[RFC PATCH] Simply module writing and allow module skipping

[Seewer Philippe <philippe.seewer@xxxxxx>]

Some dracut modules are rather simple. They just install files from 
user-space, hooks and udev rules. Instead of writing a shell-script for 
that, a module could contain $moddir/files, $moddir/rules, $moddir/hooks
which would be run through and the corresponding inst-functions applied.

With $moddir/files there's another advantage in that before copying 
stuff, these files can be checked for existence and if --skip-missing is
provided the whole module can be skipped cleanly.

Patch is built on top of Harald Hoyers merge tree
(git://git.surfsite.org/pub/git/dracut.git) and implements the suggested
stuff for module 90crypt as an example

Regards,
Philippe Seewer


---
dracut                    |   27 ++++++++++++++++++++++++++-
dracut-functions          |   13 ++++++++-----
modules.d/90crypt/files   |    1 +
modules.d/90crypt/hooks   |    1 +
modules.d/90crypt/install |    4 ----
modules.d/90crypt/rules   |    1 +
6 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/dracut b/dracut
index a691a66..eeacf1c 100755
--- a/dracut
+++ b/dracut
@@ -28,7 +28,7 @@ while (($# > 0)); do
	    exit 1 ;;
	-v|--verbose) set -x;;
	-l|--local) allowlocal="yes" ;;
-	--allow-missing) : ;;
+	--skip-missing) skipmissing="yes" ;;
	*) break ;;
    esac
    shift
@@ -63,7 +63,32 @@ for moddir in "$dsrc/modules.d"/*; do
    [[ -d $moddir || -L $moddir ]] || continue
    mod=${moddir##*/}; mod=${mod#[0-9][0-9]};
    if [[ $dracutmodules = all ]] || strstr "$dracutmodules " "$mod "; then 
+
+	skipme=""
+	[[ -f $moddir/files ]] && while read line; do 
+	    find_file $line || {
+		[[ $skipmissing ]] && skipme="yes" && break;
+		echo "Preqrequisite $line for $mod not found";
+		exit 1
+	    }
+	done < $moddir/files
+
+	[[ $skipme ]] && {
+	    echo "== Prerequisites for $mod not found, ignoring == "
+	    continue;
+	}
+
	echo "== Module $moddir == "
+	[[ -f $moddir/files ]] && while read line; do 
+	    inst $line
+	done < $moddir/files
+	[[ -f $moddir/rules ]] && while read line; do 
+	    inst_rules $line
+	done < $moddir/rules
+	[[ -f $moddir/hooks ]] && while read line; do
+	    inst_hook $line
+	done < $moddir/hooks
+
	[[ -x $moddir/install ]] && . "$moddir/install"
    fi
done
diff --git a/dracut-functions b/dracut-functions
index 504332b..0161214 100755
--- a/dracut-functions
+++ b/dracut-functions
@@ -135,7 +135,7 @@ inst_symlink() {
}

find_rule() {
-    for r in . /lib/udev/rules.d /etc/udev/rules.d $dsrc/rules.d; do
+    for r in . /lib/udev/rules.d /etc/udev/rules.d $dsrc/rules.d $moddir; do
	[[ -f $r/$1 ]] && { echo "$r/$1"; return 0; }
    done
    return 1
@@ -172,16 +172,19 @@ inst() {
# $1 = type of hook, $2 = hook priority (lower runs first), $3 = hook
# All hooks should be POSIX/SuS compliant, they will be sourced by init.
inst_hook() {
-    [[ -f $3 ]] || {
+    local type number hook
+    type=$1 number=$2 hook=$3
+    [[ "$hook" =~ $moddir ]] || hook="$moddir/$hook"
+    [[ -f $hook ]] || {
	echo "Cannot install a hook ($3) that does not exist." >&2
	echo "Aborting initrd creation." >&2
	exit 1
    }
-    strstr "$hookdirs" "$1" || {
-	echo "No such hook type $1. Aborting initrd creation." >&2
+    strstr "$hookdirs" "$type" || {
+	echo "No such hook type $type. Aborting initrd creation." >&2
	exit 1
    }
-    inst_simple "$3" "/${1}/${2}${3##*/}"
+    inst_simple "$hook" "/$type/$number${hook##*/}"
}

dracut_install() {
diff --git a/modules.d/90crypt/files b/modules.d/90crypt/files
new file mode 100644
index 0000000..836b5e7
--- /dev/null
+++ b/modules.d/90crypt/files
@@ -0,0 +1 @@
+/bin/true
diff --git a/modules.d/90crypt/hooks b/modules.d/90crypt/hooks
new file mode 100644
index 0000000..6c70749
--- /dev/null
+++ b/modules.d/90crypt/hooks
@@ -0,0 +1 @@
+mount 10 cryptroot.sh
diff --git a/modules.d/90crypt/install b/modules.d/90crypt/install
deleted file mode 100755
index 92b5169..0000000
--- a/modules.d/90crypt/install
+++ /dev/null
@@ -1,4 +0,0 @@
-#!/bin/bash
-inst cryptsetup
-inst_rules "$moddir/63-luks.rules"
-inst_hook mount 10 "$moddir/cryptroot.sh"
\ No newline at end of file
diff --git a/modules.d/90crypt/rules b/modules.d/90crypt/rules
new file mode 100644
index 0000000..5c21a81
--- /dev/null
+++ b/modules.d/90crypt/rules
@@ -0,0 +1 @@
+63-luks.rules

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