Added sample 'common.sh' in the main sources. The kernel download process has been rewritten to use the functionality from 'common.sh'. The whole project should adopt functional structure where it makes sense (e.g. the common download proces in most places).

src/01_get_kernel.sh

@@ -2,43 +2,24 @@
 
 set -e
 
+# Load common properties and functions in the current script.
+. ./common.sh
+
 echo "*** GET KERNEL BEGIN ***"
 
-SRC_DIR=$(pwd)
+# Read the 'KERNEL_SOURCE_URL' property from '.config'.
-
+DOWNLOAD_URL=`read_property KERNEL_SOURCE_URL`
-# Grab everything after the '=' character.
-DOWNLOAD_URL=$(grep -i ^KERNEL_SOURCE_URL .config | cut -f2 -d'=')
 
 # Grab everything after the last '/' character.
 ARCHIVE_FILE=${DOWNLOAD_URL##*/}
 
-# Read the 'USE_LOCAL_SOURCE' property from '.config'
+# Download kernel source archive in the 'source' directory.
-USE_LOCAL_SOURCE="$(grep -i ^USE_LOCAL_SOURCE .config | cut -f2 -d'=')"
+download_source $DOWNLOAD_URL $SOURCE_DIR/$ARCHIVE_FILE
 
-if [ "$USE_LOCAL_SOURCE" = "true" -a ! -f $SRC_DIR/source/$ARCHIVE_FILE  ] ; then
+# Extract the kernel sources in the 'work/kernel' directory.
-  echo "Source bundle $SRC_DIR/source/$ARCHIVE_FILE is missing and will be downloaded."
+extract_source $SOURCE_DIR/$ARCHIVE_FILE kernel
-  USE_LOCAL_SOURCE="false"
-fi
-
-cd source
-
-if [ ! "$USE_LOCAL_SOURCE" = "true" ] ; then
-  # Downloading kernel source bundle file. The '-c' option allows the download to resume.
-  echo "Downloading kernel source bundle from $DOWNLOAD_URL"
-  wget -c $DOWNLOAD_URL
-else
-  echo "Using local kernel source bundle $SRC_DIR/source/$ARCHIVE_FILE"
-fi
-
-# Delete folder with previously extracted kernel.
-echo "Removing kernel work area. This may take a while."
-rm -rf ../work/kernel
-mkdir ../work/kernel
-
-# Extract kernel to folder 'work/kernel'.
-# Full path will be something like 'work/kernel/linux-4.4.6'.
-tar -xvf $ARCHIVE_FILE -C ../work/kernel
 
+# Just in case we go back to the main MLL source folder.
 cd $SRC_DIR
 
 echo "*** GET KERNEL END ***"

src/02_build_kernel.sh

@@ -2,22 +2,11 @@
 
 set -e
 
+# Load common properties and functions in the current script.
+. ./common.sh
+
 echo "*** BUILD KERNEL BEGIN ***"
 
-SRC_DIR=$(pwd)
-
-# Read the 'JOB_FACTOR' property from '.config'
-JOB_FACTOR="$(grep -i ^JOB_FACTOR .config | cut -f2 -d'=')"
-
-# Read the 'CFLAGS' property from '.config'
-CFLAGS="$(grep -i ^CFLAGS .config | cut -f2 -d'=')"
-
-# Find the number of available CPU cores.
-NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
-
-# Calculate the number of 'make' jobs to be used later.
-NUM_JOBS=$((NUM_CORES * JOB_FACTOR))
-
 cd work/kernel
 
 # Prepare the kernel install area.
@@ -32,16 +21,16 @@ echo "Preparing kernel work area."
 make mrproper -j $NUM_JOBS
 
 # Read the 'USE_PREDEFINED_KERNEL_CONFIG' property from '.config'
-USE_PREDEFINED_KERNEL_CONFIG="$(grep -i ^USE_PREDEFINED_KERNEL_CONFIG $SRC_DIR/.config | cut -f2 -d'=')"
+USE_PREDEFINED_KERNEL_CONFIG=`read_property USE_PREDEFINED_KERNEL_CONFIG`
 
