[LTP] [PATCH v3 02/16] lib: Add interface to list supported filesystems

[Cyril Hrubis <chrubis@suse.cz>]

A filesystem is supported if kernel can mount it (we do not get ENODEV
when we attempt to mount it) and if there is mkfs installed so that we
can format a test device.

The function starts with a whitelist of filesystems to use and loops
over them filtering out unsupported ones, then finally returns a list
of filesystem that could be used for the testing.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
---
 include/tst_fs.h             |   4 ++
 lib/tst_supported_fs_types.c | 118 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 122 insertions(+)
 create mode 100644 lib/tst_supported_fs_types.c

diff --git a/include/tst_fs.h b/include/tst_fs.h
index 52befbec9..1f6d2bab5 100644
--- a/include/tst_fs.h
+++ b/include/tst_fs.h
@@ -146,6 +146,10 @@ int tst_get_path(const char *prog_name, char *buf, size_t buf_len);
  */
 int tst_fill_file(const char *path, char pattern, size_t bs, size_t bcount);
 
+/*
+ * Returns NULL-terminated array of kernel-supported filesystems.
+ */
+const char **tst_get_supported_fs_types(void);
 
 #ifdef TST_TEST_H__
 static inline long tst_fs_type(const char *path)
diff --git a/lib/tst_supported_fs_types.c b/lib/tst_supported_fs_types.c
new file mode 100644
index 000000000..a23b1ed52
--- /dev/null
+++ b/lib/tst_supported_fs_types.c
@@ -0,0 +1,118 @@
+/*
+ * Copyright (c) 2017 Cyril Hrubis <chrubis@suse.cz>
+ *
+ * This program 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 program 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 <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <sys/mount.h>
+#include <sys/wait.h>
+
+#define TST_NO_DEFAULT_MAIN
+#include "tst_test.h"
+#include "tst_fs.h"
+
+static const char *const fs_type_whitelist[] = {
+	"ext2",
+	"ext3",
+	"ext4",
+	"xfs",
+	"btrfs",
+	"vfat",
+	"exfat",
+	"ntfs",
+	NULL
+};
+
+static const char *fs_types[ARRAY_SIZE(fs_type_whitelist)];
+
+static int has_mkfs(const char *fs_type)
+{
+	char buf[128];
+	int ret;
+
+	sprintf(buf, "mkfs.%s >/dev/null 2>&1", fs_type);
+
+	ret = tst_system(buf);
+
+	if (WEXITSTATUS(ret) == 127) {
+		tst_res(TINFO, "mkfs.%s does not exist", fs_type);
+		return 0;
+	}
+
+	tst_res(TINFO, "mkfs.%s does exist", fs_type);
+	return 1;
+}
+
+static int has_kernel_support(const char *fs_type)
+{
+	static int fuse_supported = -1;
+	const char *tmpdir = getenv("TMPDIR");
+	char buf[128];
+	int ret;
+
+	if (!tmpdir)
+		tmpdir = "/tmp";
+
+	mount("/dev/zero", tmpdir, fs_type, 0, NULL);
+	if (errno != ENODEV) {
+		tst_res(TINFO, "Kernel supports %s", fs_type);
+		return 1;
+	}
+
+	/* Is FUSE supported by kernel? */
+	if (fuse_supported == -1) {
+		ret = open("/dev/fuse", O_RDWR);
+		if (ret < 0) {
+			fuse_supported = 0;
+		} else {
+			fuse_supported = 1;
+			SAFE_CLOSE(ret);
+		}
+	}
+
+	if (!fuse_supported)
+		return 0;
+
+	/* Is FUSE implementation installed? */
+	sprintf(buf, "mount.%s >/dev/null 2>&1", fs_type);
+
+	ret = tst_system(buf);
+	if (WEXITSTATUS(ret) == 127) {
+		tst_res(TINFO, "Filesystem %s is not supported", fs_type);
+		return 0;
+	}
+
+	tst_res(TINFO, "FUSE does support %s", fs_type);
+	return 1;
+}
+
+static int is_supported(const char *fs_type)
+{
+	return has_kernel_support(fs_type) && has_mkfs(fs_type);
+}
+
+const char **tst_get_supported_fs_types(void)
+{
+	unsigned int i, j = 0;
+
+	for (i = 0; fs_type_whitelist[i]; i++) {
+		if (is_supported(fs_type_whitelist[i]))
+			fs_types[j++] = fs_type_whitelist[i];
+	}
+
+	return fs_types;
+}
-- 
2.13.5