[bug#45046] [PATCH] build/kconfig: New module to modify a defconfig file.

[Stefan]

* guix/build/kconfig.scm (modify-defconfig): New file with a new function.
* gnu/packages/bootloaders.scm (make-u-boot-package,
make-u-boot-sunxi64-package): Adding new key arguments to pass and/or modify
a defconfig file.
(u-boot-am335x-boneblack, u-boot-pinebook, u-boot-novena): Simplify functions
by using the new key arguments of the former functions.
* Makefile.am: Adding guix/build/kconfig.scm to MODULES.
---
 Makefile.am                  |   1 +
 gnu/packages/bootloaders.scm |  89 +++++++++++-------------
 guix/build/kconfig.scm       | 127 +++++++++++++++++++++++++++++++++++
 3 files changed, 167 insertions(+), 50 deletions(-)
 create mode 100644 guix/build/kconfig.scm

diff --git a/Makefile.am b/Makefile.am
index 1a3ca227a4..c08e7be3a2 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -210,6 +210,7 @@ MODULES =                                   \
   guix/build/waf-build-system.scm              \
   guix/build/haskell-build-system.scm          \
   guix/build/julia-build-system.scm            \
+  guix/build/kconfig.scm                        \
   guix/build/linux-module-build-system.scm     \
   guix/build/store-copy.scm                    \
   guix/build/json.scm                          \
diff --git a/gnu/packages/bootloaders.scm b/gnu/packages/bootloaders.scm
index 75ae8d919b..e72c1d41e8 100644
--- a/gnu/packages/bootloaders.scm
+++ b/gnu/packages/bootloaders.scm
@@ -13,6 +13,7 @@
 ;;; Copyright © 2020 Björn Höfling <bjoern.hoefling@bjoernhoefling.de>
 ;;; Copyright © 2018, 2019, 2020 Vagrant Cascadian <vagrant@debian.org>
 ;;; Copyright © 2020 Pierre Langlois <pierre.langlois@gmx.com>
+;;; Copyright © 2020 Stefan <stefan-guix@vodafonemail.de>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -70,6 +71,7 @@
   #:use-module (guix utils)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
+  #:use-module (ice-9 optargs)
   #:use-module (ice-9 regex))
 
 (define unifont
@@ -602,8 +604,9 @@ def test_ctrl_c"))
 also initializes the boards (RAM etc).  This package provides its
 board-independent tools.")))
 
-(define-public (make-u-boot-package board triplet)
-  "Returns a u-boot package for BOARD cross-compiled for TRIPLET."
+(define*-public (make-u-boot-package board triplet #:key defconfig configs)
+  "Returns a u-boot package for BOARD cross-compiled for TRIPLET with the
+optional DEFCONFIG file and optional configuration changes from CONFIGS."
   (let ((same-arch? (lambda ()
                       (string=? (%current-system)
                                 (gnu-triplet->nix-system triplet)))))
@@ -621,8 +624,11 @@ board-independent tools.")))
       (arguments
        `(#:modules ((ice-9 ftw)
                     (srfi srfi-1)
-                    (guix build utils)
-                    (guix build gnu-build-system))
+                    (guix build gnu-build-system)
+                    (guix build kconfig)
+                    (guix build utils))
+         #:imported-modules (,@%gnu-build-system-modules
+                             (guix build kconfig))
          #:test-target "test"
          #:make-flags
          (list "HOSTCC=gcc"
@@ -633,9 +639,18 @@ board-independent tools.")))
          (modify-phases %standard-phases
            (replace 'configure
              (lambda* (#:key outputs make-flags #:allow-other-keys)
-               (let ((config-name (string-append ,board "_defconfig")))
-                 (if (file-exists? (string-append "configs/" config-name))
-                     (apply invoke "make" `(,@make-flags ,config-name))
+               (let* ((config-name (string-append ,board "_defconfig"))
+                      (config-file (string-append "configs/" config-name))
+                      (defconfig ,defconfig)
+                      (configs ',configs))
+                 (when defconfig
+                   ;; Replace the board-specific defconfig with the given one.
+                   (copy-file defconfig config-file))
+                 (if (file-exists? config-file)
+                     (begin
+                       (when configs
+                         (modify-defconfig config-file configs))
+                       (apply invoke "make" `(,@make-flags ,config-name)))
                      (begin
                        (display "Invalid board name. Valid board names are:"
                                 (current-error-port))
@@ -686,7 +701,11 @@ board-independent tools.")))
   (make-u-boot-package "malta" "mips64el-linux-gnuabi64"))
 
 (define-public u-boot-am335x-boneblack
-  (let ((base (make-u-boot-package "am335x_evm" "arm-linux-gnueabihf")))
+  (let ((base (make-u-boot-package "am335x_evm" "arm-linux-gnueabihf"
+               ;; Patch out other device trees to build image small enough to
+               ;; fit within typical partitioning schemes where the first
+               ;; partition begins at sector 2048.
+               #:configs '("CONFIG_OF_LIST=\"am335x-evm 
am335x-boneblack\"\n"))))
     (package
       (inherit base)
       (name "u-boot-am335x-boneblack")
@@ -695,25 +714,13 @@ also initializes the boards (RAM etc).
 