 if [ "$USE_PREDEFINED_KERNEL_CONFIG" = "true" -a ! -f $SRC_DIR/minimal_config/kernel.config ] ; then
-  echo "Config file $SRC_DIR/minimal_config/kernel.config does not exist."
+  echo "Config file '$SRC_DIR/minimal_config/kernel.config' does not exist."
-  USE_PREDEFINED_KERNEL_CONFIG="false"
+  USE_PREDEFINED_KERNEL_CONFIG=false
 fi
 
 if [ "$USE_PREDEFINED_KERNEL_CONFIG" = "true" ] ; then
   # Use predefined configuration file for the kernel.
-  echo "Using config file $SRC_DIR/minimal_config/kernel.config"
+  echo "Using config file '$SRC_DIR/minimal_config/kernel.config'."
   cp -f $SRC_DIR/minimal_config/kernel.config .config
 else
   # Create default configuration file for the kernel.
@@ -70,7 +59,7 @@ else
   sed -i "s/.*CONFIG_FB_VESA.*/CONFIG_FB_VESA=y/" .config
 
   # Read the 'USE_BOOT_LOGO' property from '.config'
-  USE_BOOT_LOGO="$(grep -i ^USE_BOOT_LOGO $SRC_DIR/.config | cut -f2 -d'=')"
+  USE_BOOT_LOGO=`read_property USE_BOOT_LOGO`
 
   if [ "$USE_BOOT_LOGO" = "true" ] ; then
     sed -i "s/.*CONFIG_LOGO_LINUX_CLUT224.*/CONFIG_LOGO_LINUX_CLUT224=y/" .config
@@ -86,7 +75,7 @@ else
   # Enable the EFI stub
   sed -i "s/.*CONFIG_EFI_STUB.*/CONFIG_EFI_STUB=y/" .config
 
-  # Request that the firmware clear the contents of RAM after a reboot (4.14+).
+  # Request that the firmware clear the contents of RAM after reboot (4.14+).
   echo "CONFIG_RESET_ATTACK_MITIGATION=y" >> .config
 
   # Disable Apple Properties (Useful for Macs but useless in general)

src/common.sh

@@ -0,0 +1,71 @@
+#!/bin/sh
+
+set -e
+
+SRC_DIR=`realpath --no-symlinks $PWD`
+SOURCE_DIR=$SRC_DIR/source
+WORK_DIR=$SRC_DIR/work
+CONFIG=$SRC_DIR/.config
+
+# This function reads property from the main '.config' file.
+#
+# Using () instead of {} for the function body is a POSIX
+# compliant way to execute subshell and as consequence all
+# variables in the function will become effectively in local
+# scope. Note that the 'local' keyword is supported by most
+# shells but it is not POSIX compliant.
+read_property() (
+  # The property we are looking for.
+  prop_name=$1
+
+  # The value of the property set initially to empty string.
+  prop_value=
+
+  if [ ! "$prop_name" = "" ] ; then
+    # Search in the main '.config' file.
+    prop_value=`grep -i ^${prop_name}= $CONFIG | cut -f2- -d'=' | xargs`
+  fi
+
+  echo $prop_value
+)
+
+# Read commonly used properties from the main '.config' file.
+JOB_FACTOR=`read_property JOB_FACTOR`
+CFLAGS=`read_property CFLAGS`
+NUM_CORES=$(grep ^processor /proc/cpuinfo | wc -l)
+
+# Calculate the number of 'make' jobs to be used later.
+NUM_JOBS=$((NUM_CORES * JOB_FACTOR))
+
+download_source() (
+  url=$1  # Download from this URL.
+  file=$2 # Save the resource in this file.
+
+  local=`read_property USE_LOCAL_SOURCE`
+
+  if [ "$local" = "true" -a ! -f $file  ] ; then
+    echo "Source file '$file' is missing and will be downloaded."
+    local=false
+  fi
+
+  if [ ! "$local" = "true" ] ; then
+    echo "Downloading source file from '$url'."
+    echo "Saving source file in '$file'".
+    wget -O $file -c $url
+  else
+    echo "Using local source file '$file'."
+  fi
+)
+
+extract_source() (
+  file=$1
+  name=$2
+
+  # Delete folder with previously extracted source.
+  echo "Removing '$name' work area. This may take a while."
+  rm -rf $WORK_DIR/$name
+  mkdir $WORK_DIR/$name
+
+  # Extract source to folder 'work/$source'.
+  tar -xvf $file -C $WORK_DIR/$name
+)