From f93bad1cfc731d7fd6bba8460e2f1c48281a805f Mon Sep 17 00:00:00 2001
From: Leonid Pliushch <leonid.pliushch@gmail.com>
Date: Sat, 21 Nov 2020 20:39:09 +0200
Subject: [PATCH] add script for generating or updating database

---
 update-whatprovides-db.sh | 74 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100755 update-whatprovides-db.sh

diff --git a/update-whatprovides-db.sh b/update-whatprovides-db.sh
new file mode 100755
index 0000000..cab3d52
--- /dev/null
+++ b/update-whatprovides-db.sh
@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+##
+## Script that generates or updates a Whatprovides
+## database for Termux.
+##
+
+set -e -u
+
+list_files() {
+	dpkg-deb -c "${1}" | grep -o "/data/data/com.termux/.*" | sed -E 's@(.*) ->..*@\1@g'
+}
+
+write_sql_script() {
+	local debfile_dir=$1
+	local debfile_path
+
+	# SQL statements should be executed within a single
+	# transaction, otherwise execution performance would
+	# be very slow.
+	echo "BEGIN TRANSACTION;" >> "$SQLSCRIPT_TMPFILE"
+
+	while read -r debfile_path; do
+		# .deb files are named package-name_version-revision_cpuarch.deb
+		local package_name
+		package_name=$(basename "$debfile_path" | cut -d_ -f1)
+
+		echo "[*] Processing '${debfile_path}'..." >&2
+
+		# Delete content of processed package to ensure there will not be any
+		# duplicates and stale entries.
+		echo "DELETE FROM whatprovides WHERE package_name == \"${package_name}\";" >> "$SQLSCRIPT_TMPFILE"
+
+		# Add row with matching package-name and file-name.
+		while read -r file_path; do
+			echo "${package_name}: adding '${file_path}'" >&2
+			echo "INSERT INTO whatprovides (package_name, owned_file) VALUES (\"${package_name}\", \"${file_path}\");" >> "$SQLSCRIPT_TMPFILE"
+		done < <(list_files "$debfile_path")
+	# Note: searching only for ARCH "all" (platform-independent) and "aarch64" which
+	# has 100% support by Termux packages.
+	done < <(find "$debfile_dir" -type f \( -name "*_all.deb" -o -name "*_aarch64.deb" \) -print)
+
+	echo "COMMIT;" >> "$SQLSCRIPT_TMPFILE"
+
+	# Databases which were not generated from scratch needs
+	# to be compacted.
+	echo "VACUUM;" >> "$SQLSCRIPT_TMPFILE"
+	echo "REINDEX;" >> "$SQLSCRIPT_TMPFILE"
+}
+
+if [ $# -ge 2 ]; then
+	SQLSCRIPT_TMPFILE=$(mktemp -t "whatprovides.XXXXXX.sql")
+
+	if [ ! -e "${1}" ]; then
+		echo "[*] Creating new database." >&2
+		sqlite3 "$1" "CREATE TABLE whatprovides ( id INTEGER PRIMARY KEY, package_name TEXT NOT NULL, owned_file TEXT NOT NULL);"
+	fi
+
+	echo "[*] Generating SQL script..." >&2
+	write_sql_script "$2" "$SQLSCRIPT_TMPFILE"
+
+	echo "[*] Rebuilding database..." >&2
+	sqlite3 "$1" < "$SQLSCRIPT_TMPFILE"
+
+	rm -f "${SQLSCRIPT_TMPFILE}"
+
+	echo "[*] Done." >&2
+else
+	echo
+	echo "Usage: update-whatprovides-db.sh [db path] [directory with .deb files]"
+	echo
+	echo "Regenerate a database for Termux Whatprovides utility."
+	echo
+	exit 1
+fi