libdpkg: Add new fsys-dir module

This module handles setting and getting the filesystem root directory.

7 files changed, 169 insertions, 0 deletions

diff --git a/lib/dpkg/Makefile.am b/lib/dpkg/Makefile.am
index 58bd403ab..a2828af4b 100644
--- a/lib/dpkg/Makefile.am
+++ b/lib/dpkg/Makefile.am
@@ -70,6 +70,7 @@ libdpkg_la_SOURCES = \
 	fdio.c \
 	file.c \
 	fields.c \
+	fsys-dir.c\
 	fsys-iter.c \
 	fsys-hash.c \
 	glob.c \
diff --git a/lib/dpkg/fsys-dir.c b/lib/dpkg/fsys-dir.c
new file mode 100644
index 000000000..15335b23e
--- /dev/null
+++ b/lib/dpkg/fsys-dir.c
@@ -0,0 +1,93 @@
+/*
+ * 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 const char *fsys_dir = "";
+
+/**
+ * Set current on-disk filesystem root directory.
+ *
+ * The directory is initially set to "", this function can be used to
+ * set the directory to a new value, or to set it to a default value if dir
+ * is NULL. For the latter the order is, value from environment variable
+ * DPKG_ROOT, and then the built-in default "",
+ *
+ * @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 *new_dir;
+
+	if (dir == NULL) {
+		const char *env;
+
+		env = getenv("DPKG_ROOT");
+		if (env)
+			dir = env;
+		else
+			dir = "";
+	}
+
+	new_dir = m_strdup(dir);
+	path_trim_slash_slashdot(new_dir);
+
+	fsys_dir = new_dir;
+
+	return fsys_dir;
+}
+
+/**
+ * Get current on-disk filesystem root directory.
+ *
+ * @return The current filesystem root directory.
+ */
+const char *
+dpkg_fsys_get_dir(void)
+{
+	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)
+{
+	return str_fmt("%s/%s", fsys_dir, pathpart);
+}
diff --git a/lib/dpkg/fsys.h b/lib/dpkg/fsys.h
index 8a2efbffa..72d76f715 100644
--- a/lib/dpkg/fsys.h
+++ b/lib/dpkg/fsys.h
@@ -190,4 +190,8 @@ struct filepackages_iterator *filepackages_iter_new(struct filenamenode *fnn);
 struct pkginfo *filepackages_iter_next(struct filepackages_iterator *iter);
 void filepackages_iter_free(struct filepackages_iterator *iter);
 
+const char *dpkg_fsys_set_dir(const char *dir);
+const char *dpkg_fsys_get_dir(void);
+char *dpkg_fsys_get_path(const char *pathpart);
+
 #endif /* LIBDPKG_FSYS_H */
diff --git a/lib/dpkg/libdpkg.map b/lib/dpkg/libdpkg.map
index cb3062845..082732405 100644
--- a/lib/dpkg/libdpkg.map
+++ b/lib/dpkg/libdpkg.map
@@ -419,6 +419,10 @@ LIBDPKG_PRIVATE {
 	filepackages_iter_next;
 	filepackages_iter_free;
 
+	dpkg_fsys_set_dir;
+	dpkg_fsys_get_dir;
+	dpkg_fsys_get_path;
+
 	# Package on-disk filesystem database support
 	parse_filehash;
 	write_filelist_except;
diff --git a/lib/dpkg/t/.gitignore b/lib/dpkg/t/.gitignore
index db7126c04..5b019c86e 100644
--- a/lib/dpkg/t/.gitignore
+++ b/lib/dpkg/t/.gitignore
@@ -10,6 +10,7 @@ t-deb-version
 t-ehandle
 t-error
 t-file
+t-fsys-dir
 t-fsys-hash
 t-headers-cpp
 t-macros
diff --git a/lib/dpkg/t/Makefile.am b/lib/dpkg/t/Makefile.am
index 9e83836e4..83c96f329 100644
--- a/lib/dpkg/t/Makefile.am
+++ b/lib/dpkg/t/Makefile.am
@@ -48,6 +48,7 @@ test_programs = \
 	t-pkg-queue \
 	t-pkg-hash \
 	t-pkg-show \
+	t-fsys-dir \
 	t-fsys-hash \
 	t-trigger \
 	t-mod-db \
diff --git a/lib/dpkg/t/t-fsys-dir.c b/lib/dpkg/t/t-fsys-dir.c
new file mode 100644
index 000000000..7dbe753d1
--- /dev/null
+++ b/lib/dpkg/t/t-fsys-dir.c
@@ -0,0 +1,65 @@
+/*
+ * libdpkg - Debian packaging suite library routines
+ * t-fsys.c - test filesystem handling
+ *
+ * Copyright © 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/test.h>
+#include <dpkg/fsys.h>
+
+static void
+test_fsys_dir(void)
+{
+	char *dir;
+
+	test_str(dpkg_fsys_get_dir(), ==, "");
+
+	dpkg_fsys_set_dir("/testdir");
+	test_str(dpkg_fsys_get_dir(), ==, "/testdir");
+
+	dir = dpkg_fsys_get_path("testfile");
+	test_str(dir, ==, "/testdir/testfile");
+	free(dir);
+
+	setenv("DPKG_ROOT", "/testenvdir", 1);
+	dpkg_fsys_set_dir(NULL);
+	test_str(dpkg_fsys_get_dir(), ==, "/testenvdir");
+
+	dir = dpkg_fsys_get_path("testfile");
+	test_str(dir, ==, "/testenvdir/testfile");
+	free(dir);
+
+	unsetenv("DPKG_ROOT");
+	dpkg_fsys_set_dir(NULL);
+	test_str(dpkg_fsys_get_dir(), ==, "");
+
+	dir = dpkg_fsys_get_path("testfile");
+	test_str(dir, ==, "/testfile");
+	free(dir);
+}
+
+TEST_ENTRY(test)
+{
+	test_plan(7);
+
+	test_fsys_dir();
+}