 This U-Boot is built for the BeagleBone Black, which was removed upstream,
 adjusted from the am335x_evm build with several device trees removed so that
-it fits within common partitioning schemes.")
-      (arguments
-       (substitute-keyword-arguments (package-arguments base)
-         ((#:phases phases)
-          `(modify-phases ,phases
-             (add-after 'unpack 'patch-defconfig
-               ;; Patch out other devicetrees to build image small enough to
-               ;; fit within typical partitioning schemes where the first
-               ;; partition begins at sector 2048.
-               (lambda _
-                 (substitute* "configs/am335x_evm_defconfig"
-                   (("CONFIG_OF_LIST=.*$") "CONFIG_OF_LIST=\"am335x-evm 
am335x-boneblack\"\n"))
-                 #t)))))))))
+it fits within common partitioning schemes."))))
 
 (define-public u-boot-am335x-evm
   (make-u-boot-package "am335x_evm" "arm-linux-gnueabihf"))
 
-(define-public (make-u-boot-sunxi64-package board triplet)
-  (let ((base (make-u-boot-package board triplet)))
+(define*-public (make-u-boot-sunxi64-package board triplet #:key defconfig 
configs)
+  (let ((base (make-u-boot-package board triplet #:defconfig defconfig 
#:configs configs)))
     (package
       (inherit base)
       (arguments
@@ -743,20 +750,10 @@ it fits within common partitioning schemes.")
   (make-u-boot-sunxi64-package "pine64-lts" "aarch64-linux-gnu"))
 
 (define-public u-boot-pinebook
-  (let ((base (make-u-boot-sunxi64-package "pinebook" "aarch64-linux-gnu")))
-    (package
-      (inherit base)
-      (arguments
-       (substitute-keyword-arguments (package-arguments base)
-         ((#:phases phases)
-          `(modify-phases ,phases
-             (add-after 'unpack 'patch-pinebook-config
-               ;; Fix regression with LCD video output introduced in 2020.01
-               ;; https://patchwork.ozlabs.org/patch/1225130/
-               (lambda _
-                 (substitute* "configs/pinebook_defconfig"
-                   (("CONFIG_VIDEO_BRIDGE_ANALOGIX_ANX6345=y") 
"CONFIG_VIDEO_BRIDGE_ANALOGIX_ANX6345=y\nCONFIG_VIDEO_BPP32=y"))
-                 #t)))))))))
+  (make-u-boot-sunxi64-package "pinebook" "aarch64-linux-gnu"
+   ;; Fix regression with LCD video output introduced in 2020.01
+   ;; https://patchwork.ozlabs.org/patch/1225130/
+   #:configs '("CONFIG_VIDEO_BPP32=y")))
 
 (define-public u-boot-bananapi-m2-ultra
   (make-u-boot-package "Bananapi_M2_Ultra" "arm-linux-gnueabihf"))
@@ -780,25 +777,17 @@ it fits within common partitioning schemes.")
   (make-u-boot-package "mx6cuboxi" "arm-linux-gnueabihf"))
 
 (define-public u-boot-novena
-  (let ((base (make-u-boot-package "novena" "arm-linux-gnueabihf")))
+  (let ((base (make-u-boot-package "novena" "arm-linux-gnueabihf"
+               ;; Patch configuration to disable loading u-boot.img from FAT
+               ;; partition, allowing it to be installed at a device offset.
+               #:configs '("CONFIG_SPL_FS_FAT="))))
     (package
       (inherit base)
       (description "U-Boot is a bootloader used mostly for ARM boards. It
 also initializes the boards (RAM etc).
 
 This U-Boot is built for Novena.  Be advised that this version, contrary
-to Novena upstream, does not load u-boot.img from the first partition.")
-      (arguments
-       (substitute-keyword-arguments (package-arguments base)
-         ((#:phases phases)
-          `(modify-phases ,phases
-             (add-after 'unpack 'patch-novena-defconfig
-               ;; Patch configuration to disable loading u-boot.img from FAT 
partition,
-               ;; allowing it to be installed at a device offset.
-               (lambda _
-                 (substitute* "configs/novena_defconfig"
-                   (("CONFIG_SPL_FS_FAT=y") "# CONFIG_SPL_FS_FAT is not set"))
-                 #t)))))))))
+to Novena upstream, does not load u-boot.img from the first partition."))))
 
