kbuild: rebuild initramfs if content of initramfs changes

initramfs.cpio.gz being build in usr/ and included in the
kernel was not rebuild when the included files changed.

To fix this the following was done:
- let gen_initramfs.sh generate a list of files and directories included
  in the initramfs
- gen_initramfs generate the gzipped cpio archive so we could simplify
  the kbuild file (Makefile)
- utilising the kbuild infrastructure so when uid/gid root mapping changes
  the initramfs will be rebuild

With this change we have a much more robust initramfs generation.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

2 files changed, 189 insertions, 127 deletions

diff --git a/scripts/gen_initramfs_list.sh b/scripts/gen_initramfs_list.sh
index 6d411169bfa6..56b3bed1108f 100644
--- a/scripts/gen_initramfs_list.sh
+++ b/scripts/gen_initramfs_list.sh
@@ -1,22 +1,55 @@
 #!/bin/bash
 # Copyright (C) Martin Schlemmer <azarah@nosferatu.za.org>
-# Released under the terms of the GNU GPL
-#
-# Generate a newline separated list of entries from the file/directory
-# supplied as an argument.
-#
-# If a file/directory is not supplied then generate a small dummy file.
+# Copyright (c) 2006           Sam Ravnborg <sam@ravnborg.org>
 #
-# The output is suitable for gen_init_cpio built from usr/gen_init_cpio.c.
+# Released under the terms of the GNU GPL
 #
+# Generate a cpio packed initramfs. It uses gen_init_cpio to generate
+# the cpio archive, and gzip to pack it.
+# The script may also be used to generate the inputfile used for gen_init_cpio
+# This script assumes that gen_init_cpio is located in usr/ directory
+
+# error out on errors
+set -e
+
+usage() {
+cat << EOF
+Usage:
+$0 [-o <file>] [-u <uid>] [-g <gid>] {-d | <cpio_source>} ...
+        -o <file>      Create gzipped initramfs file named <file> using
+                       gen_init_cpio and gzip
+        -u <uid>       User ID to map to user ID 0 (root).
+                       <uid> is only meaningful if <cpio_source>
+                       is a directory.
+        -g <gid>       Group ID to map to group ID 0 (root).
+                       <gid> is only meaningful if <cpio_source>
+                       is a directory.
+        <cpio_source>  File list or directory for cpio archive.
+                       If <cpio_source> is a .cpio file it will be used
+                       as direct input to initramfs.
+        -d             Output the default cpio list.
+
+All options except -o and -l may be repeated and are interpreted
+sequentially and immediately.  -u and -g states are preserved across
+<cpio_source> options so an explicit "-u 0 -g 0" is required
+to reset the root/group mapping.
+EOF
+}
+
+list_default_initramfs() {
+        # echo usr/kinit/kinit
+        :
+}
 
 default_initramfs() {
-        cat <<-EOF
+        cat <<-EOF >> ${output}
                 # This is a very simple, default initramfs
 
                 dir /dev 0755 0 0
                 nod /dev/console 0600 0 0 c 5 1
                 dir /root 0700 0 0
+                # file /kinit usr/kinit/kinit 0755 0 0
+                # slink /init kinit 0755 0 0
         EOF
 }
 
@@ -42,18 +75,28 @@ filetype() {
         return 0
 }
 
+list_print_mtime() {
+        :
+}
+
 print_mtime() {
-        local argv1="$1"
         local my_mtime="0"
 
-        if [ -e "${argv1}" ]; then
-                my_mtime=$(find "${argv1}" -printf "%T@\n" | sort -r | head -n 1)
+        if [ -e "$1" ]; then
+                my_mtime=$(find "$1" -printf "%T@\n" | sort -r | head -n 1)
         fi
-        
-        echo "# Last modified: ${my_mtime}"
-        echo
+
+        echo "# Last modified: ${my_mtime}" >> ${output}
+        echo "" >> ${output}
+}
+
+list_parse() {
+        echo "$1 \\"
 }
 
