
-
-in pseudofile "pseudo.s6-init" structure

scripts/run-qemu.sh

@@ -11,10 +11,12 @@ else
     flags="-serial mon:stdio"
 fi
 
+INIT=${INIT-/bin/init}
+
 qemu-system-mips \
     -M malta -m 256 \
     -echr 16 \
-    -append "default console=ttyS0,38400n8 panic=10 oops=panic init=/bin/init  loglevel=8 root=/dev/vda" \
+    -append "default console=ttyS0,38400n8 panic=10 oops=panic init=$INIT loglevel=8 root=/dev/vda" \
     -drive file=$2,format=raw,readonly=on,if=virtio \
     -netdev socket,id=access,mcast=230.0.0.1:1234 \
     -device virtio-net-pci,disable-legacy=on,disable-modern=off,netdev=access,mac=ba:ad:1d:ea:21:02 \

tests/pppoe/configuration.nix

@@ -68,5 +68,5 @@ in rec {
     ];
   };
 
-  systemPackages = [ pkgs.hello ] ;
+  defaultProfile.packages = [ pkgs.hello ] ;
 }

tests/pseudofiles/run.sh

@@ -4,8 +4,7 @@ expr=$(cat <<"EXPR"
 let
   overlay = import <liminix/overlay.nix>;
   nixpkgs = import <nixpkgs> { overlays = [overlay]; };
-  structure = import ./structure.nix;
-in nixpkgs.pkgs.pseudofile "pseudo.s6-init" structure
+in nixpkgs.pkgs.callPackage ./test.nix {}
 EXPR
     )
 

tests/pseudofiles/test.nix

@@ -1,5 +1,7 @@
-let
-  dir = contents: { type = "d"; inherit contents; };
+{
+  pseudofile
+}: let
+  inherit (pseudofile) dir;
   structure = {
     service = dir {
       s6-linux-init-runleveld = dir {
@@ -42,4 +44,4 @@ let
     };
     uncaught-logs = (dir {}) // {mode = "2750";};
   };
-in structure
+in pseudofile.write "pseudo.s6-init" structure

tests/smoke/configuration.nix

@@ -63,5 +63,5 @@ in rec {
     contents = with services; [ loopback ntp defaultroute4 ];
   };
 
-  systemPackages = [ pkgs.hello ] ;
+  defaultProfile.packages = [ pkgs.hello ] ;
 }