 (define-public u-boot-cubieboard
   (make-u-boot-package "Cubieboard" "arm-linux-gnueabihf"))
diff --git a/guix/build/kconfig.scm b/guix/build/kconfig.scm
new file mode 100644
index 0000000000..7554b76171
--- /dev/null
+++ b/guix/build/kconfig.scm
@@ -0,0 +1,127 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2020 Stefan <stefan-guix@vodafonemail.de>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build kconfig)
+  #:use-module  (ice-9 rdelim)
+  #:use-module  (srfi srfi-1)
+  #:use-module  (srfi srfi-26)
+  #:export (modify-defconfig))
+
+;; Commentary:
+;;
+;; Builder-side code to modify configurations for the Kconfig build system as
+;; used by Linux and U-Boot.
+;;
+;; Code:
+
+(define (modify-defconfig defconfig configs)
+  "This function can modify a given DEFCONFIG file by adding, changing or
+removing the list of strings in CONFIGS.  This allows an easy customization of
+Kconfig based projects like the kernel Linux or the bootloader 'Das U-Boot'.
+
+These are examples for CONFIGS to add (or change) and remove
+configurations to/from DEFCONFIG:
+
+'(\"CONFIG_A=\\\"a\\\"\"
+  \"CONFIG_B=0\"
+  \"CONFIG_C=y\"
+  \"CONFIG_D=m\"
+  \"CONFIG_E=\"
+  \"CONFIG_F\")"
+
+  (define (config-string->pair config-string)
+    "Parse a config-string like \"CONFIG_NET=y\" into a key-value pair.
+Spaces get trimmed.
+\"CONFIG_EXAMPLE=y\"  -> '(\"CONFIG_EXAMPLE\" . \"y\")
+\"CONFIG_EXAMPLE=\\\"\\\"\" -> '(\"CONFIG_EXAMPLE\" . \"\").
+\"CONFIG_EXAMPLE=\"  -> '(\"CONFIG_EXAMPLE\" . #f).
+\"CONFIG_EXAMPLE\"   -> '(\"CONFIG_EXAMPLE\" . #f)."
+    (let ((pair (map string-trim-both (string-split config-string #\=))))
+      (case (length pair)
+        ((2)
+         (cons (string-append (first pair))
+               (if (string-null? (second pair))
+                   #f
+                   (second pair))))
+        (else (cons (first pair) #f)))))
+
+  (define (pair->config-string pair)
+    "Convert a PAIR back to a config-string."
+    (let* ((key (car pair))
+           (value (cdr pair)))
+      (if value
+          (string-append key "=" value)
+          key)))
+
+  (define (disable-pair pair blacklist)
+    "Turn the key of a key-value PAIR into an disabled key, if listed in
+BLACKLIST."
+    (let* ((key (car pair)))
+      (if (member key blacklist)
+          (cons (string-append "# disabled " key)
+                (cdr pair))
+          pair)))
+
+  (define (disable-config-string config-string blacklist)
+    "Turn the CONFIG-STRING into a disabled one, if listed in BLACKLIST."
+    (pair->config-string (disable-pair (config-string->pair config-string)
+                                       blacklist)))
+
+  (define (unset-pair pair)
+    "Turn the key of a key-value PAIR into an unset key, if its value is #f."
+    (let* ((key (car pair))
+           (value (cdr pair)))
+      (if value
+          pair
+          (cons (string-append "# unset " key) value))))
+
+  (define (unset-config-string config-string)
+    "Turn the CONFIG-STRING into a proper unset one, if there is no assignment"
+    (pair->config-string (unset-pair (config-string->pair config-string))))
+
+  (define (write-modified-lines input modify-line)
+    "Write all lines from the INPUT after applying MODIFY-LINE to the
+ current-output-port."
+    (let loop ((line (read-line input)))
+      (when (not (eof-object? line))
+        (display (modify-line line))
+        (newline)
+        (loop (read-line input)))))
+
+  (let* ((modified-defconfig (string-append defconfig ".mod"))
+         ;; Generate a blacklist of config keys from configs.
+         (blacklist (map (lambda (config-string)
+                           (first (config-string->pair config-string)))
+                         configs))
+         (disable-config-string (cut disable-config-string <> blacklist)))
+    ;; Write to modified-defconfig file first the configs, and second
+    ;; the content of the defconfig file with disabled lines.
+    (call-with-output-file modified-defconfig
+      (lambda (output)
+        (with-output-to-port output
+          (lambda ()
+            (call-with-input-string (string-join configs "\n")
+              (lambda (input)
+                (write-modified-lines input unset-config-string)))
+            (false-if-exception
+              (call-with-input-file defconfig
+                (lambda (input)
+                  (write-modified-lines input disable-config-string))))))))
+    ;; Ensure the modified-defconfig file is used.
+    (false-if-exception (delete-file defconfig))
+    (rename-file modified-defconfig defconfig)))
-- 
2.29.2