+# for each file print a line in following format
+# <filetype> <name> <path to file> <octal mode> <uid> <gid>
+# for links, devices etc the format differs. See gen_init_cpio for details
 parse() {
         local location="$1"
         local name="${location/${srcdir}//}"
@@ -99,80 +142,112 @@ parse() {
                         ;;
         esac
 
-        echo "${str}"
+        echo "${str}" >> ${output}
 
         return 0
 }
 
-usage() {
-        printf    "Usage:\n"
-        printf    "$0 [ [-u <root_uid>] [-g <root_gid>] [-d | <cpio_source>] ] . . .\n"
-        printf    "\n"
-        printf -- "-u <root_uid>  User ID to map to user ID 0 (root).\n"
-        printf    "               <root_uid> is only meaningful if <cpio_source>\n"
-        printf    "               is a directory.\n"
-        printf -- "-g <root_gid>  Group ID to map to group ID 0 (root).\n"
-        printf    "               <root_gid> is only meaningful if <cpio_source>\n"
-        printf    "               is a directory.\n"
-        printf    "<cpio_source>  File list or directory for cpio archive.\n"
-        printf    "               If <cpio_source> is not provided then a\n"
-        printf    "               a default list will be output.\n"
-        printf -- "-d             Output the default cpio list.  If no <cpio_source>\n"
-        printf    "               is given then the default cpio list will be output.\n"
-        printf    "\n"
-        printf    "All options may be repeated and are interpreted sequentially\n"
-        printf    "and immediately.  -u and -g states are preserved across\n"
-        printf    "<cpio_source> options so an explicit \"-u 0 -g 0\" is required\n"
-        printf    "to reset the root/group mapping.\n"
+unknown_option() {
+        printf "ERROR: unknown option \"$arg\"\n" >&2
+        printf "If the filename validly begins with '-', " >&2
+        printf "then it must be prefixed\n" >&2
+        printf "by './' so that it won't be interpreted as an option." >&2
+        printf "\n" >&2
+        usage >&2
+        exit 1
+}
+
+list_header() {
+        echo "deps_initramfs := \\"
+}
+
+header() {
+        printf "\n#####################\n# $1\n" >> ${output}
+}
+
+# process one directory (incl sub-directories)
+dir_filelist() {
+        ${dep_list}header "$1"
+
+        srcdir=$(echo "$1" | sed -e 's://*:/:g')
+        dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" 2>/dev/null)
+
+        # If $dirlist is only one line, then the directory is empty
+        if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
+                ${dep_list}print_mtime "$1"
+
+                echo "${dirlist}" | \
+                while read x; do
+                        ${dep_list}parse ${x}
+                done
+        fi
 }
 
-build_list() {
-        printf "\n#####################\n# $cpio_source\n"
-
-        if [ -f "$cpio_source" ]; then
-                print_mtime "$cpio_source"
-                cat "$cpio_source"
-        elif [ -d "$cpio_source" ]; then
-                srcdir=$(echo "$cpio_source" | sed -e 's://*:/:g')
-                dirlist=$(find "${srcdir}" -printf "%p %m %U %G\n" 2>/dev/null)
-
-                # If $dirlist is only one line, then the directory is empty
-                if [  "$(echo "${dirlist}" | wc -l)" -gt 1 ]; then
-                        print_mtime "$cpio_source"
-                
-                        echo "${dirlist}" | \
-                        while read x; do
-                                parse ${x}
-                        done
+# if only one file is specified and it is .cpio file then use it direct as fs
+# if a directory is specified then add all files in given direcotry to fs
+# if a regular file is specified assume it is in gen_initramfs format
+input_file() {
+        source="$1"
+        if [ -f "$1" ]; then
+                ${dep_list}header "$1"
+                is_cpio="$(echo "$1" | sed 's/^.*\.cpio/cpio/')"
+                if [ $2 -eq 0 -a ${is_cpio} == "cpio" ]; then
+                        cpio_file=$1
+                        [ ! -z ${dep_list} ] && echo "$1"
+                        return 0
+                fi
+                if [ -z ${dep_list} ]; then
+                        print_mtime "$1" >> ${output}
+                        cat "$1"         >> ${output}
                 else
-                        # Failsafe in case directory is empty
-                        default_initramfs
+                        grep ^file "$1" | cut -d ' ' -f 3
                 fi
+        elif [ -d "$1" ]; then
+                dir_filelist "$1"
         else
-                echo "  $0: Cannot open '$cpio_source'" >&2
+                echo "  ${prog}: Cannot open '$1'" >&2
                 exit 1
         fi
 }
 
