tint: introduce the new tint build system with checksum verification

Three stages of the new tint build system:

 1) generate_core.sh extracts the core part from buildgcc script,
     most importantly the checksum calculation/verification functions.

 2) tintify_core.sh adds the tint-specific footer/header to the core,
     such as the properties of current version including its checksum.

 3) tint.sh - generated and "tintified" core script - builds a tint.

Signed-off-by: Mike Banon <mikebdp2@gmail.com>
Change-Id: Ib71f5b861ecf91949a5af12812258e60873f0498
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50991
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

payloads/external/tint/generate_core.sh

@@ -0,0 +1,102 @@
+#!/bin/sh
+#
+# generate_core.sh extracts the core part from buildgcc script,
+# most importantly the checksum calculation/verification functions.
+#
+# Copyright (C) 2019 Mike Banon <mikebdp2@gmail.com>
+#
+##############################################################################
+#
+# USAGE:
+# 	./generate_core.sh <buildgcc> <corescript> prepare_before_patch
+# where
+# 	buildgcc   - path to input buildgcc script
+# 	corescript - path to output core part script
+# 	prepare_before_patch - optional argument to insert prepare_${package}
+# 				call into the unpack_and_patch function, e.g.
+# 				for removing some files with rm command
+# 				in order to reduce the size of patch file
+#
+##############################################################################
+
+buildgcc="$1"
+corescript="$2"
+prepare_before_patch="$3"
+
+#
+# Imports the source file fragment between start and end into the
+# destination file, optionally excluding the last line if not needed
+#
+
+import_from_file() {
+        source="$1"
+        destination="$2"
+	start="$3"
+	end="$4"
+	last_line_disabled="$5"
+	if [ -z "${last_line_disabled}" ] ; then
+		sed -n "/^${start}/,/^${end}/{/^${start}/{p;n};{p}}" "$source" >> "$destination"
+	else
+		sed -n "/^${start}/,/^${end}/{/^${start}/{p;n};/^${end}/{q};{p}}" "$source" >> "$destination"
+	fi
+}
+
+#
+# Import the color defines together with UNAME/HALT_FOR_TOOLS variables
+#
+
+import_from_file "$buildgcc" "$corescript" "red=" "HALT_FOR_TOOLS=0" || exit "$?"
+
+#
+# Import the core functions
+#
+
+FUNCTIONS="please_install searchtool download compute_hash error_hash_mismatch verify_hash unpack_and_patch"
+
+for F in $FUNCTIONS ; do
+	import_from_file "$buildgcc" "$corescript" "$F()" "}" || exit "$?"
+done
+
+#
+# Import a fragment where we find tar/patch/make and other essential tools
+#
+
+import_from_file "$buildgcc" "$corescript" "# Find all the required tools" "# Allow" "last_line_disabled" || exit "$?"
+
+#
+# Import a fragment with conditional exit if some required tools were not found
+#
+
+import_from_file "$buildgcc" "$corescript" "if \[ \"\$HALT_FOR_TOOLS" "fi" || exit "$?"
+
+#
+# Avoid the unnecessary subdirectories holding a single file each
+#
+
+sed -i -e "s/patches\///g" "$corescript"
+sed -i -e "s/sum\///g" "$corescript"
+sed -i -e "s/tarballs\///g" "$corescript"
+sed -i -e "s/cd tarballs || exit 1//g" "$corescript"
+sed -i -e "s/cd \.\.//g" "$corescript"
+
+#
+# Get the known checksum without using a dedicated single-line file
+#
+
+sed -i -e "s/\tknown_hash=\"\$(get_known_hash.*/\tknown_hash=\"\$2\"/g" "$corescript"
+
+#
+# Update the paths printed at the error messages
+#
+
+sed -i -e "s/util\/crossgcc\///g" "$corescript"
+
+#
+# Insert prepare_${package} function call between the unpack and patch operations
+#
+
+if [ ! -z "${prepare_before_patch}" ] ; then
+	sed -i -e "/\$TAR \$FLAGS \"\$(basename \"\$archive\")\"/a prepare_\${package} || exit \"\$?\"" "$corescript"
+fi
+
+#