1 files changed, 119 insertions, 0 deletions
diff --git a/lib/dpkg/fsys-dir.c b/lib/dpkg/fsys-dir.c
new file mode 100644
index 0000000..76d5f39
--- /dev/null
+++ b/lib/dpkg/fsys-dir.c
@@ -0,0 +1,119 @@
+/*
+ * libdpkg - Debian packaging suite library routines
+ * fsys-dir.c - filesystem root directory functions
+ *
+ * Copyright © 2011, 2018 Guillem Jover <guillem@debian.org>
+ *
+ * This is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <compat.h>
+
+#include <stdlib.h>
+
+#include <dpkg/dpkg.h>
+#include <dpkg/string.h>
+#include <dpkg/path.h>
+#include <dpkg/fsys.h>
+
+static char *fsys_dir;
+
+/**
+ * Allocate the default on-disk filesystem root directory.
+ *
+ * The directory defaults to the value from environment variable
+ * DPKG_ROOT, and if not set the built-in default "".
+ *
+ * @return The filesystem root directory.
+ */
+static char *
+dpkg_fsys_new_dir(void)
+{
+	const char *env;
+	char *dir;
+
+	env = getenv("DPKG_ROOT");
+	if (env == NULL) {
+		dir = m_strdup("");
+	} else {
+		dir = m_strdup(env);
+		path_trim_slash_slashdot(dir);
+	}
+
+	return dir;
+}
+
+/**
+ * Set current on-disk filesystem root directory.
+ *
+ * This function can be used to set the directory to a new value, or to
+ * reset it to a default value if dir is NULL.
+ *
+ * @param dir The new filesystem root directory, or NULL to set to default.
+ *
+ * @return The new filesystem root directory.
+ */
+const char *
+dpkg_fsys_set_dir(const char *dir)
+{
+	char *dir_new;
+
+	if (dir == NULL) {
+		dir_new = dpkg_fsys_new_dir();
+	} else {
+		dir_new = m_strdup(dir);
+		path_trim_slash_slashdot(dir_new);
+	}
+
+	free(fsys_dir);
+	fsys_dir = dir_new;
+
+	return fsys_dir;
+}
+
+/**
+ * Get current on-disk filesystem root directory.
+ *
+ * This function will take care of initializing the directory if it has not
+ * been initialized before.
+ *
+ * @return The current filesystem root directory.
+ */
+const char *
+dpkg_fsys_get_dir(void)
+{
+	if (fsys_dir == NULL)
+		fsys_dir = dpkg_fsys_new_dir();
+
+	return fsys_dir;
+}
+
+/**
+ * Get a pathname to the current on-disk filesystem root directory.
+ *
+ * This function returns an allocated string, which should be freed with
+ * free(2).
+ *
+ * @param pathpart The pathpart to append to the new pathname.
+ *
+ * @return The newly allocated pathname.
+ */
+char *
+dpkg_fsys_get_path(const char *pathpart)
+{
+	pathpart = path_skip_slash_dotslash(pathpart);
+
+	return str_fmt("%s/%s", dpkg_fsys_get_dir(), pathpart);
+}