-
+prog=$0
 root_uid=0
 root_gid=0
+dep_list=
+cpio_file=
+cpio_list=
+output="/dev/stdout"
+output_file=""
 
+arg="$1"
+case "$arg" in
+        "-l")   # files included in initramfs - used by kbuild
+                dep_list="list_"
+                shift
+                ;;
+        "-o")   # generate gzipped cpio image named $1
+                shift
+                output_file="$1"
+                cpio_list="$(mktemp ${TMPDIR:-/tmp}/cpiolist.XXXXXX)"
+                output=${cpio_list}
+                shift
+                ;;
+esac
 while [ $# -gt 0 ]; do
         arg="$1"
         shift
         case "$arg" in
-                "-u")
+                "-u")   # map $1 to uid=0 (root)
                         root_uid="$1"
                         shift
                         ;;
-                "-g")
+                "-g")   # map $1 to gid=0 (root)
                         root_gid="$1"
                         shift
                         ;;
-                "-d")
+                "-d")   # display default initramfs list
                         default_list="$arg"
-                        default_initramfs
+                        ${dep_list}default_initramfs
                         ;;
                 "-h")
                         usage
@@ -181,23 +256,27 @@ while [ $# -gt 0 ]; do
                 *)
                         case "$arg" in
                                 "-"*)
-                                        printf "ERROR: unknown option \"$arg\"\n" >&2
-                                        printf "If the filename validly begins with '-', then it must be prefixed\n" >&2
-                                        printf "by './' so that it won't be interpreted as an option." >&2
-                                        printf "\n" >&2
-                                        usage >&2
-                                        exit 1
+                                        unknown_option
                                         ;;
-                                *)
-                                        cpio_source="$arg"
-                                        build_list
+                                *)      # input file/dir - process it
+                                        input_file "$arg" "$#"
                                         ;;
                         esac
                         ;;
         esac
 done
 
-# spit out the default cpio list if a source hasn't been specified
-[ -z "$cpio_source" -a -z "$default_list" ] && default_initramfs
-
+# If output_file is set we will generate cpio archive and gzip it
+# we are carefull to delete tmp files
+if [ ! -z ${output_file} ]; then
+        if [ -z ${cpio_file} ]; then
+                cpio_tfile="$(mktemp ${TMPDIR:-/tmp}/cpiofile.XXXXXX)"
+                usr/gen_init_cpio ${cpio_list} > ${cpio_tfile}
+        else
+                cpio_tfile=${cpio_file}
+        fi
+        rm ${cpio_list}
+        cat ${cpio_tfile} | gzip -f -9 - > ${output_file}
+        [ -z ${cpio_file} ] && rm ${cpio_tfile}
+fi
 exit 0
diff --git a/usr/Makefile b/usr/Makefile
index e2129cb570bb..19d74e6f2685 100644
--- a/usr/Makefile
+++ b/usr/Makefile
@@ -1,65 +1,48 @@
+#
+# kbuild file for usr/ - including initramfs image
+#
 
-obj-y := initramfs_data.o
-
-hostprogs-y  := gen_init_cpio
+klibcdirs:;
 
-clean-files := initramfs_data.cpio.gz initramfs_list
+# Generate builtin.o based on initramfs_data.o
+obj-y := initramfs_data.o
 
 # initramfs_data.o contains the initramfs_data.cpio.gz image.
 # The image is included using .incbin, a dependency which is not
 # tracked automatically.
 $(obj)/initramfs_data.o: $(obj)/initramfs_data.cpio.gz FORCE
 
-ifdef CONFIG_INITRAMFS_ROOT_UID
-gen_initramfs_args += -u $(CONFIG_INITRAMFS_ROOT_UID)
-endif
-
-ifdef CONFIG_INITRAMFS_ROOT_GID
-gen_initramfs_args += -g $(CONFIG_INITRAMFS_ROOT_GID)
-endif
-
-# The $(shell echo $(CONFIG_INITRAMFS_SOURCE)) is to remove the
-# gratuitous begin and end quotes from the Kconfig string type.
-# Internal, escaped quotes in the Kconfig string will loose the
-# escape and become active quotes.
-quotefixed_initramfs_source := $(shell echo $(CONFIG_INITRAMFS_SOURCE))
-
-filechk_initramfs_list = $(CONFIG_SHELL) \
- $(srctree)/scripts/gen_initramfs_list.sh $(gen_initramfs_args) $(quotefixed_initramfs_source)
-
-$(obj)/initramfs_list: $(obj)/Makefile FORCE
-        $(call filechk,initramfs_list)
-
-quiet_cmd_cpio = CPIO    $@
-      cmd_cpio = ./$< $(obj)/initramfs_list > $@
-
-
-# Check if the INITRAMFS_SOURCE is a cpio archive
-ifneq (,$(findstring .cpio,$(quotefixed_initramfs_source)))
-
-# INITRAMFS_SOURCE has a cpio archive - verify that it's a single file
-ifneq (1,$(words $(quotefixed_initramfs_source)))
-$(error Only a single file may be specified in CONFIG_INITRAMFS_SOURCE (="$(quotefixed_initramfs_source)") when a cpio archive is directly specified.)
-endif
-# Now use the cpio archive directly
-initramfs_data_cpio = $(quotefixed_initramfs_source)
-targets += $(quotefixed_initramfs_source)
-
-else
-
-# INITRAMFS_SOURCE is not a cpio archive - create one
-$(obj)/initramfs_data.cpio: $(obj)/gen_init_cpio \
-                            $(initramfs-y) $(obj)/initramfs_list FORCE
-        $(call if_changed,cpio)
-
-targets += initramfs_data.cpio
-initramfs_data_cpio = $(obj)/initramfs_data.cpio
-
+#####
+# Generate the initramfs cpio archive
+
+hostprogs-y := gen_init_cpio
+initramfs   := $(CONFIG_SHELL) $(srctree)/scripts/gen_initramfs_list.sh
+ramfs-input := $(if $(filter-out "",$(CONFIG_INITRAMFS_SOURCE)), \
+                    $(CONFIG_INITRAMFS_SOURCE),-d)
+ramfs-args  := \
+        $(if $(CONFIG_INITRAMFS_ROOT_UID), -u $(CONFIG_INITRAMFS_ROOT_UID)) \
+        $(if $(CONFIG_INITRAMFS_ROOT_GID), -g $(CONFIG_INITRAMFS_ROOT_GID)) \
+        $(ramfs-input)
+
+# .initramfs_data.cpio.gz.d is used to identify all files included
+# in initramfs and to detect if any files are added/removed.
+# Removed files are identified by directory timestamp being updated
+# The dependency list is generated by gen_initramfs.sh -l
+ifneq ($(wildcard $(obj)/.initramfs_data.cpio.gz.d),)
+        include $(obj)/.initramfs_data.cpio.gz.d
 endif
 
-
-$(obj)/initramfs_data.cpio.gz: $(initramfs_data_cpio) FORCE
-        $(call if_changed,gzip)
-
-targets += initramfs_data.cpio.gz
+quiet_cmd_initfs = GEN     $@
+      cmd_initfs = $(initramfs) -o $@ $(ramfs-args) $(ramfs-input)
+
+targets := initramfs_data.cpio.gz
+$(deps_initramfs): klibcdirs
+# We rebuild initramfs_data.cpio.gz if:
+# 1) Any included file is newer then initramfs_data.cpio.gz
+# 2) There are changes in which files are included (added or deleted)
+# 3) If gen_init_cpio are newer than initramfs_data.cpio.gz
+# 4) arguments to gen_initramfs.sh changes
+$(obj)/initramfs_data.cpio.gz: $(obj)/gen_init_cpio $(deps_initramfs) klibcdirs
+        $(Q)$(initramfs) -l $(ramfs-input) > $(obj)/.initramfs_data.cpio.gz.d
+        $(call if_changed,initfs)